CO methanation on ordered mesoporous Ni-Cr-Al catalysts: Effects of the catalyst structure and Cr promoter on the catalytic

CO methanation is the main route in industry to produce synthetic natural gas (SNG), and the conventional Ni-based catalysts for this reaction often deactivate severely because of sintering of the Ni particles and coke formation on them. To overcome these technical barriers, we designed and synthesized a group of ternary Ni-Cr-Al metal oxide composites with ordered mesoporous structure and various Cr and Ni contents via a one-pot evaporation-induced self-assembly strategy and tested them for CO methanation to produce SNG. The support and the catalysts before and after the catalytic reaction were thoroughly characterized. It was found that, after reduction at 700 degrees C, metallic Ni particles were generated and anchored in the ordered mesoporous alumina channels while the Cr species started to surround the metallic Ni particles. The long-range ordered mesoporous structure could be maintained well when the total loading of nickel and chromium oxides was below 22 wt.%. In general, the optimized ordered mesoporous Ni-Cr-Al catalysts show much better anti-coking and anti-sintering properties and much higher catalytic activity and stability than the conventional Ni catalysts. The improved catalytic performance is attributed to the reduced Ni particle size, the confinement effect of the mesoporous materials, and the promoting effect of Cr, which can significantly reduce the Ni particle size and increase the H-2 uptake. These findings shed light on the design of ordered mesoporous alumina-supported materials with high loading of active metal oxides for many high-temperature reactions. (C) 2016 Elsevier Inc. All rights reserved.