Preparation of Metallosilicates with MFI Structure by Atom-Planting Method

Yashima, Tatsuaki; Yamagishi, K.; Namba, Seitarô

doi:10.1016/s0167-2991(08)61897-2

Cited by 13 publications

(9 citation statements)

References 5 publications

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“…Dessau and Kerr 101 showed in the same year that alumination with AlCl 3 vapours can be successfully applied also to ZSM-11 zeolites at 773 K. In both studies, it was suggested that the metal integrates at defect sites, i.e., external and/or internal silanols, originally present in the zeolites. This was corroborated by mechanistic studies of aluminium incorporation at variable temperature, partial pressure of AlCl 3 and reaction time 102 in materials featuring distinct amounts of defect sites 103 and might explain the limited amount of aluminium incorporated into the treated samples (0.6-2.0 wt%). Alternatively, wet treatments with AlF 3 were carried out.…”

Section: Top-down Approachesmentioning

confidence: 56%

“…This effectively comprised the impregnation of silicalite-1 with an (NH 4 ) 3 AlF 6 solution, followed by heating at 403 K. In this case, due to the high reactivity of inorganic fluorides towards silica, it was supposed that alumination could proceed even in the absence of defect sites in the zeolite. Yashima et al 103 introduced also other metals besides Al, i.e., Ti, Sb, Ga, In and As, into silicalite via vapour-phase reaction at 873-923 K and Skeels et al 104 incorporated Cr and Sn into zeolite Y through treatment with the corresponding metal fluoride solutions, thus showing the versatility of the strategies in terms of the nature of the metal that can be integrated. Besides, atomic layer deposition, a technique based on the exposure of the material to sequential pulses of trimethylaluminium and water, has been exploited to introduce aluminium into various zeolites.…”

Section: Top-down Approachesmentioning

confidence: 99%

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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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Section: Top-down Approachesmentioning

confidence: 56%

Section: Top-down Approachesmentioning

confidence: 99%

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

2015

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“…By using halides of other metals, metallosilicates with the MFI structure (Ga, In, Sb, As, and Ti) and with the MOR structure (Ga, Sb, and Ti) have been prepared [88]. By using halides of other metals, metallosilicates with the MFI structure (Ga, In, Sb, As, and Ti) and with the MOR structure (Ga, Sb, and Ti) have been prepared [88].…”

Section: Other Titanium-containing Zeolitesmentioning

confidence: 99%

Metals in Zeolites for Oxidation Catalysis

Tatsumi

2010

Zeolites and Catalysis

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Zeolites have long been used as solid acid catalysts. The fluid catalytic cracking of heavy fractions of petroleum by the use of Y-type zeolites included in catalyst matrices is the world's largest catalytic process. Acidic zeolites have also widely replaced mineral and Lewis acids in large-scale chemical manufacturing such as alkylation of aromatics and the Beckmann rearrangement. Zeolites are also endowed with the redox property by the incorporation of a variety of metals, and this chapter deals with incorporation of metals and the resultant oxidation catalysis.The ways to introduce heteroatoms into zeolites are classified into two categories: heteroatoms can be introduced into the framework as well as into voids as extraframework species. Most zeolites have an intrinsic ability to exchange cations [1]. This ability to exchange is a result of isomorphous substitution of a cation of trivalent (mostly Al) or lower charges for Si as a tetravalent framework cation. As a consequence of this substitution, a net negative charge develops on the framework of the zeolite, which has to be neutralized by cations present within the channels or cages that constitute the microporous part of the crystalline zeolite. These cations may be any of the metals, metal complexes, or alkylammonium cations. If these cations are transition metals with redox properties, they can act as active sites for oxidation reactions. As a pioneering work, Wacker-type reactions were catalyzed by Y zeolite into which Pd 2+ and Cu 2+ were incorporated by ion exchange [2].Research on coordination chemistry in zeolites started in 1970s and early work was summarized by Lunsford [3]. A metal complex of the appropriate dimensions can be encapsulated in a zeolite, being viewed as a bridge between homogeneous and heterogeneous systems. Complexes that are smaller than the free diameters of the channels and windows have access to the cavities. On the other hand, complexes that are larger than the diameters of the windows must be synthesized in situ, namely, by the adsorption of the ligands into the zeolites containing transition metal ions or by the synthesis of the ligands in those zeolites [4][5][6]. Herron et al. first referred to such zeolite guest molecules as ship-in-a-bottle complexes [7]. Cationic complexes can be tethered to zeolites through the electrostatic interaction. However,

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“…The acidity of MFI can be modified by subliming a metal chloride into the zeolite [10][11][12][13][14][15]. Through this method, the corresponding metal cations can be inserted into the framework sites or loaded onto the extra-framework sites, such as at the external surface and in the channels of the zeolite.…”

Section: Introductionmentioning

confidence: 99%

“…The degree of difficulty of incorporating the metal into the zeolite framework depends on the metal radius and the concentration of zeolite defect sites, which are the four internal silanol groups, i.e. the hydroxyl nest [10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Effect of Sublimation Treatment on the Catalytic Performance of MFI Catalysts in Pyridine and 3‐Picoline Synthesis

Jin

2011

Chem Eng & Technol

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Mordenite framework inverted (MFI)-structure catalysts with framework trivalent metal cations and extra-framework metal cations were prepared by the sublimation method to synthesize pyridine and picolines. The results show that the sublimation treatment of volatile metal halides, i.e., GaCl 3 and FeCl 3 , consumes the silanol groups of the parent sample. Most of the Ga cations are incorporated into the zeolite framework, which produces hydroxyl groups and dramatically enhances the proportion of Brönsted acid sites. At the same time, a large number of Fe cations exist in the extra-framework, causing an increase in the proportion of Lewis acid sites. The increased acid amount and strength effectively improve the activity and stability of the catalyst. Moreover, the generated stronger acid sites increase the selectivity of pyridine. The Ga cations of the modified zeolite can promote the dehydrogenation step for pyridine synthesis, which markedly increases the pyridine selectivity.

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Preparation of Metallosilicates with MFI Structure by Atom-Planting Method

Cited by 13 publications

References 5 publications

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

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

Metals in Zeolites for Oxidation Catalysis

Effect of Sublimation Treatment on the Catalytic Performance of MFI Catalysts in Pyridine and 3‐Picoline Synthesis

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