Abstract: The state of surface site of catalyst for CO hydrogenation was studied with TPSR, TPR and TR. Results show that there are two kinds of active sites on the surface of Ni/Al_2O_3 catalysts. The site A comes from crystallite of Ni exposed on the surface, while the site B comes from Ni-Al intermediate which formed by the strong interaction of Ni with the support Al_2O_3. Results also show that the CO can be adsorbed on both sites, if active hydrogen is adsorbed on the surface, the ratio of adsorbed CO on both sites will be changed.

Key words: Ni/Al₂O₃ catalysts, CO hydrogenation, TPSR, TPR, TR