Kinetic studies on the liquid‐phase catalytic oxidation of 4‐methyl guaiacol to vanillin

Ma, Qiyi; Liu, Kejing; Mao, Jiale; Chen, Kexian; Cheng, Liang; Yao, Jia; Chen, Zhirong; Li, Haoran

doi:10.1002/cjce.22798

Cited by 12 publications

(3 citation statements)

References 43 publications

(92 reference statements)

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“…UV‐vis spectroscopy is a powerful tool to calculate the reaction rates . Coupled with HPLC and mass spectrometry, it monitors several wavelengths concurrently . UV‐vis spectroscopy assesses mixing in reactors and differentiates pure from blended beverages as a quality control …”

Section: Applicationsmentioning

confidence: 99%

Experimental methods in chemical engineering: Ultraviolet visible spectroscopy—UV‐Vis

et al. 2018

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UV-vis spectroscopy is an inexpensive, simple, flexible, non-destructive, analytical method appropriate for a wide class of organic compounds and some inorganic species. UV-vis spectrophotometers measure the absorbance or transmittance of light passing through a medium as a function of the wavelength. Chemical engineers apply it for quantitative analysis, to derive liquid phase reaction kinetics, and to identify the mechanism at the molecular scale. High performance liquid chromatography and ultra-high performance liquid chromatography integrate UV-vis detectors to identify and quantify the concentration of compounds in liquid streams. Combining these techniques with mass spectrometry facilitates identifying all species. UV-vis diffuse reflectance spectroscopy is a variant with enhanced scattering properties that measures the properties of solids and powders. A bibliometric analysis of the 10 000 most cited papers referring to UV-vis (2016 and 2017) groups research in four major clusters: nanoparticles and nanostucutres; photocatalysis and water treatment; crystals, complexes, and derivatives; and Ag and Au nanoparticles biological interaction.

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Section: Applicationsmentioning

confidence: 99%

Experimental methods in chemical engineering: Ultraviolet visible spectroscopy—UV‐Vis

et al. 2018

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“…Based on the above analysis, the condensation of lignin generated during the extraction and the extensive oxidative degradation of the lignin substrate and the aromatic aldehyde product during the AWOP seriously hinders the possibility of achieving high yield of aromatic aldehyde from AWOP. 4-methylguaiacol, one of the products of hydrogenolysis of lignin, can be oxidized to vanillin (Zhao 2010;Ma et al 2017). This process can reach a conversion of 100% and selectivity of 90% by Co-salt/NaOH catalytic system (Liu et al 2017) at 80 °C.…”

Section: Introductionmentioning

confidence: 99%

Rules and mechanism for the oxidation of lignin-based aromatic aldehyde under alkaline wet oxygen

Deng

Zhang

et al. 2020

BioRes

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To explore the extensive oxidative mechanism of syringaldehyde, vanillin, and p-hydroxybenzaldehyde during the alkaline wet oxidation process (AWOP), the yield of these aromatic aldehydes from AWOP at various temperatures and reaction times was studied. The results showed that the aromatic aldehydes could not be converted into the corresponding aromatic acids during the AWOP, and that the aromatic aldehyde was stable when subjected to the oxygen-free AWOP. However, as the reaction temperature increased or the number of methoxyl groups on the aromatic ring increased, the yield of aromatic aldehyde sharply decreased during the AWOP. The reason for the decreased yield was that the aromatic aldehyde underwent ring-opening reactions. The possible mechanism of the degradation indicated that the number of methoxyl groups on the phenolic ring determined the stability of the key intermediate of this reaction. The conversion of isoeugenol to vanillin during the AWOP at 60 ºC was > 99%, and the vanillin yield and selectivity were both 69.8%, indicating that the decrease in yield of the product from this degradation of lignin substrate and the product can be reduced or avoided in the AWOP at suitable temperature.

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“…On the basis of our previous work on p -cresol oxidation, ,,, we report in this paper a comprehensive analysis of cobalt/NaOH-catalyzed oxidation of 2-methoxy-4-methylphenol ( 1 ), primarily focused on identification of the true catalyst. Several methods were used to indicate that nanoparticle heterogeneous catalysis plays a critical role in 2-methoxy-4-methylphenol ( 1 ) oxidation, which includes filtration tests, centrifugation tests, dynamic light scattering (DLS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and powder X-ray diffraction (XRD).…”

Section: Introductionmentioning

confidence: 99%

Aerobic Oxidation of 2-Methoxy-4-methylphenol to Vanillin Catalyzed by Cobalt/NaOH: Identification of CoO_x(OH)_yNanoparticles as the True Catalyst

Cheng

Yuan

et al. 2018

ACS Catal.

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An investigation of aerobic oxidation of 2-methoxy-4-methylphenol to vanillin catalyzed by a number of cobalt salts, complexes, oxides, and hydroxides in alkaline solutions is reported. A good yield of vanillin (90%) was obtained when CoCl2 was used as the catalyst, while a poor yield (6%) was obtained with Co3O4. Unexpectedly, however, the Co3O4 catalytic activity was restored after heating in an alcoholic solution of NaOH for 24 h, producing a good yield of vanillin (85%). The recovered catalytic activity of Co3O4 indicated a conversion of inactivated heterogeneous particles to activated particles. In addition, precipitates were generated when “homogeneous” CoCl2 was employed as a catalyst, making us wonder about the true nature of the catalyst in this reaction. A series of experiments are described, including kinetic studies, filtration tests, centrifugation tests, dynamic light scattering, transmission electron microscopy, X-ray photoelectron spectroscopy, and powder X-ray diffraction, for the investigation of the true catalyst under catalytic conditions. The key observations led to the conclusion that the cobalt salts and complexes act as precatalysts that transform to cobalt oxide/hydroxide [CoO x (OH) y ] nanoparticles, which is responsible for the benzylic C(sp3)–H oxyfunctionalization of 2-methoxy-4-methylphenol. Additionally, the size of the particles is decisive for catalyst performance. The nature of the active nanoparticles was also studied. With regard to the identification of homogeneous or heterogeneous catalysis, this study provides a complement to existing catalytic reaction types.

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Kinetic studies on the liquid‐phase catalytic oxidation of 4‐methyl guaiacol to vanillin

Cited by 12 publications

References 43 publications

Experimental methods in chemical engineering: Ultraviolet visible spectroscopy—UV‐Vis

Experimental methods in chemical engineering: Ultraviolet visible spectroscopy—UV‐Vis

Rules and mechanism for the oxidation of lignin-based aromatic aldehyde under alkaline wet oxygen

Aerobic Oxidation of 2-Methoxy-4-methylphenol to Vanillin Catalyzed by Cobalt/NaOH: Identification of CoO_x(OH)_yNanoparticles as the True Catalyst

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Kinetic studies on the liquid‐phase catalytic oxidation of 4‐methyl guaiacol to vanillin

Cited by 12 publications

References 43 publications

Experimental methods in chemical engineering: Ultraviolet visible spectroscopy—UV‐Vis

Experimental methods in chemical engineering: Ultraviolet visible spectroscopy—UV‐Vis

Rules and mechanism for the oxidation of lignin-based aromatic aldehyde under alkaline wet oxygen

Aerobic Oxidation of 2-Methoxy-4-methylphenol to Vanillin Catalyzed by Cobalt/NaOH: Identification of CoOx(OH)yNanoparticles as the True Catalyst

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Aerobic Oxidation of 2-Methoxy-4-methylphenol to Vanillin Catalyzed by Cobalt/NaOH: Identification of CoO_x(OH)_yNanoparticles as the True Catalyst