Membrane development for applications in hydrogen production using the sulphur-iodine thermochemical route

Careful optimisation of a safe and sustainable route for hydrogen production is a pressing need. Thermochemical processes employing water as raw material and nuclear/renewable energies as energy source are believed to be the best possible option in this direction, while alarming issues such as climate change and global warming are being taken into account. Amongst the well-identified cycles, the sulphur-iodine (S-I) thermochemical route assumes the highest thermal efficiency and the best one as regards its coupling to a high temperature nuclear reactor. Material development is the key issue to be addressed to realise successfully the potential of the S-I cycle. The most important area is development of gas-permeable membranes for enhancement of the equilibrium decomposition of HI, which is the most intricate step as far as the overall process efficiency is concerned. In order to overcome the low efficiency associated with the low equilibrium decomposition of HI, the authors intend to develop a hydrogen permselective membrane reactor. As a first step towards this development, a silica membrane of asymmetric nature was developed using sol-gel processing and dip coating, and characterised using scanning electron microscopy and a BET surface area analyser. A road map towards realising the successful emergence of the membrane reactor is discussed.