Conversion of Carboxylic Acids to Alpha-Olefins

Abstract

An electrolytic method of producing olefins from alkali metal salts of carboxylic acids is disclosed. The carboxylic acid may be from a variety of sources including fermented biomass that is subsequently neutralized using an alkali metal base. The method enables the efficient production of olefins including alpha-olefins as well as useful olefin products such as synthetic oils.

1 . A electrochemical method of preparing olefins from an alkali metal salt of a carboxylic acid, comprising:
 providing an electrochemical cell comprising:
 an anolyte compartment comprising an electrochemically active anode selected to perform a two-electron decarboxylation reaction of an alkali metal salt of a carboxylic acid, wherein the anode comprises a carbonaceous surface; 
 a catholyte compartment comprising an electrochemically active cathode where reduction reactions occur; 
 an alkali ion conductive membrane separating the anolyte compartment from the catholyte compartment that permits selective transport of alkali ions between the anolyte compartment and the catholyte compartment; 
   providing a solution of an alkali metal salt of the carboxylic acid to the anolyte compartment, wherein the solution has a pH in the range from about 8 to 14; and   applying an electrical potential to the anode and cathode to electrochemically decarboxylate the carboxylic acid salt into one or more olefins.   
     
     
         2 . The method of  claim 1 , wherein the cell has a voltage between 2 and 20 volts. 
     
     
         3 . The method of  claim 1 , wherein a current density of between 5 and 100 mA/cm 2  is applied to the anode. 
     
     
         4 . The method of  claim 1 , wherein the solution has a pH in the range of about 10 to  12 . 
     
     
         5 . The method of  claim 1 , further comprising mixing the alkali metal salt of the carboxylic acid with an organic solvent. 
     
     
         6 . The method of  claims 5 , wherein the organic solvent comprises one or more organic alcohols and mixtures thereof. 
     
     
         7 . The method of  claim 6 , wherein the one or more organic alcohols are selected from the group consisting of: methanol, ethanol, propanol, isopropanol, butanol, and mixtures of the same. 
     
     
         8 . The method of  claim 5 , wherein the organic solvent is selected form the group consisting of: acetonitrile, dimethylformamide, sulfolane, pyridine, 2,6-pyridine, and mixtures thereof. 
     
     
         9 . The method of  claim 1 , further comprising adjusting the pH of the alkali metal salt of the carboxylic acid with a base. 
     
     
         10 . The method of  claim 9 , wherein the base is an alkali metal hydroxide. 
     
     
         11 . The method of  claim 1 , further comprising mixing the alkali metal salt of the carboxylic acid with an electrolyte selected from the group consisting of: a metal halide, a metal nitrate, a metal sulfate, a metal perchlorate, and a metal tetrafluoroborate. 
     
     
         12 . The method of  claim 1 , wherein the alkali ion conducting membrane is a NaSICON membrane. 
     
     
         13 . The method of  claim 1 , further comprising fermenting biomass to produce the carboxylic acid and neutralizing the carboxylic acid with an alkali metal hydroxide to form the alkali metal salt of the carboxylic acid. 
     
     
         14 . The method of  claim 1 , wherein the alkali metal salt of the carboxylic acid has an even number of carbon atoms. 
     
     
         15 . The method of  claim 1 , wherein the alkali metal salt of the carboxylic acid is derived from a carboxylic acid selected from the group consisting of: octanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, and octadecanoic acid. 
     
     
         16 . The method of  claim 1 , wherein the one or more olefins comprises an alpha-olefin. 
     
     
         17 . The method of  claim 1 , wherein the olefin comprises 1-undecene. 
     
     
         18 . The method of  claim 1 , further comprising oligomerizing the one or more olefins to make a synthetic lubricant. 
     
     
         19 . An electrochemical reactor comprising:
 an anolyte compartment comprising:
 an alkali metal salt of a carboxylic acid having a pH in the range from about 9 to 12; and 
 an electrochemically active anode selected to perform a two-electron decarboxylation reaction of the alkali metal salt of carboxylic acid, wherein the anode comprises a carbonaceous surface; 
   a catholyte compartment housing an electrochemically active cathode where reduction reactions occur;   an alkali ion conductive membrane separating the anolyte compartment from the catholyte compartment that permits selective transport of alkali ions between the anolyte compartment and the catholyte compartment; and   a source of electric potential connected to the anode and to the cathode.   
     
     
         20 . The electrochemical reactor of  claim 19 , wherein the alkali metal ion is sodium and the alkali ion conducting membrane is a NaSICON membrane.