Hydrogen Production by Hydrogen Sulfide Decomposition Using Cobalt Catalysts Doped in SBA-15 Synthetized by EISA Method

Hydrogen production by H2S catalytic thermal decomposition was studied using Co mesostructured catalysts, directly synthesized by the Evaporation-Induced Self-Assembly method with molar ratios Co/Si of 0.01, 0.05, and 0.10. Cobalt was incorporated into the tetracoordinate silica structure, and lesser amounts of cobalt were left outside the structure in the spinel species of Co3O4. The H2S decomposition reaction was conducted at 400-800 degrees C under atmospheric pressure and continuous flow. The catalytic activity of catalysts was increased with the rising of temperature, reaching H2 maximum conversions at 800 degrees C; the conversion at this temperature for 0.01Co-SBA-15 was 28.4%, 0.05Co-SBA-15 was 29.5%, and 38.0% for 0.10Co-SBA-15. All catalysts showed high stability during the reaction without apparent deactivation, and the best activity was for 0.10Co-SBA-15, with a reaction rate of 0.63 mol h-1 g-1 and an energy activation of 51 kJ mol-1. During the reaction, cobalt oxidized phases were transformed into the sulphurated phase CoS by simultaneous reduction and sulphuration processes, which are due to the stream of H2S and the temperature. On the other hand, the sulfur formed was condensed as a yellow solid in the reactor outlet. The results showed that the experimental approach is an efficient alternative for synthesizing Co catalysts under soft conditions, with high activity and stability in H2 and sulfur production using a problematic gas.