Fabrication of highly active and stable Ni/CeO2-nanorods wash-coated on ceramic NZP structured catalysts for scaled-up CO2 methanation

Abstract

The production of synthetic natural gas from CO2 methanation using green H2 produced via water electrolysis is a promising pathway regarding both the curtailment of excess power by variable renewables and the mitigation of CO2 emissions. Several catalytic systems have been employed for thermocatalytic CO2 methanation in lab-scale, with Ni-based catalysts being amongst the most cost-effective and active materials. In this regard, we have recently demonstrated the remarkable low-temperature CO2 methanation activity of a nickel catalyst supported on ceria nanorods, ascribed to the augmented metal-support synergy. Herein, we report on a scaled-up process of CO2 methanation, involving; i) fabrication of a highly porous NZP-type ceramic substrate of Ba1+xZr4P6–2xSi2xO24 in the form of extruded pellets, ii) wash-coating of Ni/CeO2-nanorods catalyst on NZP pellets, iii) design and testing of scaled-up experiments under a scaling factor of 80:1 and 65:1 in terms of mass and volume of catalysts compared to lab-scale experiments, respectively. The as-synthesized catalyst exhibited remarkable performance under variable reaction conditions and stable behavior after 75 h. Remarkably, the structured catalyst attained a methane formation rate of 277 NL gNi−1 h−1, being higher to numerous values reported in relevant works. Equally importantly, it was disclosed that increased values of space velocity led to high temperature gradient in the catalytic bed, thereby favoring the generation of CO. Intriguingly, the morphological and structural characteristics of the used catalyst remained unaltered even after various on/off reaction cycles and the stability test, which is a promising finding toward scaling-up the process at higher technology readiness levels using real feed streams.