Mechanistic understanding of humin formation in the conversion of glucose and fructose to 5-hydroxymethylfurfural in [BMIM]Cl ionic liquid

Abstract

This study provided a new mechanistic understanding of humin formation during 5-HMF production from hexose in ionic liquids.

LiCl-promoted-dehydration of fructose-based carbohydrates into 5-hydroxymethylfurfural in isopropanol

“…The result could be attributed to the complexity of the reaction and high reactivity of HMF, several side reactions may occur, the most notable of which are the acidcatalyzed HMF rehydration to levulinic and formic acids, HMF self-condensation reactions, and HMF-fructose crosspolymerization, forming soluble and insoluble polymers named humins conrmed by the brown mixture aer reaction. [29][30][31]36 As known that the solvent also affected the dehydration process of fructose conspicuously through coordinating or activating intermediates. 7,[37][38][39][40] Hence, the effect of organic solvent with different structure on fructose dehydration with an aid of LiCl was investigated inevitably.…”

Tuning Brønsted and Lewis acidity on phosphated titanium dioxides for efficient conversion of glucose to 5-hydroxymethylfurfural

“…51,66 Besides, humins formed via HMF polymerization were also observed in the reaction for an extended amount of time which could be noticed from the darker color of the used catalyst and the product solution. 67,68 Overall, the optimal reaction time is 6 h giving 86% of glucose conversion and 72% of HMF yield, showing a signicant improvement over the typical reaction setup.…”

Humic Substances Derived From Biomass Waste During Aerobic Composting and Hydrothermal Treatment: A Review

“…They also built the surface response model and equation that can reflect the humin yield changing with the parameter of reaction temperature. Xu et al (2020 ) got a similar result that the solid humin yield improved from 29.7% to 78.7% as the reaction temperature was increased in their hydrothermal system, as shown in Table 4 (entry 4). Therefore, it can be concluded that the improvement of reaction temperature helps to increase humin formation during hydrothermal reactions because higher energy input impels more complex reactions to occur which is conducive to form the humins.…”

“…Therefore, hydrochar cannot be fully regarded as a humus-like material. Recently, studies mainly focused on reaction systems that used homogeneous substances such as glucose and fructose as raw materials to prepare the humins via hydrothermal technology ( van Zandvoort et al, 2013 ; Hoang et al, 2015b ; Korner et al, 2019 ; Shi et al, 2019 ; Xu et al, 2020 ). Hydrothermal technology can also be used as an extraction method to obtain HA from humus-rich biomass such as coal process waste and lignite ( Cheng et al, 2019 ; Sriramoju et al, 2020 ).…”