Low-temperature chemisorption-enhanced catalytic decomposition of hydrogen sulfide: Thermodynamic analysis and process concept

Low-temperature chemisorption-enhanced catalytic decomposition is one of the most promising approaches for production of hydrogen and sulfur from H2S, potentially opening the way for development of non-carbon or low-carbon power generation with simultaneous prevention of sulfur emissions into atmosphere. The process is based on unsteady-state approach, including two alterating reaction stages: a) the chemisorption of hydrogen sulfide at sulfides of transient metals (Fe, Co, Ni, etc.) with emission of hydrogen and formation of metal disulfides at low (ambient) temperature and b) backward decomposition of disulfides to sulfur and initial sulfides at moderately elevated (200-300 degrees C) temperature. The performed thermodynamic studies showed that achievement of high H2S decomposition degree at such low temperatures is possible only due to separate cyclic performance of reactions stages at different temperatures and different reaction media composition. The proposed technology may be advantageous in terms of moderate operation temperatures, relatively low capital and operation costs, minimization of formation of undesirable by-products, high operation flexibility.