High-temperature low-hydration ion exchange membrane electrochemical cell

Abstract

This invention relates to an electrochemical cell having a high-temperature low-hydration (HTLH) ion exchange membrane serving as an electrolyte layer. The membrane may be a non-fluorinated ionomer membrane, such as an acid-doped polybenzimidazole (PBI) membrane. The HTLH membrane is sandwiched by an anode having a hydrogen-carrying fluid feed chamber with an inlet for receiving a hydrogen-carrying fluid, and a cathode having a hydrogen product chamber with an outlet for discharging a hydrogen product gas. The anode and cathode are electrically couplable to an electric current source for powering the electrochemical cell to produce hydrogen gas in a reduction reaction at the cathode. The hydrogen-carrying fluid may be water, in which case the electrochemical cell serves as an electrolyzer; or, the hydrogen carrying fluid may be a hydrogen gas, in which case the cell serves as a hydrogen pump.

1 . An electrochemical cell comprising 
 (a) an anode comprising a hydrogen-carrying fluid feed chamber with an inlet for receiving a hydrogen-carrying fluid;    (b) a cathode comprising a hydrogen product chamber with an outlet for discharging a hydrogen product gas; and    (c) a high-temperature low-hydration membrane sandwiched between the anode and the cathode;    the anode and the cathode being electrically couplable to an electric current source for powering the electrochemical cell to produce hydrogen gas in a reduction reaction at the cathode.    
     
     
         2 . The electrochemical cell of  claim 1  wherein the high-temperature low-hydration membrane is a non-fluorinated ionomer membrane.  
     
     
         3 . The electrochemical cell as claimed in  claim 2  wherein the membrane is an acid-doped polybenzimidazole membrane.  
     
     
         4 . The electrochemical cell as claimed in  claim 3  wherein the polybenzimidazole membrane is doped with an acid selected from the group of H 2 SO 4  and H 3 PO 4 .  
     
     
         5 . The electrochemical cell of  claim 4  wherein the hydrogen-carrying fluid feed chamber is a water feed chamber for receiving feed water and comprises an outlet for discharging reaction product and unreacted water, and the electrochemical cell is an electrolyzer that produces hydrogen gas in a reduction reaction at the cathode, and oxygen gas in an oxidation reaction at the anode.  
     
     
         6 . The electrochemical cell of  claim 4  wherein the hydrogen-carrying fluid feed chamber is a hydrogen feed chamber for receiving hydrogen-carrying feed gas, and the electrochemical cell is a pump that produces hydrogen gas in a reduction reaction at the cathode.  
     
     
         7 . An electrochemical electrolyzer comprising 
 (a) an anode comprising a water feed chamber with an inlet for receiving feed water and an outlet for discharging unreacted water and product oxygen gas;    (b) a cathode comprising a hydrogen product chamber with an outlet for discharging product hydrogen gas; and    (c) a high-temperature low-hydration membrane sandwiched between the anode and the cathode;    the anode and the cathode being electrically couplable to an electric current source for powering the electrolyzer to produce hydrogen gas in a reduction reaction at the cathode, and oxygen gas in an oxidation reaction at the anode.    
     
     
         8 . The electrolyzer as claimed in  claim 7  wherein the membrane is a non-fluorinated ionomer membrane.  
     
     
         9 . The electrolyzer as claimed in  claim 8  wherein the membrane is an acid-doped polybenzimidazole membrane.  
     
     
         10 . The electrolyzer as claimed in  claim 9  wherein the polybenzimidazole membrane is doped with an acid selected from the group of H 2 SO 4  and H 3 PO 4 .  
     
     
         11 . An electrolyzer system comprising 
 (a) the electrolyzer of  claim 7;     (b) a feed water stream in fluid flow communication with the water feed chamber inlet of the electrolyzer;    (c) a hydrogen product stream in fluid flow communication with the hydrogen product chamber outlet of the electrolyzer; and    (d) a heat exchanger thermally coupled to the electrolyzer and in fluid flow communication with the water feed stream upstream of the electrolyzer, such that heat produced by the electrolyzer is used to heat the feed water stream.    
     
