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

Abstract 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 °C with high CH4 selectivities (>99%). High CH4 yields were also observed under high GHSVs at 300 °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.