Electrolysis cell comprising sulfur dioxide-depolarized anode and method of using the same in hydrogen generation

Abstract

Electrolysis cell and method of using the same in hydrogen generation. According to one embodiment, the electrolysis cell includes a frame having an interior. A proton exchange membrane (PEM) is disposed within the frame to divide the interior into two chambers. An anode in the form of a gas diffusion electrode is disposed within the interior of the frame and is spaced apart from the PEM, the space between the anode and the PEM being filled with an aqueous sulfuric acid. A cathode is disposed within the interior of the frame and is ionically coupled to the PEM. In use, gaseous sulfur dioxide is delivered to the side of the anode facing away from the sulfuric acid solution, and a current is supplied to the electrolysis cell. Consequently, sulfur dioxide is oxidized at the anode, and molecular hydrogen is generated at the cathode.

1 . An electrolysis cell suitable for oxidizing sulfur dioxide at an anode and for generating molecular hydrogen at a cathode, the electrolysis cell comprising:
 (a) a frame, said frame having an interior;   (b) a separator disposed within the interior of said frame to divide said interior into a plurality of chambers, said separator being ionically-conductive, said separator having an anodic-facing surface and a cathodic-facing surface;   (c) an anode disposed within the interior of said frame and spaced apart from said anodic-facing surface of said separator to form a first electrolyte chamber therebetween, said anode comprising a fluid diffusion electrode;   (d) a first electrolytic solution present in said first electrolyte chamber; and   (e) a cathode disposed within the interior of said frame and ionically coupled to the cathodic-facing surface of the separator.   
   
   
       2 . The electrolysis cell as claimed in  claim 1  wherein said separator is an ion exchange membrane. 
   
   
       3 . The electrolysis cell as claimed in  claim 2  wherein said ion exchange membrane is a proton exchange membrane. 
   
   
       4 . The electrolysis cell as claimed in  claim 1  wherein said fluid diffusion electrode is a gas diffusion electrode. 
   
   
       5 . The electrolysis cell as claimed in  claim 1  wherein said fluid diffusion electrode is a liquid-liquid electrode. 
   
   
       6 . The electrolysis cell as claimed in  claim 1  wherein said first electrolytic solution is aqueous sulfuric acid. 
   
   
       7 . The electrolysis cell as claimed in  claim 1  wherein said cathode is in direct contact with said cathodic-facing surface of said separator. 
   
   
       8 . The electrolysis cell as claimed in  claim 1  wherein said cathode is spaced apart from said cathodic-facing surface of said separator to define a second electrolyte chamber, said electrolysis cell further comprising a second electrolytic solution in said second electrolyte chamber. 
   
   
       9 . The electrolysis cell as claimed in  claim 8  wherein said second electrolytic solution is aqueous sulfuric acid. 
   
   
       10 . The electrolysis cell as claimed in  claim 8  wherein said cathode comprises a gas diffusion electrode. 
   
   
       11 . The electrolysis cell as claimed in  claim 1  wherein said frame and said anode form a sulfur dioxide chamber and wherein said frame includes an inlet that opens into said sulfur dioxide chamber to permit sulfur dioxide to be introduced into said sulfur dioxide chamber. 
   
   
       12 . The electrolysis cell as claimed in  claim 1  wherein said frame includes an inlet opening into said first electrolyte chamber and an outlet exiting from said first electrolyte chamber. 
   
   
       13 . An electrolysis cell suitable for oxidizing sulfur dioxide at an anode and for generating molecular hydrogen at a cathode, the electrolysis cell comprising:
 (a) a frame, said frame having an interior;   (b) an anode disposed within the interior of said frame, said anode being a fluid diffusion electrode;   (c) a cathode disposed within the interior of said frame and spaced apart from said anode, said cathode being a gas diffusion electrode, wherein said cathode and said anode define an electrolyte chamber therebetween, a sulfur dioxide chamber being formed on the opposite side of said anode, and a hydrogen chamber being formed on the opposite side of said cathode; and   (d) an electrolytic solution present in said electrolyte chamber.   
   
