Integrated Process for Co-Production of Carboxylic Acids and Halogen Products from Carbon Dioxide

Abstract

The present disclosure is a method and system for production of carboxylic based chemicals. A method for producing at oxalic acid may include receiving an anolyte feed at an anolyte region of an electrochemical cell including an anode and receiving a catholyte feed including carbon dioxide and an alkali metal bicarbonate at a catholyte region of the electrochemical cell including a cathode. Method may include applying an electrical potential between the anode and cathode sufficient to reduce the carbon dioxide to at least one reduction product and converting the at least one reduction product and an alkali metal hydroxide to an alkali metal oxalate via a thermal reactor. The method may further include converting the alkali metal oxalate to oxalic acid at the electrochemical acidification electrolyzer. The method may further include the co-production of halogen products from the anolyte region of the electrochemical cell, by the oxidation of hydrogen halides used as an anolyte feed. The halogen may then be further reacted with other chemicals to produce chlorinated organics as well as inorganic compounds such as sodium hypochlorite.

What is claimed is: 
     
         1 . A method for producing oxalic acid and co-products, comprising:
 receiving an anolyte feed including a hydrogen halide at an anolyte region of a first electrochemical cell including an anode;   receiving a catholyte feed including carbon dioxide and an alkali metal bicarbonate at a catholyte region of the first electrochemical cell including a cathode;   applying an electrical potential between the anode and the cathode of the first electrochemical cell sufficient to reduce the carbon dioxide to formate and to oxidize the hydrogen halide to a halogen;   converting the formate to an alkali metal oxalate via a thermal reaction;   receiving the alkali metal oxalate at a first electrochemical acidification electrolyzer;   converting the alkali metal oxalate to oxalic acid and co-producing alkali metal hydroxide, hydrogen, and a halogen at the first electrochemical acidification electrolyzer;   converting an alkali metal halide in a second electrochemical acidification electrolyzer to produce a hydrogen halide containing solution, an alkali metal hydroxide, and hydrogen; and   feeding at least a portion of the hydrogen halide containing solution to the anolyte region of the first electrochemical cell;   feeding at least a portion of the hydrogen halide containing solution to the first electrochemical acidification electrolyzer.   
     
     
         2 . The method of  claim 1 , wherein the anolyte feed to the first electrochemical cell includes water and a hydrogen halide containing solution generated from the second electrochemical acidification cell, wherein the hydrogen halide solution comprises a soluble mixture of hydrogen halide and alkali metal halide with the hydrogen halide concentration ranging from about 5 wt % to 40 wt %. 
     
     
         3 . The method of  claim 1 , wherein the hydrogen halide includes at least one of hydrogen bromide or hydrogen chloride. 
     
     
         4 . The method of  claim 2 , wherein an alkali metal halide content in the hydrogen halide containing solution ranges from 0.01 wt % to a solubility limit of the alkali metal halide in the hydrogen halide solution. 
     
     
         5 . The method of  claim 2 , wherein the alkali metal halide is at least one of sodium chloride, potassium chloride, sodium bromide, or potassium bromide. 
     
     
         6 . The method of  claim 1 , wherein the alkali metal hydroxide from the first and second electrochemical acidification cells includes potassium or sodium hydroxide. 
     
     
         7 . The method of  claim 1 , wherein the converting the formate to the alkali metal oxalate via the thermal reaction includes receiving a catalyst. 
     
     
         8 . The method of  claim 7 , wherein the catalyst is selected from the group consisting of alkali metal hydroxides, alkali metal ethoxides, alkali metal methoxides, and alkali metal hydrides. 
     
     
         9 . The method of  claim 6 , wherein converting the alkali metal oxalate to oxalic acid at the first electrochemical acidification electrolyzer comprises:
 passing the alkali metal oxalate through an ion exchange region of the first electrochemical acidification electrolyzer bounded by one or more cation ion exchange membranes;   producing an alkali metal hydroxide and hydrogen in the catholyte compartment, and   oxidizing a hydrogen halide containing solution in the anode compartment to produce a halogen.   
     
