Use of specific volatile fatty esters in petrol engines in order to reduce emissions

Abstract

The invention relates to the use of esters of volatile fatty acids, such esters having a number of carbon atoms between 4 and 8, in a fuel for a petrol engine in order to reduce the emissions of nitrogen oxides, unburned hydrocarbons and particles of petrol engines.

1 . A method for reducing emissions of nitrogen oxides and unburnt hydrocarbons by a petrol engine, the method comprising adding at least one ester of a volatile fatty acid to a fuel for the petrol engine, wherein the volatile fatty acid is a mono-fatty acid having an aliphatic chain of one to six carbon atoms or one of the isomers thereof, and wherein said ester comprises a number of carbons of between 4 and 8. 
     
     
         2 - 15 . (canceled) 
     
     
         16 . The method of  claim 1 , wherein the method also reduces emission of particles by the petrol engine. 
     
     
         17 . The method of  claim 1 , wherein the ester or esters of volatile fatty acids comprising a number of carbons of between 4 and 8 are used at a rate of at least 15% by volume of fuel, the fuel being formed by the petrol, the ester or esters of volatile fatty acids comprising a number of carbons of between 4 and 8, and by possible other constituents. 
     
     
         18 . The method of  claim 1 , wherein the ester or esters of volatile fatty acids comprising a number of carbons of between 4 and 8 are used at a rate of at least 30% by volume of fuel. 
     
     
         19 . The method of  claim 17 , wherein the ester or esters of volatile fatty acids comprising a number of carbons of between 4 and 8 are used at a rate of at least 50% by volume of fuel. 
     
     
         20 . The method of  claim 1 , wherein the ester or esters of volatile fatty acids comprising a number of carbons of between 4 and 8 are selected from among the following esters: ethyl acetate, ethyl propionate, ethyl butyrate, ethyl valerate, ethyl hexanoate, propyl acetate, propyl propionate, propyl butyrate, propyl valerate, butyl acetate, butyl propionate, butyl butyrate, and the mixtures thereof. 
     
     
         21 . The method of  claim 1 , wherein the ester or esters of volatile fatty acids comprising a number of carbons of between 4 and 8 are obtained entirely or in part by esterification of volatile fatty acids of biomass origin by alcohols of biomass origin, or by esterification of volatile fatty acids produced from carbon dioxide or monoxide, in a microbial fuel cell, by alcohols of biomass origin or otherwise. 
     
     
         22 . The method of  claim 1 , wherein adding the ester to the fuel reduces the emission of nitrogen oxides by the petrol engines by at least 20% of the rate of incorporation of the esters in the fuel formed by the petrol, the ester or esters of volatile fatty acids comprising a number of carbons of between 4 and 8, and possible other constituents. 
     
     
         23 . The method of  claim 1 , wherein adding the ester to the fuel reduces the emission of unburnt hydrocarbons by the petrol engines by at least 20% of the rate of incorporation of the esters in the fuel formed by the petrol, the ester or esters of volatile fatty acids comprising a number of carbons of between 4 and 8, and possible other constituents. 
     
     
         24 . The method of  claim 1 , wherein adding the ester to the fuel reduces the emission of particles by the petrol engines by at least 25% of the rate of incorporation of the esters in the fuel formed by the petrol, the ester or esters of volatile fatty acids comprising a number of carbons of between 4 and 8, and possible other constituents. 
     
     
         25 . The method of  claim 1 , wherein the method further comprises adding to the fuel at least one alkane having a chain length of between 4 and 10 carbon atoms in order to optimize combustion. 
     
     
         26 . The method of  claim 25 , wherein the alkane or alkanes is/are selected from octane, iso-octane, decane, and the mixtures thereof. 
     
     
         27 . The method of  claim 25 , wherein the alkane or alkanes are of petroleum origin or obtained from a biomass. 
     
     
         28 . The method of  claim 25 , wherein the alkane or alkanes are used at a rate of between 0 and 50% by volume of fuel formed by the petrol, the ester or esters of volatile fatty acids comprising a number of carbons of between 4 and 8, the alkane or alkanes having a chain length of between 4 and 10 carbon atoms, and possible other constituents. 
     
     
         29 . The method of  claim 1 , wherein the method further comprises adding one or more other products to the fuel, said products being selected from: additives that improve the octane number, additives that improve lubrication, products that reduce the combustion temperature, alcohols, esters comprising a number of carbons of greater than 8, ethers, and mixtures thereof.