Elucidating the layer-number impact of MoS2 on the adsorption and hydrogenation of CO

Abstract

MoS2 is an attractive sulfur-resistant catalyst for directly converting sulfur-containing syngas to high value-added chemicals. However, the effect of the layered structure on the catalytic activity for CO hydrogenation reactions is far from clear. Herein, MoS2/carbon composite catalysts with 1–8 stacking layers in MoS2 crystallites are synthesized, and the impact of the layer numbers on the catalytic performance is probed for the low-temperature methanation of sulfur-containing syngas. The results indicate that the turnover frequency of CO methanation increases from 2.4 × 10-3 to 3.7 × 10-3 s−1 with decreasing layer numbers of MoS2 crystallites from 8.3 to 1.1. This result is thoroughly explained by the fact that the higher ratio of rim sites in MoS2 crystallites with fewer layer numbers enhances the catalytic activity, which originates from the facilitated activation of CO and H2. These understandings are important for the rational design and development of more efficient MoS2-based catalysts for CO hydrogenation.