CN110937915B - Integral titanium-doped aluminum oxide material and preparation method thereof - Google Patents

Abstract

The invention discloses an integral titanium-doped aluminum oxide material and a preparation method thereof. The material is of a honeycomb structure, the wall of the honeycomb hole is provided with microscopic macroporous pores, the pore diameter of the macroporous is 50-1000nm, the macropores are uniformly distributed and are communicated in a three-dimensional way, and the ratio of the pore diameter of the macroporous to the wall thickness of the corresponding hole wall is 1-2. The preparation method of the material comprises the following steps: (1) uniformly dispersing boehmite powder in water to obtain a boehmite suspension, slowly adding a peptizing agent into the boehmite powder suspension, and heating and aging to obtain alumina sol; (2) inorganic aluminum salt, polyethylene glycol, alumina sol, titanium alkoxide amide compounds and low-carbon alcohol aqueous solution are mixed, then propylene oxide and/or pyridine are added, and the mixture is cast into a reverse honeycomb mould for molding. The method does not add an organic template, the preparation process is environment-friendly, the process is simple and easy to implement, and the product of the invention has macroscopic and microscopic macroporous structures, is very suitable to be used as a heterogeneous catalytic carrier, and is easy for industrial production.

Description

Integral titanium-doped aluminum oxide material and preparation method thereof

Technical Field

The invention belongs to the field of inorganic material preparation, and relates to an integral titanium-doped aluminum oxide material and a preparation method thereof.

Background

The integral macroporous oxide has a larger pore channel structure, a higher specific surface area and good thermal stability, and is widely applied to the fields of heterogeneous catalysts, catalyst carriers, adsorption separation materials, chromatographic packing, electrode materials, acoustic resistance and thermal resistance materials and the like.

"Synthesis of Porous Silica and Metal Oxide Beads Using Emulsion-functionalized Polymer foams" (Chemical Material,2004,16:4245-₂、Al₂O₃、TiO₂And ZrO₂After the precursor is converted, the template is finally roasted to remove the template to obtain the corresponding macroporous oxide material, and the pore diameter of the macropore can be controlled between a micron level and a millimeter level. In the method, the preparation of the template needs to use a surfactant and a stabilizer, the preparation process is complicated, the cost of the used raw materials including the surfactant is high, and the used acrylamide organic monomer has carcinogenicity. In addition, when the template is removed by baking, the emission irritation is strong, and the environmental pollution is large.

"Macroporos aluminum monolithins prepared by filing polymer foams with aluminum hydrosols" (J Mater. Sci.,2009,44: 931-938.) reported a technique of preparing a Macroporous polystyrene foam template by a high concentration emulsion polymerization method, then filling the template with an alumina hydrosol, converting, and removing the template by calcination to obtain the monolithic Macroporous alumina. The technology takes styrene as an organic monomer, divinyl benzene as a cross-linking agent, SPAN-80 as a surfactant and azodiisobutyronitrile as an initiator, and the cost of the used organic raw materials and the surfactant is relatively low.

CN101200297A discloses a preparation method of monolithic macroporous alumina: preparing integral type by adopting reverse concentrated emulsion method and taking styrene and divinylbenzene as monomersA macroporous organic template; preparation of Al by using aluminium isopropoxide or pseudo-boehmite as precursor₂O₃Hydrosol; mixing Al₂O₃Filling the hydrosol into the integral macroporous organic template; and drying the filled integral organic/inorganic composite, and roasting at 600-900 ℃ to remove the template to obtain the integral macroporous alumina. The method has the advantages that the preparation process is simple and easy to implement, and the prepared integral macroporous alumina has micron-sized interconnected macroporous channels with the pore diameter of 1-50 mu m. The method for preparing the integral macroporous alumina is simple and easy to implement, but the volume fraction of the water phase in the method accounts for 75-90%, and correspondingly the volume fraction of the organic monomer is relatively low. The mechanical strength of the material is low. Meanwhile, similar to the other patents, the organic monomer has a certain toxicity, and when the template is removed by roasting, the emission has strong irritation, and the environment is polluted.

