IMPROVED ALKENE SELECTIVITY IN CARBON-MONOXIDE HYDROGENATION OVER SILICA-SUPPORTED COBALT-MOLYBDENUM CATALYST

The Fischer-Tropsch synthesis performance of a Co-Mo bimetallic catalyst containing 6Co:1Mo:4K:100SiO2 has been studied and compared with a similar monometallic cobalt catalyst. The bimetallic system showed nearly 100% improvement in alkene-alkane ratio at the experimental conditions of 101 kPa and 280-degrees-C (553 K) and CO-H-2 ratio of 1:19 to 19:1. Ethylene-to-methane ratio (EMR) over the Co-Mo catalyst was about 70-100% better than the cobalt catalyst over the wide composition range studied. The kinetics over the Co-Mo catalyst also followed conventional Anderson-Schulz-Flory (ASF) polymerisation kinetics suggesting that there is no fundamental change in the reaction mechanism. The increase in chain growth probability and alkene content was attributed to substantial methane suppression caused by the introduction of molybdenum to the catalyst. Activation energy values for the light hydrocarbons over the bimetallic catalyst were in the range 85-120 kJ/mol and about 10-15% lower than the corresponding estimates over the monometallic system.