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

Chao, Kuei‐Hsiang; Liu, Pang-Hung

doi:10.1007/s10563-005-3332-1

Cited by 17 publications

(13 citation statements)

References 25 publications

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“…Its very high thermal and chemical stability, along with the temperature dependent conducting behavior 1 makes it an important material in gas sensing applications. [19][20][21] Ga 2 O 3 has also been used in catalytic 22,23 and photocatalytic 24 applications. [7][8][9] With a wide band gap of 4.9 eV, Ga 2 O 3 exhibits conductive and photoluminescent [10][11][12] properties, rendering it a promising candidate for applications such as transparent conducting material [13][14][15][16] in next generation optoelectronic devices and deep-UV photodetectors.…”

Section: Introductionmentioning

confidence: 99%

Plasma enhanced atomic layer deposition of Ga₂O₃thin films

et al. 2014

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Amorphous Ga2O3 thin films have been grown on SiO2/Si substrates by atomic layer deposition (ALD) using tris (2,2,6,6-tetramethyl-3,5-heptanedionato) gallium(III) [Ga(TMHD)(3)] as a gallium source and O-2 plasma as reactant. A constant growth rate of 0.1 angstrom per cycle was obtained in a broad temperature range starting from 100 to 400 degrees C. X-ray photoelectron spectroscopy (XPS) analysis revealed stoichiometric Ga2O3 thin films with no detectable carbon contamination. A double beam - double monochromator spectrophotometer was used to measure the transmittance of Ga2O3 thin films deposited on a quartz substrate and analysis of the adsorption edge yielded a band gap energy of 4.95 eV. The refractive index of the Ga2O3 films was determined from spectroscopic ellipsometry measurements and found to be 1.84 at a wavelength of 632.8 nm. Atomic force microscopic (AFM) analysis showed surface roughness values of 0.15 and 0.51 nm for films deposited at 200 and 400 degrees C, respectively. Finally, all the films could be crystallized into a monoclinic beta-Ga2O3 crystal structure by a post deposition annealing in He as indicated by X-ray diffraction (XRD) measurements

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Section: Introductionmentioning

confidence: 99%

Plasma enhanced atomic layer deposition of Ga₂O₃thin films

et al. 2014

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“…The existence of cationic [GaO] + species in Ga-modified ZSM-5 can be identified by 71 Ga MAS NMR resonance signal at ~55 ppm [ 104 , 121 ]. The characteristic peaks of the reduction of extra-framework [GaO] + species in H 2 -TPR were observed in the range of 990 K to 1014 K [ 57 , 70 , 91 , 107 ].…”

Section: Reactive Species In Ga-modified Zsm-5mentioning

confidence: 99%

Recent Advances on Gallium-Modified ZSM-5 for Conversion of Light Hydrocarbons

et al. 2021

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Light olefins are key components of modern chemical industry and are feedstocks for the production of many commodity chemicals widely used in our daily life. It would be of great economic significance to convert light alkanes, produced during the refining of crude oil or extracted during the processing of natural gas selectively to value-added products, such as light alkenes, aromatic hydrocarbons, etc., through catalytic dehydrogenation. Among various catalysts developed, Ga-modified ZSM-5-based catalysts exhibit superior catalytic performance and stability in dehydrogenation of light alkanes. In this mini review, we summarize the progress on synthesis and application of Ga-modified ZSM-5 as catalysts in dehydrogenation of light alkanes to olefins, and the dehydroaromatization to aromatics in the past two decades, as well as the discussions on in-situ formation and evolution of reactive Ga species as catalytic centers and the reaction mechanisms.

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“…In a zeolite family, the substitution of aluminum atoms by gallium in a silicate matrix leads to the formation of gallium silicates of various structural types whose specific physicochemical properties are successfully used in a number of acid-catalyzed reactions (Fricke et al, 2000 ; Chao and Liu, 2005 ; Wu et al, 2010 ). It is therefore not surprising that a possibility to replace Al atoms by Ga atoms is also assumed in other classes of inorganic compounds.…”

Section: Introductionmentioning

confidence: 99%

Physico-Chemical Properties of MgGa Mixed Oxides and Reconstructed Layered Double Hydroxides and Their Performance in Aldol Condensation of Furfural and Acetone

et al. 2018

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MgGa layered double hydroxides (Mg/Ga = 2–4) were synthesized and used for the preparation of MgGa mixed oxides and reconstructed hydrotalcites. The properties of the prepared materials were examined by physico-chemical methods (XRD, TGA, NH3-TPD, CO2-TPD, SEM, and DRIFT) and tested in aldol condensation of furfural and acetone. The as-prepared phase-pure MgGa samples possessed hydrotalcite structure, and their calcination resulted in mixed oxides with MgO structure with a small admixture phase characterized by a reflection at 2θ ≈ 36.0°. The interaction of MgGa mixed oxides with pure water resulted in reconstruction of the HTC structure already after 15 s of the rehydration with maximum crystallinity achieved after 60 s. TGA-MS experiments proved a substantial decrease in carbonates in all rehydrated samples compared with their as-prepared counterparts. This allowed suggesting presence of interlayer hydroxyls in the samples. Acido-basic properties of MgGa mixed oxides determined by TPD technique did not correlate with Mg/Ga ratio which was explained by the specific distribution of Ga atoms on the external surface of the samples. CO2-TPD method was also used to evaluate the basic properties of the reconstructed MgGa samples. In these experiments, an intensive peak at T = 450°C on CO2-TPD curve was attributed to the decomposition of carbonates newly formed by CO2 interaction with interlayer carbonates rather than to CO2 desorption from basic sites. Accordingly, CO2-TPD method quantitatively characterized the interlayer hydroxyls only indirectly. Furfural conversion on reconstructed MgGa materials was much larger compared with MgGa mixed oxides confirming that Brønsted basic sites in MgGa catalysts, like MgAl catalysts, were active in the reaction. Mg/Ga ratio in mixed oxides influenced product selectivity which was explained by the difference in textural properties of the samples. In contrast, Mg/Ga ratio in reconstructed catalysts had practically no effect on the composition of reaction products suggesting that the basic sites in these catalysts acted similarly in aldol condensation of acetone with furfural. It was concluded that the properties of MgGa samples resembled in a great extent those of MgAl hydrotalcite-based materials and demonstrated their potential as catalysts for base-catalyzed reactions.

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

Cited by 17 publications

References 25 publications

Plasma enhanced atomic layer deposition of Ga₂O₃thin films

Plasma enhanced atomic layer deposition of Ga₂O₃thin films

Recent Advances on Gallium-Modified ZSM-5 for Conversion of Light Hydrocarbons

Physico-Chemical Properties of MgGa Mixed Oxides and Reconstructed Layered Double Hydroxides and Their Performance in Aldol Condensation of Furfural and Acetone

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

Cited by 17 publications

References 25 publications

Plasma enhanced atomic layer deposition of Ga2O3thin films

Plasma enhanced atomic layer deposition of Ga2O3thin films

Recent Advances on Gallium-Modified ZSM-5 for Conversion of Light Hydrocarbons

Physico-Chemical Properties of MgGa Mixed Oxides and Reconstructed Layered Double Hydroxides and Their Performance in Aldol Condensation of Furfural and Acetone

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Plasma enhanced atomic layer deposition of Ga₂O₃thin films

Plasma enhanced atomic layer deposition of Ga₂O₃thin films