For the alumina material, it is difficult for a simple alumina carrier to well meet the demand of the hydrogenation technology, and thus, it is necessary to prepare a composite alumina carrier by introducing a specific element. Titanium oxide has good acidity and carbon deposit and poisoning resistance, but is not suitable for catalytic carrier materials by itself due to small specific surface area and pore volume. If the modified titanium oxide is introduced onto alumina as a modifying component to form a composite carrier, the composite has the advantages of high specific surface area and high pore volume of alumina, good acidity, carbon deposit resistance, poisoning resistance and the like of titanium oxide.

The titanium modified nano self-assembled macroporous alumina carrier is prepared by adopting titanium tetrachloride as a raw material (application chemical industry, 2016, 45 (9): 1788-. However, the adopted super-solubilization self-assembly method is very similar to a nitrate emulsion explosive preparation system, and the explosion hidden danger is large under the high-temperature and high-pressure reaction. At the same time, the titanium tetrachloride solution used is hydrolyzed to produce titanium dioxide particles, which results in an uneven distribution of the titanium element in the material. "preparation of titanium-aluminum composite oxide carrier and its performance research" (inorganic salt industry, 2018, 50 (3): 74-76) adopts coprecipitation method to prepare titanium-aluminum composite oxide, and the obtained product has no three-dimensional macroporous structure.

CN99113284.X prepares titanium-containing aluminum hydroxide, but because the titanium salt solution contains chloride ions, sulfate ions and other ions, which corrode equipment, the emission generated during roasting has serious environmental pollution, and the obtained product does not have a three-dimensional macroporous structure. CN201410484413.1 adopts the extrusion to prepare titanium aluminium composite oxide honeycomb body, and the honeycomb pore wall is compact, and is difficult to have controllable and three-dimensional through macroporous structure.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides an integral titanium-doped aluminum oxide material and a preparation method thereof. The method does not add an organic template, the preparation process is environment-friendly, the process is simple and easy to implement, and the product of the invention has macroscopic and microscopic macroporous structures, is very suitable to be used as a heterogeneous catalytic carrier, and is easy for industrial production.

The integral titanium-doped aluminum oxide material is of a honeycomb structure, the wall of each honeycomb hole is provided with microscopic macroporous pores, the pore diameter of each macroporous pore is 50-1000nm, the macropores are uniformly distributed and are communicated in a three-dimensional mode, and the ratio of the pore diameter of each macroporous pore to the corresponding wall thickness is 1-2.

The total porosity of the monolithic titanium-doped alumina material of the present invention is 70% to 95%, preferably 75% to 90%; specific surface area of 150-450m²G, pore volume of 0.5-1.5cm³(ii) in terms of/g. The mechanical strength of the monolithic titanium-doped alumina material is 5 to 30N/mm, preferably 10 to 25N/mm. The titanium content, calculated as titanium dioxide, is 0.5wt% to 45wt%, preferably 1wt% to 35wt%, based on the total weight of the monolithic titanium-doped alumina material; the titanium is uniformly dispersed in the form of titanium dioxide alumina, and the cluster size of titanium element is more than 2.5nm and less than 5.0 nm.

Macroscopic appearances of the monolithic titanium-doped aluminum oxide materials of the present invention include, but are not limited to, cylindrical, bar-shaped, spherical, and other types of monolithic morphologies. The number of the honeycomb holes distributed on the cross section is 1-50/cm based on the cross section vertical to the honeycomb hole channel²Preferably 2 to 25/cm². The shape of the opening of the honeycomb hole is round, clover-shaped, square or other special shapes, and round, clover-shaped and square shapes are preferred.

The preparation method of the integral titanium-doped aluminum oxide material comprises the following steps:

(1) uniformly dispersing boehmite powder in water to obtain a boehmite suspension, slowly adding a peptizing agent into the boehmite powder suspension, and after the addition is finished, heating and aging for a certain time to obtain clear alumina sol;

(2) under the inert atmosphere, uniformly mixing aluminum sol, inorganic aluminum salt, ethyl acetoacetate, titanium alkoxide, polyethylene glycol, amide compounds and a lower alcohol aqueous solution, then adding propylene oxide and/or pyridine, uniformly mixing, and casting the mixture into a reverse honeycomb mold until gel is formed;

(3) aging the gel obtained in the step (2) at 20-80 ℃ for 12-120 hours, and removing the die to obtain an aged product;

(4) and soaking the aged product in a low-carbon alcohol aqueous solution, then carrying out solid-liquid separation, and drying and roasting a solid phase to obtain the integral titanium-doped aluminum oxide material.

