Highly dispersed Ni-La catalysts over mesoporous nanosponge MFI zeolite for low-temperature CO2 methanation: Synergistic effect between mesoporous and microporous channels

The mesoporous nanosponge MFI silicate zeolite was facilely fabricated by employing the long chain ammonium as the structure-directing agent. The zeolite with both mesoporous and microporous channels were selected as the support of Ni-La catalysts for methanation of CO2. Various techniques were used to characterize the catalysts systematically. The effects of the La2O3 promotor and pore morphology of the support on the catalytic performance were carefully investigated. Our study demonstrated that La promoter could be beneficial to the increase of the surface basicity and the enhancement of the metallic Ni dispersion. This would intensify the processes of the CO2 chemisorption and H2 dissociation in CO2 methanation. Besides, we also found that the catalyst supported on mesoporous nanosponge MFI zeolite performed higher activity and better long-term stability than the reference catalysts supported on bulk MFI and MCM-48, suggesting that the synergistic effect between the mesoporous and microporous channels displayed unique advantages. Kinetic study revealed that both the nanosponge structure and La2O3 promoter contributed to decreasing the reaction activation energy. Therefore, the present highly dispersed Ni-La catalyst over mesoporous nanosponge MFI zeolite promised a potential catalyst candidate for low-temperature CO2 methanation reaction.