Oxygen Generation Apparatus and Method

Abstract

An oxygen generator for an oxygen-generation apparatus has a proton-conducting membrane ( 60 ), a cathode ( 50 ) contacting a first side, or cathodic side, of the membrane, an anode ( 70 ) contacting a second side, or anodic side, of the membrane, and a source of water for supply to the membrane. In use, an electrolysis voltage applied between the cathode and the anode causes electrolysis of the water to generate oxygen gas at the anode. Atmospheric oxygen, i.e. oxygen in the air, is substantially prevented from coming into contact with the cathode. For an acidic proton-conducting membrane this substantially prevents the formation of hydrogen peroxide at the cathode.

1 . An oxygen-generation apparatus comprising
 a proton-conducting gas impermeable membrane;   a cathode contacting a first side of the membrane;   an anode contacting a second side of the membrane; and   a source of water for supply to the membrane;   whereby application of an electrolysis voltage between the cathode and the anode causes electrolysis of the water to generate oxygen gas at the anode,   and whereby passage of oxygen to the cathode is substantially prevented.   
   
   
       2 - 31 . (canceled) 
   
   
       32 . An oxygen-generation apparatus according to  claim 1 , in which hydrogen is generated at the cathode, flows away from the cathode and is vented to the atmosphere through a hydrogen venting means such that flow of atmospheric oxygen to the cathode is substantially prevented during operation of the generator. 
   
   
       33 . An oxygen-generation apparatus according to  claim 32 , in which the hydrogen venting means comprises one or more vent holes of predetermined dimensions. 
   
   
       34 . An oxygen-generation apparatus according to  claim 32 , in which the hydrogen venting means comprises a gas-permeable membrane. 
   
   
       35 . An oxygen-generation apparatus according to  claim 34 , in which the gas-permeable membrane is in contact with the cathode. 
   
   
       36 . An oxygen-generation apparatus according to  claim 32 , in which the hydrogen venting means comprises a cathode chamber into which hydrogen flows from the cathode before being vented to the atmosphere. 
   
   
       37 . An oxygen-generation apparatus according to  claim 1 , further comprising a catalyst, at which the hydrogen generated at the cathode reacts with atmospheric oxygen. 
   
   
       38 . An oxygen-generation apparatus according to  claim 37 , in which the hydrogen and atmospheric oxygen react to form water. 
   
   
       39 . An oxygen-generation apparatus according to  claim 38 , in which the formed water is returned to said source of water or to said proton-conducting membrane. 
   
   
       40 . An oxygen-generation apparatus according to  claim 37 , in which said atmospheric oxygen flows through a gas-permeable membrane to the catalyst. 
   
   
       41 . An oxygen-generation apparatus according to  claim 1 , in which an assembly comprising the proton-conducting membrane is retained between two end-plates, the end-plates being joined together so as to form a watertight seal therebetween. 
   
   
       42 . A catalytic apparatus for use with an oxygen generator, in which the oxygen generator produces hydrogen at a cathode, the catalytic apparatus comprising a catalyst at which at least a portion of said hydrogen reacts with atmospheric oxygen. 
   
   
       43 . A catalytic apparatus according to  claim 42 , for use with an oxygen generator which electrolyses water to produce the hydrogen at the cathode and oxygen at an anode, wherein the hydrogen and atmospheric oxygen react to produce water and the water is returned to the oxygen generator for further electrolysis. 
   
   
       44 . A catalytic apparatus according to  claim 42 , in which the atmospheric oxygen passes through a gas-permeable/liquid-impermeable membrane to reach the catalyst. 
   
   
       45 . A catalytic apparatus according to  claim 42 , in which the hydrogen passes through a gas-permeable membrane to reach the catalyst. 
   
   
       46 . A catalytic apparatus according to  claim 45 , in which said gas-permeable membrane is also liquid-permeable. 
   
   
       47 . A method of generating oxygen by electrolysis comprising the steps of supplying water to a proton-conducting membrane, the membrane being in contact with an anode on one side of the membrane and a cathode on the other side of the membrane;
 electrolysing the water to generate oxygen at the anode; and   preventing substantial access of oxygen to the cathode.   
   
   
       48 . A method of generating oxygen according to  claim 47 , in which hydrogen is generated at the cathode, comprising the step of venting the hydrogen from the apparatus so as substantially to prevent flow of atmospheric oxygen to the cathode. 
   
   
       49 . A method of generating oxygen according to  claim 47 , comprising the step of reacting hydrogen generated at the cathode with atmospheric oxygen at a catalyst. 
   
   
       50 . A method of generating oxygen according to  claim 49 , in which the catalysed reaction between hydrogen and atmospheric oxygen produces water, and comprising the step of supplying at least a portion of said produced water to the proton-conducting membrane. 
   
   
       51 . A method for reducing venting of hydrogen from an oxygen generator that produces hydrogen at a cathode, by reacting at least a portion of the hydrogen with atmospheric oxygen at a catalyst. 
   
   
       52 . A method according to  claim 51 , in which the oxygen generator electrolyses water to produce the hydrogen at the cathode and oxygen at an anode and the hydrogen subsequently reacts with the atmospheric oxygen at said catalyst, further comprising the step of supplying at least a portion of the water to the oxygen generator. 
   
   
       53 . A method of supplying water to an electrolysis portion of a proton-conducting membrane disposed between a cathode contacting a first side of the membrane and an anode contacting a second side of the membrane, by diffusion through the thickness of the membrane from a water source in contact with a portion of said membrane extending beyond said cathode and said anode. 
   
   
       54 . A method according to  claim 53 , in which electrolysis of the water occurs on the application of an electrolysis voltage between the cathode and the anode resulting in the generation of oxygen gas at the anode. 
   
   
       55 . A method according to  claim 54 , in which water supplied to the electrolysis portion of the membrane and consumed by electrolysis is replaced by water from said water source.