A Study of the Mechanisms of Guaiacol Pyrolysis Based on Free Radicals Detection Technology

Li, Guoxiang; Luo, Zhongyang; Wang, Wenbo; Cen, Jianmeng

doi:10.3390/catal10030295

Cited by 21 publications

(13 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Without the presence of a catalyst, a GUA conversion rate of only 20% was obtained, yielding 60% of ( 5) with no formation of the HDO products ( 1)-( 3). At the current stage, we speculate that (5) was formed via a free radical mechanism rather than transalkylation in the absence of a catalyst, similar to that reported in the pyrolysis of guaiacol [62].…”

Section: Catalytic Hdo Of Guasupporting

confidence: 78%

Understanding the Surface Characteristics of Biochar and Its Catalytic Activity for the Hydrodeoxygenation of Guaiacol

Adilina¹,

Widjaya²,

Hidayati³

et al. 2021

Catalysts

View full text Add to dashboard Cite

Biochar (BCR) was obtained from the pyrolysis of a palm-oil-empty fruit bunch at 773 K for 2 h and used as a catalyst for the hydrodeoxygenation (HDO) of guaiacol (GUA) as a bio-oil model compound. Brunauer–Emmet–Teller surface area analysis, NH3 and CO2-temperature-programmed desorption, scanning electron microscope–dispersive X-ray spectroscopy, CHN analysis and X-ray fluorescence spectroscopy suggested that macroporous and mesoporous structures were formed in BCR with a co-presence of hydrophilic and hydrophobic sites and acid–base behavior. A combination of infrared, Raman and inelastic neutron scattering (INS) was carried out to achieve a complete vibrational assignment of BCR. The CH–OH ratio in BCR is ~5, showing that the hydroxyl functional groups are a minority species. There was no evidence for any aromatic C–H stretch modes in the infrared, but they are clearly seen in the INS and are the majority species, with a ratio of sp3–CH:sp2–CH of 1:1.3. The hydrogen bound to sp2–C is largely present as isolated C–H bonds, rather than adjacent C–H bonds. The Raman spectrum shows the characteristic G band (ideal graphitic lattice) and three D bands (disordered graphitic lattice, amorphous carbon, and defective graphitic lattice) of sp2 carbons. Adsorbed water in BCR is present as disordered layers on the surface rather than trapped in voids in the material and could be removed easily by drying prior to catalysis. Catalytic testing demonstrated that BCR was able to catalyze the HDO of GUA, yielding phenol and cresols as the major products. Phenol was produced both from the direct demethoxylation of GUA, as well as through the demethylation pathway via the formation of catechol as the intermediate followed by deoxygenation.

show abstract

Section: Catalytic Hdo Of Guasupporting

confidence: 78%

Understanding the Surface Characteristics of Biochar and Its Catalytic Activity for the Hydrodeoxygenation of Guaiacol

Adilina¹,

Widjaya²,

Hidayati³

et al. 2021

Catalysts

View full text Add to dashboard Cite

show abstract

“…Studies on representative lignin building blocks, such as guaiacol, syringol and eugenol, can provide detailed insight into the (catalytic) pyrolysis mechanism. 8–12 Li et al used electron paramagnetic resonance (EPR) spectroscopy to show that guaiacol pyrolysis is a radical-driven process and catechol is a favored product due to the presence of mobile hydrogen atoms. 8 Verma and Kishore carried out density functional theory (DFT) calculations and showed that the lowest-energy unimolecular decomposition pathway of eugenol yields guaiacol.…”

Section: Introductionmentioning

confidence: 99%

“… 8–12 Li et al used electron paramagnetic resonance (EPR) spectroscopy to show that guaiacol pyrolysis is a radical-driven process and catechol is a favored product due to the presence of mobile hydrogen atoms. 8 Verma and Kishore carried out density functional theory (DFT) calculations and showed that the lowest-energy unimolecular decomposition pathway of eugenol yields guaiacol. 9 Detailed mechanistic studies exist for benzaldehyde, 13 phenol, 14 dimethoxybenzenes 15 and larger model systems, such as 4-phenoxyphenol and 2-methoxy-phenoxybenzene.…”

Section: Introductionmentioning

confidence: 99%

Isomer-dependent catalytic pyrolysis mechanism of the lignin model compounds catechol, resorcinol and hydroquinone

et al. 2021

View full text Add to dashboard Cite

show abstract

“…Since the structure of this natural polymer is extremely complex, model compounds are often used to study its conversion to high value-added chemicals [8,10]. Ferulic and vanillic acids, as well as pyrocatechol and guaiacol are common products of lignin processing [1,8,[11][12][13], and therefore are often used as model lignin compounds [4,8,11,[14][15][16][17]. These compounds are lignin structural units of various sizes and contain almost the entire list of functional groups present in the lignin macromolecule.…”

Section: Introductionmentioning

confidence: 99%

“…Pyrolysis is commonly used for lignin processing due to its ability to effectively separate this polymer's strong structure [8,11,33,34]. However, high-temperature conversion of these raw materials generates a large number of final pyrolysis products.…”

Section: Introductionmentioning

confidence: 99%

Catalytic Pyrolysis of Lignin Model Compounds (Pyrocatechol, Guaiacol, Vanillic and Ferulic Acids) over Nanoceria Catalyst for Biomass Conversion

et al. 2021

View full text Add to dashboard Cite

Understanding the mechanisms of thermal transformations of model lignin compounds (MLC) over nanoscale catalysts is important for improving the technologic processes occurring in the pyrolytic conversion of lignocellulose biomass into biofuels and value-added chemicals. Herein, we investigate catalytic pyrolysis of MLC (pyrocatechol (P), guaiacol (G), ferulic (FA), and vanillic acids (VA)) over nanoceria using FT-IR spectroscopy, temperature-programmed desorption mass spectrometry (TPD MS), and thermogravimetric analysis (DTG/DTA/TG). FT-IR spectroscopic studies indicate that the active groups of aromatic rings of P, G, VA, and FA as well as carboxylate groups of VA and FA are involved in the interaction with nanoceria surface. We explore the general transformation mechanisms of different surface complexes and identify their decomposition products. We demonstrate that decomposition of carboxylate acid complexes occurs by decarboxylation. When FA is used as a precursor, this reaction generates 4-vinylguaiacol. Complexes of VA and FA formed through both active groups of the aromatic ring and decompose on the CeO2 surface to generate hydroxybenzene. The formation of alkylated products accompanies catalytic pyrolysis of acids due to processes of transalkylation on the surface.

show abstract

A Study of the Mechanisms of Guaiacol Pyrolysis Based on Free Radicals Detection Technology

Cited by 21 publications

References 23 publications

Understanding the Surface Characteristics of Biochar and Its Catalytic Activity for the Hydrodeoxygenation of Guaiacol

Understanding the Surface Characteristics of Biochar and Its Catalytic Activity for the Hydrodeoxygenation of Guaiacol

Isomer-dependent catalytic pyrolysis mechanism of the lignin model compounds catechol, resorcinol and hydroquinone

Catalytic Pyrolysis of Lignin Model Compounds (Pyrocatechol, Guaiacol, Vanillic and Ferulic Acids) over Nanoceria Catalyst for Biomass Conversion

Contact Info

Product

Resources

About