An examination of tunable edge sites and catalyst deactivation in MoS2-catalyzed methanation of syngas

A simple and effective strategy based on NH4+ intercalation and thermal treatment was developed to tune the edge sites of MoS2. The catalysts were characterized by XRD, TG, TEM-EDX, SEM, Raman, BET, XPS, in situ FT-IR spectroscopy of NO adsorption and CHNS elemental analysis. The intercalation of NH4+ into the interlayers of MoS2 with thermal treatment served to reduce numbers of stacking layers and generate edge-rich MoS2 with disordered structures. An increase of NH4+ intercalation resulted in greater exposure of MoS2 edges that enhanced conversion rate of CO in the methanation reaction. FT-IR study of NO adsorption demonstrated edge sites contributed to the catalytic activity. A decrease of the activity in the long-term (100 h) stability evaluation can be attributed to sintering of MoS2, formation of MoO2 with a loss of active MoS2 components. This study established the intercalation of NH4+ into the MoS2 layers with subsequent heat treatment as an effective means to tune the edge sites and catalytic a...