Development of corrosion-stable dual-Si-layered membranes for hydrogen production via thermochemical iodine-sulfur process

Myagmarjav, O.  ; 田中 伸幸 ; 野口 弘喜  ; 上地 優; 小野 正人 ; 野村 幹弘*; 竹上 弘彰 

Myagmarjav, O.; Tanaka, Nobuyuki; Noguchi, Hiroki; Kamiji, Yu; Ono, Masato; Nomura, Mikihiro*; Takegami, Hiroaki

Hydrogen plays an important role in the transition to clean energy and the achievement of net-zero emissions. Thermochemical iodine-sulfur (IS) process, which uses nuclear heat to decompose water, is considered the most prospective method for producing large amounts of hydrogen without emitting carbon dioxide. The IS process consists of three coupled chemical reactions (Bunsen reaction, sulfuric acid decomposition, and hydrogen iodide decomposition). A major challenge for the practical application of the IS process is the efficient separation of hydrogen from the mixed corrosive gas of hydrogen iodide and iodine generated during hydrogen iodide decomposition (2HI H + I). A membrane that can efficiently separate H while treating this corrosive HI gas has not yet been developed. In this study, a membrane with high separation performance and corrosion stability was developed by fabricating a three-layer structure consisting of a base -alumina support tube, a middle silica layer and a top H-selective silica layer. By selecting the dipping time and CVD time, which are critical to the properties of the resulting silica layers, the prepared membrane showed high separation performance. For instance, the H/SF selectivity varied between 1622 and 1671 in the temperature range of 30-200 C. The result suggests that the developed membranes had no defects, especially existence of pinholes. HI stability tests also showed that these membrane were stable in corrosive environments.