The feasibility of membrane separations in the HIx processing section of the sulphur iodine thermochemical cycle

One of the most promising routes currently under development for sustainable hydrogen production is the sulphur iodine thermochemical water splitting cycle. The most important stage in determining overall process efficiency and feasibility of the cycle is the separation of HIx, a mixture of HI, H2O and I2. This paper investigates the scope for applying membrane separations to the HIx processing section, with the aim of improving the overall efficiency of the process. Simulations using ProSimPlus indicate that this efficiency can be increased from a base value of 36.9% to over 39% by applying a membrane separation unit which achieves 8.25% dewatering to the feed of the reactive distillation column. Comparison with experimental flux and separation data for both pervaporation and membrane distillation membranes gives design limits for the cost and feasibility of such a membrane system.