Simple and selective conversion of fructose into HMF using extractive-reaction process in microreactor

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

“…Due to the strong shear force generated by centrifugal forces in the CCCS, liquid-liquid mixing is enhanced considerably, accelerating reactions with fast kinetics that are limited by mass transfer. [134] Typically, microreactors have been used for single liquid phase and biphasic (gas-liquid or liquid-liquid) catalytic transformation of biomass derivatives to valuable products using homogeneous or heterogeneous catalysts (e. g., the (biphasic) synthesis of furans from sugars, [135][136][137][138][139][140][141][142][143][144] (aerobic) oxidation, [144][145][146][147][148][149] and hydrogenation of biomass derivatives [144,[150][151][152][153] ). [126] Another intensified reactor configuration for multiphase (gasliquid or liquid-liquid) catalytic biomass transformation is the spinning disc reactor, consisting of a rotating disc around which fluids are fed.…”

“…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.…”

“…Several researchers performed the biphasic dehydration of fructose to HMF using MIBK as the organic solvent in hydrophobic PEEK capillary microreactors (Table 4, entries 3-4), [136][137][138] which is a preferred wall material to prevent humin deposition on the reactor wall. The increase in the extraction rate under a biphasic slug flow operation gave higher HMF yield (88.5 %) and selectivity (91.1 %) as compared to those in batch, after 3 min reaction time using 0.025 M HCl as catalyst.…”

“…The increase in the extraction rate under a biphasic slug flow operation gave higher HMF yield (88.5 %) and selectivity (91.1 %) as compared to those in batch, after 3 min reaction time using 0.025 M HCl as catalyst. [137,138] However, the need to add high amounts of organic solvent is industrially unfavorable, as it results in a lower space-time yield and a more energy intensive product retrieval. [137] Furthermore, relatively high 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 organic to aqueous flow ratios resulted in a higher yield and selectivity towards HMF by shifting the distribution equilibrium towards the organic phase.…”

“…Many reactions have potential for intensification in microreactors, [133] and they hold great promises for improving (certain types of) biomass transformations. [134] Typically, microreactors have been used for single liquid phase and biphasic (gas-liquid or liquid-liquid) catalytic transformation of biomass derivatives to valuable products using homogeneous or heterogeneous catalysts (e. g., the (biphasic) synthesis of furans from sugars, [135][136][137][138][139][140][141][142][143][144] (aerobic) oxidation, [144][145][146][147][148][149] and hydrogenation of biomass derivatives [144,[150][151][152][153] ). Furthermore, biodiesel synthesis by the (trans)esterification of triglycerides and fatty acids derived from plant oils, waste cooking oils and animal fats has been extensively studied in microreactors using inorganic [154][155][156] or enzymatic catalysts.…”