WO2025078362A1 - Process for the manufacture of styrene acrylic copolymers having a renewably-sourced carbon content - Google Patents

Abstract

A process for the manufacture of styrene acrylic copolymers having a renewably-sourced carbon content comprises the steps of: a) subjecting a feedstock comprising a renewably-sourced ethanol to dehydration to produce a renewably-sourced ethylene stream; b) subjecting at least a portion of the renewably-sourced ethylene stream to an olefin-interconversion, to obtain a renewably-sourced propylene; the olefin- interconversion comprising (i) and (ii): (i) ethylene dimerization to obtain n-butenes; (ii) metathesis reaction between n-butenes obtained according to (i) and ethylene to obtain propylene; and c) subjecting a portion of the renewably-sourced propylene to an oxidation reaction to produce acrylic acid; d) subjecting a portion of the renewably- sourced propylene to a hydroformylation reaction with syngas to produce n-butyraldehyde; e) subjecting the n-butyraldehyde to hydrogenation to produce n-butanol; f) esterifying acrylic acid obtained in step c) and the n-butanol to produce n-butyl acrylate; g) subjecting ethylene to an alkylation reaction with benzene to produce ethylbenzene; h) subjecting the ethylbenzene to a dehydrogenation reaction to produce styrene; i) copolymerizing the styrene and the n-butyl acrylate to produce a styrene acrylic copolymer. The process has a high renewably-sourced carbon content, in particular an increased renewably-sourced carbon content with respect to the renewably-sourced carbon content available in a cracker-based process.

Description

Process for the Manufacture of Styrene Acrylic Copolymers Having a Renewably- Sourced Carbon Content

The invention relates to a process for the manufacture of styrene acrylic copolymers having a renewably-sourced carbon content.

Copolymer compositions used for such purposes as binders or coatings, e.g., paints, carpet backing and adhesives, are often made using monomers derived from fossil sources. An example of such a copolymer composition using monomers derived from a fossil source includes currently available styrene acrylic copolymers. However, the movement toward environmental sustainability has provided an impetus for the development of copolymers utilizing as much raw material from renewably sources as possible.

The starting material for the production of respective monomers, in particular styrene and n-butyl acrylate, is typically obtained from cracker products, such as ethylene and benzene for styrene and propylene for n-butyl acrylate. The fossil naphtha with which a cracker is fed can only be partially substituted by a renewable feedstock such a bio-naphtha and/or pyrolysis oil.

By employing for instance bio-naphtha in the cracker feed, one can increase the amount of renewably-sourced carbon in the cracker products. The production of bio-naphtha is for instance disclosed in US 2012/0053379 A 1 (Stora Enso). However, the technical possibilities to use bio-naphtha in large amounts in the cracker feed are limited. As stated above, this can be attributable to the fact that the chemical and physical properties of bio-naphtha do not in every case sufficiently correspond to those of naphtha. Moreover, the production of bio-naphtha can be technically and energetically challenging because its production usually involves hydrotreatment (i.e. , hydrogenation of a bio-feedstock) to obtain bio-naphtha having a sufficient quality (in particular a low number of heteroatoms). In addition, the availability of bio-naphtha is not only limited currently, but is also projected to remain so in the future, in particular in relation to the enormous amounts of hydrocarbons needed for the large-scale production of ethylene. The bio-naphtha volume currently available accounts for less than 1 % of the worldwide naphtha demand. Therefore, the substitution of cracker feed by bio-naphtha will be limited and cannot enable sufficient amount of renewably-sourced carbon in the cracker feed.

In a similar manner, one can also increase the amount of renewably-sourced carbon in the cracker products by employing pyrolysis oil in the cracker feed.

However, chemical recycling through pyrolysis and steam cracking of pyrolysis oils also has several hurdles. Firstly, steam crackers are very capital intensive, and hence need to be built at large scale to benefit from economy of scale. This means that large feed streams need to be secured to the plant. The supply of pyrolysis oil is, however, limited and, moreover, fluctuates in terms of quantity. As such, the substitution of large amounts of naphtha remains challenging. Further, undiluted pyrolysis oil may not meet steam cracker specifications. Even though pyrolysis can handle any type of organic material, the presence of polymers containing heteroatoms, like PVC, in the waste plastics can cause contaminants like organic chlorides to exist in the pyrolysis oil. The use of fossilbased diluents or co-feeds along the pyrolysis oil, however, can easily render the fossil resource and greenhouse gas savings marginal.

One way to achieve increased renewably-sourced carbon content is the development of alternative synthesis routes based on bio-feedstocks. This approach comes with certain drawbacks. In many cases the synthesis route deviates significantly from the well- established fossil-based manufacturing route. Thus, the existing productions facilities cannot be used, but new ones would have to be built which is economically, environmentally, and technically challenging. Moreover, the chemical industry, currently using naphtha and methane as its major carbon sources, would have to change to an economy that is based on a variety of different feedstocks, increasing the complexity of chemical production.

As outlined above, the major obstacle in any cracker-based production is the low amount of fossil naphtha that can be replaced by renewably-sourced feedstocks such as pyrolysis oil and bio-naphtha. Currently, a typical amount of renewably-sourced feedstocks in a cracker feed is not more than 5 wt.-%. The most optimistic projections assume a maximum of 40 wt.-%.

The preparation of styrene acrylic copolymers is taught, e.g., in WO 2017/191167 (BASF SE) and WO 2020/225348. There is no teaching on how to provide such copolymers having a renewably-sourced carbon content.

Therefore, it is an object of the present invention to provide a process for the manufacture of styrene acrylic copolymers having a high renewably-sourced carbon content, in particular, having an increased renewably-sourced carbon content with respect to the renewably-sourced carbon content available in a cracker-based process.

Summary of the Invention

The invention relates to a process for the manufacture of styrene acrylic copolymers having a renewably-sourced carbon content, said process comprising the steps of: a) subjecting a feedstock comprising a renewably-sourced ethanol to dehydration to produce a renewably-sourced ethylene stream; b) subjecting a portion of the renewably-sourced ethylene stream to an olefin- interconversion, to obtain a renewably-sourced propylene; the olefin-interconversion comprising (i) and (ii):

(i) ethylene dimerization to obtain n-butenes; (ii) metathesis reaction between n-butenes obtained according to (i) and ethylene to obtain propylene; and c) subjecting a portion of the renewably-sourced propylene to an oxidation reaction to produce acrylic acid; d) subjecting a portion of the renewably-sourced propylene to a hydroformylation reaction with syngas to produce n-butyraldehyde; e) subjecting the n-butyraldehyde to hydrogenation to produce n-butanol; f) esterifying acrylic acid obtained in step c) and the n-butanol to produce n-butyl acrylate; g) subjecting ethylene to an alkylation reaction with benzene to produce ethylbenzene; h) subjecting the ethylbenzene to a dehydrogenation reaction to produce styrene; i) copolymerizing the styrene and the n-butyl acrylate to produce a styrene acrylic copolymer.

A key step of the process according to the present invention is the production of renewably-sourced propylene from renewably-sourced ethanol. As it can be fully manufactured based on renewably-sourced ethanol (e.g. bioethanol), the resulting propylene can have a renewably-sourced carbon content of 100 wt.-%. A second key step is to use such propylene to manufacture both acrylic acid and n-butyl alcohol. The resulting n-butyl acrylate therefore has a high amount of renewably-sourced carbon content.

Detailed Description of the Invention

To define more clearly the terms used herein, the following definitions are provided, and unless explicitly provided otherwise are applicable throughout this disclosure.

The terms “renewable" or “renewably-sourced" in relation to a chemical compound are used synonymously and mean a chemical compound comprising a quantity of renewable carbon, i.e. , having a reduced or no carbon content of fossil origin. Renewable carbon entails all carbon sources that avoid or substitute the use of any additional fossil carbon from the geosphere. Renewable carbon can come from the biosphere, atmosphere or technosphere - but not from the geosphere. Thus, the expression “renewable” or “renewably-sourced” includes, in particular, biomass-derived chemical compounds. It also includes compounds derived from waste such as polymer residues, or from waste streams of chemical production processes.

The term “bio-based” means containing organic carbon of renewable origin like agricultural, plant, animal, fungi, microorganisms, marine, or forestry materials living in a natural environment in equilibrium with the atmosphere.

The term “bio-based carbon content” means the amount of bio-based carbon in the material or product as a percentage of the total organic carbon (TOC) in the material or product. The bio-based carbon content of a material may be measured using the ASTM D6866 method, which allows the determination of the bio-based content of materials using radiocarbon analysis by accelerator mass spectrometry, liquid scintillation counting, and isotope mass spectrometry. When nitrogen in the atmosphere is struck by an ultraviolet light produced neutron, it loses a proton and forms carbon that has a molecular weight of 14, which is radioactive. This¹⁴C is immediately oxidized into carbon dioxide, and represents a small, but measurable fraction of atmospheric carbon. Atmospheric carbon dioxide is cycled by green plants to make organic molecules during photosynthesis. The cycle is completed when the green plants or other forms of life metabolize the organic molecules producing carbon dioxide which is then able to return back to the atmosphere. Therefore, the¹⁴C that exists in the atmosphere becomes part of all life forms and their biological products.

The application of ASTM D6866 to derive a “bio-based carbon content” is built on the same concepts as radiocarbon dating, but without use of the age equations. The analysis is performed by deriving a ratio of the amount of radiocarbon (¹⁴C) in an unknown sample to that of a modern reference standard. The ratio is reported as a percentage, with the units “pMC” (percent modern carbon). If the material being analyzed is a mixture of present day radiocarbon and fossil carbon (containing no radiocarbon), then the pMC value obtained correlates directly to the amount of bio-based material present in the sample. The modern reference standard used in radiocarbon dating is a NIST (National Institute of Standards and Technology) standard with a known radiocarbon content equivalent approximately to the year AD 1950. The year AD 1950 was chosen because it represented a time prior to thermonuclear weapons testing which introduced large amounts of excess radiocarbon into the atmosphere with each explosion (termed “bomb carbon”). The AD 1950 reference represents 100 pMC. “Bomb carbon” in the atmosphere reached almost twice normal levels in 1963 at the peak of testing and prior to the treaty halting the testing. Its distribution within the atmosphere has been approximated since its appearance, showing values that are greater than 100 pMC for plants and animals living since AD 1950. The distribution of bomb carbon has gradually decreased over time, with today's value being near 107.5 pMC. As a result, a fresh biomass material, such as corn, could result in a radiocarbon signature near 107.5 pMC.

Petroleum-based carbon does not have the signature radiocarbon ratio of atmospheric carbon dioxide. Research has noted that fossil fuels and petrochemicals have less than about 1 pMC, and typically less than about 0.1 pMC, for example, less than about 0.03 pMC. However, compounds derived entirely from renewable resources have at least about 95 percent modern carbon (pMC), they may have at least about 99 pMC, including about 100 pMC.

Combining fossil carbon with present day carbon into a material will result in a dilution of the present day pMC content. By presuming that 107.5 pMC represents present day biobased materials and 0 pMC represents petroleum derivatives, the measured pMC value for that material will reflect the proportions of the two component types. A material derived 100% from present day biomass would give a radiocarbon signature near 107.5 pMC. If that material were diluted with 50% petroleum derivatives, it would give a radiocarbon signature near 54 pMC.

A bio-based content result is derived by assigning 100% equal to 107.5 pMC and 0% equal to 0 pMC. In this regard, a sample measuring 99 pMC will give an equivalent biobased content result of 93%.

The term “bioethanol” means ethanol obtained from a biomass feedstock, such as plant or non-crop feedstock containing a carbon source that is convertible to ethanol, for example by microbial metabolism. Bioethanol is a preferred form of renewably-sourced ethanol, although the scope of the invention is not limited to the use of bioethanol.

The key advantage of the process according to the present invention is that it can be easily integrated into an existing production site in which ethylene or propylene are manufactured based on a fossil feedstock, in particular naphtha. This means that fossil ethylene and propylene can be fully or partially substituted by respective renewably- sourced ethylene and propylene. Hereby, one obtains a product, the carbon atoms of which are fully or partially based on a renewably-sourced carbon (so-called “green” carbon).

Further benefits occur from the reduction of carbon dioxide emissions. The chemical conversions involved in the present reaction route are usually less than 100% selective. The yield losses manifest themselves in the generation of by-products that vary depending on the type of reaction involved. Oxidation reactions of a substrate to a desired product, for example, are almost invariably accompanied to a certain extent by an over-oxidation of the substrate to form carbon oxides, in particular carbon dioxide. By a full or partial replacement of fossil ethylene and propylene by their renewably-sourced counterparts, the fossil-based carbon dioxide emissions of the entire production site can be reduced because respective emissions resulting from yield losses along the value chain are at least partially based on green carbon. The resulting carbon dioxide emissions therefore do not contribute to the green house emission of the production site. For example, in the production of acrylic acid (as further described below) carbon dioxide is formed due to full oxidation of propylene. Using renewably-sourced propylene as obtained by the process according to the present invention therefore prevents the formation of fossil-based carbon dioxide emissions resulting from such productions.

In addition, in non-oxidative reactions the various species present may undergo a host of side reactions, which generate color forming species, oligomers, and various decomposition products or the like. These are generally removed during work-up, e.g., by distillation, yielding light boiler and/or high boiler fractions in addition to the desired product. The light boiler or high boiler fractions are conventionally used for their calorific value, i.e. combusted as fuel, or exploited as hydrocarbon source, e.g. as steam cracker feed. It should be appreciated that full or partial replacement of fossil ethylene and propylene by their renewably-sourced counterparts at the beginning of the processing chain reduces the emission of fossil-based carbon dioxide resulting from the combustion of downstream side-products. Hence, it is envisaged that direct and indirect benefits are associated with the process of the invention.

It is envisaged that the renewably-sourced olefins involved in the process according to the invention may be blended with complementary olefins from other sources. This can ensure the efficient utilization of downstream processes, e.g., for transitional periods when supply of renewably-sourced olefin is limited. These complementary olefins, including complementary ethylene, complementary propylene and complementary n-butenes, may be fossil-based, partially renewably-sourced or renewably-sourced by another production route.

Hence in an embodiment, the process comprises: blending the renewably-sourced ethylene with complementary ethylene prior to step b), the complementary ethylene not being obtained from renewably-sourced ethanol in accordance with step a); and/or blending the renewably-sourced propylene with complementary propylene prior to steps c) and d), the complementary propylene not being obtained from renewably- sourced ethanol in accordance with steps a) and b); and/or blending the renewably-sourced n-butenes with complementary n-butenes prior to step b)-(ii), the complementary n-butenes not being obtained from renewably-sourced ethanol in accordance with steps a) and b)-(i).

Examples for complementary ethylenes are ethylenes obtained by steam cracking of fossil based feeds, like naphtha, natural gas or crude oil. Examples for complementary propylenes are propylenes obtained by steam cracking of fossil based feeds, like naphtha, natural gas or crude oil. Examples for complementary n-butenes are n-butenes obtained by steam cracking of fossil based feeds, like naphtha, natural gas or crude oil.

All patent and literature documents addressed in the following are incorporated herein by reference in their entirety.

Renewably-Sourced Ethanol and Bioethanol

The renewably-sourced ethanol is preferably bio-based ethanol (“bioethanol”).

