This invention relates to novel fuel compositions which comprise novel surfactant compositions and to methods of preparation the fuels compositions and surfactants.[0001]
International Patent Application No WO 98/17745 describes a surfactant composition which comprises,[0002]
25% v/v of a diethanolamide,[0003]
50% v/v of an ethoxylated alcohol, and[0004]
25% v/v of a fourteen carbon chain fatty acid with seven ethoxylate groups.[0005]
WO '745 especially describes fuel compositions comprising, inter alia, an additive made up of a fatty acid diethanolamide, an alcohol ethoxylate and an ethoxylate of a fatty acid, the degree of ethoxylation being selected so that a long term stable fuel composition is formed.[0006]
Specifically, WO '745 teaches the use of lauric acid and lauric diethanolamide.[0007]
Co-pending International Patent Application No WO 99/20715 to Pure Energy Corporation describes similar surfactant compositions in which the fatty acid used has a hydrocarbon chain length of from C[0008]9to C15.
Furthermore, U.S. Pat. No. 6,017,369 describes a diesel fuel composition comprising, inter alia, diesel, ethanol and a fatty acid having a carbon chain length of from C[0009]9to C15.
Whilst such additives provide significant reductions in emissions and may be useable at low concentrations, they suffer from the disadvantage that, for example, lauric acid has a relatively high melting point of between 44 and 46° C. Thus, at room temperature, lauric acid is waxy and difficult to formulate.[0010]
We have now surprisingly found a novel surfactant fuel additive which overcomes or mitigates the problems of known prior art composition.[0011]
Thus according to the invention we provide a fuel additive composition comprising an alkanolamide, an alkoxylated alcohol and an alkoxylated C[0012]18-C22fatty acid or a derivative thereof in which the degree of alkoxylation of the fatty acid is from 0.5 to 5 mols of alkoxylate to 1 mol of oleic acid.
The alkanolamide is preferably an ethanolamide and more preferably a diethanolamide. Especially preferred are the diethanolamides and particularly the super diethanolamides. By the term super diethanolamide we mean a diethanolamide in which the nitrogen is substituted by an alkyl substituent e.g. alkyl C[0013]5to C20, preferably C8to C18, more preferably C10to C18. The most preferred diethanolamide has a C18alkyl substituent i.e. oleic diethanolamide.
There are three commercial routes to alkanolamides;[0014]
Acid+alkanolamine=alkanolamide+water[0015]
Plant or animal oil (triglyceride)+alkanolamine=alkanolamide+glycerol[0016]
Methyl ester+alkanolamine=alkanolamide+methanol[0017]
These are listed in order of increasing product quality. The route via the acid often uses an excess of alkanolamine to produce a product higher in amide than is obtainable from the acid if a stoichiometric ratio is used; these products are sometimes referred to as Kritchevsicy amides. The products derived from reaction of substantially stoichiometric proportions of an alkanolamide with a fatty acid ester, typically a methyl or glyceryl ester, are referred to as super amides.[0018]
The alkoxylated alcohol is preferably an ethoxylated alcohol. It is essential that the ethoxylated alcohol is an oil soluble alcohol. Therefore, alkanols are preferred and these may be primary, secondary or tertiary alkanols and especially primary alkanols. As the oil solubility of the alcohol may vary with the carbon chain length of the ethoxylated alkanol, the allcanol is preferably a C[0019]5to C22alkanol, more preferably C5to C15alkanol. The ethoxylated alcohol may comprise a mixture of alkanols. However, it is preferred that in such mixtures one alkanol will predominate. Thus, the most preferred alkanol is predominantly a C9to C11alkanol. In addition the degree of ethoxylation of the alcohol may be varied and the oil solubility will, generally, decrease with the increase in the degree of ethoxylation. It is preferred that the ethoxylate to alcohol ratio is greater than 2. More preferably, the ethoxylate to alcohol ratio is from between 1 and 10, preferably between 1 and 5, more preferably between 1 and 3 and especially between 2 and 3. A commercially available ethoxylated alcohol is especially preferred in which the ethoxylate to alcohol ratio is 2.75. Such an alcohol ethoxylate is available as NEODOL 91/2.5.
