Study of MoO3-γAl2O3 catalysts behavior in selective catalytic reduction of SO2 toxic gas to sulfur with CH4.

In the present study, a detailed investigation was carried out on MoO3 alumina-supported catalysts behavior in selective catalytic reduction of SO2 to sulfur with CH4. At first, four different molybdenum catalysts with weight rates of 0, 5, 10, and 15 were impregnated on γ-alumina to be characterized using XRD, SEM, BET, BJH, and N2 adsorption. Then, to find the most active catalyst, temperature dependency test was performed on all of the prepared catalysts and the result representing Al2O3-Mo10 as the best catalyst. In next step, the effects of feed gas composition, space velocity, and long-term activity, as an important industrial factor, were tested on Al2O3-Mo10. It was revealed instantaneously from the beginning, MoO3 specie started to convert mainly into MoS2 and MoO2, and a minor part into Mo2C, which is terminated after 750 min achieving a stable condition. Thereafter, SO2 conversion and sulfur selectivity increased from 85.8 to 89.4% and 99.4 to 99.7%, respectively. XRD graph of the used catalyst and TPO thermogravimetric/mass-spectra proved possible happening of the proposed mechanism in long-term activity. At the end, mean activation energy was determined based on Arrhenius model in temperature range of 550 to 800 °C, with a value of 0.33 eV for Al2O3-Mo10.