In Situ-Generated Co embedded in N-Doped Carbon Hybrids for the upgrading of levulinic acid in aqueous phase
The rational design of an efficient and robust catalyst based on earth-abundant metals for the upgrading of levulinic acid to γ-valerolactone in aqueous media still remains a significant challenge. Herein, a facile and effective approach is developed for synthesizing Co embedded in nitrogen-doped carbon matrix by coordination precipitation pyrolysis combination strategy. The as prepared Co@NC-800 (after 800 °C pyrolysis) exhibits excellent catalytic performance, namely, the yield of γ-valerolactone is not less than 99%, and the high activity could be maintained even after 10 cycles. The results of systematic characterization and control experiments confirmed that the catalytic performance of catalyst benefited from the construction strategy in two ways, a certain proportion of Co, Co-Nx and Co-Ox components are generated on the catalyst, and also a structure in which Co is confined to N-Doped carbon matrix is formed. The first aspect apparently enhanced the activity of the catalyst due to the synergistic effect of Co, Co-Nx and Co-Ox; while the second aspect greatly inhibited the metal components from leaching and agglomeration in the reaction process, and thus promised the excellent stability of the catalyst. The strategy developed here may open a new avenue toward the development of nonprecious high-performance biomass conversion catalysts.