Influence of Cobalt on Rubidium-Promoted Alumina-Supported Molybdenum Carbide Catalysts for Higher Alcohol Synthesis from Syngas

The influence of Co addition on the activity and selectivity of Rb-promoted Mo2C/α-Al2O3 catalysts in CO hydrogenation was explored. The reaction was performed in a fixed-bed reactor system operating at 573 K, 30 bar, and CO/H2 ratio of 1. Addition of Co enhanced the production rates of hydrocarbons and higher alcohols over Rb-promoted Mo2C/α-Al2O3 by about 60 % without significantly increasing the production rate of methanol, thus shifting the alcohol selectivity toward larger molecules. The addition of Co also lessened the negative impact of CO conversion on oxygenate selectivity over Rb-promoted Mo2C/α-Al2O3. Results from X-ray absorption spectroscopy revealed that highly dispersed Co and Mo domains remained more reduced in the bimetallic carbide samples than the corresponding monometallic samples.