In situ 119Sn-Mössbauer spectroscopic study on MR, MEL, and MTW tin silicalites

Lázár, K.; Szeleczky, A. M.; Mal, Nawal Kishor; Ramaswamy, A.V.

doi:10.1016/s0144-2449(97)00056-0

Cited by 31 publications

(10 citation statements)

References 14 publications

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“…The values of the IS and QS parameter obtained after oxidation in air at 670 K are characteristic of the Sn 2? coordination similar to those found in microporous zeolites for framework substituted position [62]. The IS values of the spectra of Sn-D-60 at -0.03 mm s -1 , confirm the tetrahedral substitution of tin in the samples.…”

Section: Mo¨ssbauer Spectroscopysupporting

confidence: 80%

“…reduction in MCM-41 and ZSM-5. Under the same experimental conditions, both the reduction and reoxidation are completely reversible in Sn-MCM-41, whereas in ZSM-5 the process is partial [62]. Sample Sn-D-60 shows a similar pattern to that of microporous Sn-zeolites where a large proportion of Sn 4?…”

Section: Mo¨ssbauer Spectroscopymentioning

confidence: 84%

“…Thus, it can be suggested that the distribution of tin ions among the possible positions does not depend on the tin content (in a medium Si/Sn region). For further analysis, it is worth comparing the present spectra with those recorded on microporous MFI, MEL and MTW zeolites [62] and on another type of mesoporous system, viz., MCM-41 [10], both types of materials containing tin in isomorphously substituted position. The reduction treatment performed under similar conditions (670 K in H 2 ) resulted in the dominant presence of Sn 2?…”

Section: Mo¨ssbauer Spectroscopymentioning

confidence: 99%

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Synthesis, Characterization and Catalytic Activity of Sn-SBA-15 Mesoporous Molecular Sieves

Ramaswamy

Shah

Lázár³

et al. 2008

Catal Surv Asia

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Our recent reports on the synthesis of Sn-incorporated mesoporous SBA-15 materials have been reviewed. The preparation of the samples with different Si/Sn ratios followed two procedures, the first is the post-synthesis modification of SBA-15 by impregnation with Sn chloride or acetate, and the second is the direct method in which Sn chloride was introduced in to Si precursor along with amphiphilic triblock copolymer, while varying the n H 2 O =n HCl ratio of the synthesis gel. Detailed characterization of the Sn-SBA-15 samples by a variety of techniques shows how the synthesis procedures influence the properties of the samples that reflect on the differences in (a) the structural features, (b) morphology and textural properties, such as the pore characteristics, (c) the possible location of Sn 4? ions in the meso silica structure and their reducibility, (d) the nature of the Sn species and their the coordination sphere and (e) the acid-base characteristics. We developed a possible model for the localization of Sn species in SBA-15 pore structure for different conditions of preparation. This report includes our investigations on the catalytic properties of these Sn-SBA-15 samples in 3 industrially important reactions, viz., trans-esterification of diethyl malonate, synthesis of nopol by Prins condensation of b-pinene with para-formaldehyde and the epoxidation of norbornene. In each of this reaction, while demonstrating the catalytic role of Sn species, we show that the requirement of the type and the environment of Sn species are different for these reactions.

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Section: Mo¨ssbauer Spectroscopysupporting

confidence: 80%

Section: Mo¨ssbauer Spectroscopymentioning

confidence: 84%

Section: Mo¨ssbauer Spectroscopymentioning

confidence: 99%

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Synthesis, Characterization and Catalytic Activity of Sn-SBA-15 Mesoporous Molecular Sieves

Ramaswamy

Shah

Lázár³

et al. 2008

Catal Surv Asia

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“…For further analysis, it is worth comparing the present spectra with those recorded on microporous MFI, MEL and MTW zeolites [43] and, on another type of mesoporous system, viz., on MCM-41 [44], both type of materials containing tin in isomorphously substituted state. The reduction treatment performed under similar conditions (670 K in H 2 ) resulted in dominant presence of Sn 2+ in the 77 K spectra of the tin-zeolites and in those of the Sn-MCM-41 samples, as well.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and characterization of tin oxide-modified mesoporous SBA-15 molecular sieves and catalytic activity in trans-esterification reaction

Shah

Ramaswamy

Lázár

et al. 2004

Applied Catalysis A: General

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“…This technique can be specifically applied to elements having a suitable isotope (short half-life time and small energy -rays) such as Ga and, in particular, Sn. [141] Upon reduction and subsequent oxidation of Sn-MFI, Sn(IV), Sn(II) and Sn(0) could be clearly distinguished, [142] while hydrothermally-synthesised Sn-MFI only contained tetravalent Sn centres. While precisely discriminating between oxidation states, this method is blind with respect to the structure of the metal centres, e.g., Sn(IV) atoms in framework position produce the same signal as Sn (IV) atoms in SnO2.…”

Section: Dr-uv/vis Spectroscopy This Technique Is One Of the Most 70mentioning

confidence: 99%

Design of Lewis-acid centres in zeolitic matrices for the conversion of renewables

2015

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The catalytic conversion of renewable feedstocks into chemicals is pursued as a means to sustainably fulfil future societal needs. Due to the oxygen-rich nature of bio-derived substrates, isomerisation, transfer-hydrogenation and retro-aldol reactions have emerged as relevant transformations to produce commodity chemicals and polymer building blocks. In this context, porous materials containing Lewis-acid metals (e.g., Al, Ga, Sn, Ti, Zr) play an important role. Among these, tin-containing zeolites have demonstrated superior catalytic properties which have mainly been attributed to their hydrophobicity and crystallinity. This review evaluates the versatility and the scalability of bottom-up and top-down approaches to introduce Lewis-acid functionalities in zeolitic matrices. A precise characterisation is shown to be crucial to determine the structure, acidity and environment of the sites introduced. In this regard, we highlight the limitations of conventional techniques and the advantages of analytical and modelling tools recently applied to gain an improved understanding of these solids. Thereafter, property-performance relations and important aspects for the industrial amenability of new synthetic routes are exemplified through case studies. Finally, we put forward the need for gathering deeper knowledge of the site location, surface properties and stability to aid the design of next-generation Lewis-acid catalysts.

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In situ 119Sn-Mössbauer spectroscopic study on MR, MEL, and MTW tin silicalites

Cited by 31 publications

References 14 publications

Synthesis, Characterization and Catalytic Activity of Sn-SBA-15 Mesoporous Molecular Sieves

Synthesis, Characterization and Catalytic Activity of Sn-SBA-15 Mesoporous Molecular Sieves

Synthesis and characterization of tin oxide-modified mesoporous SBA-15 molecular sieves and catalytic activity in trans-esterification reaction

Design of Lewis-acid centres in zeolitic matrices for the conversion of renewables

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