Adsorption and Decomposition of a Lignin β-O-4 Linkage Model, 2-Phenoxyethanol, on Pt(111): Combination of Experiments and First-Principles Calculations

Hamou, Cherif Aghiles Ould; Réocreux, Romain; Sautet, Philippe; Michel, Carine; Giorgi, Javier B.

doi:10.1021/acs.jpcc.7b01099

Cited by 17 publications

(22 citation statements)

References 63 publications

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“…As shown in Figure 5, the dehydrogenation of the OMe group indeed yields ArOCH 2 (Ar stands for aromatic ring) that decomposes into ArO+CH x +(1x)H (with x=0,1). The recombination of ArO and CH x then yields ArOCH x that can further get deformylated (x=1) or decarbonylated (x=0), illustrating the reducing character of carbonaceous species towards aromatic oxygenates [30,31,33] Conversely, the phenolic C-O bond is relatively recalcitrant under UHV conditions. The weakly activated dehydrogenation of ArOH to ArO even makes the situation worse since adsorbed phenoxy species (resp.…”

Section: Aromatic Oxygenates and Lignin Valorisationmentioning

confidence: 99%

“…The comparison between UHV experiments and DFT mechanistic investigations has demonstrated that carbonaceous species are reasonable reducing agents to deoxygenate aromatics without hydrogenating the aromatic cycle. [31,33] In the context of the oxygenation of ligninderived aromatics, hydrogen would therefore appear as unnecessary. However, a lack of hydrogen has also proved to favor the dehydrogenation of the aromatic ring, leading to its total decomposition.…”

Section: Aromatic Oxygenates and Lignin Valorisationmentioning

confidence: 99%

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Rational design of heterogeneous catalysts for biomass conversion – Inputs from computational chemistry

Réocreux

Michel

2018

Current Opinion in Green and Sustainable Chemistry

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The ever-growing development of biomass-based chemicals calls for a better understanding of the specificities of the corresponding catalytic processes. In this quest, ab initio modeling is a cornerstone that has proven its ability to rationalize the observed trends and then to propose novel catalysts design. Focusing on supported metal catalysts, we show that computational studies started a decade ago with alcohols and small polyols transformation, focusing on activity but also selectivity. Little by little, their scope has been extended to a variety of cellulosic-based chemicals such as levulinic acid or furanic molecules. During the last two years, it has also started to embrace lignin-derived chemicals, such as anisole, guaiacol, etc. Parallel to this scope expansion, the available methodologies have also progressed, triggered by the intrinsic difficulties of modeling biomass valorisation. In particular, improving the inclusion of the water solvent has drawn several groups to propose novel approaches.

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Section: Aromatic Oxygenates and Lignin Valorisationmentioning

confidence: 99%

Section: Aromatic Oxygenates and Lignin Valorisationmentioning

confidence: 99%

Rational design of heterogeneous catalysts for biomass conversion – Inputs from computational chemistry

Réocreux

Michel

2018

Current Opinion in Green and Sustainable Chemistry

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“…Compared to many experimental studies on lignin depolymerization, modeling has been less common and focused on adsorption, , the β-O-4 linkage cleavage mechanism, − and hydrodeoxygenation of phenolic compounds. − Mechanism studies on C–C bond cleavage over metal catalysts are much less conducted. Due to the large fraction of C–C units in lignin, theoretical investigations are urgently needed to understand the mechanism and provide guidance for catalyst development.…”

Section: Introductionmentioning

confidence: 99%

5–5 Lignin Linkage Cleavage over Ru: A Density Functional Theory Study

Vlachos

2021

ACS Sustainable Chem. Eng.

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Lignin is the most abundant natural, aromatic-containing biopolymer. Among all the C–C and C–O bonds being cleaved in catalytic fractionation, the 5–5 linkage is the strongest, and its scission requires harsh conditions. Theoretical investigations of the mechanism and kinetics could provide insights into developing better catalysts but are essentially lacking. We perform extensive density functional theory calculations on 2-methoxy-1,1′-biphenyl, a model compound, with various substitutions at all ring locations on Ru(0001). We analyze the competition between the 5–5 bond cleavage and the defunctionalization of the side functional groups at multiple degrees of depolymerization. The role of ring functional groups in the adsorption of lignin oligomers and the 5–5 bond scission and, conversely, the effect of the aromatic group on the −OCH3 decomposition are also discussed. We show that increasing the number of methoxy groups decreases the C–C barrier, and thus, we expect the following depolymerization ranking: grass > softwood > hardwood. While Ru exposes modest 5–5 bond scission reaction barriers from some intermediates, rapid side group chemistry prevents the formation of these intermediates; instead, scission happens most probably from defunctionalized compounds whose C–C scission barriers are high. Our results also expose the existence of multiple Brønsted–Evans–Polanyi relations in the catalytic transformation of biphenyl-based molecules that open up the possibility of modeling depolymerization of large lignin chains.

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“…[8][9][10]) and on model metal catalysts (see, for example, Refs. [11][12][13]). They provide a valuable context and reference frame for our study.…”

Section: Introductionmentioning

confidence: 99%

Lignin Intermediates on Palladium: Insights into Keto‐Enol Tautomerization from Theoretical Modelling

et al. 2020

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It has been suggested in the literature that keto‐to‐enol tautomerization plays a vital role for lignin fragmentation under mild conditions. On the other hand, previous modelling has shown that the adsorbed keto form is more stable than enol on the Pd(111) catalyst. The current density functional theory study of lignin model molecules shows that, in the gas‐phase, keto is more stable than enol, but on the Pd surface, we find enol conformers that are at least as stable as keto. This supports the experimental result that the favourable reaction pathway for lignin depolymerization involves keto‐enol tautomerization. An energy decomposition analysis gives insights concerning the origin of the fine energy balance between the keto and enol forms, where the molecule–surface interaction (−7 eV) and the molecular strain energy (+3 eV) are the main contributors to the adsorption energy.

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Adsorption and Decomposition of a Lignin β-O-4 Linkage Model, 2-Phenoxyethanol, on Pt(111): Combination of Experiments and First-Principles Calculations

Abstract: International audienc

Cited by 17 publications

References 63 publications

Rational design of heterogeneous catalysts for biomass conversion – Inputs from computational chemistry

Rational design of heterogeneous catalysts for biomass conversion – Inputs from computational chemistry

5–5 Lignin Linkage Cleavage over Ru: A Density Functional Theory Study

Lignin Intermediates on Palladium: Insights into Keto‐Enol Tautomerization from Theoretical Modelling

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