Preferential methanation of CO in a syngas involving CO2 at lower temperature range

摘要

Preferential elimination of CO in a model syngas involving CO2 at a low temperature range was studied on a series of Ni-based multicomponent composite catalysts supported on theta-alumina spheres. The catalysts were characterized by TPR to evaluate the change of reduction temperature with the catalyst composition, which corresponded to the catalytic performance. Performance of CO methanation on these catalysts was compared in a continuous flow reactor under atmospheric pressure. The Rh-modification onto the known highly active three-component methanation catalyst Ni-La2O3-Ru exhibited an evident enhancement in the activity. Complete conversion of CO to methane preferentially occurred on this four-component catalyst, Ni-La2O3-Ru-Rh, as low as 230 degrees C. As long as CO remained in the syngas, methanation Of CO2 was completely retarded. It was reconfirmed that La2O3 increases Ni dispersion, and Rh and Ru enhance H-2 adsorption, and induce the reduction of main catalyst component NiOx at a low temperature range by hydrogen spillover. These are the causes of the very high performance of this catalyst. (c) 2006 Elsevier B.V. All rights reserved.