Carbon-Limited Conversion of Molybdenum Carbide into Curved Ultrasmall Monolayer Molybdenum Disulfide under Effects of ZrO2 Crystal Phases for Efficient Sulfur-Resistant Methanation

摘要

MoS2 has been regarded as a highly active catalyst for the sulfur-resistant methanation because of its abundant active sites on defect and edge sites. A challenging problem is how to increase the density of the intrinsic active sites. It is a reasonable method to increase more active sites toward CO methanation by preparing ultrasmall monolayer molybdenum disulfide and curving them. Therefore, highly active ultrasmall and curved monolayer MoS2/ZrO2 catalysts are fabricated via carbon-limited conversion Mo2C species in H2S atmosphere. The physical and chemical properties of the supports and catalysts were characterized by X-ray diffraction, N-2-Physisorption, Raman spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and thermogravimetric. The results indicate that amorphous carbon on monoclinic zirconia (M-ZrO2) is the key for the formation of such MoS2 structure. The sulfided Mo2C/M-ZrO2 catalyst displays superior sulfur-resistant methanation activity and stability compared with sulfided Mo2C/tetragonal zirconia (T-ZrO2), ascribed to curved ultrasmall monolayer MoS2 well dispersed on M-ZrO2 with more active sites. This synthetic strategy provides a new method for the preparation of well-dispersed monolayer molybdenum disulfide catalysts.