Experimental and theoretical studies on glucose conversion in ethanol solution to 5-ethoxymethylfurfural and ethyl levulinate catalyzed by a Brønsted acid

Abstract

DFT calculations combined with experiments were used to discover the mechanism and reaction pathway of the glucose alcoholysis reaction.

Catalytic Upgrading of Lignocellulosic Biomass Sugars Toward Biofuel 5-Ethoxymethylfurfural

“…(ⅱ) Compare Path I and Path Ⅲ. Glucose is usually isomerized to fructose when Brønsted acid and Lewis acid are present at the same time (He et al, 2022). When there is only Brønsted acid in the system, although the DFT calculation results show that the highest energy barriers required for Path I (17.7 kcal/mol) and Ⅱ (20.8 kcal/mol) are similar, the thermodynamic reaction is more favorable for Path I (Wang et al, 2021). And the intermediate EDGP in Path Ⅲ is difficult to continue further conversion.…”

“…One possible reason for this is that glucose formed a bit intermediate 3-deoxyglucosone in Brønsted acid, which is then dehydrated to form HMF, and finally etherified to EMF (Jadhav et al, 2011;Jadhav et al, 2012). In addition, Brønsted acid and protonated ethanol ([C 2 H 5 OH 2 ] + ) can open the ring of glucose to form intermediate 1,2-enediol then isomerizes to fructose, which makes it possible to produce EMF in the next step (Guo et al, 2017;Wang et al, 2021). When there is only Lewis acid in the system, a moderate EMF yield (10-40%) can be obtained from glucose (Dutta et al, 2012;Tan et al, 2017).…”

“…Obtaining EMF from glucose usually requires a higher temperature and longer reaction time (Srinivasa Rao et al, 2020;Wang et al, 2021). However, continuously increasing the reaction temperature and time leads to the decrease in the yield of EMF, which is due to the unstable EMF and easily converted to EL under high temperature and long time (Zheng et al, 2021).…”

“…However, continuously increasing the reaction temperature and time leads to the decrease in the yield of EMF, which is due to the unstable EMF and easily converted to EL under high temperature and long time (Zheng et al, 2021). During the conversion of glucose to EMF, water may be produced due to dehydration and etherification, which makes the hydrolysis of HMF into LA inevitable in this system (Wang et al, 2021). Since the polar co-solvent limits the conversion of HMF to LA (Morales et al, 2017), such as dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), and GVL, many studies add cosolvents to this system, which significantly inhibited the production of EL (Yu et al, 2018).…”

Kinetic Study and Model Assessment for n-Butyl Levulinate Production from Alcoholysis of 5-(Hydroxymethyl)furfural over Amberlite IR-120

“…Some kinetic models of sugar hydrolysis to levulinic acid and esterification (levulinic acid to alkyl levulinates and formic acid to alkyl formate) can be found in the literature. ,− However, the development of kinetic models for the alcoholysis of sugars to alkyl levulinates is scarce, and the kinetic constant comparison is difficult due to the different ways to derive reaction rates . The kinetic modeling of this system is complex because several reactions occur simultaneously in parallel and consecutive ways (Figure ).…”