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

The Fischer-Tropsch synthesis performance of a Co-Mo bimetallic cataly st containing 6Co:1Mo:4K:100SiO2 has been studied and compared with a similar monometallic cobalt catalyst. The bimetallic system showed nea rly 100% improvement in alkene-alkane ratio at the experimental condit ions 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 abou t 70-100% better than the cobalt catalyst over the wide composition ra nge studied. The kinetics over the Co-Mo catalyst also followed conven tional Anderson-Schulz-Flory (ASF) polymerisation kinetics suggesting that there is no fundamental change in the reaction mechanism. The inc rease in chain growth probability and alkene content was attributed to substantial methane suppression caused by the introduction of molybde num to the catalyst. Activation energy values for the light hydrocarbo ns over the bimetallic catalyst were in the range 85-120 kJ/mol and ab out 10-15% lower than the corresponding estimates over the monometalli c system.