Elucidating the reactivity of methoxyphenol positional isomers towards hydrogen-transfer reactions by ATR-IR spectroscopy of the liquid–solid interface of RANEY® Ni

Castro, Ilton Barros Daltro de; Graça, Inês; Rodríguez-García, Laura; Kennema, Marco; Rinaldi, Roberto; Meemken, Fabian

doi:10.1039/c8cy00491a

Cited by 33 publications

(31 citation statements)

References 49 publications

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“…ATR-IR has been employed to understand the mechanism of methoxyphenol HDO/hydrogenolysis over RANEY Ni, for which C–O cleavage is favored under CTH conditions, but ring saturation occurs under H 2 . ATR-IR measurements suggest 2-methoxyphenol lies flat with the aromatic ring parallel to the surface, favoring demethoxylation (DMO) of 2-methoxyphenol to cyclohexanol under CTH conditions, whereas both the ring and methoxy group are tilted in the presence of H 2 . Additional studies with 3-methoxyphenol and 4-methoxyphenol isomers revealed these were tilted regardless of whether CTH conditions or H 2 gas were employed, with ring hydrogenation favored in all cases to yield 3-methylcyclohexanol and 4-methylcyclohexanol respectively as major products.…”

Section: Catalytic Transfer Hydrogenolysismentioning

confidence: 98%

Hydrogenolysis of Lignin-Derived Aromatic Ethers over Heterogeneous Catalysts

Shivhare

Jampaiah

Bhargava

et al. 2021

ACS Sustainable Chem. Eng.

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Global temperature has risen >1 °C since the preindustrial era, resulting in well-documented adverse climate impacts including extreme weather (floods, droughts, storms, and heat waves), a rise in sea level accompanying melting polar and glacial ice, and disrupted crop growth. These changes are closely correlated with anthropogenic greenhouse gas emissions, predominantly arising from the combustion of nonrenewable fossil fuels. Lignin derived from lignocellulose is the second most abundant biopolymer on Earth, and a rich source of renewable aromatic hydrocarbons to replace those currently obtained from fossil resources. Lignin depolymerization by cleavage of C–O and C–C linkages in the biopolymer can be achieved by direct pyrolysis or catalytic transformations, involving oxidation, hydrolysis, or hydrogenolysis reactions. Hydrogenolysis, in which H2 gas (or in-situ generated reactive H species) is supplied to lignin under relatively mild conditions, has attracted significant attention. This Perspective summarizes recent progress in the development of heterogeneous catalysts for the cleavage of C–O linkages in lignin-derived aromatic ethers by hydrogenolysis: it encompasses strategies using H2, hydrogen transfer, and photocatalysis for aromatic monomers production, and the determination of structure–activity relationships and underlying reaction mechanisms.

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Section: Catalytic Transfer Hydrogenolysismentioning

confidence: 98%

Hydrogenolysis of Lignin-Derived Aromatic Ethers over Heterogeneous Catalysts

Shivhare

Jampaiah

Bhargava

et al. 2021

ACS Sustainable Chem. Eng.

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“…The ATR-IR spectra revealed that the adsorbed guaiacol assumes a parallel orientation to the catalyst surface, which allows a strong interaction between the methoxy CeO bond and the surface of catalyst. Conversely, the adsorption of 3-or 4methoxyphenol leads to a tilted surface complex in which the methoxy CeO bond establishes no interaction with the catalyst [9].…”

Section: Catalytic Transfer Hydrogenation/ Hydrogenolysismentioning

confidence: 99%

Cost-effective routes for catalytic biomass upgrading

Jin

Pastor‐Pérez

et al. 2020

Current Opinion in Green and Sustainable Chemistry

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Catalytic hydrodeoxygenation (HDO) is a fundamental and promising route for bio-oil upgrading to produce petroleum-like hydrocarbon fuels or chemical building blocks. One of the main challenges of this technology is the demand of high-pressure H 2 , which poses high costs and safety concerns. Accordingly, developing cost-effective routes for biomass or bio-oil upgrading without the supply of commercial H 2 is essential to implement the HDO at commercial scale. This article critically reviewed the very recent studies relating to the novel strategies for upgrading the biofeedstocks with 'green' H 2 generated from renewable sources. More precisely, catalytic transfer hydrogenation/hydrogenolysis, combined reforming and HDO, combined metal hydrolysis and HDO, water-assisted in-situ HDO and nonthermal plasma technology and self-supported hydrogenolysis are reviewed herein. Current challenges and research trends of each strategy are also proposed aiming to motivate further improvement of these novel routes to become competitive alternatives to conventional HDO technology.

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“…Catalytic transfer hydrodemethoxylation‐hydrogenation of guaiacol over Raney® Ni yielded 95 % cyclohexanol using isopropanol as a hydrogen source (Table 1, entry 1) [67] . Use of methanol as a hydrogen source is also reported for this conversion and it gave 54 % yield of cyclohexanol using Ni/CMK catalyst (Table 1, entry 2) [68] .…”

Section: Catalytic Conversion Of Lignin‐based Compounds Into Cyclohexmentioning

confidence: 91%

Recent Catalytic Approaches for the Production of Cycloalkane Intermediates from Lignin‐Based Aromatic Compounds: A Review

Gundekari

Karmee

2021

ChemistrySelect

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Lignin is one of the primary components of lignocellulosic biomass. It is an alternative and sustainable source for aromatic and cyclic hydrocarbons. Lignin is obtained in large quantities as a co‐product in sugar, paper‐pulp, and bioethanol industries. Hydrodeoxygenation/‐hydrogenation of lignin‐based phenolic compounds is an important route to synthesize new generation products. This review focuses on recent catalytic methods for selective conversion of phenolics into cyclohexa(nol/none/ne); which are precursors for emerging polymers and fuels. Furthermore, effect of metal catalysts, supports, and parameters on different reactions were discussed along with possible industrial applications of obtained cycloalkanes. In addition, limitations, advantages, and future scope of hydrodeoxygenation/‐hydrogenation of monolignols are also described.

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Elucidating the reactivity of methoxyphenol positional isomers towards hydrogen-transfer reactions by ATR-IR spectroscopy of the liquid–solid interface of RANEY® Ni

Abstract: In the presence of Raney® Ni and 2-propanol, guaiacol is orientated parallel to the catalyst surface, whereas 3- and 4-methoxyphenol forms a titled adsorption surface complex.

Cited by 33 publications

References 49 publications

Hydrogenolysis of Lignin-Derived Aromatic Ethers over Heterogeneous Catalysts

Hydrogenolysis of Lignin-Derived Aromatic Ethers over Heterogeneous Catalysts

Cost-effective routes for catalytic biomass upgrading

Recent Catalytic Approaches for the Production of Cycloalkane Intermediates from Lignin‐Based Aromatic Compounds: A Review

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