The Active Nature of Crystal MoS₂ for Converting Sulfur‐Containing Syngas

Abstract

Abstract Molybdenum disulfides are attractive sulfur‐tolerant catalysts suitable for the direct conversion of sulfur‐containing syngas, which avoids the expensive step of the deep desulfurization. However, the catalytic activity of MoS 2 ‐based catalysts is relatively low. To improve the activity, previous works have focused on modifying MoS 2 with various promoters and supports, but the structural aspects are largely overlooked. In this work, we investigated the active nature of the MoS 2 ‐based catalysts for the catalytic hydrogenation of carbon monoxide. Thus, the bulk MoS 2 with varied crystallite sizes was synthesized by the hydrothermal and the thermal decomposition methods. The catalysts before and after catalytic tests were characterized by in‐situ X‐ray diffraction, X‐ray photoelectron spectroscopy, and transmission electron microscope techniques. The CO hydrogenation under low‐temperature methanation conditions (The syngas with a H 2 /CO=2 and 40.0 ppm H 2 S, T=360 °C, and P=2 MPa) was applied to evaluate MoS 2 as a catalyst for converting syngas. The catalytic results indicate that the MoS 2 with smaller crystallite sizes exhibited a higher CO conversion. By correlating the structural propriety with the catalytic activity, a hexagonal‐prim‐shaped model was developed to describe different sites on the MoS 2 crystallite. Based on this model, the activity of different active sites on the bulk MoS 2 for CO hydrogenation decreased in the order of rim sites > edge sites ≫ basal sites. The highest catalytic activity over the bulk MoS 2 with smallest particles was attributed to the highest exposure of the rim sites.