In the present invention, bioethanol refers to renewably-sourced ethanol obtained from a biomass feedstock, such as plant or non-crop feedstock containing a carbon source that is convertible to ethanol, for example by microbial metabolism. Typical carbon source examples are starch, sugars like pentoses or hexoses, such as glucose, fructose, sucrose, xylose, arabinose, or degradation products of plants, hydrolysis products of cellulose or juice of sugar canes, beet and the like containing large amounts of the above components.

Biomass feedstock can originate from several sources. Bioethanol production may be based on food crop feedstocks such as corn and sugar cane, sugarcane bagasse, cassava (first generation biofeedstock).

Another source of biomass feedstock is lignocellulosic materials from agricultural crops (second-generation biofeedstock). Potential feedstocks include agricultural residue byproducts such as rice, straw (such as wheat, oat and barley straw), rice husk, and corn stover. Biomass feedstock may also be waste material from the forest products industry (wood waste) and saw dust or produced on purpose as an ethanol crop. Switchgrass and napier grass may be used as on-purpose crops for conversion to ethanol.

The first-generation bioethanol is produced in four basic steps:

(1) Enzymatic saccharification or hydrolysis of starch into sugars

(2) Microbial fermentation of sugars

(3) Purification by distillation to give hydrous ethanol

(4) Dehydration (water removal) to produce anhydrous ethanol

Second-generation feedstocks are considered as renewable and sustainable carbon source. Pretreatment of this feedstock is an essential prerequisite before it is subjected to enzymatic hydrolysis, fermentation, distillation, and dehydration. Pretreatment involves milling and exposure to acid and heat to reduce the size of the plant fibers and hydrolyze a portion of the material to yield fermentable sugars. Saccharification utilizes enzymes to hydrolyze another portion to sugar. Finally, fermentation by bioengineered microorganisms converts the various sugars (pentoses and hexoses) to ethanol. The production of bioethanol is well-known and carried out on an industrial large scale.

Renewably-sourced ethanol can also be obtained from carbon-containing waste materials like waste products from the chemical industry, garbage and sewage sludge. The production of ethanol from waste materials can be done by gasification to syngas and catalytic conversion thereof the ethanol, see for example Recent Advances in Thermo-Chemical Conversion of Biomass, 2015, Pages 213-250, https://doi.org/10.1016/B978-0-444-63289-0.00008-9, and Nat Commun 11, 827 (2020), https://doi.Org/10.1038/S41467-020-14672-8.

Dehydration of Renewably-Sourced Ethanol

As a first step, the invention involves the dehydration of renewably-sourced ethanol. The production of ethylene by catalytic dehydration of ethanol is a well-known process. The reaction is commonly carried out at 300 to 400 °C and moderate pressure in the presence of a catalyst. Catalytic effects are reviewed in Ind & Eng Chem Research, 52, 28, 9505- 9514 (2013), Materials 6, 101-115 (2013) and ACS Omega, 2, 4287-4296 (2017). Examples for catalysts are activated alumina or silica, phosphoric acid impregnated on coke, heteropoly acids (HPA salts), silica-alumina, molecular sieves such as zeoliths of the ZSM-5 type orSAPO-11 type, otherzeolites or modified zeolites of various molecular structures with zeoliths and HPA salts being preferred.

Ethanol dehydration is, for example described in WO 2009/098268, WO 2010/066830, WO 2009/070858 and the prior art discussed therein, WO 2011/085223 and the prior art discussed therein, US 4,234,752, US 4,396,789, US 4,529,827 and WO 2004/078336.

The ethanol dehydration reaction is in general carried out in the vapor phase in contact with a heterogeneous catalyst bed using either fixed bed or fluidized bed reactors. For fixed bed reactors, the operation can be either isothermal (with external heating system) or adiabatic (in the presence of a heat carrying fluid). The feedstock is vaporized and heated to the desired reaction temperature; the temperature drops as the reaction proceeds in the reactor. Multiple reactor beds are usually used in series to maintain the temperature drop in each bed to a manageable range. The cooled effluent from each bed is further heated to bring it to the desired inlet temperature of the subsequent beds. Moreover, a portion of the water is recirculated along with fresh and unreacted ethanol. The presence of water helps in moderating the temperature decrease in each bed.

Prior to dehydration, the renewably-sourced ethanol feedstock may be sent to a pretreatment section to remove mineral contaminants, which would otherwise be detrimental to the downstream catalytic reaction. The pretreatment may involve contacting the renewably-sourced ethanol feedstock with cation and/or anion exchange resins. After a certain period of operation, the resins may be regenerated by passing a regenerant solution through the resin bed(s) to restore their ion exchange capacity. Two sets of beds are preferably operated in parallel to maintain continuous operation. One set of resin beds is suitably regenerated while the other set is being used for pretreatment.

In the isothermal design, the catalyst is placed inside the tubes of multitubular fixed-bed reactors which arranged vertically and surrounded by a shell (tube and shell design). A heat transfer medium, such as molten salts or oil, is circulated inside the shell to provide the required heat. Baffles may be provided on the shell side to facilitate heat transfer. The cooled heating medium is heated externally and is recirculated. The temperature drop on the process side can be reduced as compared to the adiabatic reactor. A better control on the temperature results in increased selectivity for the ethylene formation and reduction in the amount of undesireable by-products. The temperature is maintained at approximately constant levels within the range of 300° to 350°C. Ethanol conversion is between 98 and 99%, and the selectivity to ethylene is between 94 and 97 mol%. Because of the rate of coke deposition, the catalyst must be regenerated frequently. Depending on the type of catalyst used, the cycle life is between 3 weeks and 4 months, followed by regeneration, for example for 3 days. In the adiabatic design, the endothermic heat of reaction is supplied by a preheated inert diluent such as steam. Three fixed-bed reactors may typically be used, with intermediate furnaces to reheat the ethanol/ steam mixed feed stream to each reactor. Feeding steam with ethanol results in less coke formation, longer catalyst activity, and higher yields.

A further process is a fluidized-bed process. The fluidized-bed system offers excellent temperature control in the reactor, thereby minimizing by-product formation. The heat distribution rate of the fluidized bed operation approaches isothermal conditions. The endothermic heat of reaction is supplied by the hot recycled silica-alumina catalyst returning from the catalyst regenerator. Thus, external heating of the reactor is not necessary.

After dehydration, the reaction mixture is subjected to a separation step. The general separation scheme consists of quickly cooling the reaction gas, for example in a water quench tower, which separates most of the by-product water and the unreacted ethanol from ethylene and other light components which, for example exit from the top of the quench tower. In one type of separation scheme, the water-washed ethylene stream is immediately caustic-washed, for example in a column, to remove traces of CO2. The gaseous stream may enter a compressor directly or pass to a surge gas holder first and then to a gas compressor. After compression, the gas is cooled with refrigeration and then passed through an adsorber with, for example activated carbon, to remove traces of heavy components, (e.g., C4s), if they are present. The adsorber is followed by a desiccant drying and dust filtering step before the ethylene product leaves the plant. This separation scheme produces 99%+ purity ethylene. If desired, the ethylene is further purified by caustic washing and desiccant-drying, and fractionated in a low-temperature column to obtain the final product.

Several commercial processes are currently in operation, developed by Braskem, Chematur, British Petroleum (BP), and Axens together with Total and IFPEN. The processes differ, e.g., in their process conditions, catalysts and adopted heat integration scheme. The process by BP (now Technip) is called Hummingbird. In this process, a heteropoly acid is used as catalyst, and the reactor operates at 160 to 270 °C and 1 to 45 bar. The unreacted ethanol in recirculated to the reactor. The process developed by Axens is called Atol. Two fixed bed adiabatic reactors, operating at 400 to 500 °C, are used. Chematur’s process operates with four adiabatic tubular reactors. Syndol catalysts, with the main components of AI₂O₃-MgO/SiO2, are employed in this process that was developed by American Halcon Scientific Design, Inc. in the 1980s. In the Braskem process, the adiabatic reactor feed is diluted with steam to a large extent. In such a process, the reactor operates at 180 to 600 °C, preferably 300 to 500 °C, and at 1.9 to 19.6 bar. An alumina or silica-alumina catalyst is used. The Braskem process is described in more detail in US 4,232, 179. A process control in accordance with the Braskem process is particularly preferred. Dimerization of Ethylene

In one aspect, the process of the invention involves an ethylene-dimerization (also called ethylene-oligomerization) to obtain n-butenes in accordance with step b)-(i) above. Any known method can be used for ethylene dimerization to produce n-butenes. A review on dimerization and oligomerization chemistry and technology is given in Catalysis Today, vol. 14(no. 1), April 10, 1992.

Expediently, step b)-(i) comprises:

- contacting the renewably-sourced ethylene stream with a dimerization catalyst in a dimerization zone;

- operating said dimerization zone at conditions effective to produce an effluent consisting essentially of n-butenes, heavier olefins, and optionally unconverted ethylene; and

- fractionating the effluent to recover a stream consisting essentially of n-butenes, a stream consisting essentially of heavier olefins, and an optional ethylene stream ; and

- optionally subjecting the stream consisting essentially of heavier olefins to hydrogenation so as to obtain renewably-sourced naphtha.

The dimerization catalyst may be homogeneous or heterogeneous. Typical dimerization catalysts are titanium or nickel compounds activated with alkyl aluminium compounds. In general, the Ti(IV) valency is stabilized by selecting the appropriate ligands, alkyl aluminium compound, the solvent polarity and the Al/Ti ratio. Nickel compounds that can catalyse the selective production of butenes are typically based on cationic nickel salts stabilised with phosphine and activated with alkyl aluminium compounds.

In one embodiment, the oligomerization of ethylene is implemented in the presence of a catalytic system in the liquid phase comprising a nickel compound and an aluminum compound. Such catalytic systems are described in the documents FR 2 443 877 and FR 2794 038. The Dimersol E™ process is based on this technology and leads to the industrial production of olefins.

Thus, in one embodiment, the oligomerization of ethylene is implemented in the presence of a catalytic system comprising: i) at least one bivalent nickel compound, ii) at least one hydrocarbyl aluminum dihalide of formula AIRX₂, in which R is a hydrocarbyl radical comprising 1 to 12 carbon atoms, such as alkyl, aryl, aralkyl, alkaryl or cycloalkyl, X is a chlorine or bromine atom, and iii) optionally a Bronsted organic acid.

As the bivalent nickel compound, nickel carboxylates of general formula (R¹COO)2Ni are preferably used, where R¹ is an optionally substituted hydrocarbyl radical, for example alkyl, cycloalkyl, alkenyl, aryl, aralkyl, or alkaryl, containing up to 20 carbon atoms, preferably a hydrocarbyl radical of 5 to 20 carbon atoms, preferably 6 to 18 carbon atoms. Suitable bivalent nickel compounds include: chloride, bromide, carboxylates such as octoate, 2-ethylhexanoate, decanoate, oleate, salicylate, hydroxydecanoate, stearate, phenates, naphthenates, and acetyl acetonates. Nickel 2-ethylhexanoate is preferably used.

The hydrocarbyl aluminum dihalide compound corresponds to the formula AIRX₂, in which R is a hydrocarbyl radical comprising 1 to 12 carbon atoms, such as alkyl, aryl, aralkyl, alkaryl or cycloalkyl, and X is a chlorine or bromine atom. As examples of such compounds, it is possible to mention ethylaluminum sesquichloride, dichloroethyl aluminum, dichloroisobutyl aluminum, chlorodiethyl aluminum or mixtures thereof.

According to a preferred method, a Bronsted organic acid is used. The Bransted acid compound corresponds to the formula HY, where Y is an organic anion, for example carboxylic, sulfonic or phenolic. Halocarboxylic acids of formula R²COOH in which R² is a halogenated alkyl radical are preferred, in particular those that contain at least one alpha-halogen atom of the group — COOH with 2 to 10 carbon atoms in all. Preferably, a haloacetic acid of formula CX_PH_3-P — COOH is used, in which X is fluorine, chlorine, bromine or iodine, with p being an integer from 1 to 3. By way of example, it is possible to cite the trifluoroacetic, difluoroacetic, fluoroacetic, trichloroacetic, dichloroacetic, and chloroacetic acids. It is also possible to use arylsulfonic, alkylsulfonic, and fluoroalkylsulfonic acids, and picric acid and nitroacetic acid. Trifluoroacetic acid is preferably used.

The three components of the catalytic formula can be mixed in any order. However, it is preferable first to mix the nickel compound with the Bronsted organic acid, and then next to introduce the aluminum compound. The molar ratio of the hydrocarbyl aluminum dihalide to the nickel compound, expressed by the Al/Ni ratio, is 2/1 to 50/1 , and preferably 2/1 to 20/1. The molar ratio of the Bronsted acid to the nickel compound is 0.25/1 to 10/1, and preferably 0.25/1 to 5/1.

According to a preferred method, the hydrocarbyl aluminum dihalide can be enriched with an aluminum trihalide, the mixture of the two compounds then corresponding to the formula AIRnXj-n, in which R is a hydrocarbyl radical comprising 1 to 12 carbon atoms, such as alkyl, aryl, aralkyl, alkaryl or cycloalkyl, X is a chlorine or bromine atom, and n is a number between 0 and 1. Suitable mixtures include: dichloroethyl aluminum enriched with aluminum chloride, the mixture having a formula AIEto.9CI2.-i; dichloroisobutyl aluminum enriched with aluminum chloride, the mixture having a formula AliBuo.9CI2.-i; and dibromoethyl aluminum enriched with aluminum bromide, the mixture having a formula AIEto gBr₂ i.

The reaction for oligomerization of ethylene can be implemented at a temperature of -20 to 80 °C, preferably 40 to 60 °C, under pressure conditions such that the reagents are kept at least for the most part in the liquid phase or in the condensed phase. The pressure is generally between 0.5 and 5 MPa, preferably between 0.5 MPa and 3.5 MPa. The time of contact is generally between 0.5 and 20 hours, preferably between 1 and 15 hours.

The oligomerization stage can be implemented in a reactor with one or more reaction stages in a series, with the ethylene feedstock and/or the catalytic composition that is preferably pre-conditioned in advance being introduced continuously, either in the first stage, or in the first stage and any other one of the stages. At the outlet of the reactor, the catalyst can be deactivated, for example by injection of ammonia and/or an aqueous solution of soda and/or an aqueous solution of sulfuric acid. The unconverted olefins and alkanes that are optionally present in the feedstock are then separated from the oligomers by a separation stage, for example by distillation or washing cycles by means of caustic soda and/or water.

The conversion per pass is generally 85 to 98%. The selectivity of n-butenes that are formed is generally between 50 and 80%. The n-butenes consist of butene-2 (cis- and trans-) and butene-1.

The effluent generally contains less than 0.2% by weight of isobutene, or even less than 0.1 % by weight of isobutene.

Separation of a Stream Rich in n-Butenes

The effluent that is obtained by dimerization of ethylene is subjected to a separation stage in such a way as to obtain an n-butene-enriched fraction.

The separation can be carried out by evaporation, distillation, extractive distillation, extraction by solvent or else by a combination of these techniques. These processes are known by one skilled in the art. Preferably, a separation of the effluent that is obtained by oligomerization of ethylene is carried out by distillation.

Preferably, the effluent of the oligomerization is sent into a distillation column system comprising one or more columns that makes it possible to separate, on the one hand, n-butenes from ethylene, which can be returned to the oligomerization reactor, and heavier olefins with 5 carbon atoms and more.

