Membrane reactor development for efficient thermochemical hydrogen production using high-temperature gas-cooled reactor

Myagmarjav, O.  ; Tanaka, Nobuyuki ; Takegami, Hiroaki 

The high-temperature gas-cooled reactor (HTGR) has excellent safety features and can generate heat above 900C, making it possible to effectively use the heat not only for power generation but also for other purposes, such as low-cost, carbon-free hydrogen production. The thermochemical iodine-sulfur process is a promising hydrogen production method suitable for coupling with HTGRs. We, JAEA, have made a significant contribution to the iodine-sulfur process hydrogen production using HTGRs. One of the major challenges in the development of the iodine-sulfur process is the efficient separation of hydrogen during hydrogen iodide (2HI H + I) decomposition. Since the equilibrium conversion of HI decomposition is as low as 20%, it is necessary to introduce membrane reactors with H separation membranes to improve the conversion rate. No membrane exists that can efficiently separate H while handling corrosive gas (HI, I) and high temperature. Therefore, we developed a new silica membrane for H separation with the required properties. Using this membrane, we fabricated a lab-scale membrane reactor and succeeded in increasing the conversion rate of HI decomposition from the current 20% (equilibrium conversion) to the target 70%. This achievement opens up new applications of silica membrane reactor technology for nuclear H production.