Direct Observation of Phenoxy as the Key and Common Intermediate for the Decomposition of Lignin Fragments Containing the β-O-4 Linkage

Hamou, Cherif Aghiles Ould; Giorgi, Javier B.

doi:10.1021/acs.jpcc.8b07767

Cited by 5 publications

(2 citation statements)

References 49 publications

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“…This new aromatic species contributes to the broadening of the C-C peaks. A series of peaks at 1431 to 1458 cm –1 have been assigned to C–H vibrations and could also have a small C–C component. ,, There is a positive intensity feature at ∼1615 cm –1 that can be attributed to background removal (see Figure S9). The C–H bends of the ring in the range of 1151–1175 cm –1 also drastically broaden.…”

Section: Resultsmentioning

confidence: 99%

Interaction of Anisole on Alumina-Supported Ni and Mo Oxide Hydrodeoxygenation Catalysts

Hu,

Gericke,

Tong

et al. 2023

J. Phys. Chem. C

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The conversion of biomass to transportation fuels and value-added chemicals is a promising method to reduce the reliance on fossil fuels. Mo-based catalysts have been shown to be highly active in the hydrodeoxygenation of biomassderived phenolic compounds. The catalyst active phase, surface species, and the effect of adding additional metals are not comprehensively understood. Here we compare the temperature-dependent adsorption behavior of the model compound anisole on an alumina-supported mixed nickel molybdenum oxide catalyst with two reference catalysts, molybdenum oxide and nickel oxide. Raman spectroscopy showed that the catalysts contain significant amounts of molybdates and molybdoaluminates, in addition to NiMoO 4 in the nickel molybdenum catalyst and MoO 3 in the molybdenum-only catalyst. Using transmission infrared spectroscopy under a controlled environment, we find that anisole chemisorbed largely through the oxygen in the methoxy group to form surface-bound phenoxy and methoxy species on all of the catalysts. Ambient pressure X-ray photoelectron spectroscopy measurements of the catalysts in anisole vapor showed reduced Mo atoms are the binding sites. The surface interaction and removal temperature of these species varied with the metal composition. The MoO x component dominated the adsorption behavior in both MoO x and NiMoO x catalysts. The formation of new aromatics, including methylated rings, depended on the Ni composition. Upon the addition of hydrogen to induce the hydrodeoxygenation of anisole, undesirable polynuclear aromatic species were quickly formed on the Mo-based catalysts. These results suggest that the molybdenum oxide controls the adsorption and reactivity of the surface species with a cooperative effect by Ni.

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Section: Resultsmentioning

confidence: 99%

Interaction of Anisole on Alumina-Supported Ni and Mo Oxide Hydrodeoxygenation Catalysts

Hu,

Gericke,

Tong

et al. 2023

J. Phys. Chem. C

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“…In addition to its prominence in combustion chemistry, 1 is also known to play an important role in biological and environmental processes. As an example, it is an intermediate in the biocatalysis of galactose oxidase and microperoxidase, as well as being relevant in electron-transfer reactions in carotenoids. , Furthermore, 1 moieties are found in lignin and are thus likely released during depolymerization …”

Section: Introductionmentioning

confidence: 99%

Threshold Photoelectron Spectrum of the Phenoxy Radical

2022

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The high-resolution photoion mass-selected threshold photoelectron spectrum (ms-TPES) of the phenoxy radical (C6H5O•), produced by pyrolysis of anisole, was investigated at the VUV beamline of the Swiss Light Source. Adiabatic ionization energies have been determined to be 8.56, 9.42, 9.76, and 9.94 eV to the X̃+ 1A1, ã+ 3A2, Ã+ 1A2, and b̃+ 3B2 cation states, respectively, supported by DFT, WFT, and composite-method calculations. A ring deformation mode was found to be active upon ionization by Franck–Condon analysis and responsible for the vibrational structure of the TPES in all four ion states. While the X̃+ 1A1 and ã+ 3A2 states’ assignment agrees with the literature, we revise the energetic order of the Ã+ 1A2 and b̃+ 3B2 cation states in the ms-TPES, based on a pronounced lifetime broadening of the excited triplet state. This is rationalized by strong coupling between the triplet states as confirmed by EOM-EE-CCSD calculations indicating a conical intersection with a low-lying seam to the ã+ 3A2 state. Our study provides a well-resolved spectrum, to be used for the isomer-selective assignment of reactive species in combustion and catalysis and also serves as benchmark to evaluate theoretical methods to address closed- and open-shell singlet and triplet cation intermediates.

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Synergies of surface-interface multiple active sites over Al-Zr oxide solid solution supported nickel catalysts for enhancing the hydrodeoxygenation of anisole

Zhang¹,

Fan²,

Lin³

et al. 2022

Applied Catalysis A: General

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Direct Observation of Phenoxy as the Key and Common Intermediate for the Decomposition of Lignin Fragments Containing the β-O-4 Linkage

Cited by 5 publications

References 49 publications

Interaction of Anisole on Alumina-Supported Ni and Mo Oxide Hydrodeoxygenation Catalysts

Interaction of Anisole on Alumina-Supported Ni and Mo Oxide Hydrodeoxygenation Catalysts

Threshold Photoelectron Spectrum of the Phenoxy Radical

Synergies of surface-interface multiple active sites over Al-Zr oxide solid solution supported nickel catalysts for enhancing the hydrodeoxygenation of anisole

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