Density Functional Theory Study of the Concerted Pyrolysis Mechanism for Lignin Models

Elder, Thomas; Beste, Ariana

doi:10.1021/ef5013648

Cited by 86 publications

(76 citation statements)

References 39 publications

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“…The results agree well with the findings by Elder et al [40] Fig. 3 Initial pyrolysis mechanism of the lignin model dimer Pyrolysis mechanism of a b-O-4 type lignin dimer model compound who also verified that the activation energies for the concerted decomposition of some b-O-4 type lignin models were lower than the BDEs for the homolytic cleavages.…”

Section: Resultssupporting

confidence: 91%

“…Initial pyrolysis mechanism of the lignin model dimer According to previous studies, both homolytic cleavage and concerted decomposition may occur during the initial pyrolysis of lignin model compounds [39,40]. In order to elucidate the possible initial pyrolysis mechanism of this lignin model dimer, the BDEs for the C b -O and C a -C b homolysis and the activation energy for the C b -O concerted decomposition are calculated and illustrated in Fig.…”

Section: Resultsmentioning

confidence: 99%

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Pyrolysis mechanism of a β-O-4 type lignin dimer model compound

Zhang

Jiang

et al. 2015

J Therm Anal Calorim

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To help understand the pyrolysis mechanism of lignin, a non-phenolic lignin dimer model compound with b-O-4 linkage, namely 1-methoxy-2-(4-methoxyphenethoxy) benzene, was prepared. Its pyrolysis mechanism was investigated by density functional theory calculations and confirmed by the analytical pyrolysis-gas chromatography/mass spectrometry experiments. Possible pyrolytic pathways were proposed and analyzed based on three initial pyrolysis mechanisms of the model compound, including the C b -O homolytic mechanism, the C a -C b homolytic mechanism and the C b -O concerted decomposition mechanism. The results indicate that the lignin dimer model compound is thermally stable at low pyrolysis temperature (300°C), whereas at moderate pyrolysis temperature (500°C), four major pyrolytic products will be generated via the initial C b -O concerted decomposition and C b -O homolysis, including the 1-methoxy-4-vinylbenzene, 2-hydroxybenzaldehyde, 1-ethyl-4-methoxybenzene and 2-methoxyphenol. Products from the C a -C b homolysis can hardly be formed, due to the high-energy barriers and limitation of the available free hydrogen atoms. Secondary cracking of the primary pyrolytic products will take place to form some light compounds, which will be enhanced with the increase in pyrolysis temperature.

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Section: Resultssupporting

confidence: 91%

Section: Resultsmentioning

confidence: 99%

Pyrolysis mechanism of a β-O-4 type lignin dimer model compound

Zhang

Jiang

et al. 2015

J Therm Anal Calorim

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“…This system is representative of the simplest model compound without any aromatic ring substituents or side chains. In recent theoretical studies Elder and Beste [76] calculated E a values for retro-ene and Maccoll elimination type concerted mechanisms (Fig. 4), with values of 62-68 kcal mol l − 1 and 56-58 kcal mol − 1 , respectively.…”

Section: Ether Cleavage Mechanismsmentioning

confidence: 97%

“…Several concerted (heterolytic) mechanisms have been proposed for β-ether bond cleavage [42,[72][73][74][75][76]. Klein and Virk [42] proposed a six membered retro-ene mechanism based on an analysis of the kinetics for the formation of styrene and phenol from phenethyl phenyl ether.…”

Section: Ether Cleavage Mechanismsmentioning

confidence: 99%

Lignin pyrolysis reactions

2017

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“…According to previous studies, both the homolytic cleavage and the concerted decomposition may take place during the preliminary pyrolysis process of lignin (Elder and Beste 2014;Huang et al 2014;Chen et al 2015). For all β-1-type lignin dimers, the homolytic cleavage should occur on the Cα-Cβ bond because it has the lowest bond dissociation energy (BDE) value (Parthasarathi et al 2011).…”

Section: Density Functional Theory Calculations Initial Pyrolysis Mecmentioning

confidence: 99%

Experimental and Theoretical Studies on the Pyrolysis Mechanism of β-1-Type Lignin Dimer Model Compound

Jiang

Lü

et al. 2016

BioResources

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A β-1-type lignin dimer, 1,2-bis(3,5-dimethoxyphenyl)propane-1,3-diol was employed as a model compound in this study. The pyrolysis mechanisms and formation pathways of the pyrolytic products were investigated by using density functional theory (DFT) calculations and analytical pyrolysisgas chromatography/mass spectrometry (Py-GC/MS). Four possible initial pyrolysis mechanisms were proposed, including the Cα-Cβ homolysis mechanism and three concerted decomposition mechanisms (1, 2, and 3). Results indicated that the lignin dimer decomposed via two concerted decomposition mechanisms, forming 3,5-dimethoxybenzaldehyde, 1,3-dimethoxy-5-vinylbenzene, 3-hydroxy-5-methoxybenzaldehyde, and 3-methoxybenzaldehyde. 3,5-Dimethoxybenzaldehyde was the major product, accounting for greater than 50% of all pyrolytic products. In addition to the two concerted decomposition mechanisms, Cα-Cβ homolysis was a secondary pyrolysis mechanism during the lignin dimer pyrolysis process, and the pyrolytic products included 3,5-dimethoxybenzyl alcohol, 3,5-dimethoxyphenethyl alcohol, 1,3-dimethoxybenzene, and 1,3-dimethoxy-5-methylbenzene. A third concerted decomposition mechanism was judged to be the least likely pathway to occur because of the high activation energy requirement.

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Density Functional Theory Study of the Concerted Pyrolysis Mechanism for Lignin Models

Cited by 86 publications

References 39 publications

Pyrolysis mechanism of a β-O-4 type lignin dimer model compound

Pyrolysis mechanism of a β-O-4 type lignin dimer model compound

Lignin pyrolysis reactions

Experimental and Theoretical Studies on the Pyrolysis Mechanism of β-1-Type Lignin Dimer Model Compound

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