Apparatus and methods for electrochemical hydrogen manipulation

Abstract

Apparatus and methods are provided for electrochemical hydrogen manipulation. In one example, an electrochemical cell is provided utilizing an acid doped polybenzimidazole membrane having a proton conductivity of at least 0.1 S/cm and comprising phosphoric acid in a ratio of at least 20 moles phosphoric acid to polybenzimidazole repeating unit. The polybenzimidazole membrane can be produced by a sol-gel process. Additional concepts are also described.

1 . A method of operating an electrochemical cell, comprising: 
 applying an electric potential between a first electrode and a second electrode of an electrochemical cell;    wherein the first electrode has a higher electric potential with respect to zero than the second electrode;    wherein the first and second electrodes have an acid doped polybenzimidazole membrane between them, the membrane having a proton conductivity of at least 0.1 S/cm; and    flowing a hydrogen gas across the first electrode and evolving hydrogen at the second electrode.    
   
   
       2 . The method of  claim 1 , wherein the membrane comprises phosphoric acid at a ratio of at least 20 moles phosphoric acid to polybenzimidazole repeating unit.  
   
   
       3 . The method of  claim 1 , wherein the membrane comprises phosphoric acid at a ratio of at least 32 moles phosphoric acid to polybenzimidazole repeating unit.  
   
   
       4 . The method of  claim 1 , wherein the membrane comprises phosphoric acid at a ratio of at least 40 moles phosphoric acid to polybenzimidazole repeating unit.  
   
   
       5 . The method of  claim 1 , wherein the membrane is prepared by a sol-gel process.  
   
   
       6 . The method of  claim 1 , wherein the membrane is prepared by a process wherein polyphosphoric acid is used as a solvent for both polymerization and film casting.  
   
   
       7 . The method of  claim 1 , wherein the membrane has a proton conductivity of at least 0.2 S/cm.  
   
   
       8 . The method of  claim 1 , wherein the electrochemical cell further comprises a polymeric film abutting an external surface of the membrane.  
   
   
       9 . The method of  claim 1 , wherein the electrochemical cell further comprises a polymeric acid film abutting an external surface of the membrane, wherein the polymeric acid film comprises polyvinyl phosphonic acid.  
   
   
       10 . The method of  claim 1 , wherein the electrochemical cell further comprises a polymeric acid film abutting an external surface of the membrane, wherein the polymeric acid film comprises polyvinyl sulfonic acid.  
   
   
       11 . The method of  claim 1 , wherein the hydrogen gas is unhumidified.  
   
   
       12 . The method of  claim 1 , further comprising the step of reversing a polarity of the electric potential between the first electrode and second electrode to reverse a direction of hydrogen flow through the cell.  
   
   
       13 . The method of  claim 1 , further comprising the steps of removing the electric potential between the first electrode and the second electrode, and connecting an electric load between the first electrode and the second electrode.  
   
   
       14 . A method of transferring hydrogen from a source gas, comprising: 
 applying an electric potential between a first electrode and a second electrode of an electrochemical cell;    wherein the first electrode has a higher electric potential with respect to zero than the second electrode;    wherein the first and second electrodes have an acid doped polybenzimidazole membrane between them, wherein the membrane comprises phosphoric acid at a ratio of at least 20 moles phosphoric acid to polybenzimidazole repeating unit; and    flowing a hydrogen gas across the first electrode and evolving hydrogen at the second electrode.    
   
   
       15 . The method of  claim 14 , wherein the membrane has a proton conductivity of at least 0.1 S/cm.  
   
   
       16 . The method of  claim 14 , wherein the membrane has a proton conductivity of at least 0.2 S/cm.  
   
   
       17 . The method of  claim 14 , wherein the membrane comprises phosphoric acid at a ratio of at least 32 moles phosphoric acid to polybenzimidazole repeating unit.  
   
   
       18 . The method of  claim 14 , wherein the membrane comprises phosphoric acid at a ratio of at least 40 moles phosphoric acid to polybenzimidazole repeating unit.  
   
   
       19 . The method of  claim 14 , wherein the membrane is prepared by a sol-gel process.  
   
   
       20 . The method of  claim 14 , wherein the membrane is prepared by a process wherein polyphosphoric acid is used as a solvent for both polymerization and film casting.  
   
   
       21 . The method of  claim 14 , wherein the electrochemical cell further comprises a polymeric film abutting an external surface of the membrane.  
   
