Hydrogen production tests by hydrogen iodide decomposition membrane reactor equipped with silica-based ceramics membrane

Myagmarjav, O.  ; Tanaka, Nobuyuki ; Nomura, Mikihiro*; Kubo, Shinji  

The catalytic decomposition of hydrogen iodide in a membrane reactor using silica membranes derived from hexyltrimethoxysilane (HTMOS) was investigated for the production of hydrogen in the thermochemical water splitting iodine-sulfur process. The silica membranes were prepared by counter-diffusion chemical vapor deposition using porous alumina support tubes in both the absence and presence of a -alumina layer. The silica membranes formed on -alumina-coated -alumina tubes displayed a higher H permeance than that formed directly on an -alumina tube. A silica membrane based on a 1.5 m-thick -alumina layer fabricated under deposition conditions of 450C, 1200 s, and a N carrier gas velocity of 0.044 m s exhibited a high H permeance of 9.4 10 mol Pa m s while maintaining an H/N selectivity of over 80.0. The performance of a membrane reactor based on an HTMOS-derived silica membrane was evaluated at 400C by measuring the HI conversion and H flow rates. The conversion was approximately 0.48 when the HI flow rate was 9.7 mL min.