The solid content of the suspension liquid in the step (1) is 1-15 wt%.

The step (1) is carried out under the condition of stirring, and the aging is carried out in a heating reflux mode, wherein the reflux temperature is 70-95 ℃, and the reflux time is 1-12 hours.

The peptizing agent in the step (1) is a commonly used peptizing agent in the preparation process of the aluminum sol, and can be one or more of hydrochloric acid, nitric acid, sulfuric acid, formic acid or acetic acid. The peptizing agent (the dosage of which is H contained in the peptizing agent) in the step (1)⁺Calculated) with boehmite powder (in an amount calculated on the basis of Al contained)⁺The mol ratio of Al to Al is 0.05-1.

The inert atmosphere in the step (2) may be one or more of nitrogen, helium, neon, argon or xenon, and nitrogen is generally selected.

Based on the weight of the mixture obtained in the step (2), the carbon content is lowThe adding amount of the alcohol water solution is 10 to 80 weight percent, the adding amount of the inorganic aluminum salt is 5 to 30 weight percent, the adding amount of the aluminum sol is 1 to 10 weight percent, and the adding amount of the polyethylene glycol is 0.1 to 3.0 weight percent, preferably 0.2 to 2.0 weight percent; the addition amount of the titanium alkoxide is 0.5 to 10 weight percent. Wherein the mass ratio of water to the low-carbon alcohol in the low-carbon alcohol aqueous solution is 1.0-1.5; the addition amount of the amide compound is 0.1-5.0 wt%; propylene oxide and/or pyridine with Al³⁺(not including Al in the alumina sol) in a molar ratio of 1.5 to 9.5, preferably 3.0 to 7.5. The propylene oxide and pyridine may be mixed in any proportion.

The adding sequence of the materials in the step (2) is not particularly limited, wherein the lower alcohol and the water in the lower alcohol aqueous solution can be added separately, preferably: water, low carbon alcohol, inorganic aluminum salt, alumina sol, polyethylene glycol, titanium alkoxide and amide compounds are added in sequence. Before the latter material is added, the previously added materials need to be mixed uniformly.

The inorganic aluminum salt in the step (2) is one or more of aluminum nitrate, aluminum chloride or aluminum sulfate.

The titanium alkoxide in the step (2) is tetraethyl titanate, tetraisopropyl titanate, tetrapropyl titanate, tetrabutyl titanate, tetrapentyl titanate or a mixture of the tetrabutyl titanate and the tetrapropyl titanate in any proportion.

The polyethylene glycol molecular weight viscosity average molecular weight in the step (2) is 10000-.

The lower alcohol in the steps (2) and (4) is generally C₅The alcohol is preferably one or more of methanol, ethanol, n-propanol and isopropanol, and most preferably ethanol and/or propanol.

The amide compound in the step (2) can be one or more of formamide, acetamide, N-dimethylformamide, N-methylacetamide, benzamide and 2-phenylacetamide.

The shape of the reverse honeycomb mold in the step (3) can be selected or manufactured according to actual needs, and the material of the mold includes but is not limited to various plastic materials, metal materials, wood materials and other materials.

The soaking conditions in the step (4) are as follows: the soaking temperature is 10-80 ℃, and the soaking time is 12-60 hours.

The mass concentration of the lower alcohol aqueous solution used for soaking in the step (4) is not less than 50 wt%.

The drying in the step (4) is ordinary normal pressure drying, the drying temperature is not more than 120 ℃, and is preferably 20-100 ℃, and the drying is carried out until the product is not obviously reduced in weight. The roasting is carried out at 400-750 ℃ for 1-24 hours, preferably at 500-700 ℃ for 2-12 hours.

