A membrane reactor to produce hydrogen by decomposing hydrogen sulfide with a silica membrane prepared by CVD method

摘要

A membrane reactor to decompose hydrogen sulfide into hydrogen with a hydrogen-selective silica membrane has been successfully developed. The silica membrane layer was deposited by the counter-diffusion chemical vapor deposition (CVD) method at 873 K with tetramethoxysilane and oxygen onto the α -alumina substrate which had been coated with γ -alumina. It showed excellent hydrogen permeance of the order of 10-7 mol m-2 s-1 Pa-1 and high hydrogen / nitrogen selectivity of around 103 at 873 K. It was indicated that this membrane could be used at high temperature condition of 1073 K or steam condition, although the hydrogen permeance slightly decreased, and this slight deterioration of the performance was not probably attributed to the structural changes of the silica layer. The membrane reactor which was constructed with our silica membrane and a commercial catalyst was operated by feeding 1 % of hydrogen sulfide gas, and successfully decomposed hydrogen sulfide gas into hydrogen with higher conversion at 873 K. The conversion gained in this experiment greatly exceeded the equilibrium conversion (7.8%) and reached 69 % at 7 s of residence time. Additionally the conversion was well-predicted using a simple calculation study. This was because the silica membrane kept its excellent hydrogen-selective performance without deterioration of the membrane under high temperature and corrosion by hydrogen sulfide.