Effect of lanthanide promotion on catalytic performance of sol-gel Ni/Al2O3 catalysts in steam reforming of propane

The effect of lanthanide elements (La, Ce, and Yb) on the catalytic behavior of sol-gel Ni/Al(2)O(3) catalysts in propane steam reforming was investigated. Steady-state reaction experiments show that the addition of small amounts (2 wt.%) of lanthanide elements improves the catalytic activity and stability significantly. The changes in reaction performance are related to catalyst reducibility, nickel surface area and resistance to deactivation. Temperature-programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS) characterization results reveal that the presence of lanthanide elements enhances the catalyst reducibility; the positive effect is most evident with 20% Ni-2% Ce/Al(2)O(3) catalysts. H(2) chemisorption data indicate that 20% Ni-2% Ce/Al(2)O(3) catalysts exhibit larger nickel surface area compared to 20% Ni/Al(2)O(3) catalysts. Nickel surface area of sol-gel catalysts is also found to be strongly dependent on calcination and reduction temperatures. In situ DRIFTS experiments coupled with TPD and TPReaction suggest that formate and carbonate species are formed upon the reaction of adsorbed propane and water on reduced catalysts. (c) 2005 Elsevier B.V. All rights reserved.