Methanation of syngas (H2/CO) over the different Ni-based catalysts

Methanation of syngas (H-2/CO) in a fixed-bed down-flow reactor under atmospheric atmosphere was investigated over a series of Ni-based catalysts with Fe and TiO2 as the support. The prepared catalysts (Ni/Al2O3, Ni-Fe/Al2O3, and Ni-Fe/TiO2-Al2O3) were characterized by N-2 adsorption-desorption, X-ray diffraction (XRD), temperature-programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS). The characteristics of the catalysts for the methanation process were investigated with the ratio of H-2/CO as 3: 1 under an atmospheric pressure. The addition of Fe in the Ni/Al2O3 catalyst could promote the dispersion of Ni species and decrease the reduction temperature of catalyst. The optimal ratio for Ni-Fe/Al2O3 catalyst was estimated to be 1 due to the small-sized Ni particles and easily reducible beta-type NiO species, giving the CO conversion of 97% and CH4 selectivity of 94% at 262 degrees C. The addition of TiO2 (10 wt%) in Ni-Fe/Al2O3 catalyst promotes the formation of Ni-Fe alloy, facilitating the methanation reaction at low temperatures and suppressing the coke deposition. This also results in the outstanding stability of the Ni-Fe/TiO2-Al2O3 catalyst over other Ni-Fe/Al2O3 catalysts. (C) 2016 Elsevier Ltd. All rights reserved.