X-ray absorption measurement and density functional theory analysis of gallium in gallium-containing beta zeolites

Wei, A.C.; Liu, Pang-Hung; Chao, Kuei‐Hsiang; Yang, E.; Cheng, Hsiu‐Yao

doi:10.1016/s1387-1811(01)00323-7

Cited by 23 publications

(21 citation statements)

References 21 publications

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“…We attribute the shift in edge energy to the reduction of dimethylgallium to monovalent Ga + species. The other Ga species can only be slightly reduced as is evident from the decrease of the absorption maximum to 10,379 eV similar to earlier work on Ga-beta [22].…”

Section: Resultssupporting

confidence: 88%

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In situ Ga K edge XANES study of the activation of Ga/ZSM-5 prepared by chemical vapor deposition of trimethylgallium

et al. 2005

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The activation of a dimethylgallium/ZSM-5 precursor to well-defined reduced and oxidized species is studied by in situ Ga K edge XANES. The precursor is prepared by chemical implanting of trimethylgallium on acidic HZSM-5. Subsequent reduction leads to charge-compensating Ga + species. Direct oxidation of the trimethylgallium precursor leads to various forms of gallium oxide and regeneration of Brønsted acid protons. Oxidation of the reduced Ga + species yields predominantly to GaO + species. The GaO + species exhibit a much higher H 2 /D 2 exchange activity than reduced Ga + species.

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Section: Resultssupporting

confidence: 88%

“…Both k 2 -and k 3 -weighted Fourier transformation without phase correction were performed. As input to FEFF8, a known atom cluster from the reference b-Ga 2 O 3 compound and interatomic distances from the published crystal structure were used [22].…”

Section: Characterizationmentioning

confidence: 99%

In situ Ga K edge XANES study of the activation of Ga/ZSM-5 prepared by chemical vapor deposition of trimethylgallium

et al. 2005

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“…Furthermore, the in-situ EXAFS measurement has indicated that part of the framework Ga 3+ species generated by hydrothermal synthesis are stable during both 500°C air and 550°C H 2 treatments. The existence of framework Ga has been also confirmed by NMR and IR analyses, and predicted by DFT calculation that the tetrahedral Ga 3+ may be located on T 7 , T 8 or T 9 framework sites of BEA zeolites [15] (figure 1).…”

Section: Framework Galliummentioning

confidence: 66%

“…Framework Ga 3+ is usually confirmed as tetrahedral coordinated species, GaO 4 , by 71 Ga NMR and Ga K-edge EXAFS. The corresponding IR spectra are expected to exhibit Ga(OH)Si of 3619 cm )1 instead of Al(OH)Si of 3607 cm )1 [8,15]. The Brønsted acidity of gallosilicate zeolites has been known to be less acidic than that of aluminosilicate analogues [16].…”

Section: Framework Galliummentioning

confidence: 99%

“…So it concludes that nonframework gallium species does play a role in the aromatization of alkanes. The EXAFS and XANES results showed that unstable Ga 3+ O 4 species generated by calcining the sample of incipient wetness impregnation of Ga(NO 3 ) 3 on H-form zeolite was reduced to Ga 1+ during the H 2 treatment [15]. The interaction of Ga + with surface silanol group of zeolite produced a terminal Ga•O•Si group (figure 1).…”

Section: Non-framework Galliummentioning

confidence: 99%

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Gallium-containing zeolites: characterization of catalytic role of gallium species in converting light paraffins to aromatics

Chao

Liu

2005

Catal Surv Asia

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The structures and the chemical nature of gallium species in gallium-containing zeolite catalysts prepared by hydrothermal synthesis and post-synthesis treatments are discussed based on the results of X-ray absorption spectroscopy (XAS), including X-ray absorption near edge structure (XANES) and Extended X-ray absorption fine structure (EXAFS), and nuclear magnetic resonance (NMR) investigations. The in-situ analysis of properties of gallium active sites during oxidation/reduction cycles has been found to be further helpful on the understanding of the catalytic role of gallium species in the aromatization of alkanes.

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Detailed understanding on thermodynamic and kinetic features of phenanthrene hydroprocessing on Ni‐Mo/HY catalyst

et al. 2022

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Phenanthrene hydrogenation is a key reaction for improving the quality of gasoline and diesel. Herein, we conduct detailed thermodynamic and kinetic analyses for phenanthrene hydrogenation on a Ni-Mo/HY catalyst. We establish a comprehensive reaction network for phenanthrene hydrogenation, and calculate equilibrium constant, rate constant, adsorption constant, activation energy barrier, and reaction energy for each step in the reaction network. All of the steps in the reaction network are revealed to be exothermic. A kinetic model with 28 parameters is constructed for phenanthrene hydrogenation.The deviation of the product yields calculated by the kinetic model from those obtained in experiments is less than 4.5%, indicating the reasonability and accuracy of the kinetic model. The most favorable pathway for phenanthrene hydrogenation is demonstrated to be phenanthrene ! tetrahydrophenanthrene ! sym-octahydrophenanthrene ! 5,6-butyl-tetrahydronaphthalene ! tetralin. These results are helpful for efficiently tuning catalyst properties and optimizing reaction conditions for enhancing phenanthrene hydrogenation.

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X-ray absorption measurement and density functional theory analysis of gallium in gallium-containing beta zeolites

Cited by 23 publications

References 21 publications

In situ Ga K edge XANES study of the activation of Ga/ZSM-5 prepared by chemical vapor deposition of trimethylgallium

In situ Ga K edge XANES study of the activation of Ga/ZSM-5 prepared by chemical vapor deposition of trimethylgallium

Gallium-containing zeolites: characterization of catalytic role of gallium species in converting light paraffins to aromatics

Detailed understanding on thermodynamic and kinetic features of phenanthrene hydroprocessing on Ni‐Mo/HY catalyst

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