A novel interaction mechanism in lignin pyrolysis: Phenolics-assisted hydrogen transfer for the decomposition of the β-O-4 linkage

Review on Reaction Pathways in the Catalytic Upgrading of Biomass Pyrolysis Liquids

“…According to the previous definition, it can be understood that the migration of hydrogen ions could be performed not only between hydrocarbons but also between hydrocarbons and oxygenated compounds , or even between oxygenated compounds …”

“…According to the previous definition, it can be understood that the migration of hydrogen ions could be performed not only between hydrocarbons but also between hydrocarbons and oxygenated compounds 188,189 or even between oxygenated compounds. 190 The use of hydrogen and catalysts based on rare earths in hydrodeoxygenation of oxygenated compounds imposes high operation costs. 55,135,141,191,192 This fact has promoted the search for alternative processes, focused on the transfer of hydrogen from donor compounds to oxygenated compounds, also considering that the donor could be an oxygenated species to avoid the use of hydrogen.…”

Hydroxyl-Assisted Hydrogen Transfer Interaction in Lignin Pyrolysis: An Extended Concerted Interaction Mechanism

“…12−14 Generally, the pyrolysis mechanism of lignin can be classified into the radical reaction mechanism and the concerted reaction mechanism, as summarized in Figure 1. 15,16 The former is a kind of chain reaction mechanism, which includes three key reaction processes, i.e., homolytic decomposition, hydrogen abstraction, as well as radical rearrangement & decomposition. This chain mechanism is primarily initiated by direct C β −O or C α −C β homolysis to generate two free radical fragments.…”

Experimental study on light volatile products from thermal decomposition of lignin monomer model compounds: effect of temperature, residence time and methoxyl group

“…Dimmer or oligomer of lignin units were widely employed to experimentally or numerically investigate the breakage of ether bonds or carbon-carbon linkages among aromatic structures in lignin. [14][15][16][17][18][19] Cleavage mechanisms of b-O-4 linkage and a-O-4 linkage are the main topics, and were analyzed with free-radical reactions, molecular rearrangements, and concerted elimination reactions. [15][16][17] Recently, monomer model compounds were decomposed, and it was reported that inorganic gases (IGs) and light hydrocarbons (LHs) were dominant products generated from pyrolysis of monomer aromatic model compounds through ring-reduction reactions at 650-850 C. 11,[20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] Considering the ring-reductions reactions of aromatic structure to small fragments, the decomposition mechanisms of monomer phenolic compounds such as phenol, 21,22 catechol, [23][24][25][26] anisole, [27][28][29] guaiacol, 7,30-34 syringol, 34-36 eugenol 37 and vanillin 38 have recently been investigated experimentally and theoretically.…”