     
         12 . The electrolyzer system of  claim 11  further comprising a water vaporizer in fluid flow communication with the water feed stream upstream of the electrolyzer and downstream of the heat exchanger, for vaporizing the feed water.  
     
     
         13 . The electrolyzer system of  claim 11  wherein the heat exchanger is a vaporizer and comprises a pair of thermally conductive separator plates, a water vaporizing channel in between the separator plates having an inlet for receiving a liquid water feed stream and an outlet for discharging a water vapor feed stream, the vaporizer being thermally coupled to the electrolyzer by at least one of the separator plates being in thermal contact with the electrolyzer.  
     
     
         14 . The electrolyzer system of  claim 13  wherein the feed chamber outlet discharges a water vapor and oxygen gas stream, and the system further comprises a water recirculation circuit that comprises 
 (a) a condensing heat exchanger having an inlet in fluid flow communication with the water vapor and oxygen discharge stream, and an outlet for discharging a liquid water stream condensed by the heat exchanger; and  
 (b) a water tank in fluid flow communication with the liquid water stream discharged from the heat exchanger outlet, a liquid water make-up stream, and the feed water stream upstream of the vaporizer, such that liquid water recovered by the condensing heat exchanger is returned to the water feed stream.  
 
     
     
         15 . The electrolyzer system of  claim 12  wherein the feed chamber outlet discharges a water vapor and oxygen gas stream and the system further comprises a water recirculation circuit comprising a gas/water separator in fluid flow communication with the water vapor and oxygen gas discharge stream downstream of the heat exchanger, and having an oxygen gas discharge outlet, and a water discharge outlet fluidly coupled to the feed water stream upstream of the heat exchanger.  
     
     
         16 . The electrolyzer system of  claim 15  further comprising a hydrogen storage chamber in fluid flow communication with the hydrogen product stream discharged from the electrolyzer.  
     
     
         17 . An electrochemical pump comprising 
 (a) an anode comprising a hydrogen feed chamber with an inlet for receiving hydrogen-containing feed gas;    (b) a cathode comprising a hydrogen product chamber with an outlet for discharging product hydrogen gas;    (c) a high-temperature low-hydration membrane sandwiched between the electrodes;    the anode and cathode being electrically couplable to an electric current source for powering the electrochemical pump to produce the product hydrogen gas in a reduction reaction at the cathode.    
     
     
         18 . The pump as claimed in  claim 17  wherein the membrane is a non-fluorinated ionomer membrane.  
     
     
         19 . The pump as claimed in  claim 18  wherein the membrane is an acid-doped polybenzimidazole membrane.  
     
     
         20 . The pump as claimed in  claim 19  wherein the polybenzimidazole membrane is doped with an acid in the group of H 2 SO 4  and H 3 PO 4 .  
     
     
         21 . The pump as claimed in  claim 20  wherein the hydrogen feed chamber further comprises an outlet for discharging unreacted hydrogen-containing feed gas.  
     
     
         22 . An electrochemical pump system comprising 
 (a) the electrochemical pump of  claim 21;     (b) a hydrogen feed stream in fluid flow communication with the hydrogen feed chamber inlet;    (c) a hydrogen discharge stream in fluid flow communication with the hydrogen feed chamber outlet and the hydrogen and water feed stream;    (d) a heat exchanger in fluid flow communication with the hydrogen discharge stream downstream of the pump and upstream of the hydrogen feed stream, and in fluid flow communication with a coolant stream, such that the discharge stream can be cooled in the heat exchanger before joining with the feed stream; and,    (e) a recirculation pump in fluid flow communication with the discharge stream.    
     