Hence, in an embodiment, step b)-(i) comprises:

- contacting the renewably-sourced ethylene stream with a dimerization catalyst in a dimerization zone;

- operating said dimerization zone at conditions effective to produce an effluent consisting essentially of n-butenes, heavier olefins, and optionally unconverted ethylene;

- fractionating the effluent to recover a stream consisting essentially of n-butenes, a stream consisting essentially of heavier olefins, and an optional ethylene stream; and optionally subjecting the stream consisting essentially of heavier olefins to hydrogenation so as to obtain renewably-sourced naphtha.

Metathesis of Ethylene with n-Butenes

Ethylene is able to undergo metathesis with n-butenes to produce propylene. In one aspect of the invention, step b)-(ii) comprises a metathesis reaction between n-butenes obtained according to step (i) and ethylene to obtain propylene. The n-butenes obtained according during ethylene dimerization (i) are a mixed stream including 1 -butene and 2- butenes. Essentially only the 2-butenes react in a metathesis reaction, while 1 -butene is essentially inert.

In one embodiment, 1 -butene is removed from the mixed stream of 1 -butene and 2-butenes and directed to a use elsewhere in the plant. Thus, in one embodiment, step b)-(ii) comprises removal of 1 -butene from the mixed stream to obtain a stream rich in 2- butenes, and subjecting the stream rich in 2-butenes to the metathesis reaction. A stream rich in 2-butenes may comprise at least 90wt.-% of 2-butenes, based on the total amount of n-butenes.

Alternatively, 1 -butene may be converted to 2-butene by double bond isomerization. Double bond isomerization is an equilibrium-limited reaction. It is thus advantageous to subject the mixed stream of n-butenes to metathesis so as to react 2-butene with ethylene prior to double bond isomerization of 1 -butene. Hence, in one embodiment the n-butenes are a mixed stream including 1 -butene and 2-butenes, and b)-(ii) comprises b)-(iia) subjecting the mixed stream to the metathesis reaction to obtain propylene and unreacted 1 -butene; b)-(iib) subjecting the unreacted 1 -butene to double bond isomerization to obtain 2-butenes; and b)-(iic) recycling the 2-butenes obtained in step b)-(iib) to step b)-(iia).

In another embodiment, it is possible to convert 1 -butene to 2-butene simultaneously with the metathesis reaction. For this purpose, a metathesis catalyst and an isomerization catalyst may be physically mixed or provided as distinct layers to allow both reactions to proceed simultaneously. Thus, in one embodiment, step b)-(ii) comprises passing the mixed stream through a metathesis/isomerization zone comprising both a metathesis catalyst and an isomerization catalyst. As 2-butene is consumed due to the metathesis reaction over the metathesis catalyst, it is thus replenished by isomerization of 1 -butene to 2-butene over the isomerization catalyst.

The reaction is carried out in the presence of a metathesis catalyst on the basis of a metal which is selected from tungsten, molybdenum, rhenium, niobium, tantalum, vanadium, ruthenium, rhodium, iridium, osmium and nickel and the like. Tungsten, molybdenum and rhenium are preferred and tungsten is particularly preferred. Typically, tungsten catalysts are supported on silica, molybdenum and rhenium are supported on alumina based carriers. Especially preferred metathesis catalysts are WCh-based catalysts, for example silica-supported WO3 in the form of granules.

Suitable isomerization catalysts include magnesium-based catalysts such as MgO- based catalysts, for example tableted MgO.

Metathesis is carried out under conditions effective to produce an effluent comprising propylene, unconverted ethylene, and optionally 1 -butene.

Unconverted ethylene and/or unconverted n-butenes may be recycled and combined with fresh ethylene and n-butenes to provided the metathesis feedstock.

The reaction may be conducted at 340 - 375°C, 25-40 bar, a weight hourly space velocity (WHSV) of 7.5-30 hr¹, and an ethylene to 2-butene molar ratio of 3: 1 to 10:1.

The reactor effluent may be sent to a deethenizer to remove C2 and lighter material. The bottoms from the deethenizer are sent to the depropenizer. High-purity, polymer-grade propylene (> 99.9% molar purity) is recovered from the depropenizer overhead. The lighter material from the deethenizer and heavier C4+ material from the depropenizer are partly recycled to the reactors. Purge streams are provided for the lighter and heavier material to prevent buildup of inerts.

It should be noted that propane is not produced during the metathesis reaction. Consequently, polymer-grade propylene can be produced from the process, without the need for an expensive propylene-propane superfractionator.

Commercial processes for producing polymer-grade propylene by metathesis from ethylene and butenes feedstock are available from CB&I/Lummus (tradename OCT™) and from LyondellBasell.

Oxidation of Renewably-Sourced Propylene to Produce Acrolein or Acrylic Acid

Step c) of the invention comprises an oxidation reaction of propylene to produce acrolein and/or acrylic acid.

Acrylic acid is an important basic chemical. Owing to its very reactive double bond and the acid function, it is suitable in particular for use as monomer for preparing polymers. Of the amount of acrylic acid monomer produced, the major part is esterified before polymerization, for example to form acrylate adhesives, dispersions or coatings. Only the smaller part of the acrylic acid monomer produced is polymerized directly, for example to form water-absorbent resins. Whereas, in general, the direct polymerization of acrylic acid requires high purity monomer, the acrylic acid for conversion into acrylate before polymerization does not have to be so pure. It is common knowledge that acrylic acid can be produced by heterogeneously catalyzed gas phase oxidation of propylene with molecular oxygen over solid catalysts at temperatures between 200° to 400° C. in two stages via acrolein (cf. for example DE-A 19 62 431 , DE-A 29 43 707, DE-C 1 205 502, EP-A 257 565, EP-A 253 409, DE-B 22 51 364, EPA 117 146, GB-C 1 450 986 and EP-A 293224). The catalysts used are oxidic multicomponent catalysts based for example on oxides of the elements molybdenum, chromium, vanadium or tellurium. Five most commonly used catalyst systems for acrolein production are cuprous oxides, uranium antimony oxides, tin antimony oxides, bismuth molybdate oxides and multi-component bismuth molybdate based oxides. The most efficient catalysts for partial oxidation of propylene to acrolein consist of multi-component metal oxides systems. In almost every multi-component catalyst system, bismuth molybdate serves as the main ingredient. The following components are most commonly used as catalyst additives in molybdate bismuth oxide based catalysts: iron, cobalt, nickel, tungsten, potassium and phosphorous. Typical catalyst supports are inert porous solids, such as SiO₂, AI₂O₃, MgO, TiO₂, ZrO₂, aluminosilicates, zeolites, activated carbon, and ceramics.

The oxidation of propylene to acrylic acid can be carried out in one stage or two stages. Catalysts used for the heterogeneously catalyzed reaction are as a rule multimetal oxide materials which generally contain heavy metal molybdates as main component and compounds of various elements as promoters. The oxidation of propylene takes place in a first step to give acrolein and in a second step to give acrylic acid. Since the two oxidation steps may differ in their kinetics, uniform process conditions and a single catalyst do not as a rule lead to optimum selectivity. Recently, two-stage processes with optimum adaptation of catalyst and process variables have therefore preferably been developed. In general, propylene is oxidized to acrolein in the presence of molecular oxygen in the first stage in an exothermic reaction in a fixed-bed tubular reactor. The reaction products are passed directly into the second reactor and are further oxidized to acrylic acid. The reaction gases obtained in the second stage can be condensed and the acrylic acid can be isolated therefrom by extraction and/or distillation.

The oxidation of propylene to acrolein and/or acrylic acid is highly exothermic. The tubes of the fixed-bed tubular reactor which are filled with the heterogeneous catalyst are therefore surrounded by a cooling medium, as a rule a salt melt, such as a eutectic mixture of KNO₃ and NaNO₂. The heat of reaction is released through the wall of the catalyst-filled tubes to the salt bath.

Particularly preferred multimetal oxide materials have the formula I or II

[X¹_aX²_bOx]p[X%X⁴_dX%X⁶fX⁷gX²_hO_y]_q (I)

Mo₁₂BiX⁸kFeX⁹mX¹⁰_nO_z (II) where

X¹ is bismuth, tellurium, antimony, tin and/or copper, preferably bismuth, X² is molybdenum and/or tungsten,

X³ is an alkali metal, thallium and/or samarium, preferably potassium,

X⁴ is an alkaline earth metal, nickel, cobalt, copper, manganese, zinc, tin, cadmium and/or mercury, preferably nickel and/or cobalt,

X⁵ is iron, chromium, cerium and/or vanadium, preferably iron,

X⁶ is phosphorus, arsenic, boron and/or antimony,

X⁷ is a rare earth metal, titanium, zirconium, niobium, tantalum, rhenium, ruthenium, rhodium, silver, gold, aluminum, gallium, indium, silicon, germanium, lead, thorium and/or uranium, preferably silicon, aluminum, titanium and/or zirconium, a is from 0.01 to 8, b is from 0.1 to 30, c is from 0 to 4, d is from 0 to 20, e is from 0 to 20, f is from 0 to 6, g is from O to 15, h is from 8 to 16, x and y are numbers which are determined by the valency and frequency of the elements other than oxygen in I, p and q are numbers whose ratio p/q is from 0.1 to 10,

X⁸ is cobalt and/or nickel, preferably cobalt,

X⁹ is silicon and/or aluminum, preferably silicon,

X¹⁰ is an alkali metal, preferably potassium, sodium, cesium and/or rubidium, in particular potassium, i is from 0.1 to 2, k is from 2 to 10, I is from 0.5 to 10, m is from O to 10, n is from 0 to 0.5, z is a number which is determined by the valency and frequency of the elements other than oxygen in II.

Multimetal oxide materials of the formula I are known per se from EP 0000 835 and EP 0 575 897, and multimetal oxide materials of the formula II are known per se from DE 198 55 913.

Briefly, a process for preparing acrylic acid typically comprises the steps of: c)-(i) catalytic gas phase oxidation of propylene and/or acrolein to acrylic acid to obtain a gaseous reaction product comprising acrylic acid; c)-(ii) solvent absorption of the reaction product; c)-(iii) distillation of the solvent loaded with reaction product in a column to obtain a crude acrylic acid and the solvent; and c)-(iv) purification of the crude acrylic acid by crystallization.

Step c)-(i) does not afford pure acrylic acid, but a gaseous mixture which in addition to acrylic acid can substantially include unconverted acrolein and/or propylene, water vapor, carbon monoxide, carbon dioxide, nitrogen, oxygen, acetic acid, propionic acid, formaldehyde, further aldehydes and maleic anhydride.

The remaining, unabsorbed reaction gas of step c)-(i) is further cooled down so that the condensable part of the low-boiling co-components thereof, especially water, formaldehyde and acetic acid, may be separated off by condensation. This condensate is known as acid water. The remaining gas stream, hereinafter called recycle gas, consists predominantly of nitrogen, carbon oxides and unconverted starting materials. Preferably, the recycle gas is partly recirculated into the reaction stages as diluting gas.

The oxidation of propylene to acrolein, as well as the oxidation of acrolein to acrylic acid, proceed with less than 100% selectivity and are accompanied by the combustion of propylene or acrolein over the catalyst, which gives carbon monoxide and carbon dioxide, herein collectively referred to as CO_X. It should be appreciated that emission of the carbon dioxide side product does not contribute to the carbon footprint of this process, as the starting propylene is carbon neutral.

Hydroformylation of Propylene and Hydrogenation of the Produced Butyraldehyde

According to step d), a portion of the renewably-sourced propylene is subjected to a hydroformylation reaction to produce n-butyraldehyde or a mixture of n-butyraldehyde and isobutyraldehyde. According to step e), the butyraldehyde is subjected to hydrogenation to produce n-butanol.

Hydroformylation or the oxo process is an important large-scale industrial process for preparing aldehydes from olefins, carbon monoxide and hydrogen. The aldehydes can optionally be hydrogenated with hydrogen in the same operation or subsequently in a separate hydrogenation step to produce the corresponding alcohols. In general, hydroformylation is carried out in the presence of catalysts which are homogeneously dissolved in the reaction medium. Catalysts used are generally the carbonyl complexes of metals of transition group VIII, in particular Co, Rh, Ir, Pd, Pt or Ru, which may be unmodified or modified with, for example, amine-containing or phosphine-containing ligands. A summarizing account of the processes practiced on a large scale in industry is found in J. Falbe, “New Syntheses with Carbon Monoxide”, Springer Verlag 1980, p. 162 ff_, US 3,527,809; 3,917,661 ; 4, 148,830; 4,742, 178, 4,769,984; 4,885,401 ; 6,049,011. Propylene is preferably hydroformylated using ligand-modified rhodium carbonyls as the catalyst. Hydroformylation of propylene can be carried out at temperatures in the range of 50 °C to 200 °C, preferably 60 °C to 150 °C, and more preferably 70 °C to 120 °C.

In one embodiment, the hydroformylation reaction is conducted at a low pressure, e.g., a pressure in the range of 0.05 to 50 MPa (absolute), and preferably in the range of about 0.1 MPa to 30 MPa, most preferably at a pressure below 5 MPa. Desirably, the partial pressure of carbon monoxide is not greater than 50% of the total pressure.

The proportions of carbon monoxide, hydrogen, and propylene in the hydroformylation reaction medium can be selected within a wide range. In some embodiments, based on the total amount of CO, hydrogen, and ethylene, CO is from about 1 to 50 mol-%, preferably about 1 to 35 mol-%; H₂ is from about 1 to 98 mol-%, preferably about 10 to 90 mol-%; and ethylene is from about 0.1 to 35 mol-%, preferably about 1 to 35 mol-%.

The hydroformylation reaction preferably takes place in the presence of both liquid and gas phases. The reactants generally are in the gas phase. The catalyst typically is in the liquid phase. Because the reactants are gaseous compounds, a high contact surface area between the gas and liquid phases is desirable to enhance good mass transfer. A high contact surface area between the catalyst solution and the gas phase may be provided in any suitable manner. In a batch process, the batch contents are thoroughly mixed during the course of the reaction. In a continuous operation the reactor feed gas can be contacted with the catalyst solution in, for example, a continuous-flow stirred autoclave where the gas is introduced and dispersed at the bottom of the vessel, preferably through a perforated inlet (e.g., a sparger). High contact between the catalyst and the gas feed may also be provided by dispersing the solution of the Rh catalyst on a high surface area support, a technique well known in the art as supported liquid phase catalysis, or providing the Rh as part of a permeable gel.

The reaction may be conducted either in a batch mode or, preferably, on a continuous basis. One or more reactors may be used in continuous modes to carry out the reaction in one or more stages.

The ratio of H₂ to CO in the syngas used for hydroformylation is desirably in the range from 1.1 :1 to 1.01 : 1, preferably 1.06: 1 to 1.02: 1. Often, syngas may be made or otherwise initially provided in a manner such that the ratio of hydrogen to CO is much higher than this. The excess hydrogen can be separated and used in other reaction stages as desired. In some modes of practice, syngas in the practice of the present invention is anhydrous.

If desired, the produced aldehydes can be separated by fractionation. In a preferred embodiment, the syngas used in the hydroformylation reaction of step d) is obtained by: subjecting a gasifier feed stream comprising a renewably sourced material to gasification in a gasifier to obtain a gasifier effluent; recovering syngas from the gasifier effluent.