   
       22 . The method of  claim 14 , wherein the electrochemical cell further comprises a polymeric acid film abutting an external surface of the membrane, wherein the polymeric acid film comprises a material from the group consisting of polyvinyl phosphonic acid and polyvinyl sulfonic acid.  
   
   
       23 . The method of  claim 14 , wherein the hydrogen gas is unhumidified.  
   
   
       24 . The method of  claim 14 , further comprising the step of reversing a polarity of the electric potential between the first electrode and second electrode to reverse a direction of hydrogen flow through the cell.  
   
   
       25 . The method of  claim 14 , further comprising the steps of removing the electric potential between the first electrode and the second electrode, and connecting an electric load between the first electrode and the second electrode.  
   
   
       26 . An electrochemical cell, comprising: 
 a proton conducting electrolyte membrane;    a polymeric layer;    wherein the membrane has a first electrode side;    wherein the polymeric acid layer abuts the first electode side of the membrane;    wherein the membrane comprises acid doped polybenzimidazole; and    wherein a proton conductivity of the membrane is at least 0.1 S/cm.    
   
   
       27 . The electrochemical cell of  claim 26 , wherein the membrane comprises phosphoric acid at a ratio of at least 20 moles phosphoric acid to polybenzimidazole repeating unit.  
   
   
       28 . The electrochemical cell of  claim 26 , wherein the membrane has a proton conductivity of at least 0.2 S/cm.  
   
   
       29 . The electrochemical cell of  claim 26 , wherein the polymeric layer comprises a material from the group consisting of polyvinyl phosphonic acid and polyvinyl sulfonic acid.  
   
   
       30 . The electrochemical cell of  claim 26 , wherein the polymeric layer is cross-linked to the membrane.  
   
   
       31 . An electrochemical cell, comprising: 
 a membrane assembly;    wherein the membrane assembly comprises a porous support layer; and    wherein the membrane assembly comprises a polybenzimidazole layer abutting an external surface of the support layer.    
   
   
       32 . The electrochemical cell of  claim 31 , wherein a first polybenzimidazole layer abuts a first electrode side of the support layer, and wherein a second polybenzimidazole layer abuts a second electrode side of the support layer.  
   
   
       33 . The electrochemical cell of  claim 31 , wherein a first support layer abuts a first electrode side of the polybenzimidazole layer, and wherein a second support layer abuts a second electrode side of the polybenzimidazole layer.  
   
   
       34 . The electrochemical cell of  claim 31 , wherein the support layer comprises expanded polytetrafluoroethylene.  
   
   
       35 . The electrochemical cell of  claim 31 , wherein the support layer comprises pores containing phosphoric acid.  
   
   
       36 . The electrochemical cell of  claim 31 , further comprising a polymeric layer abutting the polybenzimidazole layer.  
   
   
       37 . The electrochemical cell of  claim 31 , further comprising a polymeric acid layer abutting the polybenzimidazole layer; wherein the polymeric acid layer comprises a material from the group consisting of polyvinyl phosphonic acid and polyvinyl sulfonic acid.  
   
   
       38 . The electrochemical cell of  claim 31 , wherein the polybenzimidazole layer is prepared by a sol-gel process.  
   
   
       39 . The electrochemical cell of  claim 31 , wherein the polybenzimidazole layer is prepared by a process wherein polyphosphoric acid is used as a solvent for both polymerization and film casting.  
   
   
       40 . The electrochemical cell of  claim 31 , wherein the polybenzimidazole layer has a proton conductivity of at least 0.1 S/cm.  
   
   
       41 . The electrochemical cell of  claim 31 , wherein the polybenzimidazole layer has a proton conductivity of at least 0.2 S/cm.  
   
   
       42 . The electrochemical cell of  claim 31 , wherein the polybenzimidazole layer comprises phosphoric acid at a ratio of at least 20 moles phosphoric acid to polybenzimidazole repeating unit.  
   
   
       43 . The electrochemical cell of  claim 31 , wherein the polybenzimidazole layer comprises phosphoric acid at a ratio of at least 32 moles phosphoric acid to polybenzimidazole repeating unit.  
   
   
       44 . The electrochemical cell of  claim 31 , wherein the polybenzimidazole layer comprises phosphoric acid at a ratio of at least 40 moles phosphoric acid to polybenzimidazole repeating unit.