Electrochemical hydrogen compressor

Abstract

The invention disclosed relates to an apparatus and process for electrochemical compression of hydrogen. The apparatus comprises a membrane electrolyte cell assembly (MEA), including planar gas distribution plates sandwiching the MEA, the assembly being held together by end-plates, the end-plates having complementary peripheral grooves for seating an intervening seal between the end-plates and the MEA, the end-plate on the anode side further including a hydrogen supply inlet and the end-plate on the cathode side further including a compressed hydrogen outlet. Both single cell and multi-cell assemblies are disclosed. The multi-cell assemblies comprise a plurality of such single cells connected in series, such that the compressed hydrogen from the outlet of a first cell is connected to the hydrogen outlet of the next cell in series, where each cell is electrically isolated from the adjacent cell in the series. The process involves the electrochemical compression of hydrogen in such cells, whereby pressures of up to 12,000 psi are achieved by multi-cell assemblies.

1 . An apparatus for compression of hydrogen, comprising a membrane electrolyte cell assembly (MEA), including a proton-conducting electrolyte membrane, an anode on one side of the membrane and a cathode on the other side of the membrane, the anode having an electrochemically active material for oxidizing hydrogen to protons, the cathode having an electrochemically active material for reducing protons to hydrogen, and further comprising next to the anode and cathode, planar gas distribution and support plates sandwiching the MEA, the assembly being held together by end-plates, the end-plates having complementary peripheral grooves for seating an intervening seal between the end-plates and the MEA, the end-plate on the anode side further including a hydrogen supply inlet and the end-plate on the cathode side further including a compressed hydrogen outlet.  
     
     
         2 . The apparatus according to  claim 1 , wherein the gas distribution and support plates include a central gas distribution area.  
     
     
         3 . The apparatus according to  claim 2 , wherein the gas distribution area is in the form of pores.  
     
     
         4 . The apparatus according to  claim 1 , the gas distribution and support plates are made of a porous sintered metal frit material.  
     
     
         5 . The apparatus according to  claim 4 , wherein the metal frit is stainless steel frit.  
     
     
         6 . The apparatus according to  claim 2 , wherein the end-plates each include an additional complementary pocket for seating the metal frit plates.  
     
     
         7 . The apparatus according to  claim 6 , additionally comprising on the cathode side between the gas distribution and support plate and the end plate, a spring means for ensuring adequate electrical contact.  
     
     
         8 . The apparatus according to  claim 7 , wherein both the spring and spring support are made of stainless steel.  
     
     
         9 . The apparatus according to  claim 7 , wherein the proton conducting membrane is of a material selected from the group consisting of Nafion®, sulfonated-polystyrene and the partially fluorinated ionomeric membranes, lonClad® R-1010 and R-4010.  
     
     
         10 . The apparatus according to  claim 1 , additionally comprising means for applying an electric potential to the cell, wherein the applied potential to effect a final pressure of hydrogen exiting the cathode side of the cell is determined by the Nernst equation.  
     
     
         11 . The apparatus according to  claim 1 , comprising a plurality of MEA cells connected in series, such that the compressed hydrogen from the hydrogen outlet of a first cell in the series is fed to the hydrogen inlet of the next cell in series, wherein each cell is electrically isolated from the next cell in the series.  
     
     
         12 . A process for the compression of hydrogen by means of the apparatus according to  claim 1 , wherein hydrogen is compressed electrochemically by the MEA by oxidation of the hydrogen to protons at the anode, which having passed through the membrane to the cathode side are reduced back to hydrogen and discharged under pressure.  
     
     
         13 . The process according to  claim 12 , wherein hydrogen is pressurized to 12,000 psi or greater.  
     
     
         14 . The process according to  claim 12 , wherein a plurality of MEA cells are connected in series, each cell being electrically isolated from the next cell in the series, such that hydrogen discharged under pressure from the hydrogen outlet of a first cell in the series is fed to the hydrogen inlet of the next cell in series, and hydrogen is discharged from the hydrogen outlet of the next cell at a higher pressure.  
     
     
         15 . An apparatus for compression of hydrogen, comprising a membrane electrolyte cell assembly (MEA), including a proton-conducting electrolyte membrane, an anode on one side of the membrane and a cathode on the other side of the membrane, the anode having an electrochemically active material for oxidizing hydrogen to protons, the cathode having an electrochemically active material for reducing protons to hydrogen, and further a hydrogen supply inlet and a compressed hydrogen outlet.