The extent of reduction of Co2+ to Co0 in Co/ZnO and Co/SiO2 catalysts has been ascertained by temperature-programmed reduction, chemisorption, magnetic susceptibility, and activity in propane hydrogenolysis. The results indicate that Co2+ is not fully reduced at 573 K on either ZnO or silica, but that there is a strong CO0-Co2+ interaction with ZnO which depresses hydrogen chemisorption and hydrogenolysis activity towards propane; the causes of this are considered. The metal-support interaction causes propane hydrogenolysis to occur at a rate on each hydrogen adsorption site on Co0-Cox/ZnO almost 100 times more slowly than on such sites on silica-supported Co.

The support of SERC and the Royal Society for MAML and YW, respectively, is gratefully acknowledged.