The fatty acid ethoxylate may comprise the free acid, an ester, a mixture of esters or a mixture of the acid and one or more esters. When a fatty acid ester ethoxylate is used, the ester is preferably an alkyl oleate, preferably a C[0020]1to C10alkyl oleate, such as ethyl oleate and especially methyl oleate. The fatty acid derivative is preferentially an ester which may comprise any conventionally known ester moiety, however, preferably the ester is an alkyl ester. The alkyl group may be a primary, secondary or tertiary alkyl group. However, the preferred ester group is a straight chain alkyl group, the allyl chain being from C1to C10. The methyl ester is especially preferred.
The fatty acid group may be any known C[0021]18to C22fatty acid but oleic acid (C18) is preferred.
Alkyl ester fatty acid ethoxylate may be manufactured using conventional methods known per se. However, current technology only permits ethoxylation of a fatty acid ester by the PEG/fatty acid route where, in a fatty acid of the general formula RCOOR[0022]1, R1is methyl.
We have now found that such ethoxylated fatty acid esters may be manufactured by esterification of a fatty acid with a methoxy polyethylene glycol (PEG) or any other alcohol ethoxylate, for example, a C[0023]9or C11alcohol ethoxylate.
Such novel processes can produce ethoxylated fatty acid esters of the general formula;[0024]
RCO[CH2CH2O]nOR1 I
wherein R is an alkyl C[0025]8to C20group;
R[0026]1is an alkyl, C1to C10; and
n is an integer from 1 to 10.[0027]
Alternatively, ethoxylated fatty acids of formula I may be manufactured by esterification of RCOOH with R[0028]1[OCH2CH2]nOH, wherein R, R1and n have the meanings defined above.
However, in addition, the alcohol ethoxylate might be, for example, an alkylphenol ethoxylate.[0029]
The degree of alkoxylation, e.g., ethoxylation, propyloxylation or a mixture thereof, is chosen to optimise performance in the blend with the other two selected surfactants and may be from 0.5 to 5 but more preferably from 0.5 to 2.5. It is especially preferred that the alkoxylation comprises ethoxylation. A suitable product within this range would be, for example that derived from the addition of 1 mol of ethylene oxide to 1 mol of oleic acid, or a derivative thereof.[0030]
The fatty acid ethoxylate, e.g. oleic acid ethoxylate, may be derived from a variety of feedstocks, readily available worldwide. However, in a preferred embodiment of the invention the fatty acid ethoxylate may be produced by ethoxylation or esterification of acids derived from animal fats e.g. beef tallow or vegetable oils, such as soya, etc.[0031]
Thus the oleic acid precursor may be predominantly, e.g. from 65-70% v/v, fatty acid, e.g. oleic acid, but may also contain linoleic acid, e.g., 10-12% v/v, and may also include small amounts of stearic, palmitic and/or myristic acids.[0032]
The ratio of the fatty acid alkoxylate, e.g. oleic acid alkoxylate to the alkanolamide may vary slightly, but is preferably 1:1 v/v.[0033]
The additive of the invention may be added to any known hydrocarbon fuel, e.g. diesel, petrol or alcohol, such as ethanol, which may or may not contain water. The invention is seen to particularly good effect when added to fuels based on low fraction oils.[0034]
The preferred additive of this invention is a non-ionic surfactant and preferably a blend of surfactants. It is a preferred feature of this invention that the surfactants be selected by their nature and concentration that the additive (as well as any water or other non-fuel liquid present) be solubilised within the fuel. For this purpose it is convenient to have regard to the hydrophilic-lipophilic balance (HLB) of the surfactant, the value being calculated according to the expression.
