Ionic Liquids as Tools for the Acid‐Catalyzed Hydrolysis/Dehydration of Saccharides to Furanic Aldehydes

Abstract

One of the measures associated with the socio‐political and environmental protection policies towards sustainability is the use of biomass as a renewable source of energy, fuels, and chemical products. The chemical valorization of carbohydrate biomass, in particular, the acid‐catalyzed conversion of saccharides into the furanic aldehydes, furfural and 5‐hydroxymethyl‐2‐furfuraldehyde, has been a matter of intensive research. These products possess wide application profiles in different sectors of the chemical industry and are thus considered as important platform chemicals. High expectations have been put on the use of ionic liquids (ILs) as tools for these reaction systems, partly due to the singular solubilizing properties of ILs for polysaccharides (important for process intensification), leading to favorable effects when coupled with different types of acid catalysts or when the actual IL is functionalized with acid groups, allowing it to play a dual solvent‐acid role. An assessment of the present state‐of‐the art on this topic is made in this review, showing that promising results have been reported using mild reaction conditions.

Multiscale molecular modeling can be an effective tool to aid the development of biomass conversion technology: A perspective

“…Though water is the most desirable solvent, it is reported that the presence of co-solvents like dimethyl sulfoxide, dimethyl formamide, tetrahydrofuran, to name a few, increases the selectivity in biomass reactions significantly by hindering the formation of humins and condensation products (Román-Leshkov et al, 2006;Alonso et al, 2013;Gallo et al, 2013). Novel solvents like ionic liquids have also proven to be efficient solvents for biomass reactions (Hsu et al, 2011;Lima et al, 2011;Jadhav et al, 2012;Liu et al, 2012Qu et al, 2012;Liu and Chen, 2013;Okano et al, 2013). Despite of these numerous studies demonstrating the effect of solvents on a variety of biomass reactions, the fundamental understanding of the role of solvents and their physico-chemical interactions with biomass species remain very poor.…”

Advanced Biofuels and Beyond: Chemistry Solutions for Propulsion and Production

“…[273] Themain current challenge facing the production of furfural is the development of low-cost processes that are compatible with the economic and ecological requirements for fuel components.T he traditional processes are based on strong acid catalysts,s uch as sulfuric acid, in solution, but the potential use of heterogeneous acid catalysts for the dehydration of monosaccharides has gained increasing attention in the field, as revealed by the number of related patents during the last few years. [274][275][276][277] Another concept for the formation of furfural tries to avoid the use of an external catalyst through an autocatalyzed reaction mechanism, wherein the thermal decomposition of xylose results in organic acids that act as molecular catalysts in the production of furfural. [278] 5-Hydroxymethyl-2-furaldehyde (HMF) Similar to furfural, HMF (5-hydroxymethyl-2-furaldehyde) is formed from the C 6 sugars glucose and fructose in the presence of an acidic catalyst.…”

“…[279] Chemically,H MF is ah ighly versatile intermediate for further synthetic modification of its two distinct functionalities:t he hydroxy and carboxaldehyde moieties. [274][275][276][277][280][281][282] Furthermore,the abundance of hexoses in lignocellulosic material provides greater potential for the production of HMF compared to furfural. In av ery recent techno-economic analysis of HMF production from fructose it was inferred that the market for HMF could exceed 4million metric ton per year.…”

Manufacture of furfural in biphasic media made up of an ionic liquid and a co-solvent

“…Immiscible solvents have been employed as extracting agents for furfural from a variety of different reaction media, including ionic liquids. In particular, toluene has been used to improve the furfural yields from xylose obtained in media containing acid-catalyzed 1-butyl-3-methylimidazolium chloride and 1-ethyl-3-methylimidazolium chloride (Lima et al, 2009(Lima et al, ,2011.…”