Base-free oxidative esterification of 5-hydroxymethylfurfural to furan-2,5-dimethylcarboxylate over n-doped carbon-supported Co/Fe bimetallic catalyst under batch-operation or continuous-flow conditions

Developing an efficient and easily available catalyst for the selective conversion of biomass-derived 5-hydroxymethylfurfural(HMF)into furan-2,5-dimethylcarboxylate(FDMC),a valuable biomass-based monomer,remains a high demand but formidable challenge.Herein,a facile strategy for the synthesis of N-doped carbon-supported Co/Fe bimetallic catalyst(CoFe-NC)was developed,which provided an outstanding FDMC yield of 93%in a batch reactor(base-free,80℃,2 bar O_(2),4 h).Interestingly,CoFe-NC also gave a high FDMC yield of 91%under continuous-flow conditions for 80 h(5 bar O_(2),80℃,GHSV 1320 h^(-1),LHSV 0.6 h^(-1),base-free).Notably,it is the first time that a non-noble catalyst gave such a high FDMC yield under continuous-flow conditions.The introduction of Fe could greatly improve both the electron intensity of Co-N_(x)species and basicity of the catalyst,which endowed CoFe-NC with improved O_(2)activation capacity and enhanced dehydrogenation activity for the oxidation-esterification of HMF.This work delineates the efficient strategy on the construction of N-doped carbon-supported non-noble catalyst,which might open a new avenue for developing highly efficient catalyst for FDMC production.