Dehydrogenation versus hydrogenolysis in the reaction of light alkanes over Ni-based catalysts

[Display omitted] Given the high cost of Pt-based catalysts and the environmental issue of CrOx-based catalysts in dehydrogenation processes, Ni-based catalysts have been extensively explored as alternatives. In order to take the advantage of the high activation ability of Ni towards alkanes, herein, the reaction behaviors of light alkanes, primarily dehydrogenation versus hydrogenolysis, over Ni-based catalysts have been reviewed and probed. Ni-based catalysts exhibit an extremely high hydrogenolysis activity for light alkanes. Different from the single hydrogenolysis reaction on the surface of Pt, multiple hydrogenolysis of alkane molecules occurs over Ni sites. The successive α-scission of CC bond over Ni sites results in the generation of abundant methane and coke. To selectively activate CH bond of alkanes and prohibit CC bond rupture, one feasible approach is to introduce effective barriers to destroy the aggregated Ni ensembles active for hydrogenolysis. The promoting mechanism of different barriers (S, P, Cu, Sn, etc.) has been summarized and analyzed. The geometric effect of introduced barriers facilitates the dispersion of Ni particles, and electronic effect reduces the desorption energy of olefins and avoids undesired secondary reactions. Among all these catalysts, NiS and NiSn-based catalysts demonstrate the most outstanding dehydrogenation performance and show great potential for industrial applications.