Abstract: High-purity hydrogen is recovered from a pyrolysis gas, composed mainly of hydrogen and carbon monoxide, produced by pyrolysis of an organic material such as biomass. A method for producing such high-purity hydrogen includes supplying a reducing gas produced by pyrolysis of an organic material to an anode side of a high-temperature steam electrolyzer having a diaphragm comprising solid oxide electrolyte; and supplying steam to a cathode side of the high-temperature steam electrolyzer to produce hydrogen and oxygen by electrolytic action. The oxygen produced in the cathode side of the high-temperature electrolyzer passes through the diaphragm and reacts with the reducing gas to create concentration gradient of oxygen ion, thus lowering electrolysis voltage.

Abstract: A method for producing hydrogen wherein use is made of a high temperature steam electrolysis apparatus having an electrolysis vessel being partitioned into the anode side and the cathode side by the use of a solid oxide electrolyte film as a diaphragm, steam is fed to the above cathode side and a reducing gas is fed to the anode side, and steam electrolysis is carried out at a high temperature, characterized in that the reducing gas and the steam fed to the electrolysis vessel has a temperature of 200 to 500° C.

Abstract: An electrolyzer structure is provided that is suitable for use in a method that produces hydrogen by steam electrolysis by feeding reducing gas to an anode side and feeding steam to a cathode side of an electrolyzer that is partitioned into the anode side and the cathode side by a diaphragm of solid oxide electrolyte, and feeding power to the anode and cathode of the electrolyzer. One embodiment of the present invention relates to an apparatus that produces hydrogen by high temperature steam electrolysis and that comprises an electrolyzer partitioned into an anode side and a cathode side by a solid oxide electrolyte diaphragm, a conduit that feeds reducing gas to the anode side of the electrolyzer, and a conduit that feeds steam to the cathode of the electrolyzer, in which a metal cermet stable in a reducing atmosphere is used as the material of the anode and the cathode.

Abstract: High-purity hydrogen is recovered from a pyrolysis gas, composed mainly of hydrogen and carbon monoxide, produced by pyrolysis of an organic material such as biomass. A method for producing such high-purity hydrogen includes supplying a reducing gas produced by pyrolysis of an organic material to an anode side of a high-temperature steam electrolyzer having a diaphragm comprising solid oxide electrolyte; and supplying steam to a cathode side of the high-temperature steam electrolyzer to produce hydrogen and oxygen by electrolytic action. The oxygen produced in the cathode side of the high-temperature electrolyzer passes through the diaphragm and reacts with the reducing gas to create concentration gradient of oxygen ion, thus lowering electrolysis voltage.