Outstanding low-temperature activity and stability of NiCo alloy catalysts derived from NiCoAl-LDHs for CO2 methanation

Abstract

Compared with monometallic catalysts, alloy catalysts demonstrate inferior catalytic advantages because of the synergistic promotion effect of bimetal. Here, we prepared NiCo alloy catalysts using NiCoAl-LDHs as precursors by thermal method and used them for the CO₂ methanation reaction. The Ni₇Co₃-R alloy catalyst exhibits outstanding low-temperature catalytic activity (200–300 °C) in the CO₂ methanation reaction, and has not been deactivated at 300 °C for 180 h. The synergistic effect of Ni and Co in the alloy catalysts is beneficial to reduce the particle size, promote the reduction of the catalysts and increase the number of moderately basic sites, which are beneficial to the adsorption of CO₂ and the formation of CH₄. Further, the hydrotalcite-derived NiCo alloy catalysts have a unique mosaic structure, thereby significantly improving the stability of catalysts. The in-situ FTIR analysis confirm the CO₂ methanation reaction via the CO∗ pathway over Ni₇Co₃Al-R catalyst. This work has a certain guiding effect on the preparation of Ni-base catalysts with excellent low-temperature activity and high stability.