Guidelines for performing lignin-first biorefining

Abstract

The valorisation of the plant biopolymer lignin is now recognised as essential to enabling the economic viability of the lignocellulosic biorefining industry. In this context, the “lignin-first” biorefining approach, in...

Selective electrocatalytic hydrogenation of bio-oil to oxygenated chemicals via suppression of deoxygenation

“…By using AAF with propionaldehyde as the stabilizing aldehyde, we rst fractionated the birch wood into celluloserich solids, dipropylxylose, and propionaldehyde stabilized lignin (Fig. 6b) 35 . The lignin was then hydrogenolyzed using a 5 wt% Ru/C catalyst in tetrahydrofuran (THF) to produce a complex solution consisting of lignin oligomers and monomers.…”

Pharmaceutically relevant (hetero)cyclic compounds and natural products from lignin-derived monomers: Present and perspectives

“…For the past decades, significant efforts have been directed to the development of efficient catalytic depolymerization methodologies—ranging from oxidation to reduction, acid or base catalysis—to obtain diverse aromatic monomers with high selectivity ( Schutyser et al., 2018 ; Sun et al., 2018b ). Fundamentally important concepts, such as the stabilization of reactive intermediates during fractionation or depolymerization, for preventing recondensation processes have been introduced, which markedly reduced the formation of recalcitrant side products, thereby increasing selectivity toward desired products in near theoretical yields ( Abu-Omar et al., 2020 ; Questell-Santiago et al., 2020 ). Having access to diverse lignin platform chemicals, the search for catalytic downstream processing approaches has been initiated, and several important product classes, such as fuels, bulk chemicals, or drop-in intermediates, became accessible ( Sun et al., 2020 ; Wong et al., 2020 ).…”

“…Beside oxidation, various reductive methods have been introduced ( Song, 2020 ). The recently developed stabilization strategies ( Abu-Omar et al., 2020 ; Questell-Santiago et al., 2020 ), such as reductive catalytic fractionation (RCF) ( Renders et al., 2019 ) or aldehyde-assisted fractionation ( Shuai et al., 2016 ), start directly from lignocellulose and are able to achieve near-theoretical yields of monoaromatics and high selectivity for 4-propylguaiacol and 4-propyl syringol ( Song et al., 2013 ) as well as dihydroconiferyl ( Sun et al., 2018a ) and/or dihydrosinapyl alcohols ( Lan et al., 2018 ), whereas product distribution depends on the catalytic system and specific reaction conditions. Alternatively, these methods may also result in the formation of 4-(1-propenyl)-guaiacols and syringols as main products ( Galkin and Samec, 2014 ).…”

Advances in Versatile Nanoscale Catalyst for the Reductive Catalytic Fractionation of Lignin

“…The primary roles of the catalyst are reductive stabilisation of intermediates and depolymerisation of the solubilised lignin oligomers. [15] Homogeneous catalysts have been rarely utilized due to their inherent disadvantages in respect of their thermal stability and separation. [16] In addition, homogeneous catalysis can perform selected chemistries but could cause corrosiveness (in the case of soluble acid catalysts, except for polyoxometalate), difficult product separation from reaction mixture and produce more waste.…”