硫化水素と溶融金属間の水素発生反応について

抄録

Hydrogen as a secondary source of clean energy commands world-wide attention at present, regarding its indefinite supply in the form of water, its storage and transportation characteristic which are both superior to electric power, and its wide metallurgical and chemical usage.
The decomposition reaction of H₂S to produce H₂ and S⁰for recycle can be regarded as a main step reaction in many closed thermochemical water-splitting cycles based on sulfur chemistry. For this reason, the decomposition of H₂S with molten metals was studied.
As molten metals, Pb, Sn, and Bi were examined. Experiments were carried out in two ways. One is circulation and bubbling of H₂S gas into a molten metal. The other is soft blowing at the surface of the metal bath.
Conversion of H₂S to H₂ with Bi, Pb, and Sn increased in that order. In soft blowing of H₂S at the surface of molten metals, the formation of a dense film of the solid sulfide hindered the reaction. Such prevention was not found in the experiment with molten Bi, owing to much larger solubility of S in Bi (1).
Generation of H₂ was accelerated by the addition of Ni or Cu. This is due to the catalytic action of dissolved Ni or Cu in the melt. Addition of Cu to Pb accelerated the reaction even in the soft blowing of H₂S at the surface of molten Pb. It was found that crystal growth of PbS was affected by the presence of Cu and powdery PbS was formed in stead of a dense film. Although the addition of Ni to Sn accelerated the generation of H₂ there was a marked tendency to cause strong adhesion of the solid sulfide onto the inner wall of the lance.