Preparation of an H-permselective silica membrane for the separation of H from the hydrogen iodide decomposition reaction in the iodine-sulfur process

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

A high performance hydrogen-permselective silica membrane derived from hexyltrimethoxysiline (HTMOS) Si-precursor was developed to enhance chemical equilibrium ratio of hydrogen iodide (HI) decomposition in thermochemical water-splitting iodine-sulfur (IS) process. The silica membrane, called the HTMOS membrane, was prepared via a counter diffusion chemical vapor deposition method. The HTMOS membrane prepared at an optimal condition of 450C within 5 min showed highest H permeance of the order of 10 mol Pa m s with a H/SF selectivity of 276. It was found that the HTMOS membrane was stable in HI exposure at 400C during 8 h and its HI permeance was the order of 10 mol Pa m s. It was demonstrated that the newly developed the HTMOS membrane could be a promising candidate for HI decomposition membrane reactor at working temperature of around 400C.