The invention casts the sol of inorganic aluminum salt on the reverse honeycomb mould to finally form a super large honeycomb pore structure. For the pore wall of the honeycomb super-large pore, the invention can obtain the three-dimensional through and uniformly distributed large pore by utilizing the sol-gel reaction characteristic of inorganic aluminum salt: the aluminum sol crystal seeds are introduced into the preparation system to induce the aluminum oxide precursor to evolve from the amorphous precursor to the crystalline precursor, so that the aluminum oxide precursor can be easily converted into the gamma crystalline state at a lower roasting temperature, and the energy consumption can be obviously saved. The introduction of the alumina sol crystal seed ensures that the wall of the macroporous hole generates a large amount of particles, and the wall of the macroporous hole is changed from a smooth compact state into a particle aggregate, which is beneficial to generating particle pores and improving the specific surface area of the material, thereby enlarging the contact area of the reaction material and the catalyst to improve the reaction activity. The addition of the amide compound can inhibit the generation of super-large pores, so that the large pores are more uniformly concentrated, and the stress effect caused by uneven pore channel size is favorably eliminated. The precursor of titanium adopted in the invention is titanium alkoxide, the titanium alkoxide has good miscibility with other components in a reaction system containing a large amount of low-carbon alcohol, the pH value of the system is acidic, homogeneous gel can be formed, and the titanium alkoxide can be prevented from being rapidly hydrolyzed to the maximum extent by adopting inert gas protection and ethyl acetoacetate in the reaction system, so that the uniformly dispersed titanium doping effect can be obtained. And thus can be uniformly doped in the final alumina bulk phase. The gelation reaction of the sol in the limited space of the reverse honeycomb mould is also beneficial to improving the mechanical strength of the whole material. By controlling the reaction conditions, compared with the sizes of the pore diameters of the macropores, the pore walls of the macropores of the macroporous alumina prepared by the invention are equal to or larger than the sizes of the macropores, and the relatively thick pore walls ensure that the material has higher mechanical strength and can better meet the harsh application requirements in industry. The alumina material of the present invention ultimately forms a monolithic morphology having a macro-super macro pore structure.

The integral macroporous alumina can be used as a carrier of a heterogeneous catalyst, and is applied to various macromolecular catalytic reactions, such as hydrogenation reaction, alkylation reaction, desulfurization and denitration reaction, pollutant adsorption and degradation in the water treatment process and the like.

Drawings

The left side of fig. 1 is a schematic view of the pore channel structure of the monolithic macroporous alumina material in example 1, and the right side is a scanning electron microscope image of the macroporous alumina prepared in example 1.

FIG. 2 is a STEM-EDS-MAPPING graph of titanium modified monolithic macroporous alumina prepared in example 1.

Detailed Description

The present invention will be described in further detail with reference to examples. In the invention, the shape of the honeycomb super-large hole of the integral material is directly observed by an optical microscope or an optical camera, and the large hole on the wall of the honeycomb hole and the three-dimensional through condition of the large hole are observed by a scanning electron microscope. The crystalline state was tested by XRD. The porosity and the average pore diameter of the macroporous alumina are characterized and tested by a mercury intrusion method. The mechanical strength of the material was tested using a DL2 type strength tester manufactured by daintian scientific and technological development ltd. The boehmite powder is a product sold in the market or manufactured by self. The titanium content is measured by an XRF method, the titanium phase dispersion uniformity is characterized by a STEM-EDS-MAPPING method of a field emission super-resolution transmission electron microscope, 10 positions of a sample are randomly selected in the test, a STEM-EDS-MAPPING picture of a titanium element is made, the relative size of a bright spot representing the distribution of the titanium element in the picture represents the size and the distribution uniformity of the titanium element cluster, and the average distance between adjacent titanium element clusters is not more than 30nm and is regarded as uniform distribution. The titanium element exists in the bulk phase in the form of titanium dioxide, the cluster size of the titanium element is not equal to the particle size of the titanium dioxide, but the larger the cluster size of the titanium element is, the larger the particle size or aggregate size of the titanium dioxide is, and the more uniform the cluster distribution of the titanium element is, the more uniform the distribution of the titanium dioxide is.

Example 1

Preparing aluminum sol: mixing boehmite powder and distilled water to form a suspension (solid content is 3 wt%), dropwise adding hydrochloric acid under the condition of continuous stirring to meet the acid/aluminum molar ratio of 0.08, and heating to 90 ℃ after dropwise adding, and refluxing for 8 hours to form clear aluminum sol.

