Abstract:

A series of 12.5%Ni/SBA-15 catalysts, in which 2.5% (mass fraction, w) lanthanum, cerium, magnesium, calcium or strontium was added as a promoter, were prepared by an impregnation method using SBA-15 support. Catalytic performances of the catalysts for the simulated biogas, which consisted of CH4/CO2 with a volume ratio of 2:1, and an appropriate amount of oxygen as a gas feedstock in reforming to syngas, were investigated in a continuous flow reactor under atmospheric pressure. The structures of the catalysts were characterized by X-ray diffraction (XRD), N2-adsorption/desorption, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and H2 temperature programmed reduction (H2-TPR) techniques. Results of the activity evaluation indicated that the 2.5% La/12.5%Ni/SBA-15 sample had the highest catalytic activity and stability among the catalysts. Therefore, in this study emphasis was placed on the influence of the La promoter on the structure and performance of the Ni/SBA-15 catalyst in reforming of the simulated biogas to syngas. It was found that lanthanum could significantly increase the surface nickel content in Ni/SBA-15 catalysts and could improve the resistance to carbon deposition. At 850 ℃, after reacting for 820 h, no carbon was observed on the catalyst, which might be an important factor for the improvement of catalytic activity and stability.

Key words: Nickel, La promoter, SBA-15, Biogas, Reforming, Synthesis gas