Electrolytic Process to Separate Alkali Metal Ions from Alkali Salts of Glycerine

Abstract

Methods and apparatus for separating alkali metal ions from alkali salts of glycerine to thereby form clean glycerine. These methods are enabled by the use of alkali ion conductive membranes in electrolytic cells that are chemically stable in low pH conditions. The alkali ion conductive membrane preferably includes a chemically stable ionic-selective polymer membrane. A layered composite of a chemically stable ionic-selective polymer and a cation-conductive ceramic membrane is disclosed.

1 . A method for converting alkali salts of glycerine into glycerine comprising:
 obtaining an electrolytic cell comprising an alkali ion conductive membrane configured to selectively transport alkali ions, the membrane separating an anolyte compartment configured with an anode and a catholyte compartment configured with a cathode;   introducing a solution containing an alkali salt of glycerine (C 3 H 5 (OM) 3 ) into the anolyte compartment, wherein M is an alkali metal;   applying an electric current to the electrolytic cell thereby:
 i. producing hydrogen ions at the anode in the anolyte compartment to facilitate the following reaction: C 3 H 5 (OM) 3 +3H + →C 3 H 5 (OH) 3 +3M + ; 
 ii. causing alkali ions (M + ) to pass through the alkali ion conductive membrane from the anolyte compartment to the catholyte compartment; and 
 iii. decomposing water in the presence of alkali ions in the catholyte compartment according to the following reaction: M + +H 2 O+e − →MOH+½H 2 ; and 
   removing glycerine (C 3 H 5 (OH) 3 ) from the anolyte compartment.   
     
     
         2 . A method for converting alkali salts of glycerine into glycerine according to  claim 1 , further comprising the steps of:
 introducing hydrogen gas into the anolyte compartment; and   introducing water into the catholyte compartment.   
     
     
         3 . A method for converting alkali salts of glycerine into glycerine according to  claim 2 , wherein the anode comprises a catalyst to facilitate oxidation of hydrogen gas into hydrogen ions. 
     
     
         4 . A method for converting alkali salts of glycerine into glycerine according to  claim 1 , wherein hydrogen ions are produced at the anode in the anolyte compartment by oxidation of water. 
     
     
         5 . A method for converting alkali salts of glycerine into glycerine according to  claim 1 , wherein hydrogen ions are produced at the anode in the anolyte compartment by oxidation of hydrogen. 
     
     
         6 . A method for converting alkali salts of glycerine into glycerine according to  claim 1 , wherein the alkali ion conductive membrane comprises a chemically stable ionic-selective polymer membrane. 
     
     
         7 . A method for converting alkali salts of glycerine into glycerine according to  claim 6 , wherein the chemically stable ionic-selective polymer membrane is selected from polyelectrolyte perfluorinated sulfonic polymers, polyelectrolyte carboxylic acid polymers, Nafion® materials, and polyvinyl chloride (PVC) matrix-based polymers, co-polymers or block-copolymers. 
     
     
         8 . A method for converting alkali salts of glycerine into glycerine according to  claim 1 , wherein the alkali ion conductive membrane comprises a layered composite comprising a chemically stable ionic-selective polymer and a cation-conductive ceramic membrane. 
     
     
         9 . A method for converting alkali salts of glycerine into glycerine according to  claim 8 , wherein the chemically stable ionic-selective polymer membrane is selected from polyelectrolyte perfluorinated sulfonic polymers, polyelectrolyte carboxylic acid polymers, Nafion® materials, and polyvinyl chloride (PVC) matrix-based polymers, co-polymers or block-copolymers. 
     
     
         10 . A method for converting alkali salts of glycerine into glycerine according to  claim 8 , wherein the cation-conductive ceramic membrane comprises a solid MSICON (Metal Super Ion CONducting) material, where M is Na, K, or Li. 
     
     
         11 . An apparatus for converting alkali salts of glycerine into glycerine comprising: an electrolytic cell comprising:
 an anolyte compartment comprising an electrochemically active anode having a source of oxidizable hydrogen and C 3 H 5 (OM) 3  in which oxidizable hydrogen is oxidized to form hydrogen ions to thereby facilitate the following reaction: C 3 H 5 (OM) 3 +3H + →C 3 H 5 (OH) 3 +3M + ;   a catholyte compartment comprising an electrochemically active cathode separated from the anolyte compartment by a alkali ion conductive membrane configured to selectively transport alkali ions (M+) into the catholyte compartment, wherein the catholyte compartment has a source of water, in which the water is decomposed in the presence of alkali ions to form alkali hydroxide and hydrogen gas;   a fluid path for removing alkali hydroxide produced in the catholyte compartment; and   a fluid path for removing glycerine (C 3 H 5 (OH) 3 ) from the anolyte compartment.   
     
     
         12 . An apparatus for converting alkali salts of glycerine into glycerine according to  claim 11 , wherein the source of oxidizable hydrogen is hydrogen gas. 
     
     
         13 . An apparatus for converting alkali salts of glycerine into glycerine according to  claim 12 , further comprising a fluid path for transporting hydrogen gas produced in the catholyte compartment to the anolyte compartment. 
     
     
         14 . An apparatus for producing biodiesel according to  claim 12 , wherein the anode further comprising a catalyst to facilitate oxidation of hydrogen gas into hydrogen ions. 
     
     
         15 . An apparatus for converting alkali salts of glycerine into glycerine according to  claim 11 , wherein the source of oxidizable hydrogen is water. 
     
     
         16 . An apparatus for converting alkali salts of glycerine into glycerine according to  claim 11 , wherein the alkali ion conductive membrane comprises a chemically stable ionic-selective polymer membrane. 
     
     
         17 . An apparatus for converting alkali salts of glycerine into glycerine according to  claim 16 , wherein the chemically stable ionic-selective polymer membrane is selected from polyelectrolyte perfluorinated sulfonic polymers, polyelectrolyte carboxylic acid polymers, Nafion® materials, and polyvinyl chloride (PVC) matrix-based polymers, co-polymers or block-copolymers. 
     
     
         18 . An apparatus for converting alkali salts of glycerine into glycerine according to  claim 11 , wherein the alkali ion conductive membrane comprises a layered composite comprising a chemically stable ionic-selective polymer and a cation-conductive ceramic membrane. 
     
     
         19 . An apparatus for converting alkali salts of glycerine into glycerine according to  claim 18 , wherein the chemically stable ionic-selective polymer membrane is selected from polyelectrolyte perfluorinated sulfonic polymers, polyelectrolyte carboxylic acid polymers, Nafion® materials, and polyvinyl chloride (PVC) matrix-based polymers, co-polymers or block-copolymers. 
     
     
         20 . An apparatus for converting alkali salts of glycerine into glycerine according to  claim 18 , wherein the cation-conductive ceramic membrane comprises a solid MSICON (Metal Super Ion CONducting) material, where M is Na, K, or Li.