Uniformly mixing water, absolute ethyl alcohol, aluminum chloride, ethyl acetoacetate, tetrapropyl titanate, polyethylene glycol, aluminum sol and formamide at room temperature, and then adding pyridine, wherein the mixture comprises the following components in parts by weight: 22wt% of water, 20wt% of ethanol, 20wt% of aluminum chloride, 1wt% of ethyl acetoacetate, 3.5wt% of tetrapropyl titanate, 1.0wt% of polyethylene glycol (with a viscosity average molecular weight of 50 ten thousand), 1.5wt% of aluminum sol, 1.0wt% of formamide and 30% of pyridine (in the step, nitrogen is introduced for protection). After uniform mixing, casting into a selected reverse honeycomb mould, continuing aging for 48 hours at 50 ℃ after gelation, soaking the aged mixture for 48 hours by using 50wt% of ethanol aqueous solution after demoulding, drying at 50 ℃ after soaking and liquid phase removal until the product is not obviously reduced, and then roasting for 3 hours at 550 ℃ to obtain the cylindrical integral aluminum oxide material.

The obtained monolithic alumina material had a total porosity of 78% and a specific surface area of 301m²Per g, pore volume 0.57cm³(ii) in terms of/g. The XRD results showed that the bulk material was gamma crystalline alumina. The mechanical strength of the monolithic alumina material was 14N/mm. The honeycomb holes are square holes with side length of 1.2mm and the honeycomb holes distributed on the cross section are 9/cm²The distribution of the honeycomb holes on the cross section is ordered. The walls of the honeycomb holes are provided with microscopic macroporous pores, the pore diameter of the macropores is 321nm, the macropores of the walls of the honeycomb holes are uniformly distributed and are communicated in a three-dimensional mode, and the ratio of the pore diameter of the macropores contained in the walls of the honeycomb holes to the corresponding wall thickness is 1.2. The titanium dioxide content is 14.8wt%, and the STEM-EDS-MAPPING of the field emission super-high resolution transmission electron microscope shows that the cluster size of titanium on the alumina phase is about 2.5nm, and the titanium is uniformly distributed.

Example 2

The preparation of the aluminum sol was the same as in example 1.

Uniformly mixing water, absolute ethyl alcohol, aluminum chloride, ethyl acetoacetate, tetraethyl titanate, polyethylene glycol, alumina sol and benzamide at room temperature, and then adding pyridine, wherein the mixture comprises the following components in parts by weight: 22wt% of water, 20wt% of ethanol, 22wt% of aluminum chloride, 1.5wt% of ethyl acetoacetate, 4.0wt% of tetraethyl titanate, 1.0wt% of polyethylene glycol (viscosity-average molecular weight of 100 ten thousand), 1.0wt% of alumina sol, 1.5wt% of benzamide and 27% of pyridine (nitrogen is introduced in the step for protection). And after uniform mixing, casting the mixture into a selected reverse honeycomb mould, continuously aging for 72 hours at 40 ℃ after gelation, soaking the aged mixture for 72 hours by using ethanol after demoulding, drying at 60 ℃ until the product is not obviously reduced after soaking and liquid phase removal, and then roasting for 3 hours at 750 ℃ to obtain the square column integral alumina material.

The obtained monolithic alumina material had a total porosity of 71% and a specific surface area of 231m²Per g, pore volume 0.61cm³(ii) in terms of/g. The XRD results showed that the bulk material was gamma crystalline alumina. The mechanical strength of the monolithic alumina material was 24N/mm. The honeycomb holes have a hole opening shape of a circular hole with a diameter of 0.8 mm, and the number of the honeycomb holes distributed on the cross section is 10/cm²The distribution of the honeycomb holes on the cross section is ordered. The walls of the honeycomb holes are provided with microscopic macroporous pores, the pore diameter of the macropores is 502nm, the macropores of the walls of the honeycomb holes are uniformly distributed and are communicated in a three-dimensional mode, and the ratio of the pore diameter of the macropores contained in the walls of the honeycomb holes to the corresponding wall thickness is 2.0. The titanium dioxide content is 18.1wt%, and the STEM-EDS-MAPPING of the field emission super-high resolution transmission electron microscope shows that the cluster size of titanium on the alumina phase is about 3.0nm, and the titanium is uniformly distributed.

Example 3

Preparing aluminum sol: mixing boehmite powder and distilled water to form suspension (solid content is 1.5 wt%), dropwise adding acetic acid under the condition of continuous stirring to meet the acid/aluminum molar ratio of 0.1, and heating to 90 ℃ after the dropwise adding is finished, and refluxing for 10 hours to form clear sol.