[0035]The values will depend on the length of the hydrophilic chain, typically an ethoxylate chain. The length of the chain will increase the extent of solubilisation because of a greater ability to solubilise.[0036]
As with the compositions described in WO98/17745, a blend of surfactants is preferred, preferably by selecting one appropriate to the fuel.[0037]
The invention has the ability to unify the HLB requirements of any liquid fuel which in turn allows for one dose to be used in any fuel from C5 carbon chains up. The benefit being the amount of treatment directly related to the co-solvency ability.[0038]
Preferably the ethoxylate of the oleic acid makes up about 25% by volume of the additive and further preferably the alcohol ethoxylate comprises 50% by volume of the additive.[0039]
An additive of the invention may be added to a hydrocarbon fuel, eg diesel, petrol or alcohol, such as ethanol which may or may not be contaminated with water. Alternatively the hydrocarbon fuel may be a blend of a petroleum based fuel such as diesel or petrol, with an alcohol such as ethanol. The invention is seen to particularly good effect when added to synthetic fuels based on low fraction oils.[0040]
The hydrocarbon fuel may comprise any known hydrocarbon fuel or mixtures thereof, therefore such fuels include but shall not be limited to diesel, e.g., petroleum diesel, gasoline, aviation fuel, alcohol, etc.[0041]
In one embodiment of the fuel composition of the invention the hydrocarbon fuel is a petroleum diesel fuel. Such fuels may generally be obtained from the distillation of petroleum and its efficiency can be measured by the cetane number. Suitable diesel fuels for use in accordance with the invention generally have a cetane number of from 35 to 60, preferably from 40 to 50. The amount of diesel fuel blended to form the fuel composition of the invention may be from 60% v/v to 95% v/v, based on the total volume of the fuel consumption.[0042]
In a further feature of the invention the hydrocarbon fuel, such a diesel or gasoline may include an amount of an oxygenator, e.g. alcohol, an alkanol, such as ethanol. When an alcohol is present the amount of alcohol may vary depending, inter alia, upon the nature of the fuel, but may in an amount of from 1 to 50% v/v, preferably 5 to 20% v/v.[0043]
For fuels, ethanol may be produced from fossil fuel feedstocks or by fermentation of sugars derived from grains or other biomass materials. Therefore, ethanol suitable for use in accordance with the fuel compositions of the invention may be fuel grade ethanol derived from yeast or bacterial fermentation of starch-based sugars. Such starch-based sugars may be extracted from corn, sugarcane, tapioca and sugar beet. Alternatively, fuel grade ethanol may be produced via known dilute and/or concentrated acid and/or enzymatic hydrolysis of a particular biomass material, for example, from waste industrial sources including, cellulosic portions of municipal solid waste, waste paper, paper sludge, saw dust. Biomass may also be collected from agricultural residues including, for example, rice husks and paper-mill sludge.[0044]
A suitable fuel grade ethanol for use in accordance with the invention may contain none or only contaminant levels of water. Alternatively, a suitable fuel grade ethanol for use in accordance with the invention may contain higher amounts of water, up to 5% w/w (hydrous ethanol).[0045]
Use of ethanol in combination with a diesel fuel has previously posed problems wherein the ethanol/diesel fuel mixture would undesirably separate into two distinct phases, especially when water is present, and render the resultant mixture unsuitable for use as a combustible fuel. The use of the fuel additives of the invention permits hydrous ethanol to be blended satisfactorily with conventional diesel fuel without forming two phases. The use of fuel grade ethanol blended in accordance with the invention imparts desirable combustion characteristics to the overall fuel composition; such as improved fuel stability, lower smoke and particulate matter, lower CO and NOx emissions, improved antiknock characteristics, and/or improved anti-freeze characteristics.[0046]
In another aspect the invention provides a fuel composition comprising a light weight fraction and a surfactant fuel additive as hereinbefore described.[0047]
