Comprehensive study of H2S selective catalytic oxidation on combined oxides derived from Mg/Al-V10O28 layered double hydroxides

A series of Mg2Al-V10O28-LDH (named V-LDH) were synthesized using ion-exchange method, and the derived oxides were investigated for H2S selective oxidation. The physicochemical properties of the catalysts were assessed by various methods. It was observed that vanadium species existed mainly in the form of isolated V5+ in distorted [VO4], Mg3V2O8, and Mg2V2O7. Moreover, there was a large amount of V4+ species (>25%), mainly formed with vanadyl bonds. Significantly, the catalysts exhibited excellent catalytic performances at relatively low reaction temperatures (100-200 degrees C). Furthermore, the catalyst containing 10.6 wt% vanadium (8V-LDO) was highly durable at a relatively low temperature (160 degrees C) and a high gas hourly space velocity (GHSV, 24,000 h(-1)), which can proceed consecutively for 100 h without notable deactivation. In the reaction process, the gradually produced sulfate species reacted with V4+ species to form less active VOSO4 species, which improved the redox property of V5+. The catalysts obeyed a step-wise mechanism for H2S selective catalytic oxidation. The excellent durability can be ascribed to the fact that the content of moderate basic sites was kept and the redox property of V5+ was improved. (C) 2015 Elsevier B.V. All rights reserved.