Uniformly mixing water, absolute ethyl alcohol, aluminum chloride, tetrabutyl titanate, polyethylene glycol, alumina sol and acetamide at room temperature (about 25 ℃), and then adding pyridine, wherein the mixture comprises the following components in parts by weight: 21wt% of water, 20wt% of ethanol, 22wt% of aluminum chloride, 1.5wt% of ethyl acetoacetate, 7wt% of tetrabutyl titanate, 1.5wt% of polyethylene glycol (viscosity average molecular weight is 10 ten thousand), 1wt% of alumina sol, 1wt% of acetamide and 25wt% of pyridine (nitrogen is introduced in the step for protection). And after uniform mixing, casting the mixture into a selected reverse honeycomb mould, continuously aging for 72 hours at 40 ℃ after gelation, soaking the aged mixture for 72 hours by using ethanol after demoulding, drying at 60 ℃ until the product is not obviously reduced after soaking and liquid phase removal, and then roasting for 3 hours at 600 ℃ to obtain the cylindrical integral alumina material.

The obtained monolithic alumina material had a total porosity of 86% and a specific surface area of 414m²Per g, pore volume 0.71cm³(ii) in terms of/g. The XRD results showed that the bulk material was gamma crystalline alumina. The mechanical strength of the monolithic alumina material was 25N/mm. The honeycomb holes have round holes with diameter of 0.5 mm, and the number of honeycomb holes distributed on the cross section is 16/cm²The distribution of the honeycomb holes on the cross section is ordered. The walls of the honeycomb holes are provided with microscopic macroporous pores, the pore diameter of each macroporous pore is 158nm, the macropores of the walls of the honeycomb holes are uniformly distributed and are communicated in a three-dimensional mode, and the ratio of the pore diameter of the macropores contained in the walls of the honeycomb holes to the corresponding wall thickness is 2.0. The titanium dioxide content is 23.4wt%, and the STEM-EDS-MAPPING of the field emission super-high resolution transmission electron microscope shows that the cluster size of titanium on the alumina phase is about 4.2nm, and the titanium is uniformly distributed.

Comparative example 1

Macroporous alumina was prepared according to the method of Chemical materials, 2004,16: 4245-. The material obtained has only one type of macropore distribution and a mechanical strength of only 1N/mm.

Comparative example 2

Monolithic macroporous alumina was prepared according to the method of CN101200297A, and the obtained material had only one type of macroporous distribution and mechanical strength of only 2N/mm.

Comparative example 3

A honeycomb titanium-aluminum composite oxide support was prepared by the method of example 1 of CN 201410484413.1. The pore wall of the honeycomb body after extrusion molding is compact, and a controllable three-dimensional macroporous structure is difficult to exist.

Claims (16)

1. A monolithic titanium-doped alumina material, characterized in that: the material is of a honeycomb structure, the wall of each honeycomb hole is provided with microscopic macroporous pores, the pore diameter of each macroporous is 50-1000nm, the macropores are uniformly distributed and are communicated in a three-dimensional way, and the ratio of the pore diameter of each macroporous to the wall thickness of the corresponding hole wall is 1-2; based on the total weight of the integral titanium-doped alumina material, the content of titanium is 0.5 to 45 weight percent calculated by titanium dioxide, the titanium is uniformly dispersed in an alumina bulk phase in the form of titanium dioxide, and the cluster size of titanium element sub-clusters is more than 2.5nm and less than 5.0 nm;

the preparation method of the integral titanium-doped aluminum oxide material comprises the following steps:

(1) uniformly dispersing boehmite powder in water to obtain a boehmite suspension, slowly adding a peptizing agent into the boehmite powder suspension, and after the addition is finished, heating and aging for a certain time to obtain clear alumina sol;

(2) under the inert atmosphere, uniformly mixing aluminum sol, inorganic aluminum salt, ethyl acetoacetate, titanium alkoxide, polyethylene glycol, amide compounds and a lower alcohol aqueous solution, then adding propylene oxide and/or pyridine, uniformly mixing, and casting the mixture into a reverse honeycomb mold until gel is formed;

(3) aging the gel obtained in the step (2) at 20-80 ℃ for 12-120 hours, and removing the die to obtain an aged product;

(4) and soaking the aged product in a low-carbon alcohol aqueous solution, then carrying out solid-liquid separation, and drying and roasting a solid phase to obtain the integral titanium-doped aluminum oxide material.