Preferably, the feedstock for the gasifier is selected from the group comprising biomass, municipal solid waste (MSW), shredder residues such as car shredder residues, textiles, plastic waste, packaging waste, and mixtures thereof. Such feedstocks can also be mixed with fossil feedstocks such as coal, oil, and natural gas. The amount of fossil feedstocks is typically not more than 10 wt.-%, preferably not more than 5 wt.-%.

The term “biomass” includes but is not limited to wood, wood pellets, wood chips, straw, lignocellulosic biomass, energy crops, algae, biobased-oils, biobased-fats, and mixtures thereof.

The term “waste” comprises fossil-based waste, biogenic waste, and mixtures thereof. Examples for waste suitable as a feedstock are agricultural/farming residues such as wood processing residues, waste wood, logging residues, switch grass, discarded seed corn, corn stover and other crop residues, municipal solid waste (MSW), textiles, industrial waste, sewage sludge, plastic waste, packaging waste, shredder residues such as car shredder residues and mixtures thereof.

Optionally, the feedstock is pre-treated before entering the gasifier. A suitable pretreatment method or combination of pre-treatment methods in a pre-treatment unit should provide a sufficiently homogeneous carbon-based feedstock to the gasification reaction and likewise enable the continuous production of syngas by gasification of a feedstock.

A pre-treatment method or a combination of more than one pre-treatment methods in a pre-treatment unit preferably results in a homogenization of the physical and/or chemical properties of the first feedstock and/or the second feedstock and/or the requirement(s) for a specific type of gasifier and/or the requirements for the optional at least one further chemical production unit for producing a chemical compound or mixture of chemical compounds.

The pre-treatment method for the first feedstock and/or the second feedstock is preferably selected from the group comprising drying, comminution, classification, sorting, agglomeration, thermochemical methods, and biological methods.

Suitable gasifiers comprise counter-current fixed bed reactors, co-current-fixed bed reactors, bubbling fluidized bed reactors, circulation fluidized bed reactors, and downdraft or updraft entrained flow reactors. The selection of size and reactor type depends on several parameters, including the composition of the (carbonaceous) feedstock, demand of products, moisture content and availability of the (carbonaceous) feedstock. Preferably, the gasifier is an „oxygen blown" gasifier, i.e., oxygen is preferably used as the oxidant in suitable gasifiers listed above.

The gasification reaction in a gasifier is typically carried out at a temperature of greater than 700 °C in the presence of a sub-stoichiometric amount of an oxidant such as oxygen, air, steam, supercritical water, CO2, or a mixture of the aforementioned. Oxygen is the most common oxidant used for gasification because of its easy availability and low cost. The H₂ : CO ratio depends on the composition of the feedstock and the amount of steam used in the gasification. The H₂ : CO ratio as required for the hydroformylation can for instance be adjusted by choosing an appropriate amount of steam in the gasification.

Another possibility to adjust the H₂ : CO ratio is to separate CO from the syngas. CO can be separated from the syngas in a syngas separation unit which is downstream of and fluidly connected to the syngas producing unit comprising at least one gasifier. CO can be separated from syngas by cryogenic separation methods, commonly referred to as a “cold box” which makes use of the different boiling points of CO and H₂. H₂ can be separated using H₂-selective membranes thorough which H₂ permeates and is thereby separated from a syngas stream.

When steam acts as oxidant, the syngas has a higher molar ratio H₂ : CO than when air is used as oxidant. For example, a typical molar ratio of “air : combined feedstock” ranges from 0.3 to less than 1.

The conversion of a feedstock in the gasifier produces a syngas which consists primarily of H₂, CO, CO₂, methane, other hydrocarbons, and impurities. Said syngas has a dedicated molar ratio H₂ : CO when leaving the gasifier which ranges from about 0.1 : 1 to about 3 : 1 and depends on the type of solid and/or liquid feedstocks used, the oxidant and other reaction conditions applied such as temperature and/or residence time of the reactants in the gasifier.

Typical impurities in the raw syngas obtained from the gasification reaction in a gasifier comprise chlorides, sulfur-containing organic compounds such as sulfur dioxide, trace heavy metals (e.g., as respective salts) and particulate residues. Various chemical and/or physical methods for removal of such impurities from said raw syngas such as filtration, scrubbing, hydrotreatment and ab-/adsorption are known and can be chosen and adapted according to the type and respective concentration of the impurities in said raw syngas and the tolerance to such impurities in the successive process steps. Some selected methods for removal of impurities from said raw syngas will be discussed in more detail. One or more of said methods can also be implemented into the at least one syngas purification unit of the syngas producing unit comprising at least one gasifier. However, this selection of methods is not limiting the scope of the present invention. Bulk particulate impurities can be removed from the raw syngas by a cyclone and/or filters, fine particles, and chlorides by wet scrubbing, trace heavy metals, catalytic hydrolysis for converting sulfur-containing organic compounds to H₂S and acid gas removal for extracting sulfur-containing gases such as H₂S. Bulky and fine particles in the syngas may also be removed with a quench in a soot water washing unit.

A gasification reaction usually results in further reaction products such as solid and/or highly viscous carbonaceous residues (e.g., char and/or tar) which can be further treated in separate steps not relevant for the systems and methods according to the present invention.

Esterification of Acrylic Acid

Acrylic acid is esterified in a conventional manner with n-butanol to produce n-butylacrylate. n-Butylacrylate is generally known and important, for example, as reactive monoethylenically unsaturated monomer for the preparation of aqueous polymer dispersions by a free radical aqueous emulsion polymerization method, which dispersions are used, for example, as adhesives.

Processes for the preparation of n-butylacrylate by reacting acrylic acid with n-butanol in homogeneous liquid phase at elevated temperatures and in the presence of catalysts are equilibrium reactions in which the conversion of the acrylic acid and of the n-butanol to the corresponding ester is limited by the equilibrium constant. Consequently, for an economical procedure, the unconverted starting materials have to be separated from the resulting ester and recycled to the reaction zone.

Conveniently, the reaction zone may consist of a cascade of reaction regions, connected in series, and the discharge stream of one reaction region forms a feed stream of a subsequent reaction region and the concentration of the esterification catalyst increases along the reaction cascade. Acrylic acid, the n-butanol and the catalyst are fed continuously to the reaction zone. An azeotropic mixture comprising the n-butylacrylate, water and optionally n-butanol is separated off by rectification via the top of a rectification zone mounted on the reaction zone. The azeotropic mixture is separated into an organic phase containing n-butylacrylate and an aqueous phase, with a part of the organic phase being recycled to the reaction zone. The n-butylacrylate is isolated from the excess organic phase. The latter is usually carried out by separation steps involving rectification (cf. for example DE 19536178).

The temperature in the reaction zone is suitably in the range of 70 to 160 °C, preferably 100 to 140 °C. The total residence time of the reactants in the reaction zone is as a rule from 0.25 to 15 h, frequently from 1 to 7 h, or from 2 to 5 h.

Suitable acidic esterification catalysts include acidic ion exchange resins and strong mineral acids, e.g. sulfuric acid, or organic sulfonic acids, such as methanesulfonic acid, benzenesulfonic acid, dodecanesulfonic acid or para-toluenesulfonic acid, or a mixture of some or all of the abovementioned acids. Sulfuric acid is particularly suitable for carrying out the esterification.

The content of acidic esterification catalyst in the reaction zone is expediently from 0.1 to 20 wt.-%, frequently from 0.5 to 5 wt.-%, based on the reaction mixture contained therein.

To prevent undesired formation of polymer initiated by free radicals, a polymerization inhibitor is typically used during esterification. Examples of suitable polymerization inhibitors are hydroquinone, 4-methoxyphenol, and phenothiazine, which may be used singly or in admixture with each other. It is usual to add from about 0.01 to 0.1 wt.-% of polymerization inhibitor to the esterification mixture and mixtures containing the n- butylacrylate.

Alkylation of Benzene with Renewably-Sourced Ethylene

In accordance with step g), ethylene is subjected to an alkylation reaction with benzene to produce ethylbenzene.

Benzene can be alkylated with ethylene preferably in liquid phase to produce ethylbenzene. In general, the alkylation is carried out at a temperature of 80 to 130 °C and in the presence of a Lewis acid catalyst such as AICI 3, AIBr₃, FeCh, ZrCL, and BF₃ with AlCh being preferred. Ethyl chloride or hydrogen chloride may be used as a catalyst promoter. Further details can be taken from Ullmann’s Encyclopedia of Industrial Chemistry, 5^th ed., vol. A10, 35-40, 1987.

Suitably, the ethylene is obtained by at least one of: subjecting a cracker feed to steam cracking to obtain a cracker effluent; recovering ethylene from the cracker effluent; and subjecting a feedstock comprising a renewably-sourced ethanol to dehydration to produce ethylene.

This means that the ethylene used in step g) may be a portion of the renewably-sourced ethylene stream obtained according to step a) or else is cracker-derived ethylene or any mixture thereof.

An important source of benzene is a highly aromatic fraction known as pyrolysis gasoline resulting from steam cracking of gases, naphthas, and gas oils to produce olefins. This means that benzene is obtained by

(i) subjecting a cracker feed to steam cracking to obtain a cracker effluent;

(ii) recovering from the cracker effluent a pyrolysis gasoline; (iii) recovering benzene from the pyrolysis gasoline.

One of the problems encountered in the utilization of the pyrolysis gasoline is that pyrolysis gasoline contains an amount of highly unsaturated hydrocarbon compounds, such as acetylenes, aliphatic diolefins, vinyl substituted aromatics, and cyclic diolefins, and these compounds polymerize readily to form polymeric compounds, generally referred to as gums. Hence, the pyrolysis gasoline is hydrogenated under conditions that will saturate the gum-forming compounds but will not saturate the monoolefin or aromatic compounds. Because the pyrolysis naphtha contains nonaromatic compounds boiling close to benzene which are not removed by the hydrogenation step, solvent extraction is generally employed rather than simple distillation, in order to separate the valuable compounds. The order of solubility of hydrocarbon material in a solvent that is selective for aromatics, such as sulfolane, is as follows: the least soluble material is the paraffinic material followed in order of increasing solubility by naphthenes, olefins, diolefins, acetylenes, sulfur bearing molecules, and aromatics. After solvent extraction, the impure benzene could be separated by distillation. Additional benzene con be retrieved by a hydrodealkylation stage to further convert alkyl aromatics to benzene.

Cracking Process

Hydrocarbon cracking, in particular steam cracking, may be the source of the complementary olefins described above, as well as the source of benzene and/or ethylene employed in step g).

Complementary ethylene, propylene and n-butenes may be obtained by

(i) subjecting a cracker feed to steam cracking to obtain a cracker effluent;

(ii) recovering from the cracker effluent a stream comprising ethylene, propylene and n-butenes; and

(iii) subjecting the stream to fractional distillation to recover ethylene or propylene or n- butenes.

Typically, the cracker feed comprises naphtha. Fossil-based naphtha is a hydrocarbon feedstock that may originate from upstream refinery processes such as an atmospheric distillation tower, hydrocracker or coker unit. Different types of fossil-based naphtha may be distinguished, e.g., via their boiling point. Thus, “light naphtha” has a boiling point in the range of 30 to 90 °C and comprises a major fraction of molecules with 5 to 6 carbon atoms, whereas “heavy naphtha” has a boiling point in the range of 90 to 200 °C and comprises a major fraction of molecules with 6 to 12 carbon atoms. Preferably, the fossilbased naphtha is heavy naphtha.

In an embodiment, the cracker feed comprises at least one of pyrolysis oil and bionaphtha. The partial substitution of fossil-based naphtha by pyrolysis oil or bio-naphtha may increase the sustainability of cracker products. Bio-naphtha may be added to fossil naphtha in order to provide benzene having a bio-based carbon content of greater than zero.

In an embodiment, the cracker feed stream comprises, relative to the total weight of the cracker feed, 60 to 99.9 wt.% of fossil-based naphtha. In another embodiment, the cracker feed stream comprises 60 to 99.8 wt.% of fossil-based naphtha. In another embodiment, the cracker feed stream comprises 55 to 99 wt.% of fossil-based naphtha.

In another embodiment, the cracker feed comprises at least one of pyrolysis oil and bionaphtha. The partial substitution of fossil-based naphtha by pyrolysis oil or bio-naphtha may increase the sustainability of cracker products. Bio-naphtha may be added to fossil naphtha in order to provide products having a bio-based carbon content of greater than zero.

In another embodiment, the cracker feed stream comprises, relative to the total weight of the cracker feed:

0.1 to 40 wt.% pyrolysis oil; and

60 to 99.9 wt.-% fossil-based naphtha; preferably

1 to 35 wt.% pyrolysis oil; and

65 to 99 wt.-% fossil-based naphtha.

In the context of the present invention, the term “pyrolysis” relates to a thermal decomposition or degradation of end of life solid organic feedstock, such as plastics or rubber, under inert conditions and results in a gas, a liquid and a solid char fraction. During the pyrolysis, the plastics and rubber are converted into a great variety of chemicals including gases such as H₂, Ci-C4-alkanes, C2-C4-alkenes, ethyne, propyne, 1 -butyne, pyrolysis oil having a boiling temperature of 25 to 500 °C, and char. The term “pyrolysis” includes slow pyrolysis, fast pyrolysis, flash catalysis and catalytic pyrolysis. These types of pyrolysis differ in the process temperature, heating rate, residence time, feed particle size, etc. resulting in different product quality.

In the context of the present invention, the term “pyrolysis oil” is understood to mean any oil originating from the pyrolysis of waste solid organic feedstock, such as plastic waste or rubber waste.

In the context of the present invention, the term “plastic waste” refers to any plastic material discarded after use, i.e. the plastic material has reached the end of its useful life. The plastic waste can be pure polymeric plastic waste, mixed plastic waste or film waste, including soiling, adhesive materials, fillers, residues etc. The plastic waste has a nitrogen content, sulfur content, halogen content and optionally also a heavy metal content. The plastic waste can originate from any plastic material containing source. Accordingly the term “plastic waste” includes industrial and domestic plastic waste including used tires and agricultural and horticultural plastic material. The term “plastic waste” also includes used petroleum-based hydrocarbon material such as used motor oil, machine oil, greases, waxes, etc.

Typically, plastic waste is a mixture of different plastic material, including hydrocarbon plastics, e.g., polyolefins such as polyethylene (HDPE, LDPE) and polypropylene, polystyrene and copolymers thereof, etc., and polymers composed of carbon, hydrogen and other elements such as chlorine, fluorine, oxygen, nitrogen, sulfur, silicone, etc., for example chlorinated plastics, such as polyvinylchloride (PVC), polyvinylidene chloride (PVDC), etc., nitrogen-containing plastics, such as polyamides (PA), polyurethanes (Pll), acrylonitrile butadiene styrene (ABS), etc., oxygen-containing plastics such as polyesters, e.g. polyethylene terephthalate (PET), polycarbonate (PC), etc.), silicones and/or rubber, such as sulfur bridges crosslinked rubbers. PET plastic waste is often sorted out before pyrolysis, since PET has a profitable resale value. Accordingly, the plastic waste to be pyrolyzed often contains less than about 10% by weight, preferably less than about 5% by weight and most preferably substantially no PET based on the dry weight of the plastic material. One of the major components of waste from electric and electronic equipment are polychlorinated biphenyls (PCB). Typically, the plastic material comprises additives, such as processing aids, plasticizers, flame retardants, pigments, light stabilizers, lubricants, impact modifiers, antistatic agents, antioxidants, etc. These additives may comprise elements other than carbon and hydrogen. For example, bromine is mainly found in connection to flame retardants. Heavy metal compounds may be used as lightfast pigments and/or stabilizers in plastics; cadmium, zinc and lead may be present in heat stabilizers and slip agents used in plastics manufacturing. The plastic waste can also contain residues. Residues in the sense of the invention are contaminants adhering to the plastic waste. The additives and residues are usually present in an amout of less than 50% by weight, preferably less than 30% by weight, more preferably less than 20% by weight, even more preferably less than 10% by weight based on the total weight of the dry weight plastic.

