Catalytic lignin valorisation by depolymerisation, hydrogenation, demethylation and hydrodeoxygenation: Mechanism, chemical reaction kinetics and transport phenomena

Selective demethylation reactions of biomass-derived aromatic ether polymers for bio-based lignin chemicals

“…Lignin undergoes various structural modifications and rearrangements with each type of treatment (i.e., depolymerization, hydrogenation, demethylation, etc.). 155 This means that the characterization of demethylated lignin cannot be limited to a single NMR method. 31 P NMR provides the content of hydroxyl groups, while C 5 -substituted and guaiacyl phenolic OH groups overlap with either hydroxyl or methoxyl groups in the C 3 or C 5 position.…”

Bio-based platform chemicals synthesized from lignin biorefinery

“…and organic N-base catalysts. 191–193 Alkaline properties and reaction parameters are crucial factors to determine the product's yield and distribution. Compared with a weak base ( e.g.…”

“…Based on the difference in hydrogen source, reductive depolymerization was categorized as non-self-transfer hydrogenolysis/hydrogenation (NSTH) and self-transfer hydrogenolysis/hydrogenation (STH). 193,228,229 In the NSTH process, exogenous hydrogen, such as hydrogen gas or hydrogen-donor solvents, is used to cleave the β-O-4 bond. Simultaneously, reactive intermediates are stabilized to enhance phenolic monomer yield and reduce char formation.…”

Reductive Partial Depolymerization of Acetone Organosolv Lignin to Tailor Lignin Molar Mass, Dispersity, and Reactivity for Polymer Applications

“…As the M w of a large part of the sample is too high for optimal application, controlled depolymerization of especially the large lignin fragments to a lower molar mass may have potential to tailor lignin characteristics for a better control over its solubility, reactivity, and thermal properties. Most literature examples however focus on deep polymerization and target the production of monomeric phenolics via full lignin depolymerization using thermochemical, oxidative, reductive, photocatalytic, and biochemical processes. − Only very few studies report on, e.g., optimization of the oligomer product instead. , Indeed, the strategy of tailoring macromolecular properties via partial depolymerization of an isolated lignin (and its fractions) remains to be demonstrated. Within the deep depolymerization examples, reductive approaches have gained particular interest as they achieve high monomer yields, in particular when applied in a lignin-first-type strategy.…”