Why Ni/CeO2 is more active than Ni/SiO2 for CO2 methanation? Identifying effect of Ni particle size and oxygen vacancy

An impregnated Ni/CeO2 catalyst with an array structure and a phyllosilicate-based Ni/SiO2 catalyst prepared by hydrothermal method were designed for CO2 methanation. The assynthetized Ni/SiO2 catalyst exhibits a high Ni content of 25.9 wt%, while its CO2 conversion at low temperature is far lower than that of Ni/CeO2, whose Ni content is only 10.0 wt %. TEM and XRD results show that the Ni/CeO2 catalyst possesses very tiny Ni particle size of around 1.2 nm, which leads to large H-2 uptake capacity. XPS and Raman analyses indicate that Ni/CeO2 obtains more oxygen vacancies resulting in promotion of the CO2 activation. The combined effect of the Ni/CeO2 catalyst to enhance chemisorption of H-2 and CO2 leads to high low-temperature activity. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

Two catalysts, impregnated Ni/CeO2 with an array structure and phyllosilicate-based Ni/SiO2 prepared by hydrothermal method, were designed for CO2 methanation. The Ni/CeO2 catalyst showed small Ni particle size and more oxygen vacancies, resulting in enhanced CO2 activation and high low-temperature activity.