Corrigendum: Realizing the Commercial Potential of Hierarchical Zeolites: New Opportunities in Catalytic Cracking

Li, Kunhao; Valla, Julia A.; García‐Martínez, Javier

doi:10.1002/cctc.201402667

Cited by 5 publications

(3 citation statements)

References 29 publications

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“…However, the subnanometer (<1 nm) micropores of zeolites often limit accessibility of reactant molecules to the internal catalytic sites. This creates a number of limitations such as the inability to convert larger molecules, as well as issues of deactivation due to formation of side products that are too large to be removed though the micropores. , One way of overcoming this problem is by means of hierarchical zeolites, which contain both the subnanometer micropores as well as mesopores (>2 nm) in the same particle. , The introduction of mesopores improves accessibility of reactants to catalytic sites, leading to higher activity and capability for processing molecules that are larger than the micropores, as well as an increased catalyst lifetime by providing faster transport paths for removal of products and byproducts. , …”

Section: Introductionmentioning

confidence: 99%

Hierarchical Ga-MFI Catalysts for Propane Dehydrogenation

Kim

Choi

et al. 2017

Chem. Mater.

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We report the synthesis, characterization, and enhanced propane dehydrogenation properties of hierarchical Ga-MFI zeolite catalysts synthesized by two different methods: (i) repetitive branching and (ii) utilization of a long chain alkyl SDA. Structural, compositional, and morphological characterizations confirm that the Ga-MFI catalyst materials have hierarchical structures including micropores and mesopores in a single particle and show that Si/Ga ratios comparable to bulk Ga-MFI catalysts can be obtained. Acid site analysis using NH 3 -TPD and pyridine adsorption followed by in situ IR spectroscopy allowed quantification of the number and types of acid sites present and show that the hierarchical catalysts have considerably higher Lewis acid site concentrations than the bulk catalysts. The hierarchical Ga-MFI catalysts show superior PDH performance (at 600 °C) compared to bulk Ga-MFI catalysts. Propane conversion rates are increased 2−6-fold and propylene selectivities are 10−100% higher. We also examine the effects of synthesis variationssuch as addition of 3-mercaptopropyltrimethoxysilane during synthesis and H + ion-exchangeand find that both these steps have a beneficial effect on PDH properties. Calculations suggest that PDH in both the bulk and the hierarchical Ga-MFI is not diffusion-limited. Therefore, the superior performance of hierarchical Ga-MFI is due to intrinsically higher activity and selectivity. Potential reasons for this behavior are outlined. The present findings showing enhancement of PDH in hierarchical Ga-MFI catalysts suggests that the utility of the hierarchical zeolites is not limited to diffusion-limited reactions involving large, bulky molecules and that they may be useful in more diverse applications involving gas-phase reactions with small molecules.

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Section: Introductionmentioning

confidence: 99%

Hierarchical Ga-MFI Catalysts for Propane Dehydrogenation

Kim

Choi

et al. 2017

Chem. Mater.

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“…The intracrystalline diffusivity of molecular species involved in these processes is often the rate-limiting factor in the whole kinetics of the processes. Given this situation, how to overcome the diffusion limitation of zeolite has been a major issue in enhancing the accessibility and availability of active sites within the zeolite and further improving the catalytic performance of the zeolite [1][2][3]. It is well-known that introducing mesopores into conventional microporous zeolites to form mesoporous materials is an effective solution to eliminate the diffusion limitation of micropores in zeolites.…”

Section: Introductionmentioning

confidence: 99%

“…The presence of mesopores in zeolite catalysts can enhance the mass transport of reactive molecules due to their shorter average diffusion path length, which significantly improves both catalytic activity and the lifetime of zeolite catalysts. The positive effect of mesopores on zeolites has been proven in a number of industrial processes where zeolite catalysts are used [2,[4][5][6][7][8]. Jiao et al [9] studied the acetalization reaction of cyclohexanone with pentaerythritol in hierarchically structured Y-zeolite, discovering that the introduction of mesopores leads to a much better performance than the conventional Y-zeolite, which could be attributed to the enhanced diffusion ability of large-sized guest molecules through the combination of meso-and microstructures.…”

Section: Introductionmentioning

confidence: 99%

Protolytic Ring-Opening Cracking of Methylcyclohexane over Hierarchical High-Silica USY Zeolite: A Haag-Dessau Cracking

Qin

Hao

et al. 2022

Catalysts

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To reveal the influence of acid sites with different spatial locations of USY zeolite with different micro-/mesoporous structures and Si/Al ratio, catalytic cracking of methylcyclohexane on the zeolites is employed to study the synergism effects of acid sites and porous structures (“active region”) in the hierarchical USY zeolites. The results showed that the hierarchical USY zeolites have increased numbers of accessibly strong Brønsted acid sites and greatly enhanced diffusion ability due to the hierarchical pore-structure, resulting in mainly monomolecular protolytic scission in cracking reactions and less bimolecular hydrogen transfer. The isomerization reaction is from intramolecular transalkylation and the isomerics are the intermediates of the cracking reaction. The protolytic cracking that occurs in hierarchical high-silica USY-zeolites follows the Haag-Dessau cracking.

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