Dehydrogenation of n-Butane on Metal Cobalt Sites Confined within Ceria Nanoislands

Preparation of highly efficient alkane dehydrogenation catalysts working at high temperatures is still a great challenge due to the sintering property of metal components under reducing atmospheres. To improve the thermal stability of cobalt on the support, we propose a confinement strategy using ceria nanoislands located on the silicalite-1 support, which improves the resistance to sintering of cobalt species. Unlike the coke-coated cobalt particles and carbon nanotubes observed on 1Co/S-1, ceria nanoislands on 1Co6CeOx/S-1 restrain the overaggregation of metallic cobalt, preventing the occurrence of side reactions such as cracking and coking induced by large metallic cobalt particles. Comprehensive analysis results show that active lattice oxygen species within ceria participate in the oxidative dehydrogenation reaction in the initial stage of the reaction, boosting the deep dehydrogenation of n-butane to 1,3-C4H6. During the transition from Ce(IV) to Ce(III), the depletion of active lattice oxygen lowers oxidative dehydrogenation activity, triggering the reduction of cobalt species and shifting the reaction pathway from oxidative dehydrogenation to direct dehydrogenation. The proposed confinement strategy using ceria nanoislands on silicalite-1 support offers a promising solution to the challenge of sintering in metal catalysts.