Co nanoclusters derived from zinc-trimesic acid fiber for efficient levulinic acid hydrogenation

Abstract

The hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) is significant for producing chemicals and fuels from renewable resources, a promising direction in biomass refining. Currently, non-precious metal catalysts suffer from low activity due to a single electronic structure, which is incapable of effectively activating both CO in LA and H₂. Herein we report in situ fabricated Co nanoclusters within positive and metallic Co sites on N-doped carbon, which can simultaneously activate LA's CO and H₂, enhancing the activity and selectivity for GVL production. Urea-assisted Co dispersion coupled with variation of pyrolysis temperature, Co nanoclusters were formed via direct conversion of Co-containing zinc trimesic acid fibers. The resulting Co nanoclusters possess dual active sites of Co-N_x and metallic Co, with adjustable electronic structures. Under the reaction conditions of 200 °C and 4.5 MPa H₂ for 4 h, LA was completely converted, achieving 95 % yield of GVL. The outstanding catalytic activity is attributed to the Co-N_x and metallic Co active sites, which facilitate the activation of CO and H₂, respectively. This research provides a new concept for converting N-free metal-organic frameworks into non-precious metal nanoclusters, offering valuable insights for designing high-performance non-precious metal catalysts for biomass-derived chemical and fuel production.