High alcohol synthesis (HAS) from syngas over supported molybdenum carbide catalysts

Abstract

In this work, different kinds of supported molybdenum carbide catalysts have been prepared using temperature programmed carburization method with 20 vol% CH4/H2. Cobalt and potassium were later loaded over the resultant carbides. The catalysts were evaluated on the new alcohols test rig under 70 bar pressure with syngas feed gas with a H2/CO ratio of 2.0 at various temperatures. The carbide catalysts supported over boron-modified Al2O3 produced higher alcohols in significant yields. The best catalyst achieved 46.7 % selectivity to alcohol at 31.8 % conversion of CO. This corresponds to 199.7 g/alcohol/liter of catalyst/hour. In addition, 72.5 % selectivity to alcohol (93.1 % on CO2 free basis) was achieved at lower temperature with a conversion of 14.1 %. Characterization results showed that the boron-modified supports result in smaller molybdenum carbide crystallite size which might be responsible for the high activity. Higher potassium content benefits the high alcohol selectivity, but affects the catalyst activity to some extent.