Progress in Fractionation Processes of Lignocellulosic Biomass for Biorefinery: A Review

Abstract

Due to the awareness of fossil fuel depletion and global warming, biorefinery for production of biofuels and valuable platform chemicals from lignocellulosic biomass has attracted growing interest in the past decades. With the rising concept of comprehensive utilization of lignocellulosic biomass,fractionation processes are generally necessary prior to its subsequent conversion with aims to produce purified cellulose with specific recovery of hemicellulose and lignin. In this review, ionic liquids fractionation,steam explosion based fractionation,twin-screw extrusion and organosolv fractionation are described and their features and comparative performances are discussed.

Perspective on Technical Lignin Fractionation

“…Typically, technical lignin after extraction and purification from black liquor has an average molecular weight ( M w ) of 1 kDa to 100 kDa, with polydispersity ( M w / M n ) from 1.8 to 3.6 depending on wood sources and pulping process condition. ,,,,,,,, …”

“…10 Cooking liquor from the pulping process is a mixture of dissolved lignin contaminated with cooking chemicals, degraded carbohydrates, wood extractives, and metal-salt or ash. 11,12 Different methods have been reported to recover and purify lignin from the black liquor solution. The process usually starts with reducing the solubility of lignin using acidification agents such as CO 2 or H 2 SO 4 followed by lignin separation by filtration.…”

“…Typically, technical lignin after extraction and purification from black liquor has an average molecular weight (M w ) of 1 kDa to 100 kDa, with polydispersity (M w /M n ) from 1.8 to 3.6 depending on wood sources and pulping process condition. 3,4,5,7,8,11,16,17,23 Recovered lignin is a mixture of different fractions of lignin with wide range of molecular weights with each having their own unique chemical and physical properties for each fraction. 3 To obtain a more uniform structure of lignin, fractionation has been proposed as a promising method to obtain specific lignin polymer properties.…”

Modeling of Pretreatment and Acid/Alkaline Hydrolyses of Lignocellulosic Biomasses in Twin-Screw Extruders

“…Steam explosion is typically initiated at a temperature of 160–260 °C (corresponding pressure, 0.69–4.83 MPa) for several seconds to a few minutes before the material is exposed to atmospheric pressure. The process causes hemicellulose degradation and lignin transformation due to the high temperatures, thus increasing the potential of cellulose hydrolysis. − Other pretreatment processes of technological or scientific relevance include acid hydrolysis (diluted), alkaline hydrolysis (diluted), organosolv fractionation, twin-screw extrusion, and fractionation using ionic liquids. ,− …”

An integral method for determining the molecular composition of lignin and its application

“…Lignin is the most abundant natural renewable aromatic polymer, and it can be used to produce biomass-based chemicals and materials, such as dispersants, adhesives, activated carbon, carbon fiber, and phenolic resin [1][2][3][4][5][6] . Therefore, the process of lignin refining can be potentially used to replace the process of petroleum refining.…”