Depending on the waste plastic material subjected to the pyrolysis, the crude pyrolysis oil may have varying contents of sulfur, nitrogen, halogen and, if present, heavy metal. If desired, pyrolysis oil may be purified prior to its use in a cracker feed stream.

The term “rubber material” as used herein is meant to indicate a polymeric material that constitutes the elastomeric, partially cross-linked (e.g., vulcanized) polymer materials that may be stretched at room temperature to at least twice their original length and, after having been stretched and the stress removed, returns its force to approximately its original length in a short time.

The rubber materials, due to their partially cross-linked structure, show improved thermal stability, compared to the thermoplastic materials (plastics). The rubber cannot be molten but, at higher temperatures, it undergoes thermal degradation, wherein the temperature of degradation and the degradation rate depend, inter alia, on the crosslinking degree of the rubber material. Thus, during pyrolysis, the heat cannot be evenly distributed within the rubber mass and this leads to a wide large temperature gradients inside the pyrolysis reactor. A system for pyrolysis of the rubber materials should have improved heat and mass transfer properties, as compared to the one that is used for pyrolysis of the plastic (thermoplastic) materials.

The rubber materials which may be processed by pyrolysis may be of different types: waste rubber such as natural or synthetic rubber comprising polymers, such as for example polyisoprene, polychloroprene, polybutadiene, polyisobutylene, or copolymers such as: poly(styrene-butadiene-styrene). The term “rubber material” is meant to indicate natural rubber (1 ,4-polyisoprene) and synthetic rubbers such as: styrene-butadiene rubbers (SBR), butyl rubbers (consisting of polyisobutylene with addition of diolefin e.g. isoprene) or neoprene (2-chlorobutadiene-1 ,3).

The rubber materials to be pyrolysed may further comprise different additives, plastificators or fillers. Exemplary rubber materials that may be pyrolysed are worn tires.

Useful pyrolysis oils may be characterized by their heating value and/or bromine number. The heating value can be assessed in accordance with DIN 51900. The olefin content may be determined with reference to a bromine number. “Bromine number” refers to g of bromine reacting with 100 g of a material, ASTM Method D1159.

In an embodiment, pyrolysis oil exhibits at least one of the following parameters: a heating value in the range of 35 to 46 kJ/g; a bromine number in the range of 2 to 160 g Br₂/100g.

Generally, the cracker feed stream comprises, relative to the total weight of the cracker feed, 0.1 to 40 wt% pyrolysis oil. In another embodiment, the cracker feed stream comprises 1 to 35 wt% pyrolysis oil.

In the present process, pyrolysis oil from waste solid organic feedstock including plastics and/or rubber is recycled back as starting materials for high value chemical products, including virgin plastics, to establish a circular economy by combining distinct industrial processes. Benefits accrue if the waste solid organic feedstock has a bio-based carbon content of greater than zero. In this way, high value chemical products with steadily increased bio-based carbon content may be obtained.

Hence, in an embodiment the pyrolysis oil is obtained from the pyrolysis of a waste solid organic feedstock having a bio-based carbon content of greater than zero, e.g., having a bio-based carbon content of 1 % or more, or 3 % or more. In general, the waste has a bio-based carbon content 10 % or less.

In an embodiment, bio-naphtha may be added to fossil naphtha as cracker feed stock. In an embodiment, the cracker feed stream comprises, relative to the total weight of the cracker feed stream, up to 10 wt.% bio-naphtha. In another embodiment, the cracker feed stream comprises, relative to the total weight of the cracker feed stream, 0.1 to 10 wt.% bio-naphtha.

Bio-naphtha may be produced from complex mixtures of fats and oils, such as vegetable oils, industrial fats and waste oils. Thus, bio-naphtha is a renewable source of energy.

In an embodiment, the bio-naphtha is at least partially obtained from the hydrogenation of fatty acids, fatty acid derivatives, mono-, di- or, triglycerides, or a combination thereof. Bio-naphtha is known as such and its production is, for example, disclosed in US20120053379 A1. The starting material for producing bio-naphtha may be tall oil based. Tall oil is an oil product obtained from wood such as pine and other softwood trees. In general, the starting material comprises at least 75 wt.% of fatty acids of tall oil and no more than 25 wt.% resin acids of tall oil. The starting material may comprise other suitable vegetable oils, e.g. palm oil. The starting material is subjected to hydrodeoxygenation by a method known as such which is, for example described in US20120053379 A1. The hydrodeoxygenation product is a hydrocarbon mixture which suitable to be subjected to steam cracking.

Steam cracking is a petrochemical process wherein saturated hydrocarbons having long molecular structures are broken down, i.e. cracked, into smaller saturated or unsaturated molecules. Generally, steam crackers aim at producing light alkenes as valuable products, especially ethylene and propylene.

Conventional steam cracking utilizes a pyrolysis furnace which has two main sections: a convection section and a radiant section. The hydrocarbon feedstock typically enters the convection section of the furnace as a liquid, or, in a case where light feedstocks are used, as a vapor, wherein it is typically heated and, if necessary, vaporized by indirect contact with hot off-gas from the radiant section and by direct contact with steam. The vaporized feedstock and steam mixture is then introduced into the radiant section where the cracking takes place.

The resulting stream having a temperature typically in the range of from 500 to 650 °C enters a fired tubular reactor and is heated to a temperature typically in the range of from 750 to 875 °C for 0.1 to 0.5 s, wherein the residence time, temperature profile and partial pressure is controlled. During this short reaction time, hydrocarbons in the feedstock are cracked into smaller molecules yielding light olefins such as ethylene, propylene, butylenes, other small olefins, and diolefins as major products besides methane. These reaction products suitably typically leave the radiant tube at a temperature in the range of 800 to 850 °C and are preferably cooled to a temperature typically in the range of from 550 to 650 °C within 0.02 to 0.1 s in order to prevent degradation of the highly reactive compounds by secondary reactions. Then, the resulting reaction products leave the furnace for further downstream processing. Herein, the designator “C_x” refers to a hydrocarbon including x carbon atoms, “C_x+” refers to a hydrocarbon or mixture of hydrocarbons including x or greater carbon atoms, and “Cxminus” refers to a hydrocarbon of mixture of hydrocarbons including x or fewer carbon atoms.

Usually, the cracker effluent mixture comprising light olefins such as ethylene, propylene, butylenes, other small olefins, and diolefins besides methane is separated by using a sequence of separation and chemical-treatment steps. The process typically also generates light side products such as hydrogen, carbon oxides, light saturated hydrocarbons, and water.

The hot cracked gas leaving the cracker is cooled down quickly in order to prevent unwanted follow-up reactions. This is usually done in several steps. In a first step, the cracked gas is cooled down to about 450° C by heat exchangers. A further cooling step occurs via direct contact between the cracked gas and a high boiling liquid, usually referred to as quench oil. The quench results in a partial condensation of the cracked gas. In this step, a heavy stream rich in C10+ hydrocarbons is separated from the cracked gas. A further cooling step of the cracked gas takes place in a water quench column for primary fractionation, cooling down the gas to around 30 °C. In this step, a C5-9 fraction, commonly referred to as pyrolysis gasoline, is separated from C_4minus components.

The recovery of the various olefin products from cracked gas is usually carried out by fractional distillation using a series of distillation steps or columns to separate out the various components. The unit which separates hydrocarbons with one carbon atom (Ci) and lighter fraction is referred to as “demethanizer”. The unit which separates hydrocarbons with two carbon atoms (C₂) from the heavier components is referred to as “deethanizer”. The unit which separates the hydrocarbon fraction with three carbon atoms (C3) from the heavier components is referred to as “depropanizer”. The unit which separates the hydrocarbon fraction with four carbon atoms (C₄) from the heavier components is referred to as “debutanizer”. The various fractionation units may be arranged in a variety of sequences in order to provide desired results based upon various feedstocks.

The residual heavier components having a higher carbon number fraction (C5+) may be used as gasoline or recycled back to the cracker.

The various fractionation units may be arranged in a variety of sequences in order to provide desired results based upon various feedstocks. To that end, a sequence which uses the demethanizer first is commonly referred to as the “front-end demethanizer” sequence. Similarly, when the deethanizer is used first, it is commonly referred to as the “front-end deethanizer” sequence. And, when the depropanizer is used first, it is commonly referred to as “front-end depropanizer” sequence. In the conventional front-end demethanizer sequence, the cracked gas containing hydrocarbons having one to five or more carbon atoms per molecule (Ci to Cs+) first enters a demethanizer, where methane and lighter fractions (hydrogen) are separated as an over-head stream. The demethanizer operates at relatively low temperatures, typically ranging from about -100 °C to about 25 °C.

The heavy ends exiting the demethanizer consist mainly of C₂ to C₅₊ molecules. These heavy ends then are routed to a deethanizer where the C₂ hydrocarbons are taken over the top and the C3 to C5+ compounds leave as bottoms. The C₂ components leaving the top of the deethanizer may be fed to an acetylene converter or acetylene removal unit. As some methane remains dissolved in the heavy ends exiting the demethanizer and ends up in the C₂ components leaving the deethanizer, the C₂ components stream may be subsequently sent to a demethanizer for removal of the remaining methane.

The C₂ components from which methane has been removed are then sent to a C₂ splitter which produces ethylene as the light product and ethane as the heavy product. The C₃ to C5+ stream leaving the bottom of the deethanizer is routed to a depropanizer, which sends the C₃ components overhead and the C4 to C5+ components below.

The C₃ product may be hydrotreated to remove C₃ acetylene and dienes before being fed to a C₃ splitter, where it is separated into propylene at the top and propane at the bottom.

The C4 to C5+ stream is fed to a debutanizer, which produces C4 components at the top with the balance of C5+ components leaving as bottoms. Both the C4 and the C5+ streams may be separately hydrotreated to remove undesirable acetylenes and dienes.

In conventional front-end deethanizer sequences, the cracked gas containing Ci to C₅₊ components first enters a deethanizer. The light ends exiting the deethanizer consist of C₂ and Ci components along with any hydrogen (C_2minus fraction). These light ends are fed to a demethanizer (C_2minus demethanizer) where the hydrogen and Ci are removed as light ends and the C₂ components are removed as heavy ends. The C₂ stream leaving the bottom of the demethanizer may be fed to an acetylene converter and then to a C₂ splitter which produces ethylene as the light product and ethane as the heavy product. The heavy ends exiting the deethanizer which consist of C₃ to C5+ components are routed to a depropanizer which sends the C₃ components over-head and the C₄ to C₅₊ components below. The C₃ product is fed to a C₃ splitter where it is separated into propylene at the top and propane at the bottom, while the C₄ to C₅₊ stream is fed to a debutanizer which produces C4 compounds at the top with the balance leaving as bottoms to be used for gasoline or to be recirculated as feed into the cracking process. As with the front-end demethanizer sequence, the C₃, C4, and C5+ streams may be separately hydrotreated to remove undesirable acetylenes and dienes. In conventional front-end depropanizer sequences, the quenched and acid-free gases containing hydrocarbons having from one to five or more carbon atoms per molecule (Ci to Cs+) first enter a depropanizer. The heavy ends exiting the depropanizer consist of C4 to C5+ components. These are routed to a debutanizer where the C4 components and lighter species are taken over the top with the rest of the feed leaving as bottoms which can be used for gasoline or other chemical recovery. These streams may be separately hydrotreated to remove undesired acetylenes and dienes. The tops of the depropanizer, containing Ci to C3 components, may be fed to an acetylene converter and then to a demethanizer system, where the Ci components and any remaining hydrogen are removed as an over-head. The heavy ends exiting the demethanizer system, which contains C₂ and C₃ components, are introduced into a deethanizer wherein C₂ components are taken off the top and C₃ compounds are taken from the bottom. The C₂ components are, in turn, fed to a C₂ splitter which produces ethylene as the light product and ethane as the heavy product. The C₃ stream is fed to a C₃ splitter which separates the C₃ species, sending propylene to the top and propane to the bottom.

As with the front-end demethanizer sequence, the saturated C₂ hydrocarbons and/or the saturated C₃ hydrocarbons obtained in the front-end deethanizer sequence or the frontend depropanizer sequence or a partial stream thereof may be recycled as feed into the cracking process.

Dehydrogenation of Ethylbenzene to Styrene

To produce styrene the obtained ethylbenzene is dehydrogenated in the vapor phase with steam over a catalyst comprising iron oxide. The dehydrogenation can be carried out adiabatically or isothermally. Further details can be taken from Ullmann’s Encyclopedia of Industrial Chemistry, 6^th ed., vol. 34, 386-390, 2003.

Copolymerization of Styrene and n-Butylacrylate

Any known method can be used for the copolymerization of styrene and n-butylacrylate.

A preferred embodiment relates to the manufacture of an aqueous polymer latex having a renewably-sourced carbon content by polymerizing n-butyl acrylate, styrene and, optionally, one or more other ethylenically unsaturated compound(s) by aqueous radical emulsion polymerization.

Another preferred embodiment relates to the manufacture of an aqueous polymer latex having a renewably-sourced carbon content by polymerizing a monomer composition M by aqueous radical emulsion polymerization, the monomer composition M comprising or consisting of:

A) 30 to 70 wt.-% of n-butyl acrylate;

B) 30 to 70 wt.-% of styrene;

C) 0.1 to 20 wt.-% of one or more other ethylenically unsaturated compound(s); based on the total weight of the monomer composition M.

In some embodiments, the monomers and the amounts of monomers used to form the copolymer are selected to provide a glass transition temperature (“Tg”) of the copolymer from -10° C to 25° C. The glass transition temperature of a polymer is the temperature region of the change from a rigid “glassy” state to a flexible “rubbery” state. It is, for example, determined according to DIN EN ISO 11357-2.

In some embodiments, one or more additional ethylenically unsaturated monomers can be used in the copolymerization. Such monomers must be copolymerizable with styrene and n-butylacrylate. Examples of such monomers are (meth)acrylic acid, acrylonitrile, 4-methylstyrene, butadiene, (meth)acrylates other than n-butylacrylate, such as methyl(meth)acrylate, ethyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, vinylesters of saturated aliphatic carboxylic acids having 2 to 10 carbon atoms such as vinyl acetate and vinyl propionate. The monomers may be used in amounts such that the glass transition temperature of the copolymer is in the range as mentioned above.

