Hydrolysis of Hemicellulose and Derivatives—A Review of Recent Advances in the Production of Furfural

Abstract

Biobased production of furfural has been known for decades. Nevertheless, bioeconomy and circular economy concepts is much more recent and has motivated a regain of interest of dedicated research to improve production modes and expand potential uses. Accordingly, this review paper aims essentially at outlining recent breakthroughs obtained in the field of furfural production from sugars and polysaccharides feedstocks. The review discusses advances obtained in major production pathways recently explored splitting in the following categories: (i) non-catalytic routes like use of critical solvents or hot water pretreatment, (ii) use of various homogeneous catalysts like mineral or organic acids, metal salts or ionic liquids, (iii) feedstock dehydration making use of various solid acid catalysts; (iv) feedstock dehydration making use of supported catalysts, (v) other heterogeneous catalytic routes. The paper also briefly overviews current understanding of furfural chemical synthesis and its underpinning mechanism as well as safety issues pertaining to the substance. Eventually, some remaining research topics are put in perspective for further optimization of biobased furfural production.

Enhancing Lignocellulosic Biomass Hydrolysis by Hydrothermal Pretreatment, Extraction of Surface Lignin, Wet Milling and Production of Cellulolytic Enzymes

“…Removal of these barriers by various pretreatment and fractionation methods has greatly increased the yields of enzymatic hydrolysis of cellulose, providing sugars that can be exploited by fermentation or chemo‐catalytic processes into various fuels or platform chemicals . On the other hand, efficient fractionation removal of hemicellulose and lignin as well as their recovery is critical for their exploitation, considering that whole biomass valorization is the main goal of the future biorefinery . Finally, the cost of enzyme production still represents a major issue that increases the overall process economics.…”

The Effect of Solvent Polarity on Autocatalytic Furfural Production Confirmed by Multivariate Statistical Analysis

“…

Autocatalytic dehydration of xylose to furfural was studied in pure aqueous and monophasic organic/water mixtures to determine the effect reaction media and conditions have on conversion and yield. [3] Solvent selection has been identified as an important reaction variable with mentions of solvent polarity [4] and the number of oxygen containing groups [5] being potential explanations as to why solvents improve furan yields, but currently no systematic method for solvent selection exists. Increasing the R o and δ P increased both conversion and yield in pure aqueous and organic/water mixtures of sulfolane, γ-butyrolactone, γ-valerolactone, γ-hexalactone, and tetrahydrofuran.

…”

“…Increasing the R o and δ P increased both conversion and yield in pure aqueous and organic/water mixtures of sulfolane, γ-butyrolactone, γ-valerolactone, γ-hexalactone, and tetrahydrofuran. [3,9] In biphasic systems using aluminium sulfate as the catalyst, Yang et al hypothesized that as the polarity of a solvent increases, furfural yields increase in γ-valerolactone (GVL), methyl isobutyl ketone, tetrahydrofuran (THF), and 2-methyltetrahydrofuran; [10] however, no direct measure of solvent polarity was provided.Although acid catalysts increase the rate of reaction, furans can be produced through an autocatalytic process (Scheme 1), with the mechanism initiated by the formation of hydronium ions in high temperature water. Using principal component analysis and projection to latent structures, a semi-empirical model was developed that provided estimates of xylose conversion and furfural yield over a range of experimental R o and δ P values.…”

“…[3,9] In biphasic systems using aluminium sulfate as the catalyst, Yang et al hypothesized that as the polarity of a solvent increases, furfural yields increase in γ-valerolactone (GVL), methyl isobutyl ketone, tetrahydrofuran (THF), and 2-methyltetrahydrofuran; [10] however, no direct measure of solvent polarity was provided. Previous research has explored acid-catalyzed reactions in organic solvent mixtures for both monophasic and biphasic systems.…”

“…The use of organic solvents for xylose dehydration reactions has recently gained interest due to faster reaction rates [2] and the higher furfural yields obtained, which have been reported as high as 80 % in biphasic systems. [3] Solvent selection has been identified as an important reaction variable with mentions of solvent polarity [4] and the number of oxygen containing groups [5] being potential explanations as to why solvents improve furan yields, but currently no systematic method for solvent selection exists. Researchers have previously used Kamlet-Taft theory [6] or Hansen Solubility Parameters (HSPs) [7] to explain differences in selectivities, conversions, and yields; however, the HSP parameters (dispersion (δ D ), polarity (δ P ), and hydrogen bonding (δ H )) are functions of both solvent mixture and temperature, [8] which often times are not considered.…”