Influence of support and potassium on CO hydrogenation catalyzed by molybdenum

The influences of catalyst support and K on the activity and product selectivity of CO hydrogenation by Mo (10wt%) have been studied. Active-carbon-supported catalysts showed high activity and selectivity for producing CH₄. Carbon-black-supported catalysts exhibited high activity and high selectivity for C₂₊ hydrocarbons. Addition of K (1.7wt%) reduced the activity of all the catalysts, except for the carbon-black-supported catalyst. Except for the Al₂O_3-, TiO_2-, and MgO-supported catalysts, the selectivity for CH₄ decreased. Over the carbon-black-supported catalysts, the olefin selectivity was greatly improved by the addition of K₂CO₃, without significant decrease in activity. Suppression of CH₄ formation concomitant with relatively high activity was also attained by supporting Mo and K on SiO₂, whereas the C₂₊ selectivity remained low and olefin production was negligible over the active-carbon-supported catalysts. When a large amount of K was added to the SiO₂-supported catalyst, the activity markedly increased with time on stream. The catalyst thus activated favoured formation of C₂₊ hydrocarbons anomalously rich in 1-alkenes.