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

Abstract

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 overall yield. 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 °C after only 45 minutes under microwave irradiation. These, in turn, result in optimal energy efficiency and excellent green credentials relative to conventional heating.