Effects of Next-Nearest-Neighbor Aluminum Location on the Brønsted Acidity of HY Zeolites

Zhao, Wenru; Zhang, Weiwei; Peng, Shaozhong; Liu, Wei; Mei, Donghai

doi:10.1021/acs.jpcc.2c06508

Cited by 4 publications

(4 citation statements)

References 38 publications

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“…For low Si/Al ratios, a repulsion between ammonia ions can further decrease the adsorption heats. In contrast, it has been shown that the interaction with the nearest neighbor Al atoms can play an important role, and thus a comparison/interpretation of theoretical and experimental values is difficult unless proton distributions along with ammonia loading are treated in the correct statistical fashion for medium to lower Si/Al ratios 15 , 24 , 59 .…”

Section: Resultsmentioning

confidence: 99%

“…The adsorption of probe base molecules in zeolites is one of the most used techniques to access aluminosilicate's acidity and properties (Fig. 1B) [20][21][22][23][24][25][26][27][28][29][30] . Hydrogen-bonded complexes or ionic pairs are formed in dependence on the proton affinity (PA) of the base probe and temperature.…”

Section: Investigation Of Brønsted Acidity In Zeolites Through Adsorb...mentioning

confidence: 99%

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Investigation of Brønsted acidity in zeolites through adsorbates with diverse proton affinities

Trachta,

Bludský,

Vaculík

et al. 2023

Sci Rep

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Understanding the adsorption behavior of base probes in aluminosilicates and its relationship to the intrinsic acidity of Brønsted acid sites (BAS) is essential for the catalytic applications of these materials. In this study, we investigated the adsorption properties of base probe molecules with varying proton affinities (acetonitrile, acetone, formamide, and ammonia) within six different aluminosilicate frameworks (FAU, CHA, IFR, MOR, FER, and TON). An important objective was to propose a robust criterion for evaluating the intrinsic BAS acidity (i.e., state of BAS deprotonation). Based on the bond order conservation principle, the changes in the covalent bond between the aluminum and oxygen carrying the proton provide a good description of the BAS deprotonation state. The ammonia and formamide adsorption cause BAS deprotonation and cannot be used to assess intrinsic BAS acidity. The transition from ion-pair formation, specifically conjugated acid/base interaction, in formamide to strong hydrogen bonding in acetone occurs within a narrow range of base proton affinities (812–822 kJ mol−1). The adsorption of acetonitrile results in the formation of hydrogen-bonded complexes, which exhibit a deprotonation state that follows a similar trend to the deprotonation induced by acetone. This allows for a semi-quantitative comparison of the acidity strengths of BAS within and between the different aluminosilicate frameworks.

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Section: Resultsmentioning

confidence: 99%

Section: Investigation Of Brønsted Acidity In Zeolites Through Adsorb...mentioning

confidence: 99%

Investigation of Brønsted acidity in zeolites through adsorbates with diverse proton affinities

Trachta,

Bludský,

Vaculík

et al. 2023

Sci Rep

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“…Density functional theory (DFT) calculations are widely acknowledged as a valuable tool for gaining insight into the structure–performance relationship of zeolite-supported metal catalysts at the atomic level . In a study by Garnica et al the isomerization reaction of 1,2-dihydrophenanthrene catalyzed by mordenite zeolite was investigated.…”

Section: Introductionmentioning

confidence: 99%

“…Density functional theory (DFT) calculations are widely acknowledged as a valuable tool for gaining insight into the structure−performance relationship of zeolite-supported metal catalysts at the atomic level. 15 In a study by Garnica et al 16 the isomerization reaction of 1,2-dihydrophenanthrene catalyzed by mordenite zeolite was investigated. They found that the electrostatic adducts, resembling ion-pairs and π complexes commonly observed in zeolite catalysts, play a crucial role in enabling the reaction to proceed through an energetically favorable pathway and account for its selectivity.…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Understanding of Anthracene Hydrocracking over HY Zeolite Encapsulated Single-Atom Pt Catalysts

Zhao,

Yu,

Peng

et al. 2024

ACS Catal.

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The hydrocracking of polycyclic aromatic hydrocarbons (PAHs) leading to the production of benzene, toluene, and xylene (BTX) is one of most important industrial petrochemical processes. Although experiencing extensive experimental effort and industrial practice, the underlying hydrocracking reaction mechanisms of PAHs over zeolite-supported metal catalysts are still elusive. In particular, when, where, and how the aromatic rings of PAHs are open via C–C bond breaking is not clear. In the present work, the hydrocracking reaction pathways of anthracene over the HY zeolite encapsulated single-atom Pt catalyst (Pt1/HY) as a demonstration case for the hydrocracking of PAHs have been investigated using density functional theory (DFT) calculations. The ring-opening processes of the terminal and the central rings of anthracene with respect to the saturated hydrogenation degrees of aromatic rings and the hydrogen sources, which result in different BTX products, have been systematically examined. The hydride transfer over the same aromatic ring is facile, while it is kinetically hindered at the connecting C atoms (Ca) between the neighboring aromatic rings. The hydride transfer between the terminal and the central rings, in the case of the isomerization of 2,3-dihydroanthracene to 9,10-dihydroanthracene, can be achieved through the intermolecular hydride transfer mechanism with the assistance of anthracene. Compared to the hydrogenation from the Pt1 site, the addition of a proton from the Brønsted acidic sites (BAS) on the aromatic ring of partially hydrogenated anthracene would pronouncedly weaken the C–C bond, resulting in the central ring-opening process. DFT calculation results show the central ring opening is kinetically favorable in the anthracene hydrocracking over the Pt1/HY catalyst, generating BTX as the major product rather than butylbenzene and n-butane. The first protonation step by BAS on both rings is the most kinetically relevant step. In addition, the hydrocracking reaction of branched PAHs, using octylanthracene as the probe molecule, has also been investigated. It has been found that the dealkylation of octylanthracene at the ring-branched chain connection position is kinetically more feasible than the central ring opening and the cleavage of the octyl chain. The present work provides a comprehensive and insightful mechanistic understanding of the hydrocracking reaction pathways of PAHs over bifunctional HY zeolite supported metal catalysts.

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The synthesis for adamantane derivatives of high energy density fuel catalyzed by HY zeolite based on the DFT

Ma,

Ling,

Zhang

et al. 2024

Molecular Catalysis

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Effects of Next-Nearest-Neighbor Aluminum Location on the Brønsted Acidity of HY Zeolites

Cited by 4 publications

References 38 publications

Investigation of Brønsted acidity in zeolites through adsorbates with diverse proton affinities

Investigation of Brønsted acidity in zeolites through adsorbates with diverse proton affinities

Mechanistic Understanding of Anthracene Hydrocracking over HY Zeolite Encapsulated Single-Atom Pt Catalysts

The synthesis for adamantane derivatives of high energy density fuel catalyzed by HY zeolite based on the DFT

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