Conversion of Hemicellulose Sugars Catalyzed by Formic Acid: Kinetics of the Dehydration of D‐Xylose, L‐Arabinose, and D‐Glucose

Abstract

The pre-treatment of lignocellulosic biomass produces a liquid stream of hemicellulose-based sugars, which can be further converted to high-value chemicals. Formosolv pulping and the Milox process use formic acid as the fractionating agent, which can be used as the catalyst for the valorisation of hemicellulose sugars to platform chemicals. The objective of this study was to investigate the reaction kinetics of major components in the hemicelluloses fraction of biomass, that is, D-xylose, L-arabinose and D-glucose. The kinetics experiments for each sugar were performed at temperatures between 130 and 170 °C in various formic acid concentrations (10-64 wt %). The implications of these kinetic models on the selectivity of each sugar to the desired products are discussed. The models were used to predict the reaction kinetics of solutions that resemble the liquid stream obtained from the fractionation process of biomass using formic acid.

Conversion of d -glucose to 5-hydroxymethylfurfural using Al 2 O 3 -promoted sulphated tin oxide as catalyst

“…It was also observed that a greater amount of undesirable products such as dark fine solids (humins) were formed at high temperatures. The HMF yields observed in the aqueous phase using homogeneous catalysts such as H 2 SO 4 and HCl do not exceed 2-6% at 170-175 • C and tend to be lower at lower temperatures [46][47][48]. Higher HMF yields from glucose (Y HMF = 13%) have been observed with high concentrations of formic acid at 170 • C, however, due mostly to a solvent effect that stabilises HMF in the formic acid phase [48].…”

“…The HMF yields observed in the aqueous phase using homogeneous catalysts such as H 2 SO 4 and HCl do not exceed 2-6% at 170-175 • C and tend to be lower at lower temperatures [46][47][48]. Higher HMF yields from glucose (Y HMF = 13%) have been observed with high concentrations of formic acid at 170 • C, however, due mostly to a solvent effect that stabilises HMF in the formic acid phase [48]. It becomes evident that the TSA 350 catalyst offered not only higher selectivities than conventional homogeneous catalysts at high temperatures, but also a relatively high conversion and high selectivity at mild temperatures.…”

A Bibliometric Study of Scientific Publications regarding Hemicellulose Valorization during the 2000–2016 Period: Identification of Alternatives and Hot Topics

“…The first commercial process for furfural production from biomass was designed in the 1920s and used oat hulls as raw material [194]. Traditional operation conditions include temperature in the 200-250 °C range and the presence of sulfuric acid as catalyst, but alternative acids have been proposed, such as formic acid [195]. However, efforts to improve the process by heterogeneous catalysis have been carried out [196][197][198][199] and the recent employment of ionic liquids as catalysts has opened a new opportunity to furfural production [200,201].…”

“…Moreover, diphenolic acid, which can be employed to replace bisphenol-A in the production of polycarbonates, can be easily obtained by reaction of LeA with phenol [87,163]. The controlled thermal degradation of hexoses in the presence of diluted mineral acids is the most widely used approach to obtain LeA from lignocellulosic biomass [195]. HMF is formed as intermediate, which reacts with water to give LeA and formic acid as by-product.…”

New Frontiers in the Catalytic Synthesis of Levulinic Acid: From Sugars to Raw and Waste Biomass as Starting Feedstock

“…When raw lignocellulosic biomass is employed, acid depolymerization of hemicellulose fraction releases pentoses (xylose and arabinose), which are converted to furfural, while from the different hexoses (glucose, galactose and mannose) of the cellulose fraction, levulinic acid is formed ( Figure 3) [36]. In this case, the solid by-product contains humins and also lignin residues.…”