Metal-foam-structured Ni-Al2O3 catalysts: Wet chemical etching preparation and syngas methanation performance

Production of substitute natural gas (SNG) by methanation of syngas generated from various carbon sources provides a promising route towards coal clean utilization and sustainable energy future. Monolithic Ni (or Cu, NiCu-alloy)-foam-structured Ni-Al2O3 catalysts were developed by a facile modified wet chemical etching method. The as-prepared catalysts were characterized by X-ray diffraction, scanning electron microscopy, inductively coupled plasma atomic emission spectrometry and H-2-temperature programmed reduction. Among these catalysts, Ni-Al2O3/Ni-foam has the most surface active Ni atoms and exhibits the best catalytic methanation performance, achieving 99.9% CO conversion with 90.0% methane selectivity and being stable for at least 1000 h for a feed gas of H-2/CO (3/1) at 330 degrees C and gas hourly space velocity (GHSV) of 5000 h(-1). Effects of reaction temperature, reaction pressure and GHSV are also investigated on the catalytic performance of Ni-Al2O3/Ni-foam for CO methanation. Computational fluid dynamics calculation and experimental measurement consistently show that such monolithic Ni-Al2O3/Ni-foam can dramatically reduce the "hotspot" temperature due to its high thermal conductivity. Moreover, the feasibility of our Ni-Al2O3/Ni-foam catalyst for co-methanation of a simulated feed gas from coal gasification is studied as well as CO2 methanation in the presence of high CH4 concentration. We anticipate that our present work might stimulate commercial exploitation of the new-generation structured catalyst and reactor technology for the strongly exothermic syngas methanation toward energy-efficient process for SNG production. (C) 2015 Elsevier B.V. All rights reserved.