Effects of potassium as a promoter in CO hydrogation reaction were examined using $H_2$ and CO adsorptions, $O_2$ titrations, differential reactor studies, and temperature programmed desorption. Addition of small amount of potassium to alumina supported nickel increased the selectivity for hydrocarbons with more than two carbon atoms, whereas it decreased the overall CO conversion activity. With potassium addition, the activation energy of methanation increased and the reaction rate became more sensitive to CO partial pressure than to $H_2$ partial pressure. Potassium reduced CO adsorption more significantly than $H_2$ adsorption, and the extent of the catalyst reduction to nickel metal was also reduced. TPD and CO adsorption measurements showed that CO is strongly bound to nickel by the presence of potassium.