Further monomers copolymerizable with styrene and n-butylacrylate include monoethylenically unsaturated monomers having a solubility in deionized water at 20°C and 1 bar of at least 60 g/L. These monomers may usually be present in amounts of up 20% by weight, e.g. 0.01 to 20% by weight, in particular 0.1 to 10% by weight, based on the total weight of monomers to be polymerized, and include in particular anionic monoethylenically unsaturated monomers, non-ionic monoethylenically unsaturated monomers, such as monoethylenically unsaturated monocarboxylic acids having 3 to 8 C atoms such as acrylic acid, methacrylic acid or itaconic acid; ethylenically unsaturated sulfonic acids and their salts such as vinylsulfonic acid, allylsulfonic acid, sulfoethyl acrylate, sulfoethyl methacrylate, sulfopropyl acrylate, sulfopropyl methacrylate, 2-hydroxy-3-acryloyloxypropylsulfonic acid, 2-hydroxy-3- methacryloyloxypropylsulfonic acid, styrenesulfonic acids, and 2-acrylamido-2- methylpropanesulfonic acid, especially their salts, more particularly their sodium salts and their ammonium salts; ethylenically unsaturated phosphonic acid and ethyleneically unsaturated phosphoric acids and their salts such as vinylphosphonic acid, allylphosphonic acid, phosphoethyl acrylate, phosphoethyl methacrylate, phosphopropyl acrylate, phosphopropyl methacrylate, phospho-oligo(C₂-C₃-alkyleneether)acrylate, phospho-oligo(C₂-C₃-alkyleneether)methacrylate, especially their salts, more particularly their sodium salts and their ammonium salts; primary amides of monoethylenically unsaturated monocarboxylic acids having 3 to 8 C atoms such as acrylamide and methacrylamide; monoethylenically unsaturated monomers which carry urea groups or keto groups, such as 2-(2-oxoimidazolidin-1-yl)ethyl (meth)acrylate, 2-ureido(meth)acrylate, N-[2-(2-oxo-oxazolidin-3-yl)ethyl] methacrylate, acetoacetoxyethyl acrylate, acetoacetoxypropyl methacrylate, acetoacetoxybutyl methacrylate, 2- (acetoacetoxy)ethyl methacrylate, diacetoneacrylamide (DAAM) and diacetonemethacrylamide; esters of acrylic and/or methacrylic acid with alkandiols having 2 to 4 C atoms, such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxyethyl ethacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, 3-hydroxybutyl acrylate,

3-hydroxybutyl methacrylate, 4-hydroxybutyl acrylate or 4-hydroxybutyl methacrylate.

In addition to the aformementioned monoethylenically unsaturated monomers the monomers may comprise a small amount of ethylenically unsaturated monomers which bear at least 2, e.g. 2 to 6 non-conjugated ethylenically unsaturated double bonds. These monomers will result in a crosslinking of the polymer chain during polymerization and thus are referred to as crosslinking monomers M3. Exemplary crosslinking monomers include divinylbenzene, diesters or triesters of dihydric and trihydric alcohols with monoethylenically unsaturated C3-C6 monocarboxylic acids, e.g., di(meth)acrylates, tri(meth)acrylates), and tetra(meth)acrylates, e.g. alkylene glycol diacrylates and dimethacrylates, such as ethylene glycol diacrylate, 1 ,3-butylene glycol diacrylate, 1 ,4-butylene glycol diacrylate and propylene glycol diacrylate, trimethylolpropan triacrylate and trimethacrylate, pentaerythrit triacrylate and pentaerythrit tetraacrylate, but also vinyl and allyl esters of ethylenically unsaturated acids such as vinyl methacrylate, vinyl acrylate, allyl methacrylate, allyl acrylate, and divinyl and diallyl esters of dicarboxyilic acids, such as diallyl maleate and diallyl fumarate and also methylenebisacrylamide. The amount of said monomers M3 will usually not exceed 3 pphm and, if present, is in particular in the range of 0.01 to 3, based on the total weight of monomers to be polymerized.

In addition to the aforementioned monoethylenically unsaturated monomers, the monomers may comprise a small amount of ethylenically unsaturated monomers which have one unsaturated double bond and a further reactive group susceptible to a postcrosslinking reaction, including monoethylenically unsaturated monomers containing a keto group, e.g., acetoacetoxyethyl(meth)acrylate or diacetonacrylamide; monoethylenically unsaturated monomers, which bear an epoxy group, such as monoeglycidyl allyl ether, glycidyl acrylate, glycidyl methacrylate, 2-glycidyloxyethyl acrylate, 2-glycidyloxyethyl methacrylate, 3-glycidyloxypropyl acrylate, 3-glycidyloxypropyl methacrylate, 4-glycidyloxybutyl acrylate

4-glycidyloxybutyl methacrylate, 3,4-epoxybutyl acrylate, 3,4-epoxybutyl methacrylate, 4,5-epoxypent-2-yl acrylate or 4,5-epoxypent-2-yl methacrylate with preference given to epoxy functionalized (meth)acrylate monomers;

N-alkylolamides of a,p-monoethylenically unsaturated carboxylic acids having 3 to 10 carbon atoms and esters thereof with alcohols having 1 to 4 carbon atoms, e.g. N-methylol acrylamide and N-methylol methacrylamide unsaturated silan functional monomers, e.g. monomers which in addition to an ethylenically unsaturated double bond bear at least one mono-, di- and/or tri-Ci - C₄-alkoxysilane group, such as vinyl trimethoxysilane, vinyl triethoxysilane, methacryloxyethyl trimethoxysilane, methacryloxyethyl triethoxysilane, and mixtures thereof.

The amount of said monomers M4 will usually not exceed 10 pphm and is in particular in the range of 0.01 to 10 pphm, based on the total weight of monomers to be polymerized.

The copolymer can be prepared by polymerizing the monomers using free-radical aqueous emulsion polymerization. The emulsion polymerization temperature is generally from 30 to 115° C or from 75 to 95° C. The polymerization medium can include water alone or a mixture of water and water-miscible liquids, such as methanol. Water may be used alone.

In emulsion polymerization the polymerization medium typically contains surface active compounds including emulsifiers and protective colloids and combinations thereof.

Frequently, the monomers comprising styrene and butyl acrylate, hereinafter monomers M, are polymerized in a radical emulsion aqueous emulsion polymerization, in particular in a free radical emulsion polymerization. This technique has been exhaustively described in the art, and is therefore well known to the skilled person [cf. , e.g., Encyclopedia of Polymer Science and Engineering, vol. 8, pages 659 to 677, John Wiley & Sons, Inc., 1987; D. C. Blackley, Emulsion Polymerisation, pages 155 to 465, Applied Science Publishers, Ltd., Essex, 1975; D. C. Blackley, Polymer Latices, 2nd edition, vol. 1 , pages 33 to 415, Chapman & Hall, 1997; H. Warson, The Applications of Synthetic Resin Emulsions, pages 49 to 244, Ernest Benn, Ltd., London, 1972; J. Piirma, Emulsion Polymerisation, pages 1 to 287, Academic Press, 1982; F. Hdlscher, Dispersionen synthetischer Hochpolymerer, pages 1 to 160, Springer-Verlag, Berlin, 1969, and patent specification DE-A 40 03422],

The radically initiated aqueous emulsion polymerization is normally accomplished by dispersing the ethylenically unsaturated monomers in aqueous medium, generally with accompanying use of surfactants, such as emulsifiers and/or protective colloids, and polymerizing them by means of at least one polymerization initiator, in particular a water- soluble radical polymerization initiator. These surfactants typically comprise emulsifiers and provide micelles in which the polymerization occurs, and which serve to stabilize the monomer droplets during aqueous emulsion polymerization and also growing polymer particles. The surfactants used in the emulsion polymerization are usually not separated from the polymer dispersion, but remain in the aqueous polymer dispersion obtainable by the emulsion polymerization of the monomers. The free- radically initiated aqueous emulsion polymerization is triggered by means of a free-radical polymerization initiator (free-radical initiator). These may in principle be peroxides or azo compounds. Of course, redox initiator systems are also useful . Peroxides used may, in principle, be inorganic peroxides, such as hydrogen peroxide or peroxodisulfates, such as the mono- or di-alkali metal or ammonium salts of peroxodisulfuric acid, for example the mono- and disodium, -potassium or ammonium salts, or organic peroxides such as alkyl hydroperoxides, for example tert-butyl hydroperoxide, p-menthyl hydroperoxide or cumyl hydroperoxide, and also dialkyl or diaryl peroxides, such as di-tert-butyl or di-cumyl peroxide. Azo compounds used are essentially 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile) and 2,2'-azobis(amidinopropyl) dihydrochloride (AIBA, corresponds to V-50 from Wako Chemicals). Suitable oxidizing agents for redox initiator systems are essentially the peroxides specified above. Corresponding reducing agents which may be used are sulfur compounds with a low oxidation state, such as alkali metal sulfites, for example potassium and/or sodium sulfite, alkali metal hydrogensulfites, for example potassium and/or sodium hydrogensulfite, alkali metal metabisulfites, for example potassium and/or sodium metabisulfite, formaldehydesulfoxylates, for example potassium and/or sodium formaldehydesulfoxylate, alkali metal salts, specifically potassium and/or sodium salts of aliphatic sulfinic acids and alkali metal hydrogensulfides, for example potassium and/or sodium hydrogensulfide, salts of polyvalent metals, such as iron(ll) sulfate, iron(ll) ammonium sulfate, iron(ll) phosphate, ene diols, such as dihydroxymaleic acid, benzoin and/or ascorbic acid, and reducing saccharides, such as sorbose, glucose, fructose and/or dihydroxyacetone. Preferred free-radical initiators are inorganic peroxides, especially peroxodisulfates, and redox initiator systems. In general, the amount of the free-radical initiator used, based on the total amount of monomers M, is 0.01 to 5 pphm, preferably 0.1 to 3 pphm.

The amount of free-radical initiator required in the process of the invention for the emulsion polymerization M can be initially charged in the polymerization vessel completely. However, it is also possible to charge none of or merely a portion of the free- radical initiator, for example not more than 30% by weight, especially not more than 20% by weight, based on the total amount of the free-radical initiator required in the aqueous polymerization medium and then, under polymerization conditions, during the free- radical emulsion polymerization of the monomers M to add the entire amount or any remaining residual amount, according to the consumption, batchwise in one or more portions or continuously with constant or varying flow rates.

Preferably, the radical emulsion polymerization of the monomers M is performed by a so-called feed process, which means that at least 90%, in particular at least 95% or the total amount of the monomers to be polymerized are metered to the polymerization reaction under polymerization conditions during a metering period P. The duration of the period P may depend on the production equipment, the reactivity of the monomers and the polymerization initiator and the feed rate of the monomers (starved conditions vs. flooded conditions) and may vary from e.g. 20 minutes to 12 h. Frequently, the duration of the period P will be in the range from 0.5 h to 5 h, especially from 1 h to 4 h.

The term "polymerization conditions" is generally understood to mean those temperatures and pressures under which the free-radically initiated aqueous emulsion polymerization proceeds at sufficient polymerization rate. They depend particularly on the free-radical initiator used. Advantageously, the type and amount of the free-radical initiator, polymerization temperature and polymerization pressure are selected such that a sufficient amount of initiating radicals is always present to initiate or to maintain the polymerization reaction.

It may be suitable to establish the polymerization conditions and to initially charge at least a portion of the free-radical initiator into the polymerization vessel before the metering of the monomers M is started.

In some cases it has been found advantageous to perform the free-radical emulsion polymerization in the presence of seed latex. A seed latex is a polymer latex which is present in the aqueous polymerization medium before the metering of the monomers M is started. The seed latex may help to better adjust the particle size of the final polymer latex obtained in the free-radical emulsion polymerization of the invention.

Principally every polymer iatex may serve as seed latex. For the purpose of the invention, preference is given to seed latices, where the particle size of the polymer particles is comparatively small. In particular, the Z average particle diameter of the polymer particles of the seed latex, as determined by dynamic light scattering at 20°C (see below) is preferably in the range from 10 to 80 nm, in particular from 10 to 50 nm. Preferably, the polymer particles of the seed latex is made of ethylenically unsaturated monomers, which comprise at least 95% by weight, based on the total weight of the monomers forming the seed latex, of one or more monomers M1 as defined above. In the polymer particles of the seed latex particular comprise at least 95% by weight, based on the total weight of the monomers forming the seed latex, of at least one monomer M1 or of a mixture of at least two monomers M1.

For this, the seed latex is usually charged into the polymerization vessel before the metering of the monomers M is started. In particular, the seed latex is charged into the polymerization vessel followed by establishing the polymerization conditions, e.g. by heating the mixture to polymerization temperature. It may be beneficial to charge at least a portion of the free-radical initiator into the polymerization vessel before the metering of the monomers M is started. However, it is also possible to meter the monomers and the free-radical polymerization initiator in parallel to the polymerization vessel.

The amount of seed latex, calculated as solids, may frequently be in the range from 0.01 to 10% by weight, in particular from 0.1 to 5% by weight, based on the total weight of the monomers M to be polymerized. The radical aqueous emulsion polymerization of the invention can be conducted at temperatures in the range from 0 to 170°C. Temperatures employed are generally in the range from 50 to 120°C, frequently from 60 to 120°C and often from 70 to 110°C. The free-radical aqueous emulsion polymerization of the invention can be conducted at a pressure of less than, equal to or greater than 1 atm (atmospheric pressure), and so the polymerization temperature may exceed 100°C and may be up to 170°C. Polymerization of the monomers is normally performed at ambient pressure but it may also be performed under elevated pressure. In this case, the pressure may assume values of 1.2, 1.5, 2, 5, 10, 15 bar (absolute) or even higher values. If emulsion polymerizations are conducted under reduced pressure, pressures of 950 mbar, frequently of 900 mbar and often 850 mbar (absolute) are established. Advantageously, the free-radical aqueous emulsion polymerization of the invention is conducted at ambient pressure (about 1 atm) with exclusion of oxygen, for example under an inert gas atmosphere, for example under nitrogen or argon.

The polymerization of the monomers M can optionally be conducted in the presence of chain transfer agents. Chain transfer agents are understood to mean compounds that transfer free radicals and which reduce the molecular weight of the or control chain growth in the polymerization. Examples of chain transfer agents are aliphatic and/or araliphatic halogen compounds, for example n-butyl chloride, n-butyl bromide, n-butyl iodide, methylene chloride, ethylene dichloride, chloroform, bromoform, bromotrichloromethane, dibromodichloromethane, carbon tetrachloride, carbon tetrabromide, benzyl chloride, benzyl bromide, organic thio compounds, such as primary, secondary or tertiary aliphatic thiols, for example ethanethiol, n-propanethiol, 2- propanethiol, n-butanethiol, 2-butanethiol, 2-methyl-2-propanethiol, n-pentanethiol, 2-pentanethiol, 3-pentanethiol, 2-methyl-2-butanethiol, 3-methyl-2-butanethiol, n-hexanethiol, 2-hexanethiol, 3-hexanethiol, 2-methyl-2-pentanethiol, 3-methyl-

2-pentanethiol, 4-methyl-2-pentanethiol, 2-methyl-3-pentanethiol, 3-methyl-

3-pentanethiol, 2-ethylbutanethiol, 2-ethyl-2-butanethiol, n-heptanethiol and the isomeric compounds thereof, n-octanethiol and the isomeric compounds thereof, n-nonanethiol and the isomeric compounds thereof, n-decanethiol and the isomeric compounds thereof, n-undecanethiol and the isomeric compounds thereof, n-dodecanethiol and the isomeric compounds thereof, n-tridecanethiol and isomeric compounds thereof, substituted thiols, for example 2-hydroxyethanethiol, aromatic thiols such as benzenethiol, ortho-, meta- or para-methylbenzenethiol, alkylesters of mercaptoacetic acid (thioglycolic acid), such as 2-ethylhexyl thioglycolate, alkylesters of mercaptopropionic acid, such as octyl mercapto propionate, and also further sulfur compounds described in Polymer Handbook, 3rd edition, 1989, J. Brandrup and E.H. Immergut, John Wiley & Sons, section II, pages 133 to 141, but also aliphatic and/or aromatic aldehydes, such as acetaldehyde, propionaldehyde and/or benzaldehyde, unsaturated fatty acids, such as oleic acid, dienes having nonconjugated double bonds, such as divinylmethane or vinylcyclohexane, or hydrocarbons having readily abstractable hydrogen atoms, for example toluene. Alternatively, it is possible to use mixtures of the aforementioned chain transfer agents that do not disrupt one another. The total amount of chain transfer agents optionally used in the process of the invention, based on the total amount of monomers M, will generally not exceed 1% by weight. However, it is possible, that during a certain period of the polymerization reaction the amount of chain transfer agent added to the polymerization reaction may exceed the value of 1% by weight, based on the total amount of monomers already added to the polymerization reaction.

