Effect of cobalt promotion on hydrotalcite-derived nickel catalyst for CO2 methanation

A series of cobalt-promoted Ni-Mg-Al hydrotalcite-derived catalysts were tested towards CO2 methanation reaction. The best among examined catalysts was the one with 1 wt% of cobalt in fresh hydrotalcite, obtaining 77% of CO2 conversion and 99% of CH4 selectivity at 300 degrees C. Above that temperature, the catalyst was working with-near-equilibrium parameters. It was also stable for up to 24 h on stream. Other cobalt-containing samples were likewise very active and selective during the time on stream. Due to the use of a low amount of cobalt (0.5-4 wt%) the Co-Ni alloy was not the subject of research - both materials formed probably solid solution of cobalt in the nickel matrix. Although the behavior of cobalt as a textural and electronic promoter was confirmed. Co was found to improve reducibility of nickel species, hydrogen uptake, and the acidic/basic properties by increasing the number of medium strength and strong basic sites. Tendency to sintering of nickel crystallites on cobalt-promoted catalysts was not confirmed in this study, however, with increased content of Co, bigger metal crystallites were formed under the reduction conditions. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

A series of cobalt-promoted Ni-Mg-Al hydrotalcite-derived catalysts showed good performance in CO2 methanation reaction. Cobalt was found to enhance the reducibility of nickel species and the acidic/basic properties. While the Co-Ni alloy was not the subject of research, it was believed to form a solid solution in the nickel matrix.