Paired electrosynthesis process for (co)production hydroxylamine and ammonia

Abstract

The present invention is directed to a paired electrosynthesis process for the (co)production of hydroxylamine (HA) and/or ammonia out of N 2 or air and water. It further provides an electrolyzer developed for said purpose comprising both a porous cathode and anode with an effective catalyst layer and based on a continuous flow process. The process and electrolyzer of the present invention are particularly useful to efficiently convert reactants such as NOs′, NO 2 ; NOx and N 2 at both, the cathode and anode.

1 . An electrochemical flow reactor configured for paired electrosynthesis of NH 3  and/or Hydroxylamine (HA), said reactor comprising;
 metal electrocatalyst based porous gas diffusion electrodes (GDEs) as cathode and anode,   an anode and a cathode compartment each comprising an electrolyte compartment and a gas compartment separated from one another by means of the metal electrocatalyst based porous GDEs, configured for gas from the gas compartment to reach the metal electrocatalyst from the GDEs, and configured to be in contact with the electrolyte from the electrolyte compartment; and being characterized in that,   the outlet of the electrolyte compartment of the anode compartment is fluidly connected to the inlet of the electrolyte compartment of the cathode compartment.   
     
     
         2 . The electrochemical flow cell reactor according to  claim 1 , wherein the metal electrocatalysts are selected from Bismuth/Molybdate based catalysts, Copper based catalysts, Ruthenium based catalysts, Platinum based catalysts, Cobalt based catalysts, Nickel based catalysts, Palladium based catalysts, Cobalt/Iron/Zinc/Oxide alloy based catalysts, Iron/Tin alloy based catalysts and combinations thereof. 
     
     
         3 . The electrochemical flow cell reactor according to  claim 1 or 2 , wherein the metal electrocatalysts of the cathode is selected from Bismuth/Molybdate based catalysts, Bismuth/Tin based catalysts, Copper based catalysts, Ruthenium based catalysts, Platinum based catalysts, Cobalt based catalysts, Nickel based catalysts, Palladium based catalysts, and combinations thereof; and the metal electrocatalysts of the anode is selected from Ruthenium and Ruthenium/Manganese oxide based catalysts, Platinum based Rhodium based catalysts, Palladium based catalysts, catalysts, Cobalt/Iron/Zinc/Oxide alloy based catalysts, Tungsten based, Iron/Tin alloy based catalysts, (supported) boron doped diamond, (supported) nitrogen doped carbon and combinations thereof. 
     
     
         4 . The electrochemical flow cell reactor according to  claim 1 , wherein the metal electrocatalysts of the cathode is selected from a Bismuth/Molybdate alloy, a Bismuth/Tin alloy, Copper, a Platinum/Ruthenium alloy, a Platinum/Tin alloy, Cobalt, Nickel, and Palladium; more in particular the metal electrocatalysts of the cathode is selected from Bismuth/Molybdate alloy, Copper, a Platinum/Ruthenium alloy, a Platinum/Tin alloy, Cobalt, and Nickel, 
     
     
         5 . The electrochemical flow cell reactor according to  claim 1 , wherein the metal electrocatalysts of the anode is selected from Platinum, a Ruthenium/Titanium alloy, a Ruthenium/Manganese oxide alloy, Rhodium, Palladium, a Cobalt/Iron/Zinc/Oxide alloy, an Iron/Tin alloy, a Palladium/Ruthenium alloy, (supported) boron doped diamond, (supported) nitrogen doped carbon; more in particular the metal electrocatalysts of the anode is selected from Platinum, a Ruthenium/Titanium alloy, a Cobalt/Iron/Zinc/Oxide alloy, an Iron/Tin alloy, and a Palladium/Ruthenium alloy 
     
     
         6 . The electrochemical flow cell reactor according to  any one of the preceding claims  wherein the anode and cathode compartment are separated by an ion exchange membrane. 
     
     
         7 . The electrochemical flow cell reactor according to  claim 1 , wherein the gas compartment of the anode compartment and the gas compartment of the cathode compartment comprise a gas inlet for a Nitrogen (N 2 ) containing gas. 
     
     
         8 . The electrochemical flow cell reactor according to  claim 7 , wherein the Nitrogen (N 2 ) from the Nitrogen containing gas from the gas compartment of the anode compartment is oxidized at the anode with the formation of Nitrate (NO 3   − ), Nitrite (NO 2   − ) and/or NOx in the electrolyte of the anode compartment, wherein the thus obtained Nitrate (NO 3   − ) Nitrite (NO 2   − ) and/or NOx containing electrolyte is fed into to electrolyte compartment of the cathode compartment, to be reduced at the cathode together with the Nitrogen (N 2 ) from the Nitrogen containing gas from the gas compartment of the cathode compartment with the formation of Ammonia (NH 3 ) and hydroxylamine (HA) in the electrolyte of the cathode compartment, and removing the thus obtained Ammonia (NH 3 ) and hydroxylamine (HA) containing electrolyte from the electrolyte compartment of the cathode compartment. 
     
     
         9 . The electrochemical flow cell reactor according to  claim 8 , further comprising a separator to retrieve the Ammonia (NH 3 ) and hydroxylamine (HA) from the Ammonia (NH 3 ) and hydroxylamine (HA) containing electrolyte of the cathode compartment, and recycling the electrolyte into the electrolyte compartment of the anode compartment. 
     
     
         10 . A method of paired electrosynthesis of NH 3  and Hydroxylamine (HA) in an electrochemical flow cell reactor comprising an anode and a cathode compartment separated by an ion exchange membrane, said method comprising;
 oxidizing Dinitrogen (N 2 ) from a Nitrogen containing gas using a metal electrocatalyst based porous gas diffusion electrodes (GDEs) as anode with the formation of Nitrate (NO 3   − ), Nitrite (NO 2   − ) and/or NOx in an alkaline or acidic electrolyte present in an electrolyte compartment of the anode compartment,   feeding the thus obtained Nitrate (NO 3   − ) containing alkaline/acidic electrolyte into an electrolyte compartment of the cathode compartment,   reducing the Nitrate (NO 3   − ) from said Nitrate (NO 3   − ) containing alkaline electrolyte together with Dinitrogen (N 2 ) from a Nitrogen containing gas using a metal electrocatalyst based porous gas diffusion electrodes (GDEs) as cathode, with the formation of Ammonia (NH 3 ) and hydroxylamine (HA) in the alkaline/acidic electrolyte of the cathode compartment, and   removing the thus obtained Ammonia (NH 3 ) and hydroxylamine (HA) containing alkaline/acidic electrolyte from the electrolyte compartment of the cathode compartment.   
     
     
         11 . The method of paired electrosynthesis of NH 3  and/or Hydroxylamine (HA) according to  claim 10 , further comprising;
 separating the Ammonia (NH 3 ) and hydroxylamine (HA) from the Ammonia (NH 3 ) and hydroxylamine (HA) containing alkaline electrolyte, and   recycling the alkaline electrolyte into the electrolyte compartment of the anode compartment.   
     
     
         12 . The method of  claim 10 or 11 , wherein the metal electrocatalysts of the cathode is selected from Bismuth/Molybdate based catalysts, a Bismuth/Tin alloy, Copper based catalysts, Ruthenium based catalysts, Platinum based catalysts, Cobalt based catalysts, Nickel based catalysts, Palladium based catalysts, and combinations thereof; and wherein the metal electrocatalysts of the anode is selected from Ruthenium based catalysts, Platinum based catalysts, Palladium based catalysts, Cobalt/Iron/Zinc/Oxide alloy based catalysts, Iron/Tin alloy based catalysts and combinations thereof.