Supercritical CO2–subcritical H2O system: A green reactive separation medium for selective conversion of glucose to 5-hydroxymethylfurfural

Metal-Free Synthesis of HMF from Glucose Using the Supercritical CO2–Subcritical H2O–Isopropanol System

“…Meanwhile, the degradation of HMF was found to be the slowest step. This was consistent with the trend in the study by Inoue et al, 77 but in this current work, there were significantly higher rate constants for the conversion of fructose, k 2 and k 3 . The ratio of the rate constant for the conversion of fructose to HMF to that for the degradation of HMF k 2 /k 4 was 8.26 when the system consisted of scCO 2 and subH 2 O only, but the value increased to 23.38 when isopropanol was used as an additive.…”

“…75 Similarly, a consumption term with k 4 as the rate constant was included in the rate equation of HMF to account for its degradation into products like levulinic acid as well as humins. 76 The rate equations were therefore formulated as This set of equations was also used in a previous study 77 on the conversion of glucose to HMF in the scCO 2 −subH 2 O system with no additive nor cosolvent. These equations were solved for the rate constants k 1 to k 4 using the Runge−Kutta method and the resulting concentration profile is shown in Figure 3.…”

“…The authors also performed the conversion of glucose to HMF in scCO 2 −subH 2 O under reactive separation in a different study. 77 Upon formation of HMF in the stagnant aqueous phase, a fraction of it was extracted by the continuously flowing scCO 2 stream, which essentially contains organic compounds with HMF reaching a purity of 82.75 wt %. This mode of operation has a great potential in industrial applications because of the selective extraction of HMF.…”

“…In this current work, the highest attainable HMF yield in the scCO 2 –subH 2 O–isopropanol system was dictated by the thermodynamic and kinetic restrictions under the batch operation. The authors also performed the conversion of glucose to HMF in scCO 2 –subH 2 O under reactive separation in a different study . Upon formation of HMF in the stagnant aqueous phase, a fraction of it was extracted by the continuously flowing scCO 2 stream, which essentially contains organic compounds with HMF reaching a purity of 82.75 wt %.…”

Sustainable Approaches to Selective Conversion of Cellulose Into 5-Hydroxymethylfurfural Promoted by Heterogeneous Acid Catalysts: A Review

“…With the microcrystalline or amorphous form of cellulose coming up, it is usually utilized as a biomass raw material for the synthesis of various refining chemicals such as glucose, fructose, and 5-HMF. The selective conversion of cellulose into D-glucose is essentially a crucial step for other high valuable refining chemicals obtained from lignocellulosic biomass ( Inoue et al, 2021 ; Yao, 2022 ). D-glucose as the complete hydrolysate of cellulose, with a six-membered ring framework, is flexible to be isomerized into a five-membered ring skeleton of fructose under acidic conditions.…”