The structural evolution of Mo2C and Mo2C/SiO2under dry reforming of methane conditions: morphology and support effectsElectronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d2cy00729k

The thermal carburization of MoO3nanobelts (nb) and SiO2-supported MoO3nanosheets under a 1 : 4 mixture of CH4 : H2yields Mo2C-nb and Mo2C/SiO2. Following this process by in situMo K-edge X-ray absorption spectroscopy (XAS) reveals different carburization pathways for unsupported and supported MoO3. In particular, the carburization of α-MoO3-nb proceeds viaMoO2, and that of MoO3/SiO2viathe formation of highly dispersed MoOxspecies. Both Mo2C-nb and Mo2C/SiO2catalyze the dry reforming of methane (DRM, 800 °C, 8 bar) but their catalytic stability differs. Mo2C-nb shows a stable performance when using a CH4-rich feed (CH4 : CO2= 4 : 2), however deactivation due to the formation of MoO2occurs for higher CO2concentrations (CH4 : CO2= 4 : 3). In contrast, Mo2C/SiO2is notably more stable than Mo2C-nb under the CH4 : CO2= 4 : 3 feed. The influence of the morphology of Mo2C and its dispersion on silica on the structural evolution of the catalysts under DRM is further studied by in situMo K-edge XAS. It is found that Mo2C/SiO2features a higher resistance to oxidation under DRM than the highly crystalline unsupported Mo2C-nb and this correlates with an improved catalytic stability. Lastly, the oxidation of Mo in both Mo2C-nb and Mo2C/SiO2under DRM conditions in the in situXAS experiments leads to an increased activity of the competing reverse water gas shift reaction.