Hierarchical zeolite catalysed fructose dehydration to 5-hydroxymethylfurfural within a biphasic solvent system under microwave irradiation

Realising sustainability within the chemical industry necessitates a shift from the traditional linear approach, based on crude oil, to a circular economy using alternative feedstock such as biomass, from which 5-hydroxymethylfurfural (HMF) is a potentially highly interesting platform chemical. While its production is relatively straightforward via the dehydration of fructose, derived from either saccharides or lignocellulosic biomass, its production is hindered by undesirable side reactions, which decrease the selectivity of the intended reaction to HMF, hence diminishing the overallyield. Here we report a green, highly selective approach to producing 5-hydroxymethylfurfural (HMF) from fructose based on the co-deployment of a biphasic reaction medium, microwave radiation, and a commercial solid acid catalyst (FAU Y zeolites). Following an initial evaluation of catalyst-solvent interactions and diffusion, a hierarchical mesoporous Y zeolite was chosen and deployed within a range of reaction media and process conditions for process optimisation, identifying a biphasic system consisting of ((6:4 Water:DMSO) / (7:3 MIBK:2-BuOH)) as the optimal reaction medium. This solvent combination facilitated an HMF yield of ~73.9 mol% with an excellent selectivity of ~86.1 % at 160 ℃ after only 45 minutes under microwave irradiation. These, in turn, result in optimal energy efficiency and excellent green credentials relative to conventional heating.

Sustainability spotlight
Biomass-derived 5-hydroxymethylfurfural is regarded as a versatile and key intermediate for the production of a range of sustainable bio-based chemicals, and thus it has drawn widespread academic and industrial attention. To further cement HMF as a sustainable platform chemical, synthetic routes with greater efficiency and reduced waste production are critical. The research presented here demonstrates a highly selective and energy-efficient HMF production route from fructose, based on the cooperation of a biphasic reaction media, microwave irradiation, and commercially available FAU Y zeolites, and aligns with the UN sustainable development goals: affordable and clean energy (SDG 7), responsible consumption and production (SDG 12), and climate action (SDG 13).