Low Temperature Thermolysis of Lignins - I. Reactions of ß—O—4 Model Compounds

Lignin pyrolysis reactions

“…1 Thermogravimetric analysis of milled wood lignin isolated from Japanese cedar (Cryptmeria japonica) [9] understanding the pyrolytic reactions of lignins. Hence, various model dimers including β-ether [20,27,28,34,[40][41][42][43][44][45][46][47][48][49][50][51][52][53], α-ether [20,30,34,45,47,49,51,54], β-aryl [20,31,32,47,54], β-β [33], and biphenyl [20,47,54] types, trimers [34,49,51] and oligomers/polymers such as dehydrogenative polymerization products of cinnamyl alcohols [35] and β-ether type polymers [55][56][57] have been used in pyrolysis studies. Phenolic (Ph) and non-phenolic (Non-Ph) model compounds are commonly used to represent the ends and repeating units of lignin macromolecules, respectively.…”

“…The Ph β-aryl type dimers give stilbenes selectively, but this reaction does not lead to depolymerization of lignins [20,47]. Normally, Ph dimers are more reactive than corresponding Non-Ph ones [20,40,41,47,49,53]. Compared with hardwood lignins, softwood lignins contain a greater proportion of condensed type linkages.…”

Computational Study of Bond Dissociation Enthalpies for Substituted β‐O‐4 Lignin Model Compounds

“…[5,6] On the other hand, research is conducted to understand the thermal decomposition of this biopolymer to extract methanol, phenols, and substituted phenolic compounds. [3,4,[7][8][9][10][11][12][13][14][15][16][17][18][19][20] Lignin also shows promise as an alternative in the manufacture of carbon fibers. [21,22] Lignin pyrolysis comprises a profusion of varied processes that are difficult to probe in the laboratory and is often studied through model compounds.…”

Formation of phenols from the low-temperature fast pyrolysis of Radiata pine (Pinus radiata)

“…In contrast to the wood polysaccharides, the basic units of lignin exhibit a variety of inter-unit linkage types. However, aryl-ether bonds predominate, accounting for more than half of the inter-unit linkages [40,[42][43][44], and also have the lowest thermal stability such that they may be cleaved even at temperatures less than 310 8C [45][46][47]. In the absence of molecular oxygen and with low rates of heat transfer, carbonisation, or condensation, is the main process occurring when lignin is pyrolysed at low-temperatures [48].…”