Oxidative Esterification of 5-Hydroxymethylfurfural with an N-doped Carbon-supported CoCu Bimetallic Catalyst.

Abstract

The direct fabrication of furan-2,5-dimethylcarboxylate (FDMC), a promising renewable monomer, from biomass-derived 5-hydroxymethylfurfural (HMF) is a cutting-edge process. In this contribution, an elaborately designed N-doped carbon-supported CoCu bimetallic catalyst (Cox Cuy -NC; x/y=9:1, 7:3, 4:6, which represents the designed molar ratio of Co and Cu in the catalyst), which could offer a desirable FDMC yield of 95 % under mild and base-free conditions (Co7 Cu3 -NC, 2 bar O2 , 80 °C, 4 h) is described for the oxidative esterification of HMF. Notably, an FDMC formation rate of 6.1 molFDMC molCo -1 h-1 was achieved over Co7 Cu3 -NC, which represents the highest catalytic efficiency so far among Co-based catalytic systems. It has been demonstrated that Cu-doping in Co7 Cu3 -NC catalyst brings about more active sites (Co-Nx species) with stronger molecular oxygen activation ability. The increase of surface N content of Co7 Cu3 -NC also improves basicity of the catalyst, which favors the hydrogen abstraction process during the HMF oxidative esterification reaction. These findings may pave an efficient and green way for the synthesis of sustainable bio-based polymer monomers.