Unveiling the promotion effect of Zr species on SBA-15 supported nickel catalysts for CO2 methanation

Introducing promoters on Ni-based catalysts for CO2 methanation have been proved to be positive for enhancing their performance. And the correlation of the promotion mecha-nism and the reaction pathway is significant for designing efficient catalysts. In this contribution, series of Zr species promoted SBA-15 supported Ni catalysts were prepared by citric acid complexation method under a range of Zr/Ni atomic ratios from 0 to 2.5. In situ and ex situ characterizations were carried out. It was found that the addition of citric acid was conductive to improve CH4 selectivity due to the higher concentrations of Ni0 confined in SBA-15, harvesting sufficient H atoms for CH4 formation following formate pathway via a formyl intermediate. Furthermore, a coverage layer of Zr species was found on the support at Zr/Ni = 1.7, which interacted with the Ni particles, providing higher concen-trations of medium basic sites for CO2 activation. Accordingly, the optimum catalytic performance was obtained on ZrNi-1.7(CI), achieving CO2 conversion as high as 78.1% and nearly 100% CH4 selectivity at 400 degrees C, following the formate hydrogenation pathway. In addition, the ZrNi-1.7(CI) showed good stability owing to the confinement effect of SBA-15 and the Ni-Zr interaction, no carbon deposits were detected after 50 h test.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

Introducing promoters on Ni-based catalysts has been proven to enhance their performance in CO2 methanation. The correlation between the promotion mechanism and the reaction pathway is significant for designing efficient catalysts. In this study, Zr-promoted SBA-15 supported Ni catalysts were prepared, and it was found that the addition of citric acid improved CH4 selectivity and the presence of Zr species on the support activated CO2. The ZrNi-1.7(CI) catalyst showed excellent catalytic performance with high CO2 conversion and CH4 selectivity, as well as good stability without carbon deposits after 50 hours of testing.