Cost and Energy Efficient Cyclic Separation of 5-Hydroxymethyl Furfural from an Aqueous Solution

The efficient separation of 5-hydroxymethyl furfural (HMF) – a platform chemical in biomass valorization – from the reactive aqueous mixture of sugars is key to improving its economic production. Here we demonstrate a cyclic fixed-bed process that selectively adsorbs HMF from the aqueous phase, purifies the solute, and enables its subsequent desorption using a suitable solvent for downstream applications. This intensified process bypasses the traditional energy-intensive recovery of HMF via vacuum distillation. The adsorption and desorption performances of a commercially available polymer-based spherical activated carbon (PBSAC) are quantified in batch and continuous systems. The effects of temperature (25 – 90 °C) and co-existence of other components from the fructose dehydration reaction (fructose, formic acid, and levulinic acid) on adsorption are evaluated. It is demonstrated that HMF can be selectively purified and recovered, and the adsorption column can be reused for at least seven cycles tested here. Model predictions based on parameters extracted from batch isotherms describe the continuous experimental breakthrough curve well with suitable transport parameters. A simple economic analysis further showcases nearly tenfold cost and energy savings for HMF separation. The cyclic mechanism promotes flexible solvent choice, where an intensified downstream hydrodeoxygenation (HDO) reaction using the desorbed HMF is demonstrated. The framework outlined here highlights the potential for modular biorefineries and can be applied to other biomass solutes.