Effect of Ni content on CO2 methanation performance with tubular-structured Ni-YSZ catalysts and optimization of catalytic activity for temperature management in the reactor

This paper presents high-performance Ni-YSZ tubular catalysts for CO2 methanation prepared by the extrusion molding. We fabricated tubular-shaped Ni-YSZ catalysts with various Ni contents (25-100 wt% NiO) and investigated the effect of Ni content on CO2 methanation performance under various temperatures and gas flow rates. Catalysts with Ni contents >75 wt% showed CH4 yields >91% above 270 degrees C with high CH4 selectivities (>99%). High CH4 yields were also observed under high GHSVs at 300 degrees C: 93% and 92% at 8700 and 17,500 h(-)(1), respectively. Investigation of methanation with the catalysts revealed that CO2 methanation was accelerated by a localized hotspot at the reactor inlet arising from the interaction between reaction kinetics and heat generation. Using a numerical simulation, we considered the optimum arrangement of catalytic activity in the reactor to avoid hotspot generation and realize a stable high CO2 methanation performance. We can simultaneously achieve high CH4 production and prevent hotspot formation by properly arranging catalysts with different activities. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.