Thermoanalytical characterization of MFI-type zeolites prepared either in the presence of OH− or of F− ions

Soulard, Michel; Bilger, S.; Kessler, H.; Guth, J.L.

doi:10.1016/0144-2449(87)90016-9

Cited by 98 publications

(48 citation statements)

References 10 publications

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“…1). The effects observed occur at higher temperature than in the MFI-silicates crystallized from alkaline media [6], as it was previously reported [10]. These effects have been attributed to the decomposition of the TPA § ions to tri-and dipropylamine and propylene with the succesive release of propylene and ammonia.…”

Section: Nafsupporting

confidence: 60%

Thermal analysis of fluorine containing gels and precursors of high silica zeolites

Crea

Mostowicz

Testa

et al. 1992

Journal of Thermal Analysis

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By means of simultaneous DTA-, TG-and DTG-technique, the silicate gels and the MFI crystals obtained from these gels have been investigated. The gels have been prepared in presence and in absence of tetrapropylammonium cation (TPA t) and with Li t, Na t, NH~ and K t fluorides. In absence of TPA t no thermal effects have been observed in Li t-and Nat-gels. The effects observed in the NH~ -gel stem from a decomposition and release of inorganic phases: SiF4, NH4F, NH3. The DTA/DTG effects in the TPA t containing gels and in the MFI crystals of monodisperse size are attributed to the decomposition of TPA t cation. It can be concluded from these effects that the interaction between the gels and the TPA t cation is rather weak. The interaction between TPA t and MFI crystals obtained in fluoride medium is stronger than the interaction with crystals obtained from alkaline media. Similar thermal effects are obtained after grinding the long crystals to those having a large distribution of crystal sizes.

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Section: Nafsupporting

confidence: 60%

Thermal analysis of fluorine containing gels and precursors of high silica zeolites

Crea

Mostowicz

Testa

et al. 1992

Journal of Thermal Analysis

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“…The latter are structural elements (not known in faujasite, an AlP analog), therefore their content is considerably greater (about half [2]) than in SAPO-5: Al/P » 1. 4 The results obtained, in particular the presence of a satisfactory amount of C 1 -C 3 hydrocarbons shows that in this temperature range the large pores of SAPO-37 with inward proton acid centers effectively behave as nano-reactors.…”

mentioning

confidence: 90%

“…On the basis of an analysis of the products of thermal conversions of TPAOH (TMAOH) in SAPO-37 a scheme typical for ZP of the time sequence with increasing temperature of the catalytic processes destruction of the template and secondary syntheses, including subsequent b-elimination, cracking, dehydrogenation, oligomerization, cyclization, aromatization, alkylation: [(C 3 H 7 ) 4 , and analogously 2C 3 H 6 ® C 6 H 12 ; 3C 2 H 2 ® C 6 H 6 ; C 6 H 12 + n(C 1 -C 3 ) ® C 6 H 12-n -n(C 1 -C 3 ); C 6 H 6 + n(C 1 -C 3 ) ® C 6 H 6-n -n(C 1 -C 3 ). It seems clear that these reactions occur at different acid centers (with Si/Al = 0.3 in SAPO-37 four Al-O(H)-Si fragments in large holes) and in structures with different porosity which leads to consecutive desorption of products at high temperatures.…”

mentioning

confidence: 99%

Characteristics of the dehydration and thermal destruction of organic templates in microporous alumo-and silicaalumophosphates

et al. 2006

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The characteristics of the dehydration, thermal desorption, and thermal destruction of organic templates in zeolite-like alumo-and silicaalumophosphates of different structural types has been elucidated. The influence of pore size and acid centers on the composition of the products of thermal destruction, including processes of secondary synthesis of normal, cyclic, and aromatic hydrocarbons, has been established. The possibility of dehydration, oligomerization, cyclization, cracking, aromatization and alkylation of hydrocarbons in zeolite-like phosphates has been shown.Zeolite-like alumo-and silicaalumophosphates (ZP) differ from aluminosilicate zeolites (ZT) in the wide size range of micropores (3-13 Å [1-3]) and acid properties. The stability of ZP as inclusion compounds and the strength of the organic template linked to the skeleton is determined by the nature and strength of the acid centers and also the dimensions of the micropores. Evidently detailed studies of the process of dehydration and the products of thermolysis of the organic templates in ZP with different structural types can give valuable information not only of the conditions for their activation as adsorbents and catalysts, but also on the chemical nature of the surfaces, adsorption and catalytic properties. Until recently only a single type of investigation has been carried out on the thermolysis of templates predominantly thermal analysis and IR spectroscopy on and by mass spectrometry (ions with m/z < 45) on , however systematic studies of ZT and ZP of different structural types have received practically no attention.The present work is connected with a comparative investigation of the dehydration and destruction of organic templates in ZP by thermogravimetric desorption with mass spectrometric control (ionization of the products by electron impact) (TPDM).For this investigation phosphates of different structural types, different chemical composition, and varying micropore size were synthesized: SAPO-34 of shabazite type (~3.8 Å, template tetraethylammonium hydroxide (TEAOH); AlPO 4 -5 and SAPO-5 (~7.3 Å, TEAOH [1]); SAPO-37 of faujasite type (~7.4 Å, tetramethylammonium hydroxide (TMAOH) and tetrapropylammonium hydroxide (TPAOH)) [2]; VPI-5 and SiVPI-5 (~13.0 Å, di-n-propylamine (DPA)) [3]. 2600040-5760/06/4204-0260

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“…The decomposition of the TPA + cations occurs either in one or two steps, similarly to that of the [Al]-ZSM-5 samples (Fig. 7) [213,216]. In one sample synthesized in the presence of 18 NH 4 F and 0.3 Ga(NO 3 ) 3 , essentially one hightemperature peak at ca.…”

Section: [Ga]-mfimentioning

confidence: 84%

“…We can see now that the maximum of four B/u.c. observed in previous studies carried out in both alkaline [212] and fluoride [213] media is essentially linked to Na + , which was the inorganic cation 29 Si MAS NMR spectra of a precursor and b calcined Cs-borosilicalites synthesized with 10 moles of H 3 BO 3 used. It was shown, indeed, in [212] that Na + preferentially accompanied Al in the structure, while B preferred TPA + .…”

Section: [B]-mfimentioning

confidence: 89%

Isomorphous Substitution in Zeolites

et al.

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Thermoanalytical characterization of MFI-type zeolites prepared either in the presence of OH− or of F− ions

Cited by 98 publications

References 10 publications

Thermal analysis of fluorine containing gels and precursors of high silica zeolites

Thermal analysis of fluorine containing gels and precursors of high silica zeolites

Characteristics of the dehydration and thermal destruction of organic templates in microporous alumo-and silicaalumophosphates

Isomorphous Substitution in Zeolites

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