Recovery of hydrogen from hydrogen sulfide with metals or metal sulfides

The following two types of reactions were investigated for the recovery of hydrogen from hydrogen sulfide: Type 1 H2S → H2 + S0, Type 2 H2S + O2 → H2 + SO2 Each type of reaction is constructed by a two-step cycle, in which H2S is reacted with metal or metal sulfide and then the resulting sulfide undergoes thermal decomposition or oxidation. Ag2S, FeS, Co9S8, Ni3S2, and the double sulfide CuFeS2 were examined in the former type of reaction, while Ag, Cu, Ni, liquid Pb, and liquid BiAg alloy were used as an intermediate in the latter.