Electrochemical synthesis of ammonia

Abstract

A method for electrochemical synthesis of ammonia gas comprising providing an electrolyte between an anode and a cathode, providing hydrogen gas to the anode, oxidizing negatively charged nitrogen-containing species present in the electrolyte at the anode to form an adsorbed nitrogen species, and reacting the hydrogen with the adsorbed nitrogen species to form ammonia. Preferably, the hydrogen gas is provided to the anode by passing the hydrogen gas through a porous anode substrate. It is also preferred to produce the negatively charged nitrogen-containing species in the electrolyte by reducing nitrogen gas at the cathode. However, the negatively charged nitrogen-containing species may also be provided by supplying a nitrogen-containing salt, such as lithium nitride, into the molten salt electrolyte mixture in a sufficient amount to provide some or all of the nitrogen consumed in the production of ammonia.

1 - 36 . (canceled)  
     
     
         37 . An apparatus comprising: 
 an anode substrate adapted for fluid communication with a source of hydrogen gas;    a porous cathode substrate; and    a liquid electrolyte disposed within a matrix, wherein the matrix is disposed between the anode substrate and the porous cathode substrate, wherein the liquid electrolyte comprises an electroactive species containing nitrogen, and wherein the liquid electrolyte is not an aqueous solution.    
     
     
         38 . The apparatus of  claim 37 , further comprising: 
 a catalyst disposed on the anode substrate facing the electrolyte matrix.    
     
     
         39 . The apparatus of  claim 37 , further comprising: 
 a catalyst disposed on the cathode substrate facing the electrolyte matrix.    
     
     
         40 . The apparatus of  claim 37 , wherein the anode substrate is porous.  
     
     
         41 . The apparatus of  claim 40 , wherein the porous anode substrate has a porosity greater than 40 percent.  
     
     
         42 . The apparatus of  claim 40 , wherein the porous anode substrate has a porosity greater than 90 percent.  
     
     
         43 . The apparatus of  claim 37 , further comprising: 
 a metal membrane having a thickness of between 1 and 200 microns disposed on the anode substrate facing the electrolyte matrix.    
     
     
         44 . The apparatus of  claim 43 , wherein the metal membrane is made from a metal selected from palladium, a palladium alloy, iron, tantalum, lanthanide metals, or combinations thereof.  
     
     
         45 . The apparatus of  claim 43 , further comprising a matrix supporting the metal membrane, wherein the matrix is formed from a material selected from nickel or nickel-containing alloys.  
     
     
         46 . The apparatus of  claim 43 , further comprising a matrix supporting the metal membrane, wherein the matrix is formed from a material selected from transition metals or transition metal-containing alloys.  
     
     
         47 . The apparatus of  claim 43 , further comprising a matrix supporting the metal membrane, wherein the matrix is formed from an electrically conducting inorganic ceramic material.  
     
     
         48 . The apparatus of  claim 37 , further comprising: 
 a metal membrane having a thickness of between 1 and 200 microns disposed on both sides of the porous anode substrate, wherein the porous anode substrate is a non-noble metal and the metal membrane is palladium or a palladium-containing alloy.    
     
     
         49 . The apparatus of  claim 48 , wherein the non-noble metal is selected from iron, tantalum, or lanthanide metals.  
     
     
         50 . The apparatus of  claim 43 , wherein a catalyst is disposed on a surface of the metal membrane facing the electrolyte.  
     
     
         51 . The apparatus of  claim 50 , wherein the catalyst comprises a metal selected from iron, ruthenium or combinations thereof.  
     
     
         52 . The apparatus of  claim 37 , wherein the porous cathode substrate is made from nickel, a nickel-containing compound, or a nickel alloy.  
     
     
         53 . The apparatus of  claim 37 , wherein the porous cathode substrate is made from metal, metal alloy, ceramic or a combination thereof.  
     
     
         54 . The apparatus of  claim 37 , wherein the porous cathode substrate has a pore size of about 0.2 microns.  
     
     
         55 . The apparatus of  claim 37 , wherein the electroactive species is selected from nitrides, azides or combinations thereof.  
     
     
         56 . The apparatus of  claim 37 , wherein the electroactive species is one or more azides.  
     
     
         57 . The apparatus of  claim 37 , wherein the porous cathode substrate is adapted for fluid communication with a source of nitrogen gas.  
     
     
         58 . The apparatus of  claim 37 , wherein the electrolyte supports migration of negatively charged nitrogen-containing species between the cathode substrate and the anode.  
     
     
         59 . The apparatus of  claim 37 , wherein the electrolyte comprises a molten salt.  
     
     
         60 . The apparatus of  claim 58 , wherein the molten salt comprises one or more metal chlorides.  
     
     
         61 . The apparatus of  claim 58 , wherein the molten salt comprises one or more metal salts selected from chlorides, iodides, bromides, sulfides, phosphates, carbonates, or mixtures thereof.  
     
     
         62 . The apparatus of  claim 58 , wherein the molten salt comprises lithium chloride and potassium chloride.  
     
     
         63 . The apparatus of  claim 61 , wherein the molten salt further comprises a metal nitride salt.  
     
     
         64 . The apparatus of  claim 61 , wherein the molten salt electrolyte has a greater molar concentration of lithium chloride than potassium chloride.  
     
     
         65 . The apparatus of  claim 61 , wherein the molten salt electrolyte further comprises rubidium chloride, cesium chloride, ruthenium chloride, iron chloride, or a mixture thereof.  
     
     
         66 . The apparatus of  claim 37 , wherein the electrolyte comprises a salt dissolved in an organic solvent.