One-step fabrication of Ni-embedded hierarchically-porous carbon microspheres for levulinic acid hydrogenation

The facile fabrication of highly stable non-noble-supported carbonaceous catalysts for the hydrogenation of levulinic acid (LA) to gamma-valerolactone (GVL) is still a major challenge. In an effort to address this challenge, we put forward a novel strategy to fabricate Ni and N co-decorated hierarchically-porous carbon microspheres (Ni@ NCMs) through one-step synthesis. The developed micron-sized sphere catalyst possesses a hierarchically porous interior structure integrating uniform macropores and mesopores, in which Ni NPs are homogeneously located. The key to such a success is the utilization of the Pickering emulsion droplet-confined spaces, within which the co-assembly of carbon source, nitrogen source, surfactant and metal salt leads to the enhanced interactions. Moreover, such a catalyst exhibits superior activity and significantly enhanced stability in the hydrogenation of LA to GVL compared to the benchmarking catalyst, Ni-supported commercial active carbon (Ni/AC) prepared through the conventional wet impregnation. The present strategy may open up new horizons in the integration of rationally designed hierarchically porous structure with highly stable metal supported carbonaceous catalysts for various potential applications.