Efficient Production of 5-Hydroxymethylfurfural Enhanced by Liquid–Liquid Extraction in a Membrane Dispersion Microreactor

Abstract

Aimed at efficient production of 5-hydroxymethylfurfural (HMF) in a green and sustainable way, dehydrogenation of fructose was enhanced by liquid–liquid extraction in a membrane dispersion microreactor. On account of the high mass-transfer rate resulted from dripping flow, the obtained HMF was readily extracted from the aqueous phase to the organic phase, effectively preventing the sequence side reaction and leading to high HMF selectivity. Enhanced by efficient extraction, the reaction duration decreased from 60 min in a traditional stirred reactor to 4 min in the microreactor, leading to an increase in the space-time yield by 3 orders of magnitude. The effects of total volume flow rate, droplet size, and phase ratio relating to extraction efficiency and HMF yield were systematically investigated. The highest extraction efficiency of nearly 100% coupled with the HMF yield of 93.0% was achieved at the phase ratio of 2 with volume flow rate of 600 mL/h. Overall, this work not only delineates an efficient strategy for synthesizing HMF but also opens a new avenue for reaction systems with subsequent side reaction, which suffer from low selectivity of the intermediates due to the in-line separation bottleneck under conditions of limited mass transfer.

Catalytic Transformation of Biomass Derivatives to Value‐Added Chemicals and Fuels in Continuous Flow Microreactors

“…With this, 60 % HMF yield at 91 % fructose conversion could be obtained from the homogeneous acid (0.25 M HCl) catalyzed dehydration of 30 wt% fructose after 2.5-3 min at 180°C in a biphasic aqueous-organic (2 : 3 volume ratio) batch system. [135][136][137][138][139][140][141][142]216] A glass chip-based microreactor was used for the biphasic synthesis of HMF by dehydration of fructose using a mixture of MIBK and 2-butanol as the organic solvent (70/30 wt%) and HCl as the catalyst in the aqueous phase (Table 4, entry 2). [215] By operating such a biphasic system in a microreactor under slug flow operation (Figures 2D, 3B and 5), the superior mixing for an efficient reaction in the aqueous phase is ensured and the extraction rate of HMF towards the non-reactive organic phase is accelerated by the enhanced mass transfer inside droplets/slugs and across the interface (due to internal circulation and high interfacial area available), thus reducing the occurrence of side reactions and increasing the yield and selectivity towards HMF.…”

“…[232,233] No HMF condensation products (i. e. humins) were found. [216] Copyright 2018 ACS Publications. Graphical presentation of the synthesis of HMF by the dehydration of fructose in an aqueous phase, followed by its rapid extraction to an organic phase through tiny droplets in dripping flow generated by a membrane dispersion microreactor.…”

Protection Strategies Enable Selective Conversion of Biomass

“…However, the slow mass transfer and the possible contamination of membranes by humins and other compounds such as lignin and proteins from sugar streams may limit its extensive use in industry. To increase the mass transfer during liquid–liquid extraction, a membrane dispersion microreactor and a slug flow reactor could improve the liquid–liquid interface contact and substantially improve extraction efficiency . For example, due to the high mass‐transfer rate resulted from dripping flow in the membrane dispersion microreactor, an extraction efficiency of nearly 100 % with an HMF yield of 93 % was achieved .…”

Conversion of Glucose to 5-Hydroxymethylfurfural in a Microreactor

“…This was because the larger amount of MIBK in the system transferred 5-HMF from aqueous phase into the organic phase more effectively, preventing the rehydration of 5-HMF into undesired products (Leshkov and Dumesic, 2009;Dalessandro and Pliego, 2018). Higher extraction efficiency was strongly related to the mass transfer rate of 5-HMF into the organic phase (Zhou et al, 2018). However, the negative effect on the yield and selectivity is observed (see Figure 7) when the organic-to-aqueous volumetric ratio was higher than 0.5:1.…”