Highly stable Ni/SiC catalyst modified by Al sub(2)O sub(3) for CO methanation reaction

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, Al sub(2)O sub(3) 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/Al sub(2)O sub(3)-SiC catalysts were successfully prepared by the co-deposition-precipitation method. The catalysts were investigated by N sub(2) adsorption, XRD, SEM/EDS, TEM, XPS, H sub(2)-TPR, H sub(2)-TPD and TG. The elemental mapping images indicated that the introduced Al sub(2)O sub(3) particles were uniformly deposited on the surface of the SiC support, which evidently enhanced the interaction between Ni and the support by forming Ni-Al sub(2)O sub(3) complexes as proved by H sub(2)-TPR results. The Ni/Al sub(2)O sub(3)-SiC catalyst with an optimal amount of Al sub(2)O sub(3) content showed a high catalytic activity and strong resistance to sintering, which can be attributed to two main factors: (1) the addition of Al sub(2)O sub(3) 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.