   
       14 . The electrolysis cell as claimed in  claim 13  wherein said electrolytic solution is aqueous sulfuric acid. 
   
   
       15 . The electrolysis cell as claimed in  claim 14  wherein said frame includes a first inlet that opens into said sulfur dioxide chamber to permit sulfur dioxide to be introduced into said sulfur dioxide chamber, wherein said frame includes a second inlet that opens into said electrolyte chamber to permit the electrolytic solution to be introduced into the electrolyte chamber and a first outlet that removes the electrolytic solution from said electrolyte chamber, and wherein said frame includes a second outlet to permit molecular hydrogen to be removed from said hydrogen chamber. 
   
   
       16 . The electrolysis cell as claimed in  claim 13  wherein said anode is a gas diffusion electrode. 
   
   
       17 . The electrolysis cell as claimed in  claim 13  wherein said anode is a liquid-liquid electrode. 
   
   
       18 . A method for generating molecular hydrogen, said method comprising the steps of:
 (a) providing an electrolysis cell, said electrolysis cell comprising
 i. a separator, said separator being ionically-conductive, said separator having an anodic-facing surface and a cathodic-facing surface; 
 ii. an anode spaced apart from said anodic-facing surface of said separator to form a first space, said anode comprising a fluid diffusion electrode; and 
 iii. a cathode ionically coupled to the cathodic-facing surface of the separator; 
   (b) filling the first space between said anode and said separator with an aqueous electrolytic solution;   (c) supplying sulfur dioxide to the anode from the side opposite the aqueous electrolytic solution; and   (d) supplying current to the electrolysis cell, whereby sulfur dioxide is oxidized at the anode and molecular hydrogen is generated at the cathode.   
   
   
       19 . The method as claimed in  claim 18  wherein the sulfur dioxide supplied to the anode is in liquid form and wherein the fluid diffusion electrode is a liquid-liquid electrode. 
   
   
       20 . The method as claimed in  claim 18  wherein the sulfur dioxide supplied to the anode is in gaseous form and wherein the fluid diffusion electrode is a gas diffusion electrode. 
   
   
       21 . The method as claimed in  claim 18  wherein the cathode is in direct contact with the cathodic-facing surface of the separator. 
   
   
       22 . The method as claimed in  claim 18  wherein the cathode is a gas diffusion electrode and is spaced apart from the cathodic-facing surface of the separator to form a second space, said method further comprising filling said second space with an aqueous electrolytic solution. 
   
   
       23 . The method as claimed in  claim 18  wherein said separator is an ion exchange membrane. 
   
   
       24 . The method as claimed in  claim 23  wherein said ion exchange membrane is a proton exchange membrane. 
   
   
       25 . The method as claimed in  claim 18  wherein the aqueous electrolytic solution is aqueous sulfuric acid. 
   
   
       26 . A method for generating molecular hydrogen, said method comprising the steps of:
 (a) providing an electrolysis cell, said electrolysis cell comprising an anode and a cathode, the anode and the cathode being spaced apart from one another by a space, the space being filled with an aqueous electrolytic solution, the anode comprising a fluid diffusion electrode, the cathode comprising a gas diffusion electrode;   (b) supplying sulfur dioxide to the anode from the side opposite the aqueous electrolytic solution; and   (c) supplying current to the electrolysis cell, whereby sulfur dioxide is oxidized at the anode and molecular hydrogen is generated at the cathode.   
   
   
       27 . The method as claimed in  claim 26  wherein the sulfur dioxide supplied to the anode is in liquid form and wherein the fluid diffusion electrode is a liquid-liquid electrode. 
   
   
       28 . The method as claimed in  claim 26  wherein the sulfur dioxide supplied to the anode is in gaseous form and wherein the fluid diffusion electrode is a gas diffusion electrode. 
   
   
       29 . The method as claimed in  claim 26  wherein the aqueous electrolytic solution is a solution of aqueous sulfuric acid.