     
         10 . The method of  claim 9 , further comprising:
 converting the oxalic acid to an oxalic acid ester with an alcohol.   
     
     
         11 . The method of  claim 10 , further comprising:
 converting the oxalic acid ester to ethylene glycol by hydrogenation.   
     
     
         12 . The method of  claim 1 , further comprising:
 reacting the halogen with an organic compound to produce a halogenated organic compound.   
     
     
         13 . The method of  claim 1 , further comprising:
 reacting the halogen with an alkali metal hydroxide to produce an alkali metal hypochlorite product.   
     
     
         14 . The method of  claim 12 , wherein the organic compound is at least one of ethylene or propylene. 
     
     
         15 . The method of  claim 14 , wherein the halogenated organic is at least one of ethylene chloride, propylene chloride, ethylene bromide or propylene bromide. 
     
     
         16 . A method for producing formic acid and co-products comprising:
 receiving an anolyte feed including a hydrogen halide at an anolyte region of a first electrochemical cell including an anode;   receiving a catholyte feed including carbon dioxide and an alkali metal bicarbonate at a catholyte region of the first electrochemical cell including a cathode;   applying an electrical potential between the anode and the cathode sufficient to reduce the carbon dioxide to at least an alkali metal formate and to oxidize the hydrogen halide to a halogen;   converting the alkali metal formate to formic acid and co-producing alkali metal hydroxide, hydrogen, and halogen at a first electrochemical acidification electrolyzer;   converting an alkali metal halide in a second electrochemical acidification electrolyzer to produce a hydrogen halide containing solution, an alkali metal hydroxide, and hydrogen;   feeding at least a portion of the hydrogen halide containing solution to the anolyte compartment of the first electrochemical cell; and   feeding at least a portion of the hydrogen halide containing solution to the first electrochemical acidification electrolyzer.   
     
     
         17 . The method of  claim 16 , wherein the anolyte feed to the first electrochemical cell includes water, hydrogen halide, and alkali metal halide with the hydrogen halide concentration ranging from about 5 wt % to 40 wt %. 
     
     
         18 . The method of  claim 16 , wherein the hydrogen halide includes at least one of hydrogen bromide or hydrogen chloride. 
     
     
         19 . The method of  claim 16 , wherein the alkali metal halide content in the hydrogen halide containing solution ranges from 0.01 wt % to a solubility limit of the alkali metal halide in the hydrogen halide solution. 
     
     
         20 . The method of  claim 16 , wherein the alkali metal halide is at least one of sodium chloride, potassium chloride, sodium bromide or potassium bromide. 
     
     
         21 . The method of  claim 16 , wherein the alkali metal hydroxide from the first and second electrochemical acidification cells is at least one of potassium hydroxide or sodium hydroxide. 
     
     
         22 . The method of  claim 16 , wherein the alkali metal formate is at least one of potassium formate or sodium formate. 
     
     
         23 . The method of  claim 16 , wherein converting the alkali metal formate to formic acid at the first electrochemical acidification electrolyzer comprises:
 passing the alkali metal formate through an ion exchange region of the first electrochemical acidification electrolyzer bounded by one or more cation ion exchange membranes;   producing an alkali metal hydroxide and hydrogen in the catholyte compartment; and   oxidizing a hydrogen halide containing solution in the anode compartment to produce a halogen.   
     
     
         24 . The method of  claim 23 , further comprising:
 converting the formic acid to a formate ester with an alcohol.   
     
     
         25 . The method of  claim 23 , further comprising:
 converting the formic acid to a formamide.   
     
     
         26 . The method of  claim 16 , further comprising:
 reacting the halogen with an organic compound to produce a halogenated organic compound.   
     
     
         27 . The method of  claim 16 , further comprising:
 reacting the halogen with an alkali metal hydroxide to produce an alkali metal hypochlorite product.   
     
     
         28 . The method of  claim 16 , wherein the halogen is at least one of bromine or chlorine. 
     
     
         29 . The method of  claim 26 , wherein the organic compound is at least one of ethylene or propylene.