The radical emulsion polymerization of the invention is usually effected in an aqueous polymerization medium, which, as well as water, comprises at least one surface-active substance (surfactant) for stabilizing the emulsion of the monomers and the polymer particles of the polymer latex.

The surfactant may be selected from emulsifiers and protective colloids. Protective colloids, as opposed to emulsifiers, are understood to mean polymeric compounds having molecular weights above 2000 Daltons, whereas emulsifiers typically have lower molecular weights. The surfactants may be anionic or nonionic or mixtures of non-ionic and anionic surfactants.

Anionic surfactants usually bear at least one anionic group, which is selected from phosphate, phosphonate, sulfate, and sulfonate groups. The anionic surfactants, which bear at least one anionic group, are typically used in the form of their alkali metal salts, especially of their sodium salts or in the form of their ammonium salts.

Preferred anionic surfactants are anionic emulsifiers, in particular those, which bear at least one sulfate or sulfonate group. Likewise, anionic emulsifiers, which bear at least one phosphate or phosphonate group may be used, either as sole anionic emulsifiers or in combination with one or more anionic emulsifiers, which bear at least one sulfate or sulfonate group.

Examples of anionic emulsifiers, which bear at least one sulfate or sulfonate group, are, for example, the salts, especially the alkali metal and ammonium salts, of alkyl sulfates, especially of C₈-C₂2-alkyl sulfates, the salts, especially the alkali metal and ammonium salts, of sulfuric monoesters of ethoxylated alkanols, especially of sulfuric monoesters of ethoxylated C8-C22- alkanols, preferably having an ethoxylation level (EO level) in the range from 2 to 40, the salts, especially the alkali metal and ammonium salts, of sulfuric monoesters of ethoxylated alkylphenols, especially of sulfuric monoesters of ethoxylated C4-Ci8-alkylphenols (EO level preferably 3 to 40), the salts, especially the alkali metal and ammonium salts, of alkylsulfonic acids, especially of C8-C22-alkylsulfonic acids, the salts, especially the alkali metal and ammonium salts, of dialkyl esters, especially di-C4-Ci₈-alkyl esters of sulfosuccinic acid, the salts, especially the alkali metal and ammonium salts, of alkylbenzenesulfonic acids, especially of C4-C22-alkylbenzenesulfonic acids, and the salts, especially the alkali metal and ammonium salts, of mono- or disulfonated, alkyl-substituted diphenyl ethers, for example of bis(phenylsulfonic acid) ethers bearing a C₄-C₂4-alkyl group on one or both aromatic rings. The latter are common knowledge, for example from US-A-4,269,749, and are commercially available, for example as Dowfax® 2A1 (Dow Chemical Company).

Also suitable are mixtures of the aforementioned salts.

Preferred anionic surfactants are anionic emulsifiers, which are selected from the following groups: the salts, especially the alkali metal and ammonium salts, of alkyl sulfates, especially of C₈-C22-alkyl sulfates, the salts, especially the alkali metal salts, of sulfuric monoesters of ethoxylated alkanols, especially of sulfuric monoesters of ethoxylated C₈-C₂2-alkanols, preferably having an ethoxylation level (EO level) in the range from 2 to 40, of sulfuric monoesters of ethoxylated alkylphenols, especially of sulfuric monoesters of ethoxylated C₄-Ci₈-alkylphenols (EO level preferably 3 to 40), of alkylbenzenesulfonic acids, especially of C4-C22-alkylbenzenesulfonic acids, and of mono- or disulfonated, alkyl-substituted diphenyl ethers, for example of bis(phenylsulfonic acid) ethers bearing a C₄-C₂4-alkyl group on one or both aromatic rings.

Examples of anionic emulsifiers, which bear a phosphate or phosphonate group, include, but are not limited to the following, salts selected from the following groups: the salts, especially the alkali metal and ammonium salts, of mono- and dialkyl phosphates, especially C₈-C₂2-alkyl phosphates, the salts, especially the alkali metal and ammonium salts, of phosphoric monoesters of C₂-C₃-alkoxylated alkanols, preferably having an alkoxylation level in the range from 2 to 40, especially in the range from 3 to 30, for example phosphoric monoesters of ethoxylated C₈-C₂2-alkanols, preferably having an ethoxylation level (EO level) in the range from 2 to 40, phosphoric monoesters of propoxylated C₈-C22-alkanols, preferably having a propoxylation level (PO level) in the range from 2 to 40, and phosphoric monoesters of ethoxylated-co-propoxylated C₈-C₂2-alkanols, preferably having an ethoxylation level (EO level) in the range from 1 to 20 and a propoxylation level of 1 to 20, the salts, especially the alkali metal and ammonium salts, of phosphoric monoesters of ethoxylated alkylphenols, especially phosphoric monoesters of ethoxylated C4-Ci₈-alkylphenols (EO level preferably 3 to 40), the salts, especially the alkali metal and ammonium salts, of alkylphosphonic acids, especially C8-C22-alkylphosphonic acids and the salts, especially the alkali metal and ammonium salts, of alkylbenzene- phosphonic acids, especially C4-C22-alkylbenzenephosphonic acids.

Further suitable anionic surfactants can be found in Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], volume XIV/1, Makromolekulare Stoffe [Macromolecular Substances], Georg-Thieme-Verlag, Stuttgart, 1961 , p. 192-208.

Preferably, the surfactant comprises at least one anionic emulsifier, which bears at least one sulfate or sulfonate group. The at least one anionic emulsifier, which bears at least one sulfate or sulfonate group, may be the sole type of anionic emulsifiers. However, mixtures of at least one anionic emulsifier, which bears at least one sulfate or sulfonate group, and at least one anionic emulsifier, which bears at least one phosphate or phosphonate group, may also be used. In such mixtures, the amount of the at least one anionic emulsifier, which bears at least one sulfate or sulfonate group, is preferably at least 50% by weight, based on the total weight of anionic surfactants used in the process of the present invention. In particular, the amount of anionic emulsifiers, which bear at least one phosphate or phosphonate group does not exceed 20% by weight, based on the total weight of anionic surfactants used in the process of the present invention.

As well as the aforementioned anionic surfactants, the surfactant may also comprise one or more nonionic surface-active substances, which are especially selected from nonionic emulsifiers. Suitable nonionic emulsifiers are e.g. araliphatic or aliphatic non ionic emulsifiers, for example ethoxylated mono-, di- and trialkylphenols (EO level: 3 to 50, alkyl radical: C4-C10), ethoxylates of long-chain alcohols (EO level: 3 to 100, alkyl radical: Cs-Cse), and polyethylene oxide/polypropylene oxide homo- and copolymers. These may comprise the alkylene oxide units copolymerized in random distribution or in the form of blocks. Very suitable examples are the EO/PO block copolymers. Preference is given to ethoxylates of long-chain alkanols, in particular to those where the alkyl radical Cs-Cso having a mean ethoxylation level of 5 to 100 and, among these, particular preference to those having a linear C12-C20 alkyl radical and a mean ethoxylation level of 10 to 50, and also to ethoxylated monoalkylphenols.

Preferably, the surfactant will be used in such an amount that the amount of surfactant is in the range from 0.2 to 5% by weight, especially in the range from 0.5 to 3% by weight, based on the monomers M to be polymerized.

The aqueous reaction medium in polymerization may in principle also comprise minor amounts (usually at most 5% by weight) of water-soluble organic solvents, for example methanol, ethanol, isopropanol, butanols, pentanols, but also acetone, etc. Preferably, however, the process of the invention is conducted in the absence of such solvents. It is frequently advantageous when the aqueous polymer dispersion obtained on completion of polymerization of the monomers M is subjected to an after-treatment to reduce the residual monomer content. This after-treatment is effected either chemically, for example by completing the polymerization reaction using a more effective free-radical initiator system (known as postpolymerization), and/or physically, for example by stripping the aqueous polymer dispersion with steam or inert gas. Corresponding chemical and physical methods are familiar to those skilled in the art - see, for example, EP-A 771328, DE-A 19624299, DE-A 19621027, DE-A 19741184, DE-A 19741187, DE- A 19805122, DE-A 19828183, DE-A 19839199, DE-A 19840586 and DE-A 19847115. The combination of chemical and physical aftertreatment has the advantage that it removes not only the unconverted ethylenically unsaturated monomers but also other disruptive volatile organic constituents (VOCs) from the aqueous polymer dispersion.

The radical aqueous emulsion polymerization may be carried out by a singlestage or by a multistage emulsion polymerization, in particular an aqueous radical emulsion polymerization, of a monomer composition M. The term "multistage" in the context of aqueous emulsion polymerization is well understood to mean that the relative concentration of the monomers in the monomer composition M added to the polymerization reaction is altered at least once during the aqueous emulsion polymerization. Such a procedure results in at least two polymer populations of different monomer compositions in the polymer particles of the latex. For example, it will be possible to change the monomer composition such that the multistage latex polymer features populations having different glass transition temperatures or a glass transition temperature (T_g) gradient. It may also be possible to change the monomer composition such that the multistage latex polymer features populations having different concentrations of polymerized acidic monomers.

During the addition of the monomers M, the type of monomers and/or the relative amounts thereof can be altered continuously or stepwise. However, it is also possible that the type and relative amounts of monomers M, which are added to the polymerization reaction remains constant. For example, it is possible that the ratio of styrene and butyl acrylate increases or decreases during the addition.

Preferably, the aqueous polymer dispersion is prepared by a radical aqueous emulsion polymerization by the so-called feed method, where during the feeding of the monomer composition M, where where at least 90% of the monomer composition M to be polymerised are metered to the polymerisation reaction under polymerisation conditions during a metering period P, and where the composition of the portion of the monomer composition M, which is metered to the polymerisation reaction under polymerisation conditions is changed at least once during the metering period P.

The copolymer emulsion includes, as a disperse phase, particles of the copolymer dispersed in water. The copolymer emulsion can be prepared with a total solids content of from 10 to 75% by weight, 15 to 65% by weight, or 20 to 60% by weight. The copolymer dispersion can then be concentrated if desired to provide a total solids content of 40 to 75% by weight.

The copolymer particles can have a Z-average particle size of from 80 nm to 1000 nm, or from 90 nm to 800 nm. For example, the copolymer particles can have a median particle size of 800 nm or less, 500 nm or less, 400 nm or less, 350 nm or less, 300 nm or less, 250 nm or less, 220 nm or less, 200 nm or less, or 50 nm or greater, 60 nm or greater, 70 nm or greater, 80 nm or greater, 90 nm or greater, 100 nm or greater. The average particle diameter as referred herein relates to the Z average particle diameter as determined by means of photon correlation spectroscopy (PCS), also known as quasielastic light scattering (QELS) or dynamic light scattering (DLS). The measurement method is described in the ISO 13321 : 1996 standard. The determination can be carried out using an HPPS (High Performance Particle Sizer). For this purpose, a sample of the aqueous polymer latex will be diluted and the dilution will be analysed. In the context of DLS, the aqueous dilution may have a polymer concentration in the range from 0.001 to 0.5% by weight, depending on the particle size. For most purposes, a proper concentration will be 0.01% by weight. However, higher or lower concentrations may be used to achieve an optimum signal/noise ratio. The dilution can be achieved by addition of the polymer latex to water or an aqueous solution of a surfactant in order to avoid flocculation. Usually, dilution is performed by using a 0.1% by weight aqueous solution of a non-ionic emulsifier, e.g. an ethoxylated C16/C18 alkanol (degree of ethoxylation of 18), as a diluent. Measurement configuration: HPPS from Malvern, automated, with continuous-flow cuvette and Gilson autosampler. Parameters: measurement temperature 20.0°C; measurement time 120 seconds (6 cycles each of 20 s); scattering angle 173°; wavelength laser 633 nm (HeNe); refractive index of medium 1.332 (aqueous); viscosity 0.9546 mPa s. The measurement gives an average value of the second order cumulant analysis (mean of fits), i.e. Z average. The "mean of fits" is an average, intensity-weighted hydrodynamic particle diameter in nm.

The polymers in the polymer dispersion may have a monomodal particle size distributions, including narrow and broad monomodal particle size distributions but also multimodal particle size distributions, depending on the desired purpose. The particle size distribution is characterized by the polydispersity index, which is a dimensionless number calculated from a simple 2 parameter fit to the correlation data of the cumulant analysis. The calculation is normally done as described in ISO 13321 :1996. Frequently, the PDI will be the range of 0.1 to 5.

Depending on the desired use, the polymer dispersions may have glass transition temperatures in a very broad range, e. g. in the range of -60 to 150°C. They may have more than one phase, e. g. 2, 3 or 5 different phases having identical or different glass transition temperatures. The glass transition temperature can be determined by the DSC method (differential scanning calorimetry, 20 K/min, midpoint measurement) in accordance to DIN 53765:1994-03 or ISO 11357-2, with sample preparation preferably to DIN EN ISO 16805:2005. The pH of the polymer dispersion may range from acidic to alkaline pH values, depending on the desired purpose and is frequently in the range of pH 2 to pH 10 or may be even higher e. g. up to pH 12.

The copolymer emulsion can be converted, in a manner known per se, to redispersible copolymer powders (e.g., spray drying, roll drying or suction-filter drying). If the copolymer dispersion is to be dried, drying aids can be used with the dispersion. The copolymer may have a long shelf life and can be redispersed in water for use in the coating or binding formulation.

The polymer dispersion obtained by the radical aqueous emulsion polymerization of the monomers M can be tailored to the desired purpose by choosing proper compositions of the monomers M. In particular, the polymer dispersions obtained by the radical aqueous emulsion polymerization of the monomers M can be used as binders in coating compositions, including masonry paints, interior paints, paints for wood coating and wood stains, and coating compositions for concrete and cement fiber board, as binder in paper coatings, as modifiers in hydraulically binding construction materials, such as concrete, plaster, and mortar, as binders in waterproofing membranes, as binders in flexible roofing, as binders for fiber bonding, and in adhesives, including e. g. pressure sensitive adhesives, construction adhesives and laminating adhesives.