     
         23 . An electrochemical pump system comprising 
 (a) the electrochemical pump of  claim 21;     (b) a hydrogen and water feed stream in fluid flow communication with the hydrogen feed chamber inlet;    (c) a hydrogen discharge stream in fluid flow communication with the hydrogen feed chamber outlet;    (d) an electrolyzer having a hydrogen discharge outlet in fluid flow communication with the hydrogen feed stream upstream of the pump, and an inlet in fluid flow communication with a water feed stream, for producing hydrogen from the water feed stream.    
     
     
         24 . The pump system of  claim 23  wherein the electrolyzer is an electrochemical electrolyzer comprising an anode, a cathode and a high-temperature low-hydration membrane sandwiched between the anode and the cathode.  
     
     
         25 . The pump system of  claim 24  further comprising a heat recirculation circuit comprising a 
 (a) a water vaporizer in fluid flow communication with the water feed stream upstream of the electrolyzer; and  
 (b) a heat exchanger in fluid flow communication with the water feed stream upstream of the vaporizer and thermally coupled to at least one of the electrolyzer and the pump, such that heat generated by at least one of the electrolyzer and the pump is transferable to the water feed stream.  
 
     
     
         26 . The pump system of  claim 25  further comprising a water recirculation circuit comprising 
 (a) an oxygen and water discharge stream in fluid flow communication with the electrolyzer;  
 (b) a gas/water separator having an inlet in fluid flow communication with the oxygen and water discharge stream downstream of the electrolyzer, and a water discharge outlet fluidly coupled to the feed water stream upstream of the heat exchanger, and an oxygen vent.  
 
     
     
         27 . An electrochemical pump system comprising: 
 (a) the electrochemical pump of  claim 17;  and,    (b) a natural gas reformer comprising a hydrogen gas outlet in fluid flow communication with the hydrogen feed chamber inlet of the pump and a natural gas inlet in fluid flow communication with a natural gas source.    
     
     
         28 . The electrochemical pump system of  claim 27  further comprising a water vaporizer comprising a water feed inlet in fluid flow communication with a liquid water feed source, and a water discharge outlet in fluid flow communication with a water discharge stream that is in turn in fluid flow communication with the reformer.  
     
     
         29 . The electrochemical pump system of  claim 28  further comprising a thermal recirculation circuit comprising a thermal conduction conduit thermally coupling the vaporizer and at least one of the pump and reformer, such that heat generated by the reformer or the pump is transferable to the vaporizer.  
     
     
         30 . An electrochemical pump system comprising 
 (a) the electrochemical pump of  claim 17;  and,    (b) a vaporizer in fluid flow communication with a water feed stream, and being thermally coupled to the pump such that heat generated by the pump is transferable to the water feed stream in the vaporizer.    
     
     
         31 . The pump system of  claim 30  wherein the vaporizer comprises a pair of thermally conductive separator plates, a water vaporizing channel in between the separator plates, a water feed inlet and water vapor outlet, the vaporizer being thermally coupled to the pump by one of the separator plates being in thermal contact with the pump.  
     
     
         32 . The electrochemical pump as claimed in  claim 17  wherein the hydrogen feed chamber further comprises a contaminant discharge outlet downstream of the inlet, such that the contaminants in the feed gas are filtered by operation of the electrochemical pump and discharged via the contaminant discharge outlet.  
     
     
         33 . An electrochemical filter comprising 
 (a) an anode comprising a hydrogen feed chamber with an inlet for receiving an unfiltered feed gas comprising hydrogen and contaminants, and an outlet downstream of the inlet and for discharging the contaminants;    (b) a cathode comprising a hydrogen product chamber with an outlet for discharging a hydrogen product gas;    (c) a high-temperature low-hydration membrane sandwiched between the electrodes; and    the anode and cathode being electrically couplable to an electric current source for powering the electrochemical filter to produce the hydrogen product gas in a reduction reaction at the cathode, thereby separating the contaminants from the hydrogen in the feed gas.