Apparatus and method for producing hydrogen peroxide

Abstract

The present invention is directed to an apparatus for producing hydrogen peroxide, comprising one or more electrochemical cells, the apparatus further comprising at least one electrically conductive porous gas transport layer disposed next to a cathode gas diffusion layer, the gas transport layer being configured to deliver a flow of oxygen-containing gas towards the cathode gas diffusion layer and being configured to collect current, further including water which is configured to flow through the porous gas transport layer.

1 . An apparatus for producing hydrogen peroxide, comprising one or more neighboring electrochemical cells ( 1 ),
 each electrochemical cell ( 1 ) comprising:   a membrane electrode assembly ( 4 ) comprising at least one cathode gas diffusion layer ( 13 ), at least one cathode catalyst layer ( 14 ), at least one ion exchange membrane ( 15 ), at least one anode catalyst layer ( 16 ), at least one anode current collector ( 17 ) and a cathode water inlet connected to a cathode pump ( 23 ) for the delivery of water,   wherein in said membrane electrode assembly ( 4 ) a first side of the ion exchange membrane ( 15 ) being bound against a second side of said cathode catalyst layer ( 14 ) and said anode catalyst layer ( 16 ) being bound against an opposing second side of the ion exchange membrane ( 15 ), and   at least one electrically conductive porous gas transport layer ( 3 ) having a hydrophobic surface, being flat and homogenously contacting the cathode gas diffusion laver ( 13 ) on a first side, said gas transport layer ( 3 ) being configured to deliver a flow of oxygen-containing gas in a through plane direction towards the cathode gas diffusion layer ( 13 ) said gas diffusion layer having a pore size larger than the electrically conductive porous gas transport layer to facilitate water flow through it and the gas transport laver further being configured to collect current and the cathode gas diffusion layer further comprising water which is configured to flow through the porous gas transport layer  3  in an in plane direction; and   wherein said gas diffusion layer ( 13 ) is suitable to transport oxygen, water and hydrogen peroxide to/from the cathode catalyst layer ( 14 ).   
     
     
         2 . The apparatus of  claim 1 , comprising at least one additional gas diffusion layer ( 20 ) situated between the gas transport layer ( 3 ) and the cathode gas diffusion layer ( 13 ). 
     
     
         3 . The apparatus of  claim 1 ,
 wherein within said at least one anode catalyst layer ( 16 ) a water oxidation reaction is configured to occur, and   wherein within said at least one cathode catalyst layer ( 14 ) an oxygen reduction reaction is configured to occur.   
     
     
         4 . The apparatus of  claim 2 ,
 wherein a surface of the gas diffusion layer  13  (or additional gas diffusion layer  20 ) adjacent to the gas transport layer  3  is covered at least in proportion of 10% with the gas transport layer  3 , preferably at least 70% and even more preferably at least 95%.   
     
     
         5 . The apparatus of  claim 1 ,
 wherein a porosity of said electrically conductive porous gas transport layer ( 3 ) is between about 0.1 micrometers and 100 micrometers and a thickness between 0.5 and 10 mm.   
     
     
         6 . The apparatus of  claim 1 ,
 wherein a pressure drop induced by the electrically conductive porous gas transport layer ( 3 ) between a gas cavity from which said oxygen-containing gas is sourced and said cathode gas diffusion layer ( 13 ) is of at least 1 mbar.   
     
     
         7 . The apparatus of  claim 1 ,
 wherein said electrically conductive porous gas transport layer ( 3 ) comprises one of: porous transition metals, post-transition metals, carbon comprising materials or a combination thereof.   
     
     
         8 . The apparatus of  claim 1 ,
 wherein current density at the membrane electrode assembly ( 4 ) is between about 30 mA/cm 2  and 900 mA/cm 2 .   
     
     
         9 . The apparatus of  claim 1 ,
 wherein a voltage applied between the at least one cathode catalyst layer ( 14 ) and the at least one anode catalyst layer ( 16 ) is between about 1.2V and about 3.5V.   
     
     
         10 . A system, comprising:
 an apparatus in accordance with  claim 1 , and   a device facilitating the combination of hydrogen peroxide generated by said apparatus and ultra-violet light or ozone to facilitate the formation of hydroxyl radicals.   
     
     
         11 . (canceled) 
     
     
         12 . A method of producing hydrogen peroxide, using the apparatus of  claim 1   said gas transport layer ( 3 ) delivering a flow of oxygen-containing gas in a through plane direction toward the cathode gas diffusion layer ( 13 ) and collecting current wherein water is flowing through the porous gas transport layer ( 3 ) in an in-plane direction, and   wherein hydrogen peroxide is generated at the cathode catalyst layer ( 14 ) and is dissolved in the flowing water, and wherein the hydrogen peroxide is pushed out of the cathode catalyst layer ( 14 ).   
     
     
         13 . A method according to  claim 12 , whereby the hydrogen peroxide concentration is measured and is used to automatically regulate the flow of water delivered by a cathode pump  23  and the current at the power supply in keeping a constant concentration.