Co-embedded N-doped hierarchical porous biocarbons: Facile synthesis and used as highly efficient catalysts for levulinic acid hydrogenation

Abstract

The production of highly active noble metal-free catalysts was still quite challenging for levulinic acid (LA) hydrogenation to γ-valerolactone (GVL). Here, N-doped hierarchical carbons embedded Co-particles were obtained by carbonization using urea, bamboo shoot shells, and Co(NO3)2 as the raw materials, where the as-made Co@NC samples exhibited abundant active N-species with dispersed Co particles, acting as efficient catalysts for LA hydrogenation. The composition and coordination of Co@NC catalysts were modulated by simply changing carbonization temperature, where Co@NC-700 carbonized at 700 °C had superior catalytic performance with a 100% LA conversion and GVL yield under the conditions of 190 °C and 1.9 MPa H2 for 2 h. The reusability of Co@NC-700 up to five times recycling had little loss in selectivity with conversion still up to 80%, resulting from synergistic effects of metallic Co, Co-Ox and Co-Nx active sites. This work offered a facile method to develop highly efficient Co-N co-doped biocarbons for LA hydrogenation, and the present catalysts can be easily removed from reaction medium and can be reused for several times without significant loss in reaction efficiency.