The copolymers are, in general, used in the form of a composition which can be a coating or binding formulation and can include one or more mineral fillers and/or coating pigments. Mineral fillers generally have a substantial proportion of particles having a particle size greater than 2 microns whereas coating pigments have a substantial proportion of particles having a particle size less than 2 microns. In some embodiments, the mineral fillers and/or coating pigments can be added to impart certain properties to a coating such as smoothness, whiteness, increased density or weight, decreased porosity, increased opacity, flatness, glossiness, and the like. The mineral fillers and/or coating pigments can include calcium carbonate (precipitated or ground), kaolin, clay, talc, diatomaceous earth, mica, barium sulfate, magnesium carbonate, vermiculite, graphite, carbon black, alumina, silicas (fumed or precipitated in powders or dispersions), colloidal silica, silica gel, titanium oxides, aluminum hydroxide, aluminum trihydrate, satine white, and magnesium oxide. The formulation can include exclusively mineral fillers or coating pigments but generally includes a blend of mineral fillers and coating pigments (e.g. weight ratios of 90: 10, 80:20, 70:30, 60:40, 50:50, 40:60, 30:70, 20:80 or 10:90). Exemplary coating pigments include MIRAGLOSS 91 (a kaolin clay coating pigment commercially available from BASF Corporation) and HYDROCARB 90 (a calcium carbonate coating pigment commercially available from Omya Paper). An exemplary mineral filler is a calcium carbonate mineral filler such as DF 50 from Franklin Industrial Minerals. In some embodiments, the formulation can include non-toxic anticorrosive pigments. Examples of such anticorrosive pigments include phosphate-type anticorrosive pigments such as zinc phosphate, calcium phosphate, aluminum phosphate, titanium phosphate, silicon phosphate, and ortho- and fused-phosphates thereof.

In some embodiments, the formulation can include one or more dyes and/or colored pigments to produce a colored or patterned paper or to change the shade of the coating. Exemplary dyes can include basic dyes, acid dyes, anionic direct dyes, and cationic direct dyes. Exemplary colored pigments include organic pigments and inorganic pigments in the form of anionic pigment dispersions and cationic pigment dispersions.

In some embodiments, one or more thickeners (rheology modifiers) can be added to increase the viscosity of the coating or binding formulation. Suitable thickeners include acrylic copolymer dispersions sold under the STEROCOLL and LATEKOLL trademarks from BASF Corporation, Florham Park, N.J., hydroxyethyl cellulose, guar gum, jaguar, carrageenan, xanthan, acetan, konjac mannan, xyloglucan, urethanes and mixtures thereof. The thickeners can be added to the paper coating or binding formulation as an aqueous dispersion or emulsion, or as a solid powder. Exemplary dispersants can include sodium polyacrylates in aqueous solution such as those sold under the DARVAN trademark by R.T. Vanderbilt Co., Norwalk, Conn.

The coating or binding formulation described herein can include additives such as dispersants, initiators, stabilizers, chain transfer agents, buffering agents, salts, preservatives, fire retardants, wetting agents, protective colloids, biocides, corrosion inhibitors, crosslinkers, crosslinking promoters, and lubricants.

The binding or coating composition described herein can include greater than 50 wt % solids, 55 to 75 wt % solids, or 60 to 70 wt % solids. The one or more mineral fillers and/or coating pigments can be present in an amount greater than 65 wt %, 70 wt %, 80 wt %, or 90 wt % of the coating or binding formulation. For example, the one or more mineral fillers and/or coating pigments can be present in an amount of 70 to 98 wt %, 80 to 95 wt %, or 85 to 90 wt % of the total volume of the formulation. The copolymer can be present in an amount of 2 to 12 wt %, 4 to 10 wt %, or 6 to 9 wt % of the solid content. A thickener can be present in an amount of 0 to 5 wt %, greater than 0 to 3 wt %, or greater than 0 to 1 wt % of the solid content. Anticorrosive pigments, dyes and colored pigments can be present in an amount of 0 to 3 wt %, 0 to 2 wt %, or 0 to 1 wt % of the solid content. Other additives can be present in an amount of 0 to 5 wt %, 0 to 3 wt %, or 0 to 1 wt % of the solid content.

The compositions as described herein can be used in many applications and particularly as binding or coating compositions. For example, the compositions as described herein can be used as paper coatings, carpet backing, paints, surface coatings, and binders. When used as carpet backing the compositions as described herein can meet the low VOC limit requirements of the carpet industry (e.g., less than 75 ppm total of unreacted monomers such as styrene, ethylbenzene, 4-VCH (4-vinylcyclohexene), and 4-PCH (4- phenylcyclohexene); of this 75 ppm less than 50 ppm of either 4-VCH or 4-PCH, less than 40 ppm styrene, and less than 5 ppm ethylbenzene). Additionally, when used as paint, the compositions as described herein can meet the low VOC limit requirements of the paint industry set forth in EPA Method 24 (e.g., less than 50 g/l VOC's or even less than 10 g/l VOC's). Further, when used as carpet backing the compositions as described herein provide good resistance to wet delamination.

The invention is further illustrated by the examples that follow.

Examples (prophetical)

The effects of the invention are illustrated with respect to an exemplary embodiment of a copolymer having a composition as follows: styrene: 46 wt.-% n-butyl acrylate: 49 wt.-% acrylic acid: 3 wt.-% acrylamide: 2 wt.-%

The weight percentages are based on the total amount of monomers.

The copolymer (aqueous polymer latex) is produced by polymerizing a monomer composition as defined above by aqueous radical emulsion polymerization.

The renewably-sourced carbon content is the number of carbon atoms in percent that is derived from a renewable starting material based on the stoichiometry of the underlying chemical reaction(s).

Comparative Example (prophetical):

Styrene and n-butyl acrylate are manufactured based on a steam cracker that is fed with a feedstock consisting of: fossil naphtha: 95 wt.-% bio-naphtha: 1 wt.-% pyrolysis oil: 4 wt.-%.

The weight percentages are based on the total amount of the cracker feed.

The feedstock is fed to a steam cracker and subjected to steam cracking. Upon purification of the steam cracker effluent, one obtains ethylene, propylene and benzene, any one of which having a renewably-sourced carbon content of 5% (based on the assumption that the renewable carbon contained in the bio-naphtha and pyrolysis oil is equally distributed among the cracker products).

Styrene is manufactured by subjecting the ethylene to an alkylation reaction with benzene to obtain ethylbenzene. In a second reaction, the ethylbenzene is subjected to dehydrogenation to obtain styrene. The styrene thus obtained has a renewably-sourced carbon content of 5%.

A part of the propylene is subjected to oxidation to obtain acrylic acid having a renewably- sourced carbon content of 5%.

Another part of the propylene is subjected to hydroformylation to obtain butyraldehyde which is subsequently hydrogenated to obtain n-butyl alcohol. The syngas used in the hydroformylation is obtained from the gasification of a fossil feedstock. The resulting carbon monoxide is therefore fossil. The renewably-sourced carbon content of the n-butyl alcohol amounts to 3.8%.

The acrylic acid (renewably-sourced carbon content is 5%) and the n-butyl alcohol (renewably-sourced carbon content is 3.8%) are subjected to an esterification to obtain n-butyl acrylate having a renewably-sourced carbon content of 4.4%.

Since the amount of acrylic acid and acrylamide in the copolymer is only 5 wt.-% in total, they are employed as fossil based (their impact on the renewably-sourced carbon content of the resulting copolymer being low).

The copolymer obtained from the respective monomer has a renewably-sourced carbon content as specified in table below.

Example 1 (prophetical)

Propylene is manufactured from bio-ethanol by ethanol dehydration, ethylene dimerization and metathesis. The resulting propylene has a renewably-sourced carbon content of 100%.

The propylene thus obtained is mixed with fossil propylene in a ratio of 1 : 1 . The resulting propylene has a renewably-sourced carbon content of 50%. n-Butyl acrylate is manufactured in accordance with the comparative example with the proviso that the propylene having a renewably-source carbon content of 50% is used. The n-butyl acrylate thus obtained has renewably-source carbon content of 42.9%.

The copolymer is manufactured in accordance with the comparative example with the proviso that styrene, acrylic acid and acryl amide are all fossil based. The renewably- sourced carbon content of the resulting copolymer is specified in the table below. Example 2 (prophetical):

Propylene is manufactured from bio-ethanol by ethanol dehydration, ethylene dimerization and metathesis. The resulting propylene has a renewably-sourced carbon content of 100% and is used for the manufacture of n-butyl acrylate. The n-butyl acrylate thus obtained has renewably-source carbon content of 85.7%.

The copolymer is manufactured in accordance with Example 1 with the proviso that the n-butyl acrylate being employed has a renewably-sourced carbon content of 85.7%. The renewably-sourced carbon content of the resulting copolymer is specified in table below.

Example 3 (prophetical):

The copolymer is manufactured in accordance with Example 2 with the proviso that the styrene being employed has a renewably-sourced carbon content of 5% (manufactured as specified in the comparative example). The renewably-sourced carbon content of the resulting copolymer is specified in table below.

Example 4 (prophetical) n-Butyl acrylate is manufactured in accordance with Examples 3 with the proviso that the syngas used in the hydroformylation of n-butyraldehyde is obtained from the gasification of wood waste. The resulting carbon monoxide having a renewably-sourced carbon content of 100%. The n-butyl acrylate thus obtained has a renewably-sourced carbon content of 100%.

The copolymer is manufactured in accordance with Example 3 with the proviso that the n-butyl acrylate being employed has a renewably-sourced carbon content of 100%. The renewably-sourced carbon content of the resulting copolymer is specified in table below.

Example 5 (prophetical)

The ethylene used for the production of styrene is a 1 :1 mixture of ethylene obtained from a cracker feed having a renewably-sourced carbon content of 5% and ethylene obtained from dehydration of bio-ethanol. The styrene thus obtained has a renewably- sourced carbon content of 28.75%.

The copolymer is manufactured in accordance with Example 3 with the proviso that the styrene being employed has a renewably-sourced carbon content of 28.75%. The renewably-sourced carbon content of the resulting copolymer is specified in table below. Example 6 (prophetical)

The copolymer is manufactured in accordance with Example 4 with the proviso that the styrene being employed has a renewably-sourced carbon content of 28.75%. The renewably-sourced carbon content of the resulting copolymer is specified in table below.

The results for the Comparative Example and Examples 1 to 6 are summarized in the following table:

rc: renewably-sourced carbon content

Claims

Claims

1. A process for the manufacture of styrene acrylic copolymers having a renewably- sourced carbon content, said process comprising the steps of: a) subjecting a feedstock comprising a renewably-sourced ethanol to dehydration to produce a renewably-sourced ethylene stream; b) subjecting at least a portion of the renewably-sourced ethylene stream to an olefin-interconversion, to obtain a renewably-sourced propylene; the olefin- interconversion comprising (i) and (ii):

(i) ethylene dimerization to obtain n-butenes;

(ii) metathesis reaction between n-butenes obtained according to (i) and ethylene to obtain propylene; and c) subjecting a portion of the renewably-sourced propylene to an oxidation reaction to produce acrylic acid; d) subjecting a portion of the renewably-sourced propylene to a hydroformylation reaction with syngas to produce n-butyraldehyde; e) subjecting the n-butyraldehyde to hydrogenation to produce n-butanol; f) esterifying acrylic acid obtained in step c) and the n-butanol to produce n-butyl acrylate; g) subjecting ethylene to an alkylation reaction with benzene to produce ethylbenzene; h) subjecting the ethylbenzene to a dehydrogenation reaction to produce styrene; i) copolymerizing the styrene and the n-butyl acrylate to produce a styrene acrylic copolymer.

2. The process according to claim 1, comprising blending the renewably-sourced ethylene with complementary ethylene prior to step b), the complementary ethylene not being obtained from renewably-sourced ethanol in accordance with step a); and/or blending the renewably-sourced propylene with complementary propylene prior to steps c) and d), the complementary propylene not being obtained from renewably-sourced ethanol in accordance with steps a) and b); and/or blending the renewably-sourced n-butenes with complementary n-butenes prior to step b)-(ii), the complementary n-butenes not being obtained from renewably- sourced ethanol in accordance with steps a) and b)-(i).

3. The process according to claim 1 or 2, wherein step b)-(i) comprises:

- contacting the renewably-sourced ethylene stream with a dimerization catalyst in a dimerization zone; - operating said dimerization zone at conditions effective to produce an effluent consisting essentially of n-butenes, heavier olefins, and optionally unconverted ethylene;

- fractioning the effluent to recover a stream consisting essentially of n-butenes, a stream consisting essentially of heavier olefins, and an optional ethylene stream; and

- optionally subjecting the stream consisting essentially of heavier olefins to hydrogenation so as to obtain renewably-sourced naphtha.

4. The process according to any one of claims 1 to 3, wherein the n-butenes are a mixed stream including 1 -butene and 2-butenes, and wherein b)-(ii) comprises removal of 1 -butene from the mixed stream to obtain a stream rich in 2-butenes, and subjecting the stream rich in 2-butenes to the metathesis reaction.

5. The process according to any one of claims 1 to 3, wherein the n-butenes are a mixed stream including 1 -butene and 2-butenes, and wherein b)-(ii) comprises b)-(iia) subjecting the mixed stream to the metathesis reaction to obtain propylene and unreacted 1 -butene; b)-(iib) subjecting the unreacted 1 -butene to double bond isomerization to obtain 2-butenes; and b)-(iic) recycling the 2-butenes obtained in step b)-(iib) to step b)-(iia).

6. The process according to any one of claims 1 to 3, wherein the n-butenes are a mixed stream including 1 -butene and 2-butenes, and wherein b)-(ii) comprises passing the mixed stream through a metathesis/isomerization zone comprising both a metathesis catalyst and an isomerization catalyst.

7. The process according to any one of the preceding claims, wherein the oxidation of the renewably-sourced propylene according to step c) is carried out in one stage or in two stages with acrolein as intermediate.

8. The process according to claim 7, wherein propylene is oxidized to acrolein in the presence of molecular oxygen in the first stage and the reaction product is then further oxidized to acrylic acid.

9. The process according to claim 7 or 8, wherein the propylene oxidation comprises c)-(i) catalytic gas phase oxidation of propylene and/or acrolein to obtain a gaseous reaction product comprising acrylic acid; c)-(ii) solvent absorption of the reaction product; c)-(iii) distillation of the solvent loaded with reaction product to obtain crude acrylic acid; and c)-(iv) purification of the crude acrylic acid by crystallization.

10. The process according to any one of the preceding claims, wherein the alkylation of benzene with the renewably-sourced ethylene according to step g) is carried out at a temperature of 80 to 130 °C and in the presence of a Lewis acid catalyst to produce ethylbenzene.

11. The process according to any one of the preceding claims, wherein the dehydrogenation of ethylbenzene according to step h) is carried out with steam over a catalyst comprising iron oxide.

12. The process according to any one of the preceding claims, wherein the benzene is obtained by

- subjecting a cracker feed to steam cracking to obtain a cracker effluent;

- recovering from the cracker effluent a pyrolysis gasoline;

- recovering benzene from the pyrolysis gasoline.

13. The process according to any one of the preceding claims, wherein the ethylene of step g) is obtained by at least one of

- subjecting a cracker feed to steam cracking to obtain a cracker effluent;

- recovering ethylene from the cracker effluent; and

- subjecting a feedstock comprising a renewably-sourced ethanol to dehydration to produce ethylene.

14. Process according to claim 12 or 13, wherein the cracker feed comprises at least one of pyrolysis oil and bio-naphtha.

15. The process according to any one of the preceding claims, wherein the syngas of step d) is obtained by:

- subjecting a gasifier feed stream comprising a renewably-sourced material to gasification in a gasifier to obtain a gasifier effluent; recovering syngas from the gasifier effluent.