Development of a silica membrane for H production from HI decomposition in the IS process

HI分解反応用シリカ水素選択透過性分離膜の開発

Myagmarjav, O.  ; 池田 歩*; 野村 幹弘*; 久保 真治  

Myagmarjav, O.; Ikeda, Ayumi*; Nomura, Mikihiro*; Kubo, Shinji

熱化学水素製造法ISプロセスにおけるHI分解反応のワンパス分解率を向上させるため、水素選択透過性シリカ膜の開発を行った。対向拡散CVDを用い、多孔質アルミナを基材(直径10mm)とした水素分離膜を作製した。Hガス, HガスおよびSFを用いたガス透過試験により、CVDプロセス中の製膜条件(窒素ガス流量,酸素ガス流量)が膜性能(選択率)に関連すること明らかにし、製膜条件の最適化により膜性能が向上する可能性を示した。

In this study, we have developed a highly hydrogen permeable silica membrane derived from hexyltrimethoxysilane as a Si precursor using porous alumina support. Modification of alumina support tubes in the absence of and in the presence of -alumina coating was carried out by a counter diffusion chemical vapor deposition (CVD). A membrane with intermediate -alumina layer showed higher H permeance (7.7 10 mol m s Pa) than that formed directly on the -alumina tube (3.8 10 mol m s Pa). It was found that the thickness of -alumina layer played an important role in the improvement of membrane permeation performance. Modified membrane based on -alumina coating with a thickness of 1.5 m exhibited H/SF selectivity over 3000 at 270C, while maintaining H permeance in the order of 10 mol m s Pa. The results led to the conclusion that the modified membrane is a promising candidate for further enhancement of HI decomposition in membrane reactor.