Oxygen vacancy boosted oxidation of 5-hydroxymethylfurfural to 2, 5-furandicarboxylic acid over CuCoOx

A bimetallic catalyst CuCoOx was developed for the efficient production of 2, 5-Furandicarboxylic acid (FDCA) by the catalytic oxidation 5-hydroxymethylfurfural (HMF) using NaClO as oxidant. CuCoOx exhibited remarkable catalytic activity and exceptional stability. Under optimized conditions, complete conversion of HMF, as well as the 96 % FDCA yield was obtained at ambient temperature within 15 min. The oxidation of HMF toward FDCA proceeds though 5-hydroxymethyl-2- furoic acid (HMFCA) and 5-Formyl-2-furoic acid (FFCA) as key intermediates in sequence. The synergistic interaction between Cu and Co species boosted oxygen vacancy, enhanced oxygen species mobility, and created an appropriate amount of strong acid/basic sites, improving catalytic activity of CuCoOx. The oxidation of -C-OH in HMF was a rate-determining step. The involvement of lattice oxygen was proved to be crucial in facilitating the whole oxidation process from HMF toward FDCA. Combining reaction kinetics and oxidation mechanism studies, the oxygen vacancy density on the surface CuCoOx was identified as the oxidation rate controlling factor during the whole HMF oxidation process toward FDCA.