Laboratory- to Pilot-Scale Fractionation of Lignocellulosic Biomass Using an Acetone Organosolv Process

Abstract

Acetone organosolv fractionation of beech and birch wood at the lab-scale results in high sugar yields from the (hemi)cellulose and the isolation of a high-purity lignin. In this study, the process is scaled up to validate the technology at the pilot scale using industrial-size beech and birch wood chips and low liquid-to-solid ratios as a next step toward commercialization. Translation of the fractionation process to the pilot-scale showed a similar performance as compared to the lab-scale processing with a good conversion of the wood polymeric pentoses to mostly monomeric sugars and a high delignification. Continuous lignin precipitation by solvent evaporation using the LigniSep process resulted in the formation of nonsticky lignin aggregates with a good filterability. The improved lignin yields and advanced process design as compared to the traditional dilutive lignin precipitation approaches are likely to translate to a better process economy. The pulp washing efficiency and the recovery of (nonprecipitable) lignin from the aqueous hemicellulose stream still need to be improved for an efficient process design. However, the fractionation performance and high product concentrations in the spent liquor provide an excellent start position for improved process design at the commercial scale.

Fractionation and Absolute Molecular Weight Determination of Organosolv Lignin and Its Fractions: Analysis by a Novel Acetone-Based SEC─MALS Method

“…Beech wood lignin is processed with a mild acetone OS process (Fabiola) and subsequently precipitated by the LigniSep process , from the pulping liquor. Further details of the process conditions can be found in the literature . Lignin samples are dried and stored at room temperature prior to use.…”

“…Further details of the process conditions can be found in the literature. 9 Lignin samples are dried and stored at room temperature prior to use. Acetone >99.9% was purchased from VWR International (CAS: 67-65-1), formic acid from Fisher Scientific (CAS: 64-18-6), and polyethylene glycol/ polyethylene oxide (PEG/PEO) standards from Agilent Technologies, and tap water was purified using a Millipore filter system [resistivity 18.2 MΩ cm, total organic carbon (TOC) 3 ppb].…”

“…5−7 The combination of organic solvent mixtures and a low amount of an acid or base catalyst in the OS pulping is relatively mild and enables the production of high-quality lignin in comparison to other technical lignins. 8,9 In particular, lignins isolated from the acetone OS Fabiola process show relatively high purities paired with an overall energy-efficient process. 7,9,10 From a chemical perspective, lignin is a highly complex three-dimensional biopolymer based on three cinnamyl alcohols as shown in Figure 1.…”

“…This renewable biopolymer contributes almost 30 wt % of lignocellulosic biomass [lignified material (LCB)]. − Besides the pulp and paper industry, several biorefineries process LCB into the key components cellulose, hemicellulose, and lignin. Hereby, the organosolv (OS) is widely considered a promising pretreatment process in biorefineries, which is based on the delignification of biomass with hot organic solvent–water mixtures, such as ethanol– or acetone–water. − The combination of organic solvent mixtures and a low amount of an acid or base catalyst in the OS pulping is relatively mild and enables the production of high-quality lignin in comparison to other technical lignins. , In particular, lignins isolated from the acetone OS Fabiola process show relatively high purities paired with an overall energy-efficient process. ,, …”

“…8,9 In particular, lignins isolated from the acetone OS Fabiola process show relatively high purities paired with an overall energy-efficient process. 7,9,10 From a chemical perspective, lignin is a highly complex three-dimensional biopolymer based on three cinnamyl alcohols as shown in Figure 1. 6,11 The heterogeneity of lignin biopolymers arises from the molecular composition and linkage types between the hydroxycinnamyl alcohols, so called monolignols.…”