Electrochemical Process for Conversion of Biodiesel to Aviation Fuels

Abstract

Methods for the conversion of a biofuel such as biodiesel into an alkane composition such as an aviation fuel, kerosine, or liquified petroleum gas product involve a series of electrochemical reactions. The reactions include oxidation of methanol to carbon dioxide, reduction of fatty acid esters, and cleavage of fatty acid chains at C═C double bonds. The methods are carried out by systems of two or more electrochemical reactors.

1 . A method for the chemical conversion of a biodiesel to an alkane composition, the method comprising the steps of:
 providing a crude biodiesel composition, the biodiesel composition comprising fatty acid esters and methanol;   reducing the amount of methanol in the biodiesel composition by electrochemical oxidation of methanol to carbon dioxide in a first electrochemical reactor;   fragmenting fatty acid chains of the biodiesel composition in a second electrochemical reactor that cleaves the fatty acid chains at carbon-carbon double bonds to yield short chain fatty acids and aldehydes; and   hydrogenating the short chain fatty acids and aldehydes in a third electrochemical reactor to yield a composition comprising alkanes.   
     
     
         2 . The method of  claim 1 , wherein the biodiesel source material comprises aliphatic chains of about 16 to about 22 carbon atoms in length. 
     
     
         3 . The method of  claim 1 , wherein the final alkane composition comprises aliphatic chains of about 8 to about 11 carbon atoms in length. 
     
     
         4 . A method for the chemical conversion of a biodiesel to an alkane composition, the method comprising the steps of:
 providing a crude biodiesel composition, the biodiesel composition comprising fatty acid esters and methanol;   fragmenting fatty acid chains in the biodiesel composition in a first electrochemical reactor that cleaves the fatty acid chains at carbon-carbon double bonds to yield short chain fatty acids and aldehydes;   oxidizing the short chain aldehydes to short chain fatty acids; and   performing a Kolbe reaction in a second electrochemical reactor, whereby the short chain fatty acids are decarboxylated to form alkanes.   
     
     
         5 . The method of  claim 4 , wherein the biodiesel source material comprises aliphatic chains of about 16 to about 22 carbon atoms in length. 
     
     
         6 . The method of  claim 4 , wherein the final alkane composition comprises aliphatic chains of about 8 to about 11 carbon atoms in length. 
     
     
         7 . The method of  claim 4 , further comprising the step of
 reducing the amount of methanol in the biodiesel composition by electrochemical oxidation of methanol to carbon dioxide.   
     
     
         8 . A method for the chemical conversion of a biodiesel to an alkane composition, the method comprising the steps of:
 providing a crude biodiesel composition, the biodiesel composition comprising fatty acid esters and methanol;   fragmenting fatty acid chains in the biodiesel composition in a first electrochemical reactor that cleaves the fatty acid chains at carbon-carbon double bonds to yield short chain fatty acids and aldehydes; and   hydrogenating the short chain fatty acids and aldehydes in a second electrochemical reactor to form alkanes.   
     
     
         9 . The method of  claim 8 , wherein the biodiesel source material comprises aliphatic chains of about 16 to about 22 carbon atoms in length. 
     
     
         10 . The method of  claim 8 , wherein the final alkane composition comprises aliphatic chains of about 8 to about 11 carbon atoms in length. 
     
     
         11 . The method of  claim 8 , further comprising the step of reducing the amount of methanol in the biodiesel composition by electrochemical oxidation of methanol to carbon dioxide. 
     
     
         12 . The method of  claim 8 , wherein the step of hydrogenating comprises first the step of hydrogenating fatty acids to alcohols and subsequently the step of hydrogenating the alcohols to alkanes.