Silica membrane reactor for the thermochemical iodine-sulfur process to produce hydrogen

Silica membranes prepared by chemical vapor deposition were applied to the decomposition reaction of HI of the iodine-sulfur process in order to improve one-pass conversion of HI. Equilibrium conversion of HI is 22% at 723 K without hydrogen removal. Hydrogen was successfully extracted from the decomposition reactor using the silica membranes between 723 and 873 K. HI conversions were increased with an increase in the hydrogen extraction ratio. The maximum HI one-pass conversion was 76.4% at 873 K. The total thermal efficiency can be improved by 1% for this HI conversion by calculating the heat/mass balance of the process. The concentration profile in the reactor was evaluated by using the simple two-dimensional simulation. H-2 permeances measured by the experimental method were almost the same as those of the simulation, and the membrane reactor system was found to have permeation limitations. Membranes with higher H-2 permeances should be developed for the membrane reactor.