Catalytic properties of potassium- or lanthanum-promoted Co/γ-Al2O3 catalysts in carbon monoxide hydrogenation

The effects of potassium or lanthanum additives on the catalytic properties of alumina-supported cobalt catalysts were examined through carbon monoxide hydrogenation reaction. The catalysts were characterized by hydrogen or carbon monoxide chemisorption, oxygen titration, and temperature-programmed desorption. The reactions were carried out at 270 degreesC and atmospheric pressure. When a small amount of potassium was added to alumina-supported cobalt catalysts, the amount of hydrogen adsorption decreased more significantly than that of carbon monoxide adsorption, and the extent of reduction also decreased. With the addition of potassium, the overall carbon monoxide conversion decreased, while the selectivity to higher hydrocarbon and olefin increased. The effect of lanthanum on activity and selectivity in carbon monoxide hydrogenation was less significant than the effect of potassium. Temperature-programmed desorption showed that the presence of additives changed the adsorbed state of CO on cobalt.