Analytical method for the determination of intra- and extraframework gallium species in zeolite catalyst

Monqueca, Reinaldo; Parisi, Adriano; González, Simón; Giannetto, G.

doi:10.1016/0144-2449(92)90053-r

Cited by 20 publications

(10 citation statements)

References 4 publications

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“…In order to clarify the influence of the extra-framework Ga species in MTA, an acid treatment for freshly prepared catalysts was employed to selectively remove the amorphous Ga species. 29 Approximately 1 g of the sample was immersed in 20 mL of the 0.2 M HCl solution for 1 h at 60 °C. The remaining mixture was filtered, washed with deionized water three times, dried at 80 °C for 12 h, and transformed into the proton form following the method mentioned above.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…The N 2 adsorption−desorption isotherms and microporosity measured by the t-plot method were all performed by an automated N 2 physisorption analyzer (Micromeritics ASAP 2010 Plus). The 27 Al and 29 Si magic angle spinning nuclear magnetic resonance (MAS NMR, Bruker Avance 400) spectra were obtained at the spinning speeds of 10 and 8 kHz in the magnetic field of 9.4 T. The 27 Al spectra were recorded using a 3-μs single-pulse time (90°) with a 4-s acquisition delay. For the 29 Si spectra, a 3-μs single-pulse time and a 60-s delay were used.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…The 27 Al and 29 Si magic angle spinning nuclear magnetic resonance (MAS NMR, Bruker Avance 400) spectra were obtained at the spinning speeds of 10 and 8 kHz in the magnetic field of 9.4 T. The 27 Al spectra were recorded using a 3-μs single-pulse time (90°) with a 4-s acquisition delay. For the 29 Si spectra, a 3-μs single-pulse time and a 60-s delay were used. Also, 1 M of [Al(H 2 O) 6 ] 3+ and tetramethylsilane were used to correct the 27 Al and 29 Si chemical shifts.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…For the 29 Si spectra, a 3-μs single-pulse time and a 60-s delay were used. Also, 1 M of [Al(H 2 O) 6 ] 3+ and tetramethylsilane were used to correct the 27 Al and 29 Si chemical shifts. The NMR spectra were all normalized to the sample weight.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

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Ga-Substituted Nanoscale HZSM-5 in Methanol Aromatization: The Cooperative Action of the Brønsted Acid and the Extra-Framework Ga Species

Hsieh

Chen

Lin

2018

Ind. Eng. Chem. Res.

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A series of nanosized [Al]-, [Ga, Al]-, and [Ga]-HZSM-5 catalysts with a fixed Si-to-M3+ ratio (M = Al or Ga) was synthesized by a seed-induced crystallization method. In order to reveal the catalytic nature of the extra-framework Ga species, an acid treatment was applied to selectively extract Lewis acidic amorphous Ga cations of as-synthesized catalysts. A comparative evaluation of freshly prepared and acid-treated catalysts in methanol conversion to aromatics showed the dehydrogenative nature of the extra-framework Ga species, which is essential in the enhancement of aromatics. Among tested catalysts, [Ga, Al]-HZSM-5 with a low extra-framework Ga-to-Brønsted acid ratio (0.06) was the most effective. The efficacy is due to the contact synergy of the extra-framework Ga species and the Brønsted acid, by which aromatics originated from the dual-cycle mechanism of methanol conversion can be accelerated.

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Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

See 2 more Smart Citations

Ga-Substituted Nanoscale HZSM-5 in Methanol Aromatization: The Cooperative Action of the Brønsted Acid and the Extra-Framework Ga Species

Hsieh

Chen

Lin

2018

Ind. Eng. Chem. Res.

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“…Gallosilicate is one such important m a t e ¡ where zeolitic a l u m i n u m atoms are replaced by gallium atoms [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. The galliu m analogs o f zeolites usually possess physical and chemical properties differem from their a l u m i n u m analogs [1,2].…”

Section: Introductionmentioning

confidence: 99%

Adsorbate interactions of Cu(II) in Cu(II)-exchanged K-L gallosilicate studied by CW and Pulsed electron spin resonance

Yu¹,

Hong

Kevan

1996

Appl. Magn. Reson.

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The interactions of Cu(II) in Cu(II)-exchanged K-L gallosilicate with adsorbates containing coordinative nitrogens in ammonia, pyridine, aniline, acetonitrile and hydrazine, and with the adsorbates carbon monoxide, benzene, propanol and dimethyl sulfoxide ate investigated by electron spin resonance (ESR) and electron spin echo modulation (ESEM) spectroscopies. These results are compared with those in Cu(II)-exchanged K-L aluminosilicate and the differences are discussed. Adsorption of ammonia produces a complex comaining four molecules of ammonia based on resolved nitrogen superhyperfine imeraction. Upon equilibrium with pyridine, Cu(II) forms a complex containing four molecules of pyridine in CuK-L gallosilicate and a complex containing only three molecules of pyridine in CuK-L aluminosilicate based on resolved nitrogen superhyperfine. Upon adsorption of aniline and acetonitrile, Cu(II) forms complexes containing two molecules of each in CuK-L gallosilicate based on resolved nitrogen superhyperfine. However, no resolved nitrogen superhyperfine between hydrazine and Cu(II) is seen. Adsorption of carbon monoxide, benzene, propanol and dimethyl sulfoxide causes changes in the ESR spectrum of Cu(II), indicating migration of Cu(II) into cation positions in the main channels where adsorbate coordination can occur. Cu(II) forms complexes with one moleeule of benzene and two molecules of propanol based on ESEM data in both K-L gallosilicate and K-L aluminosilicate. However, Cu(II) interacts directly with one dimethyl sulfoxide in K-L aluminosilicate but only indirectly at a longer distance with one dimethyl sulfoxide in K-L gallosilicate based on ESEM data.

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Chemical Analysis of Aluminosilicates, Aluminophosphates and Related Molecular Sieves

Kosslick¹,

Fricke²

Molecular Sieves

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Analytical method for the determination of intra- and extraframework gallium species in zeolite catalyst

Cited by 20 publications

References 4 publications

Ga-Substituted Nanoscale HZSM-5 in Methanol Aromatization: The Cooperative Action of the Brønsted Acid and the Extra-Framework Ga Species

Ga-Substituted Nanoscale HZSM-5 in Methanol Aromatization: The Cooperative Action of the Brønsted Acid and the Extra-Framework Ga Species

Adsorbate interactions of Cu(II) in Cu(II)-exchanged K-L gallosilicate studied by CW and Pulsed electron spin resonance

Chemical Analysis of Aluminosilicates, Aluminophosphates and Related Molecular Sieves

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