Microwave-Assisted Conversion of 5-Hydroxymethylfurfural into 2,5-Furandicarboxylic Acid over CuCo Oxide

A series of CuCo bimetallic catalysts were prepared via the co-precipitation method for the catalytic transformation of biomass-derived 5-hydroxymethylfurfural (HMF) into 2,5-furandicarboxylic acid (FDCA). FDCA acts as a precursor for biodegradable biopolymer polyethylene furanoate production, thereby achieving a carbon-neutral approach. Out of all the synthesized catalysts, CuCo(1 : 1) showed remarkable catalytic activity and yielded 70.67 % FDCA while achieving 100 % HMF conversion in 5 minutes at 50 °C temperature in the presence of tert-butyl hydroperoxide as an oxidant. Synergistic effects of the catalyst, such as adsorbed oxygen, relative oxygen vacancy, lesser pore size, and pore volume, were key factors attributed to the catalyst's excellent activity. The synthesized catalyst showed good recyclability with a minimal decrease in FDCA yield up to 5 cycles. Pre and post-characterization of catalysts such as BET, TEM, FE-SEM, XRD, H₂-TPR, CO₂ TPD, ICP-OES, and XPS were done to correlate the catalyst's properties with its activity. In addition, the effect of reaction parameters such as stirring speed, temperature reaction time, catalyst weight, base, and oxidant were studied to achieve optimum reaction conditions. The reaction products were analyzed quantitatively and qualitatively using HPLC and HR-MS.