From biomass to feedstock: one-step fractionation of lignocellulose components by the selective organic acid-catalyzed depolymerization of hemicellulose in a biphasic system

Abstract

A concept for a highly integrated fractionation of lignocellulose in its main components (cellulose-pulp, soluble hemicellulose sugars and lignin) is described, based on the selective catalytic depolymerization of hemicellulose in a biphasic solvent system. This leads to an effective disentanglement of the compact lignocellulose structure, liberating and separating the main components in a single step. At mild temperatures (80–140 °C), oxalic acid catalyzes selectively the depolymerization of hemicellulose to soluble sugars in aqueous solution, whereas the more crystalline cellulose-pulp remains solid and inaccessible to the acid catalysis. In the presence of a second organic phase consisting of bio-based 2-methyltetrahydrofuran (2-MTHF), lignin is directly separated from the pulp and the soluble carbohydrates by in situ extraction. The oxalic acid catalyst can be crystallized from the aqueous solution, recovered and re-used. The delignified cellulose-pulp obtained from this biphasic system can be directly subjected to enzymatic depolymerization, affording soluble oligomers and glucose at rates almost comparable to those observed for the hydrolysis of commercial microcrystalline Avicel^®. Overall, the concept may offer a promising approach for an efficient and selective pre-treatment of lignocellulosic materials under mild and environmentally-friendly conditions

Physicochemical Characterisation of Technical Lignins for Their Potential Valorisation

“…A new biphasic Organosolv-like process also accounting for biomass pretreatment and lignin recovery called Organocat has been improved and proposed recently [15]. In principle, it uses an aqueous solution of 2-methyltetrahydrofuran (2-MTHF) as an organic solvent and oxalic acid as a catalyst, where effective separation of the primary constituents of the compact lignocellulosic material is attained in a single step [16]. To this end, the pretreatment of lignocellulosic biomass and the detailed understanding of their composition and structure are much-needed steps in order to devise efficient biomass and lignin valorisation strategies [17].…”

The effects of combined catalysis of oxalic acid and seawater on the kinetics of xylose and arabinose dehydration to furfural

“…Different organic acid catalysts (e.g. fumaric, oxalic or maleic acid) have already been investigated as substitutes for the more widely applied mineral acids (mostly H 2 SO 4 or HCl) [19,29,33,34]. Formic acid, a byproduct of furfural degradation, has been shown to be an effective catalyst for furfural production [20].…”

Early Transition Metal Doped Tungstite as an Effective Catalyst for Glucose Upgrading to 5-Hydroxymethylfurfural

“…Glucose can be obtained from lignocellulosic biomass in relatively pure form, making it cheap and abundant compared to fructose. These aspects make glucose an attractive feedstock for HMF [10][11][12][13]. However, the upgrading of glucose to HMF is much more challenging than that of fructose [14][15][16].…”