Promotion Effect of H2S at High Concentrations on Catalytic Dry Reforming of Methane in Sour Natural Gas

Abstract

The effect of high concentrations of H2S in sour natural gas on the catalytic dry reforming of methane (DRM) process has seldom been studied previously in the literature. Herein, several types of catalysts, including MgO, NiO/MgO, and LaNiO3 in different states, were prepared for conducting DRM at 800 °C and 0.1 MPa in a feed of 20 vol% CO2 and 20 vol% CH4, and their catalytic performance under conditions of the absence and presence of H2S was compared. A promotion effect of increasing H2S concentration on both the conversions of CO2 and CH4 and the molar yields of CO and H2 was observed on all the catalysts and was particularly remarkable on the MgO and the pristine NiO/MgO. For NiO/MgO, the addition of 15 vol% H2S increased the conversion of CH4 from 6.92% to 26.86% and CO2 from 9.15% to 42.10%. While there was a significant decline in the catalytic activity of the reduced NiO/MgO and LaNiO3 catalysts after adding H2S, moderate reactant conversions were still sustained. The results of process analysis and catalyst structure characterization suggest that H2S participation can contribute to the increment in CO2 and CH4 conversion, and active S-adsorbed species may play the key role of catalysis in reactions involving H2S.