CO2 methanation over nanocrystalline Ni catalysts supported on mechanochemically synthesized Cr2O3-M (M=Fe, Co, La, and Mn) carriers

Abstract

In the present study, a series of Cr2O3 powders modified by different promoters such as Fe, Co, La, and Mn were synthesized using a facile and solvent-free mechanochemical method and the prepared powders were used as a catalyst carrier for the preparation of 20 wt%Ni catalysts in CO2 methanation. The results indicated that among all catalysts, the nickel catalyst supported on the Mn-promoted Cr2O3 exhibited the best catalytic performance. The results showed that there was an optimum for the Mn content and the increment in Mn content up to 15 wt% improved the catalytic performance due to its positive influence on increasing nickel dispersion and catalyst reducibility. The 20 wt%Ni/15 wt%Mn–Cr2O3 catalyst possessed a CO2 conversion of 72.12% and CH4 selectivity of 100% at 350 °C (H2/CO2 = 3 M ratio, GHSV = 18,000 ml/gcat.h) with high stability during 12 h on stream. The obtained results showed that the increment in H2/CO2 molar, and the decrement in GHSV value and calcination temperature improved the catalytic performance.