Highly stable Ni/SiC catalyst modified by Al2O3 for CO methanation reaction

Abstract

It is still a great challenge to prevent sintering of supported Ni catalysts in highly exothermic reactions. To address this problem, in this work, highly thermal conductive and stable SiC is explored as a Ni catalyst support for CO methanation to produce synthetic natural gas; simultaneously, Al₂O₃ is utilized to modify the SiC surface to enhance the interaction between the metal and support and restrain the Ni active component from sintering or loss during the reaction. A series of Ni/Al₂O₃–SiC catalysts were successfully prepared by the co-deposition–precipitation method. The catalysts were investigated by N₂ adsorption, XRD, SEM/EDS, TEM, XPS, H₂-TPR, H₂-TPD and TG. The elemental mapping images indicated that the introduced Al₂O₃ particles were uniformly deposited on the surface of the SiC support, which evidently enhanced the interaction between Ni and the support by forming Ni–Al₂O₃ complexes as proved by H₂-TPR results. The Ni/Al₂O₃–SiC catalyst with an optimal amount of Al₂O₃ content showed a high catalytic activity and strong resistance to sintering, which can be attributed to two main factors: (1) the addition of Al₂O₃ can enhance the interactions between Ni and the support, thus inhibiting the migration of Ni particles on the support surface and improving the dispersion of them; (2) the superior heat conductivity of SiC can decrease the generation of hot spots in the catalyst bed.