Supported molybdenum carbide for higher alcohol synthesis from syngas

• Mo2C on carbon nanotubes, TiO2, and active carbon exhibit different catalytic properties.
• Supported Mo2C shows improved activity and selectivity of alcohols compared to bulk Mo2C.
• Unpromoted supported Mo2C shows high activity for hydrocarbon synthesis.
• The K2CO3 promoter plays an essential role in obtaining alcohols over supported Mo2C.
• Different loadings of Mo2C on active carbon exhibit different catalytic properties.

Molybdenum carbide supported on active carbon, carbon nanotubes, and titanium dioxide, and promoted by K2CO3, has been prepared and tested for methanol and higher alcohol synthesis from syngas. At optimal conditions, the activity and selectivity to alcohols (methanol and higher alcohols) over supported molybdenum carbide are significantly higher compared to the bulk carbide. The CO conversion reaches a maximum, when about 20 wt% Mo2C is loaded on active carbon. The selectivity to higher alcohols increases with increasing Mo2C loading on active carbon and reaches a maximum over bulk molybdenum carbide, while the selectivity to methanol follows the opposite trend. The effect of Mo2C loading on the alcohol selectivity at a fixed K/Mo molar ratio of 0.14 could be related to the amount of K2CO3 actually on the active Mo2C phase and the size, structure and composition of the supported carbide clusters. Unpromoted, active carbon supported Mo2C exhibits a high activity for CO conversion with hydrocarbons as the dominant products. The K2CO3 promoter plays an essential role in directing the selectivity to alcohols rather than to hydrocarbons. The optimum selectivity toward higher alcohols and total alcohols is obtained at a K/Mo molar ratio of 0.21 over the active carbon supported Mo2C (20 wt%).

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