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 Al2O3-, TiO2-, 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.
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