Defect-free, high-performance support preparation via a novel rotary method for hydrogen-separation membranes in HI decomposition of the thermochemical iodine-sulfur process

Myagmarjav, O. ; 野口 弘喜  ; 田中 伸幸 ; 上地 優; 杉本 千紘 ; 石井 克典  ; 野村 幹弘*; 竹上 弘彰 

Myagmarjav, O.; Noguchi, Hiroki; Tanaka, Nobuyuki; Kamiji, Yu; Sugimoto, Chihiro; Ishii, Katsunori; Nomura, Mikihiro*; Takegami, Hiroaki

The thermal efficiency of hydrogen production via the thermochemical iodine-sulfur (IS) process can be significantly improved by applying a membrane reactor to the HI decomposition step. A key component in such systems is the hydrogen separation membrane, whose performance is strongly influenced by the properties of its support, consisting of a base -alumina tube and middle -alumina and silica layers. In this study, an innovative rotary coating technique was developed to fabricate middle -alumina layer with a smooth, defect-free surface and controlled thickness along an industrial-scale 400 mm length, an aspect not sufficiently addressed in previous studies. Key process parameters, including rotation speed, coating period, number of coating cycles, and coating solution concentration were systematically investigated. Unlike the conventional dip-coating method, which produced non-uniform layers (ranging from 31 to 56 m from top to bottom of the support tube) and frequent defects, the rotary method yielded a uniform and thinner layer of 21 m along the full length. The resulting supports also demonstrated superior permeation performance and structural integrity, confirming their suitability for high-efficiency membrane applications in HI decomposition.