Catalytic Conversion of Syngas into Higher Alcohols over Carbide Catalysts

Abstract

This work investigates the use of the bulk carbides Mo 2 C, WC, and NbC as catalysts for the conversion of syngas into higher alcohols. K 2 CO 3 /WC produces mainly CH 3 OH and CH 4 with a low activity. NbC has a very low activity in CO hydrogenation. K 2 CO 3 /Mo 2 C produces mixed alcohols with a reasonable activity and selectivity. In a 94 h test the activity and the specific surface area of the K 2 CO 3 /Mo 2 C catalyst decreased significantly, but X-ray diffraction and transmission electron microscopy did not indicate a strong sintering of the carbide. A likely cause for the deactivation is the formation of carbonaceous deposits on the catalyst. At the same general activity level Li, K, and Cs provide similar promotional effects for Mo 2 C, although K at a loading level of alkali metal/Mo = 0.164 mol/mol provides the better behavior at equal conditions. The effect of further additives on the K 2 CO 3 /Mo 2 C system was evaluated, but only Cu yielded an improvement.