The presence of the additive of the invention ensures that the fuel composition forms a consistent stable homogenous composition and creates a monolayer simultaneously a result of which leads to a better more complete burn which reduces pollution and increases miles per gallon.[0048]
As a result a blended fuel, particularly alcohol based, is able to combust more precisely with a cooler charge to reduce the iron-formates present from the aldehyde peracids and peroxide reactions normally attributable to engine degradation.[0049]
Thus we further provide a fuel composition comprising a fuel and a hydrocarbon fuel additive as herein before described.[0050]
The concentration of the additive in such fuel compositions can be very low, typically of the order of 0.5-50:1000 v/v, preferably from about 1:1000 to 30:1000 v/v and most preferably from 1 to 3:100 v/v. There appears to be no technical or economic benefit in adding more unless a co-solvent dual action is required, when the priority will be dosage against performance. However, the additive to fuel ratio may vary depending upon, inter alia, the nature of the fuel. Thus, for example, when the fuel is a hydrous ethanol/diesel blend, the additive to fuel ratio may be as much as 5% v/v, e.g. from 0.1 to 5% v/v, more preferably from 1 to 3% v/v. Alternatively, when the fuel is an anhydrous ethanol/diesel blend the additive to fuel ratio may be as much as 3% v/v, e.g. from 0.1 to 3% v/v. The amount of ethanol present in the diesel/ethanol blends of the invention may be from 5 to 25% v/v, preferably from 7 to 10% v/v and especially 7.7% v/v. When the ethanol in the blend is hydrous ethanol, the amount of water present may be from 4 to 6% v/v based as a percentage of the ethanol.[0051]
Alternatively, when the fuel is gasoline or a gasoline/ethariol blend, then the additive to fuel ratio may be as much as 5% v/v, from 0.1 to 5% v/v, preferably up to 3% v/v, e.g. 0.1 to 3% v/v, more preferably from 1 to 3% v/v. The amount of ethanol present in the gasoline/ethanol blends of the invention may be from 1 to 25% v/v, preferably 5 to 25% v/v, more preferably from 7 to 10% v/v and especially 7.7% v/v. When the fuel is a hydrous ethanol/gasoline blend, the additive to fuel ratio may be as much as 5% v/v. Alternatively, when the fuel is an anhydrous ethanol/gasoline blend the additive to fuel ratio may be as much as 3% v/v.[0052]
The presence of the additive of the invention ensures that the fuel composition forms a consistent stable homogenous composition and creates a monolayer simultaneously a result of which leads to a better more complete burn which reduces pollution and increases miles per gallon.[0053]
As a result a blended fuel, particularly alcohol based, is able to combust more precisely with a cooler charge to reduce the iron-formates present from the aldehyde peracids and peroxide reactions normally attributable to engine degradation.[0054]
We also provide a method of running an engine adapted to use a hydrocarbon or an alcohol based fuel which comprises the use of a fuel composition as hereinbefore described.[0055]
The use of a fuel additive composition comprising an oleic acid ethoxylate or a derivative thereof is especially advantageous in conjunction with diesel fuel compositions and especially diesel/alcohol compositions. Thus, according to a further feature of the invention we provide a fuel composition comprising a diesel fuel, an alcohol and a surfactant additive as hereinbefore described.[0056]
The alcohol is preferably ethanol. Optionally, the diesel composition of the invention may additionally include the use of an alkyl ester of oleic acid e.g. an alkyl C1 to 6 alcohol or a long chain fatty alcohol and, optionally a co-solvent of an alkyl alcohol, e.g. a C[0057]3to C6alcohol.
According to a further feature of the invention we provide the use of oleic acid or a derivative thereof in the manufacture of a surfactant additive as hereinbefore described.[0058]
According to a yet further feature of the invention we provide the use of oleic acid or a derivative thereof in the manufacture of a fuel composition as hereinbefore described.[0059]
The invention will now be described by way of example only.[0060]