Pre-treatment of lignocellulosic feedstocks using biorenewable alcohols: towards complete biomass valorisation

Abstract

Here, we report on the ability of the biomass derived solvents ethanol and, in particular,n-butanol to fractionate lignocellulose into its main components. The developed process gives high quality carbohydrate and lignin fractions in good yields.

Selective Depolymerisation of γ‐Oxidised Lignin via NHC Catalysed Redox Esterification

“…As a result, new pre‐treatment methods have been developed which feature in situ stabilisation strategies to preserve β‐aryl ether units, at the same time as providing high quality carbohydrate streams . We have recently reported on the use of n‐butanol (BuOH) as a pre‐treatment solvent (butanosolv) for this purpose . This process provides butanosolv lignins in high yield and with relatively high β‐aryl ether content, but in contrast to native lignins which have an −OH at the α‐position of the β‐aryl ether unit, they display extensive incorporation of BuOH at this position.…”

“…With optimised conditions identified for the NHC catalysed cleavage of model compounds 1 a – 1 d , we turned our focus to the depolymerisation of a real lignin substrate. Thus, a beech butanosolv lignin was prepared according to previous reports and the oxidation of the primary alcohol groups to aldehydes in the β‐aryl ether linkages was attempted using the biphasic TEMPO/NCS catalytic system developed by Einhorn et al . In contrast to our previous reports on the direct TEMPO‐catalysed oxidation of this alcohol to carboxylic acids, attempts to perform this reaction on the butanosolv lignin failed to provide the expected aldehyde product.…”

Selective Primary Alcohol Oxidation of Lignin Streams from Butanol‐Pretreated Agricultural Waste Biomass

“…[13,14] In addition, due to the frequent use of acidic conditions, some organosolv lignins are still condensed. Our group [15] ando thers [16][17][18][19][20] have previously reported the use of biorenewable butanol as ap retreatment solventf or woody-biomass sources, using both hardwoods and softwoods. [15] Under the acidic butanosolv conditions, the hydroxy at the a positiono ft he b-O-4 unit is replaced by butanol leadingt os tabilization of the b-O-4 unit in a" protected" [21] form (structure 2,F igures 1a nd S1).…”

Alcoholysis: A Promising Technology for Conversion of Lignocellulose and Platform Chemicals

“…Ethylene glycol can effectively trap C 2 aldehydes generated by the cleavage of β‐O‐4 linkages together with formaldehyde released from β‐O‐4 and β‐5 linkages. Recently, they reported an improvement to the conventional Alcell method to isolate lignin from native wood biomass . In Alcell organosolv conditions, most of hemicellulose and β‐O‐4 linkages of lignin are degraded, which results from the high water content under acidic conditions.…”