Carbohydrate stabilization extends the kinetic limits of chemical polysaccharide depolymerization

Abstract

Polysaccharide depolymerization is an essential step for valorizing lignocellulosic biomass. In inexpensive systems such as pure water or dilute acid mixtures, carbohydrate monomer degradation rates exceed hemicellulose-and especially cellulose-depolymerization rates at most easily accessible temperatures, limiting sugar yields. Here, we use a reversible stabilization of xylose and glucose by acetal formation with formaldehyde to alter this kinetic paradigm, preventing sugar dehydration to furans and their subsequent degradation. During a harsh organosolv pretreatment in the presence of formaldehyde, over 90% of xylan in beech wood was recovered as diformylxylose (compared to 16% xylose recovery without formaldehyde). The subsequent depolymerization of cellulose led to carbohydrate yields over 70% and a final concentration of ~5 wt%, whereas the same conditions without formaldehyde gave a yield of 28%. This stabilization strategy pushes back the longstanding kinetic limits of polysaccharide depolymerization and enables the recovery of biomass-derived carbohydrates in high yields and concentrations.

Catalyst Evolution Enhances Production of Xylitol from Acetal-Stabilized Xylose

“…Alternatively, the ring opening of HMXF could have also lead to the formation of xylulose. 8 In any of these cases, the selectivity of the process decreases, which is what we observed.…”

Synthesis of ethanol from aryl methyl ether/lignin, CO2 and H2

“…1 Transformation of lignin and/or CO 2 into value-added chemicals has attracted great interest. [2][3][4][5][6][7][8][9][10][11][12][13][14][15] Lignin is a major component of lignocellulosic biomass, and its valorization remains a challenge because of the complex and robust structure. 16 Aryl methyl ethers are commonly used as model compounds to study lignin conversion, which has been successfully transformed into various chemicals, such as benzene, phenol, terephthalic acid, cyclohexanone, cyclohexane, methanol, methane, acetates, acetic acid, etc.…”

Ketal Sugar Conversion Into Green Hydrocarbons by Faujasite Zeolite in a Typical Catalytic Cracking Process

“…For instance 1,2:3,5-di-O-isopropylidene-α-D-xylofuranose (DX) and 1,2: 5,6- Isopropylidene- α-D -glucofuranose (DG) were produced in high concentration, 50 wt.%. A later publication also applied similar condition to depolymerization wood biomass and avoided undesirable reaction of sugars (Questell-Santiago et al, 2018).…”