Acid Function in Zeolites: Recent Progress

Rabó, Jule A.; Gajda, G. J.

doi:10.1080/01614948909349936

Cited by 212 publications

(67 citation statements)

References 109 publications

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“…For instance, these have explored the in uence of pore structure and Si/Al ratio, characterised the di erent types of acid site that may be present, investigated coking and deactivation, and proposed reaction mechanisms (Corma, 1993;Rabo and Gajda, 1989;Farneth and Gorte, 1995;Bhatia et al, 1989;Karge, 1991;Cumming and Wojciechowski, 1996;Corma and OrchillÃ es, 2000). Molecular transport within zeolites has also been extensively studied because it can in uence overall reaction rates, and also because of the use of zeolites in separations processes (K arger and Ruthven, 1992;Chen et al, 1994).…”

Section: Introductionmentioning

confidence: 99%

Adsorption and desorption kinetics of hydrocarbons in FCC catalysts studied using a tapered element oscillating microbalance (TEOM). Part 1: experimental measurements

Lee

Ashtekar

Gladden

et al. 2004

Chemical Engineering Science

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Section: Introductionmentioning

confidence: 99%

Adsorption and desorption kinetics of hydrocarbons in FCC catalysts studied using a tapered element oscillating microbalance (TEOM). Part 1: experimental measurements

Lee

Ashtekar

Gladden

et al. 2004

Chemical Engineering Science

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“…[1][2] Zeolite acidity is understood to a significant degree. [3][4][5] Acid catalytic activity resides at sites involving tetrahedral aluminum species substituting silicon atoms in the framework. Zeolite Y, the preferred zeolite in hydrocracking catalysts, has the faujasite structure which features a single crystallographic tetrahedral site.…”

Section: Introductionmentioning

confidence: 99%

Chemical Vapor Deposition of Trimethylaluminum on Dealuminated Faujasite Zeolite

et al. 2013

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Chemical vapor deposition of trimethylaluminum (TMA) was explored as an approach for the preparation of model faujasite-type catalysts containing extraframework aluminum. The decomposition of the grafted organoaluminum species was investigated in hydrogen and oxygen atmosphere. The process of grafting Al-containing species and the associated changes of the zeolite hydroxyl groups were followed by in situ FTIR spectroscopy. The state of intrazeolite Al atoms, the changes in zeolite structure and acidity caused by the CVD procedure as well as by subsequent treatment were analyzed in detail by 1H, 29Si, and 27Al MAS NMR, COads IR, H/D exchange of acidic hydroxyl groups with perdeuterobenzene, and propane cracking. Reaction of an extraframework aluminum-free high-silica faujasite zeolite with TMA leads to nearly complete substitution of the bridging hydroxyl groups with Al species. The reaction, however, does not produce uniform homogeneously distributed species. Because of the high reactivity of TMA, the zeolite lattice is partially decomposed resulting in its partial dealumination and formation of stable Si-CH3 moieties. The exact conditions of post-CVD treatment influence strongly the chemical and catalytic properties of the zeolites. The strongest increase of the propane conversion rate was observed when grafted TMA species were decomposed in H2 at high temperature. Such zeolite displays much higher activity per Brønsted acid site in propane cracking than a commercial ultrastabilized Y zeolite. It is proposed that the activity enhancement is related to strong polarization of a fraction of the zeolite Brønsted acid sites by Lewis acid sites formed by the hydrogenolysis of grafted TMA complexes.

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“…It has been reported that the overall activity of Zr-beta type materials may result from different contributions of framework sites at different crystallographic positions [152]. On the other hand, the structural order of the catalytic materials may affect the ranges of bond angles/lengths and ligand lability of the metal sites, with effects on intrinsic activity [153,154]. Accordingly, it may not be straightforward to establish relationships between the catalytic activity and active sites between different families of materials, such as zeolite beta and TUD-1 type materials.…”

Section: Influence Of Materials Propertiesmentioning

confidence: 99%

Integrated reduction and acid-catalysed conversion of furfural in alcohol medium using Zr,Al-containing ordered micro/mesoporous silicates

Antunes

Lima

Neves

et al. 2016

Applied Catalysis B: Environmental

103

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Ordered porous silicates of the type TUD-1 and zeolite beta possessing zirconium and aluminium sites were evaluated as eco-friendly heterogeneous, multifunctional catalysts for the integrated reduction-acid conversion of furfural (Fur, industrially produced from hemicellulosic components of biomass) to useful bio-products, namely, furfuryl alcohol (FA), alkyl furfuryl ethers (FEs), alkyl levulinate esters (LEs), levulinic acid (LA), angelica lactones (AnLs), and γ-valerolactone (GVL); the bio-products spectrum was obtained by GC × GC-ToFMS. Carrying out the one-pot conversion of Fur to bioproducts using a multifunctional catalyst is challenging since various reactions are involved and it is difficult to control all of these to meet high reaction efficiencies and selectivities. Aiming at designing improved multifunctional catalysts for this reaction system, the TUD-1 and zeolite beta type silicates possessing zirconium and aluminium sites in different ratios were prepared and characterised on microstructural and molecular levels. Systematic characterisation, catalytic testing using 2-butanol as dual functional solvent-H-donor, and kinetic modelling studies were performed using the Zr,Al-containing micro-and mesoporous materials. Different steps of the overall reaction of Fur were studied separately starting from intermediate products using the same materials, which helped understand the influence of the material properties on 2 reactivity of intermediates and reaction selectivity. Zr-sites of the silicate catalysts were essential for effectively initialising the overall process (reduction of Fur to FA), and for the reduction of LEs to GVL; the co-presence of Al-sites promoted acid-catalysed steps (FA to FEs, LEs, AnLs, LA). The good stability of the catalysts was verified by catalytic and characterisation studies of the spent catalysts.

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Acid Function in Zeolites: Recent Progress

Cited by 212 publications

References 109 publications

Adsorption and desorption kinetics of hydrocarbons in FCC catalysts studied using a tapered element oscillating microbalance (TEOM). Part 1: experimental measurements

Adsorption and desorption kinetics of hydrocarbons in FCC catalysts studied using a tapered element oscillating microbalance (TEOM). Part 1: experimental measurements

Chemical Vapor Deposition of Trimethylaluminum on Dealuminated Faujasite Zeolite

Integrated reduction and acid-catalysed conversion of furfural in alcohol medium using Zr,Al-containing ordered micro/mesoporous silicates

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