A new way to obtain acid or bifunctional catalysts. II. Straightforward calcination of as-synthesized [Ga,A1]-ZSM-5 zeolites obtained from alkali-free media

Giannetto, G.; León, Gladys; Papa, José; Monque, R.; Galiasso, R.; Gabélica, Z.

doi:10.1016/s0920-5861(96)00025-9

Cited by 17 publications

(8 citation statements)

References 30 publications

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“…Unlike previous methods [8,10,30], our method relies neither on complicated and expensive hard templates nor on compounds with hydrophobic groups. Methylamine was used as a mineralizing agent in the works reported by Gabelica et al [34,[39][40][41][42][43], however, only bulk micro-sized zeolite crystals were obtained. Zeolites in Gabelica's works were prepared by hydrothermal method under high temperature and pressure, which was not beneficial for formation of nano-sized zeolite crystals, comparing to the preparation process in mild conditions in this work.…”

Section: Resultsmentioning

confidence: 99%

Facile synthesis of hierarchical nanocrystalline ZSM-5 zeolite under mild conditions and its catalytic performance

Sun

et al. 2011

Journal of Colloid and Interface Science

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Section: Resultsmentioning

confidence: 99%

Facile synthesis of hierarchical nanocrystalline ZSM-5 zeolite under mild conditions and its catalytic performance

Sun

et al. 2011

Journal of Colloid and Interface Science

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“…Both impregnated and ion-exchanged samples contained similar gallium contents (Table 1, entries 4-5), which were only moderately inferior compared to FAU-AT2Ga. Interestingly, as the amount of gallium incorporated in FAU-IE is larger than that expected to arise from the exchange process (in which one Ga 3+ cation should replace three H + cations) and no distinct gallium phases were identified over this sample, it is speculated that significant migration of gallium atoms into framework defects of the zeolite occurred [25]. Upon catalytic evaluation in the isomerization of DHA in ethanol, FAU-IE and FAU-DI attained similar EL selectivities of 69% and 71%, respectively, at almost full DHA conversion (Fig.…”

Section: Production Of El Over Ga-modified Fau Zeolitesmentioning

confidence: 86%

Gallium-modified zeolites for the selective conversion of bio-based dihydroxyacetone into C1–C4 alkyl lactates

Dapsens

Kusema

Mondelli

et al. 2014

Journal of Molecular Catalysis A: Chemical

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Recently, we have demonstrated that post-synthetic alkaline-assisted galliation of FAU-type zeolites generates outstanding Lewis-acid tin-free catalysts for the production of ethyl lactate from dihydroxyacetone under mild conditions. Herein, we show that this preparation method is superior with respect to conventionally practiced strategies for metal incorporation in zeolites, such as dry impregnation and ion exchange with gallium salts. By means of IR spectroscopy of adsorbed pyridine and 71 Ga MAS NMR, it is evidenced that, although gallium migration to the zeolite framework likely occurs also during the traditional preparation, the highly selective tetra-coordinated gallium centers identified for the galliated zeolite in alkaline medium are less abundant in the impregnated and exchanged samples. Furthermore, alkaline-assisted galliation was successfully applied to other zeolite frameworks including MFI, MOR, FER, and BEA, thus evidencing the versatility of the approach. The GaUSY catalyst also proved to be the best tin-free system for the production of n-propyl and nbutyl lactates. In addition, its remarkable performance in ethanol remained unaltered even upon a fivefold increase of the DHA feed concentration, i.e. from the typically applied 3 wt.% to 15 wt.%, thus strengthening its potential for an industrial application.

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“…The effect of high temperature calcination on MFI zeolite acidity has been researched in numerous papers. According to [17][18][19], high temperature treatment of zeolite of MFI structure (from 823 to 1373 K), results in gradual surface dehydroxylation and in addition, in partial dealumination. It brings about a dramatic decrease in protonic acidity, while the Si/Al ratio remains unchanged and crystallinity, up to 1173 K of calcination temperature, changes slightly.…”

Section: Catalyst Aciditymentioning

confidence: 99%

“…The role of acidic centres for oxidation reaction has been extensively discussed in a number of papers. High thermal treatment of Fe-ZSM-5 zeolites, modifies catalyst acidity resulting in the reduction of protonic acidity, which was discussed in part 3.1 [17][18][19], as well as bringing about the formation of iron (II) surface complexes in zeolite channels, as a result of the autoreduction process [30,44]. According to the NMR study, reported by Derouane et al [45], Brønsted acidity is indispensable for propane activation over modified zeolites.…”

Section: Activity For Oxydehydrogenationmentioning

confidence: 99%

Oxydehydrogenation of Ethane and Propane over Alkaline Metal Modified Fe-ZSM-5 Zeolites

2010

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Iron modified zeolites of MFI structure, calcined at 873 and 1173 K, were doped with sodium cations in amounts corresponding to , , and to the total number of acidic centres, estimated from TPD of ammonia. Sodium modified Fe-ZSM-5(900) gradually lost their oxidative activity with an increase in the concentration of alkaline cations, while the activity of Na/Fe-ZSM-5(600) changed slightly and diminished considerably only after significant removal of acidic centres. The results of propane ODH reaction, performed at different contact times over alkaline free and alkaline modified Fe-ZSM-5 indicated, that oxydehydrogenation and cracking reactions on the samples calcined at 1173 K occurred as consecutive reactions, while in the presence of catalysts activated at 873 K, and characterised by strong acidic centres, both reactions occurred simultaneously.

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A new way to obtain acid or bifunctional catalysts. II. Straightforward calcination of as-synthesized [Ga,A1]-ZSM-5 zeolites obtained from alkali-free media

Cited by 17 publications

References 30 publications

Facile synthesis of hierarchical nanocrystalline ZSM-5 zeolite under mild conditions and its catalytic performance

Facile synthesis of hierarchical nanocrystalline ZSM-5 zeolite under mild conditions and its catalytic performance

Gallium-modified zeolites for the selective conversion of bio-based dihydroxyacetone into C1–C4 alkyl lactates

Oxydehydrogenation of Ethane and Propane over Alkaline Metal Modified Fe-ZSM-5 Zeolites

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