CO₂-Catalysed conversion of carbohydrates to 5-hydroxymethyl furfural

Abstract

CO2 in water catalyzes the conversion of cellulose, starch, xylan, or glucose to HMF.

Controlling the Reaction Networks for Efficient Conversion of Glucose into 5‐Hydroxymethylfurfural

“…On one hand, CO 2 is nontoxic; on the other hand, the use of an in situ‐generated carbonic acid catalyst avoids the typical drawbacks for both homogeneous and heterogeneous acid catalysts because it could be removed by simple depressurization and reused easily . For example, Lee et al . reported the use of a CO 2 ‐involved H 2 O‐CaCl 2 /1‐pentanol biphasic solvent for converting glucose (10 wt %) and a wide range of sugars into HMF, wherein CaCl 2 acts as a phase splitting agent whereas 1‐pentanol serves as an extractive phase for isolating HMF from the CO 2 ‐containg aqueous phase.…”

“…A highest HMF yield of 64.0 % with the carbon balance of 64.0 % has been achieved at 200 °C with an initial CO 2 pressure of 7.0 MPa. However, the imbalance of carbon demonstrated the formation of oligomers or insoluble humins . In addition, Fu et al .…”

CO2-Catalysed aldol condensation of 5-hydroxymethylfurfural and acetone to a jet fuel precursor

“…6,15 However, CO 2 addition played an important role in the reaction as an acid catalyst, given that thermal conversion alone showed lower yields by comparison to CO 2 catalyzed aldol condensation. It has been shown previously by Lee et al 21 that CO 2 is an effective catalyst for the conversion of glucose to 5-HMF. Additionally, CO 2 catalysed conversion of polysaccharides of hexoses has been reported.…”

“…It was previously found that an increase in aldol condensation product could be promoted by reducing the reaction pressure, as shown in Table 2. Additionally it was reported by Lee et al 21 that reducing the CO 2 pressure could also increases the 5-HMF yield from glucose. However, the effect of CO 2 pressure on the aldol reaction of glucose is unclear; at 1 wt% glucose, the yields are all very low and, within error, are the same for 2.5 and 15 MPa.…”

“…Additionally, the use of secondary solvents in the reaction should allow for greater yield through the reduction of secondary side reactions that have been shown to occur during the formation of 5-HMF from hexoses. 21 , 22 The addition of either excess water or secondary solvents such as toluene to the reaction inhibited the formation of the aldol condensation product, as shown in entries 1, 2 and 3 by comparison to entry 4. However, when the toluene-rich phase was not present in the system (entries 3 vs 1 and entries 4 vs 2), there was a significant increase in the yield of aldol condensate.…”