2. The monolithic titanium-doped aluminum oxide material of claim 1, wherein: the total porosity of the material is 70-95%, and the specific surface area is 150-450m²G, pore volume of 0.5-1.5cm³(ii) a mechanical strength of 5 to 30N/mm.

3. The monolithic titanium-doped aluminum oxide material of claim 1, wherein: cross section perpendicular to the honeycomb duct is taken as referenceThe number of the upper honeycomb holes is 1 to 50/cm²(ii) a The shape of the hole opening of the honeycomb hole is round, clover-shaped, square or other special shapes.

4. A preparation method of an integral titanium-doped aluminum oxide material comprises the following steps: (1) uniformly dispersing boehmite powder in water to obtain a boehmite suspension, slowly adding a peptizing agent into the boehmite powder suspension, and after the addition is finished, heating and aging for a certain time to obtain clear alumina sol; (2) under the inert atmosphere, uniformly mixing aluminum sol, inorganic aluminum salt, ethyl acetoacetate, titanium alkoxide, polyethylene glycol, amide compounds and a lower alcohol aqueous solution, then adding propylene oxide and/or pyridine, uniformly mixing, and casting the mixture into a reverse honeycomb mold until gel is formed; (3) aging the gel obtained in the step (2) at 20-80 ℃ for 12-120 hours, and removing the die to obtain an aged product; (4) and soaking the aged product in a low-carbon alcohol aqueous solution, then carrying out solid-liquid separation, and drying and roasting a solid phase to obtain the integral titanium-doped aluminum oxide material.

5. The method of claim 4, wherein: the solid content of the suspension liquid in the step (1) is 1-15 wt%.

6. The method of claim 4, wherein: the aging in the step (1) is carried out in a heating reflux mode, wherein the reflux temperature is 70-95 ℃, and the reflux time is 1-12 hours.

7. The method of claim 4, wherein: the peptizing agent in the step (1) is one or more of hydrochloric acid, nitric acid, sulfuric acid, formic acid or acetic acid; the peptizing agent is used in the amount of H⁺The mole ratio of the boehmite powder to the amount of the boehmite powder is 0.05-1 in terms of Al contained.

8. The method of claim 4, wherein: based on the weight of the mixture obtained in the step (2), the adding amount of the lower alcohol aqueous solution is 10-80 wt%, the adding amount of the inorganic aluminum salt is 5-30 wt%, the adding amount of the aluminum sol is 1-10 wt%, the adding amount of the polyethylene glycol is 0.1-3.0 wt%, and the adding amount of the titanium alkoxide is 0.5-10 wt%; wherein the mass ratio of water to the low-carbon alcohol in the low-carbon alcohol aqueous solution is 1.0-1.5; the addition amount of the amide compound is 0.1-5.0 wt%.

9. The method of claim 4, wherein: propylene oxide and/or pyridine with Al³⁺Is 1.5 to 9.5, and does not contain Al in the alumina sol.

10. The method of claim 4, wherein: the inorganic aluminum salt in the step (2) is one or more of aluminum nitrate, aluminum chloride or aluminum sulfate.

11. The method of claim 4, wherein: the titanium alkoxide in the step (2) is one or more of tetraethyl titanate, tetraisopropyl titanate, tetrapropyl titanate, tetrabutyl titanate or tetrapentyl titanate.

12. The method of claim 4, wherein: the polyethylene glycol molecular weight viscosity average molecular weight in the step (2) is 10000-.

13. The method of claim 4, wherein: the lower alcohol in the steps (2) and (4) is C₅The following alcohols.

14. The method of claim 4, wherein: the amide compound in the step (2) is one or more of formamide, acetamide, N-dimethylformamide, N-methylacetamide, benzamide and 2-phenylacetamide.

15. The method of claim 4, wherein: the soaking conditions in the step (4) are as follows: the soaking temperature is 10-80 ℃, and the soaking time is 12-60 hours; the mass concentration of the low-carbon alcohol aqueous solution used for soaking is not less than 50 wt%.

16. An application of the integral titanium-doped aluminum oxide material as claimed in any one of claims 1 to 3 in adsorption and degradation of pollutants in hydrogenation reaction, alkylation reaction, desulfurization and denitration reaction or water treatment process.

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