Efficient continuous-flow separation and purification processes of 5-hydroxymethylfurfural

Abstract

This study aimed to develop a green process for separating and purifying 5-hydroxymethylfurfural (5-HMF) that could accommodate various levels of 5-HMF production performance. The aim was to achieve a high purity level of 5-HMF exceeding 98%. The 5-HMF, initially containing high impurities, was produced from fructose in a multi-stage methyl isobutyl ketone/water fixed-bed reactor, achieving a 5-HMF selectivity of 53.2% and yield of 31.9%. This impure 5-HMF served as the feedstock for the proposed continuous purification system. The study integrated and evaluated various separation and purification technologies, including adsorption/desorption, solvent extraction, and distillation, to identify the most effective and practical approach. Optimization of process variables was conducted to enhance efficiency. Different techniques were required for purifying 5-HMF in both aqueous and organic phases. A two-stage microextraction process using methyl isobutyl ketone was identified as the most effective method for separating 5-HMF from the aqueous phase, achieving an extraction efficiency of 93.6% with a residence time of less than 2 min. Impurities in the organic phase were efficiently removed using a fixed-bed adsorber filled with Amberlyst 21 at 80 °C and 15 min. Subsequently, the solvent was removed through a one-stage distillation process. The sugar component in the solution was purified using activated carbon adsorption and could be recycled back into the production unit. The stability and reusability of the catalyst/adsorbent were also demonstrated. Furthermore, this research proposed an overall conceptual design for the 5-HMF production process, guiding further development of 5-HMF purification processes.