Study of MoO 3 -γAl 2 O 3 catalysts behavior in selective catalytic reduction of SO 2 toxic gas to sulfur with CH 4

Abstract

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.

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