The active site of acidic aluminosilicate catalysts

Haag, Werner O.; Lago, R.M.; Weisz, Paul B.

doi:10.1038/309589a0

Cited by 474 publications

(265 citation statements)

References 15 publications

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“…Notice that contrary to previous work [27,51,75], recent publications are coming to the conclusion that in ZSM-5 there is different acid site reactivity and selectivity as a result of effects of spatial constraints and of entropic factors [60,76] or by location at the intersection of straight and sinusoidal channel and within the sinusoidal channel [77].…”

Section: Temperature-programmed Desorption (Tpd) Of Ammoniacontrasting

confidence: 39%

“…If one considers that there are two energetically differentiated adsorption sites, the heat exchanged in adsorption-desorption process of a given amount of adsorbate on those sites, assuming adsorption of one molecule per site, can be written as: 27) where N i represents the number of occupied sites type i, and H i . their heat of adsorption.…”

Section: Differential Heat Of Adsorption (H Ads )mentioning

confidence: 99%

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Catalytic cracking of n-alkane naphtha: The impact of olefin addition and active sites differentiation

Corma

Cuquerella

Miguel

2015

Journal of Catalysis

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An extended dual kinetic model allows to fit the n-heptane cracking results working in a wide range of reaction conditions. The duality of the model is provided by the contribution of monomolecular and bimolecular cracking mechanisms. It takes into account the role played by the olefins formed on the global cracking or added within the feed. Furthermore by means of this model and the kinetic parameters obtained when cracking n-heptane on ZSM-5, it has been observed that, while some characterization techniques show a homogeneous zeolite surface from the point of view of the active sites, rigorous kinetic experiments point to the possibility that the reactant sees a heterogeneous surface with, at least, two group of cracking active sites. Those differentiated active sites give different cracking rates and different activation energies for the process and, in the case of ZSM-5, could be assimilated to sites pointing to the 10R channels and sites pointing into the crossing of the 10R channels, mainly due to differences in acid site location and confinement effects.3

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Section: Temperature-programmed Desorption (Tpd) Of Ammoniacontrasting

confidence: 39%

Section: Differential Heat Of Adsorption (H Ads )mentioning

confidence: 99%

Catalytic cracking of n-alkane naphtha: The impact of olefin addition and active sites differentiation

Corma

Cuquerella

Miguel

2015

Journal of Catalysis

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“…This discovery gained further importance after Haag et al 109 subsequently demonstrated that the aluminum T-sites are the active sites in ZSM-5. Since then, the number of unique T-sites in many other zeolites has been determined.…”

Section: Cation-zeolite Interactionsmentioning

confidence: 99%

Molecular Simulations of Zeolites: Adsorption, Diffusion, and Shape Selectivity

2008

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“…As mentioned earlier (Boudart 1997), the best example of heterogeneous singlesites is illustrated by zeolites such as H-ZSM-5 (MFI) for the catalytic cracking of n-hexane (Haag et al 1984). By contrast to X and Y acidic zeolite catalysts, the aluminium concentration in ZSM-5 is low enough to represent a dilute solution.…”

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confidence: 99%

Elaboration, characterization and properties of silica-based single-site heterogeneous photocatalysts

2012

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This study concerns single-site heterogeneous photocatalysts, composed of isolated transition metals ions (single-sites) dispersed on silica-based supports, which can be used as photocatalysts. The first part gives the definition of single-site heterogeneous catalysts. The main difficulty to prepare the latter resides in the speciation of the key elements (metal of the catalytically active phase and oxygen of the solid support) and other species (notably counter ions and ligands) the presence of which depends on the synthesis method adopted. The best preparation methods as well as the ideal features of singlesite heterogeneous photocatalysts are discussed before the study focuses on single-site heterogeneous photocatalysts. Case studies are presented with photocatalysts involving titanium and chromium, and their photocatalytic reactions such as CO 2 reduction with H 2 O, degradation of organic pollutants diluted in water, NO decomposition and selective oxidation of propane are also described.

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The active site of acidic aluminosilicate catalysts

Cited by 474 publications

References 15 publications

Catalytic cracking of n-alkane naphtha: The impact of olefin addition and active sites differentiation

Catalytic cracking of n-alkane naphtha: The impact of olefin addition and active sites differentiation

Molecular Simulations of Zeolites: Adsorption, Diffusion, and Shape Selectivity

Elaboration, characterization and properties of silica-based single-site heterogeneous photocatalysts

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