The functional and synergetic optimization of the thermal-catalytic system for the selective oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran: a review

In order to alleviate oil consumption, biomass energy is being developed to produce petroleum derivatives. The thermal-catalytic oxidation of 5-hydroxymethyl furfural (HMF) into 2,5-furandicarboxaldehyde (DFF) seems to be an effective strategy for synthesizing the intermediates of valuable petroleum derivatives. The breakage of the O–H bond and αH–C in the hydroxyl group and the protection of the aldehyde group are the key points for the selective production of DFF. In order to summarize the common rule of promoting HMF conversion and selectivity of DFF, the modification methods for various types of catalysts and the current challenges have been sorted and described in this review according to the correlation and logic between different reports. The basic reaction pathway (the redox mechanism of Mars-van Krevelen) suitable for composite metal oxides and the “oxoammonium” mechanism for (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) catalysts are also introduced. Besides, the solvent system, as a crucial part of synergetic catalysis, has been introduced in detail.