Kinetic Studies on the Conversion of Levoglucosan to Glucose in Water Using Brønsted Acids as the Catalysts

Abstract

Fast pyrolysis is as a promising and versatile technology to depolymerize and concentrate sugars from lignocellulosic biomass. The pyrolysis liquids produced contain considerable amounts of levoglucosan (1,6-anhydro-β-d-glucopyranose), which is an interesting source for glucose (GLC). Here, we report a kinetic study on the conversion of levoglucosan (LG) to GLC in water using sulfuric and acetic acid as the catalysts under a wide range of conditions in a batch setup. The effects of the initial LG loading (0.1–1 M), sulfuric and acetic acid concentrations (0.05–0.5 M and 0.5–1 M, respectively), and reaction temperatures (80–200 °C) were determined. Highest GLC yields were obtained using sulfuric acid (98 mol %), whereas the yields were lower for acetic acid (maximum 90 mol %) due to the formation of byproducts such as insoluble polymers (humins). The experimental data were modeled using MATLAB software, and relevant kinetic parameters were determined. Good agreement between experimental and model was obtained when assuming that the reaction is first order with respect to LG. The activation energies were 123.4 kJ mol–1 and 120.9 kJ mol–1 for sulfuric and acetic acid, respectively.

Catalytic production of hexane-1,2,5,6-tetrol from bio-renewable levoglucosanol in water: effect of metal and acid sites on (stereo)-selectivity

“…This reaction is similar to the hydrolysis of LGA to glucose (Scheme S2 †), in that water is added to the anhydro-bridge facilitated by an acid catalyst. 25,26 In the case of lgol hydrolysis, both C 2 epimers (i.e., the 3,4dideoxy-versions of glucose and mannose) are produced because both the erythro-and threo-isomers of lgol are present. This reaction reaches equilibrium at 83% conversion of erythro-lgol and 58% conversion of threo-lgol, indicated by the fact that the lgol conversion and product yields do not change significantly between 30-120 min (Fig.…”

Valorization of humin type byproducts from pyrolytic sugar conversions to biobased chemicals

“…Other products are 1, 6-anhydro-β-cellobiose (cellobiosan) and higher molecular weight sugars. Levoglucosan is readily hydrolyzed to glucose using acid catalysts [13,14], which subsequently can be converted to numerous biobased chemicals including HMF and LA.…”

Levoglucosan: a promising platform molecule?

“…The conversion of LG to GLC in water using solid and homogeneous acid catalysts such as Amberlyst 16 and sulfuric acid is also possible. Abdilla-Santes et al 136,137 studied the effects of reaction temperature, initial LG concentration and catalyst loading. The highest glucose yield of 98% was obtained for the Amberlyst 16 catalyst at 115°C.…”