A critical overview of the catalytic potential of zeolite supported metal complexes

Vos, Dirk De; Thibault‐Starzyk, Frédéric; Knops-Gerrits, Peter-Paul; Parton, Rudy F.; Jacobs, Pierre

doi:10.1002/masy.19940800112

Cited by 77 publications

(17 citation statements)

References 109 publications

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“…Although their preparation and properties have been reviewed in a number of recent articles [e.g., [227][228][229][230], it is difficult to keep track of the fast development. Whereas in the 1980s, only faujasites were used as hosts, this basis has recently been extended to other structures (e.g., VPI-5, EMT, MCM-22).…”

Section: Host/guest Chemistry In Zeolitesmentioning

confidence: 99%

Shape-Selective Catalysis in Zeolites

Weitkamp

Puppe

1999

Catalysis and Zeolites

119

129

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ScopeAmong the primary tasks of catalysis is the control of the selectivity in chemical reactions. In heterogeneously catalyzed reactions in zeolites and zeolite-related microporous solids, this can, inter alia, be achieved by exploiting the phenomenon of shape-selective catalysis. In a very simplified manner, shape-selective catalysis can be described as the combination of catalysis with the molecular sieve effect. Shape selectivity effects can occur, if the sizes and shapes of reactants, of products, of transition states or of reaction intermediates are similar to the dimensions of the pores and cavities of the zeolite.The first examples of shape-selective catalysis in zeolites were reported more than 35 years ago by Weisz and Frilette from the Mobil laboratories [1,2]. Since those days, research in the field of shape-selective catalysis has expanded both at universities and in industrial laboratories in an impressive manner. This has resulted in numerous examples of shape selectivity effects in the course of catalytic conversions over zeoli tic catalysts, which are nowadays no longer restricted to acid-catalyzed reactions as described in the early days. Rather, there are also examples for shape-selective catalysis on metals, on redox active sites, on basic guests in zeolites, and even for shape-selective photochemistry in a zeoli tic environment. Moreover, from the intensive research done in the field of shapeselective catalysis during the last decades, several large-scale commercial applications in the refining and the petrochemical industries have emerged, demonstrating the usefulness and importance of the phenomenon of shape-selective catalysis.In the past, numerous review papers on shape-selective catalysis, its principles and its commercial applications have been published [e. g., 3 -19]. In view of the vast amount of work that has been done in this field in recent years, it is obvious that a review on shape-selective catalysis cannot be exhaustive. Rather, the discussion has to be restricted to selected topics. In the present contribution, emphasis will be placed on a thorough discussion of the classical and of more recent principles of shape-selective catalysis and on how these principles can be used to rationalize the observed catalytic behavior in selected examples. In addition, it is the aim of the present contribution to discuss the available methods for tailoring the shape-selective properties of zeolite catalysts and for their characterization by catalytic methods. Finally, an attempt will be under-

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Section: Host/guest Chemistry In Zeolitesmentioning

confidence: 99%

Shape-Selective Catalysis in Zeolites

Weitkamp

Puppe

1999

Catalysis and Zeolites

119

129

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“…There have been several attempts at encapsulation [24] of some of the above types of complex [and others such as Mn(bpy) 3 ]: in zeolite cavities (e.g., zeolite Y) [25]; smectite interlayers (e.g., montmorillonite, layered double hydroxide) [26]; mesopore channels (e.g., MCM-41) [27]; amorphous silica [28]; or membranes (e.g., polydimethylsiloxane) [29]-using many synthetic approaches. So far, moderately good catalysts have resulted in a few cases.…”

Section: Redox Metal Complexesmentioning

confidence: 99%

Cleaner industrial processes using hydrogen peroxide

Sanderson

2000

Pure and Applied Chemistry

161

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Recent research progress in catalytic systems for potential use with hydrogen peroxide in industrial chemical synthesis is reviewed, with special focus on work published in the last five years. The main types of chemistry employed are critically appraised regarding their suitability for industrial exploitation. The most significant catalyst types are discussed in terms of the positive features identified to date, and the obstacles yet to be surmounted in order to become more widely adopted. It is believed that fully inorganic systems have more scope for commercialization than those containing organic ligands or supports, however robust. Critical targets are larger-pore analogs of titanium silicalite TS-1, more exploration of smectitebased materials, effective immobilization of activated metal peroxo systems, and improvements in design and manipulation of polyoxometallate compounds. Cooperation between branches of chemistry that have not traditionally worked closely together is advocated.

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“…The method to be used depends on the charge, stability and solubility of the guest molecule. Cationic guest molecules such as the cationic dyes thionine [14] and methylene blue [15] and cationic metal complexes such as [Cu(ethylenediamine) 2 ] 2 [16] can be incorporated via ion exchange in the negatively charged molecular sieve. Another method is diffusion from the gas or liquid phase into the molecular sieve under the condition that the channel diameter of the molecular sieve is wider than the dimension of the guest [17,18].…”

Section: Introductionmentioning

confidence: 99%

“…The dyes are added to the gel before the hydrothermal synthesis. Negatively charged (1)(2)(3)(4)(5), positively charged (6)(7)(8) and hydrophobic uncharged (9,10) phthalocyanines were employed (Scheme 1). A recent report described the encapsulation of unsubstituted Zn(II) phthalocyanine into Si-, Al-and Ti-MCM-41 [26] by adding the Zn complex to the gel mixture.…”

Section: Introductionmentioning

confidence: 99%

“…Novel composite materials based on molecular sieves such as zeolites and AlPO 4 -5 have been increasingly studied in recent years, where a wide range of encapsulated guests such as dyes [1], metal complexes [2], polymers [3], metal clusters [4] and semiconductor nanoclusters [5] have been used. The molecular sieve framework represents a host material exhibiting a higher stability against organic solvents, acids and bases as well as a higher resistance to temperature and radiation than organic polymers.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Incorporation of Differently Substituted Phthalocyanines into the Mesoporous Molecular Sieve Si-MCM-41

Ganschow

Wöhrle

Schulz‐Ekloff

1999

J. Porphyrins Phthalocyanines

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Substituted phthalocyanine Zn complexes exhibiting negative, positive or no charge are incorporated in the mesopores of Si -MCM-41 materials during hydrothermal synthesis in the presence of cetyltrimethylammonium chloride. The nature of the intermolecular interaction between the surfactant micelle and the capped chromophores determines (i) the resistance of the dye towards hydrolytic degradation during the synthesis and (ii) its stability of anchoring towards extraction with ethanol in the composite material. Loadings up to 2 × 10−5 mol/g molecular sieve are achieved, corresponding to an average distance between the encapsulated dye molecules between 2 and 3 nm. The UV-vis spectra reveal the non-aggregated state of the chromophores, pointing to a uniform distribution and a perfect separation by the surfactant molecules.

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A critical overview of the catalytic potential of zeolite supported metal complexes

Cited by 77 publications

References 109 publications

Shape-Selective Catalysis in Zeolites

Shape-Selective Catalysis in Zeolites

Cleaner industrial processes using hydrogen peroxide

Incorporation of Differently Substituted Phthalocyanines into the Mesoporous Molecular Sieve Si-MCM-41

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