Tailoring nanoscopic confines to maximize catalytic activity of hydronium ions

Shi, Hui; Eckstein, Sebastian; Vjunov, Aleksei; Camaioni, Donald M.; Lercher, Johannes A.

doi:10.1038/ncomms15442

Cited by 53 publications

(101 citation statements)

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“…Lercher and co‐workers employed a combination of DFT and aiMD simulations to investigate the aqueous propanol dehydration over H‐ZSM‐5 zeolite . The analysis of the dehydration activity of the hydronium ion in MFI, BEA and FAU zeolites revealed that the catalytic activity can be tuned by altering the compensation between enthalpy and entropy induced by microporous environment via either enhancement of the interaction between hydronium ions and alcohol reactant or offset of the higher activation enthalpies by more positive activation entropies …”

Section: Brønsted Acidity Of Zeolitesmentioning

confidence: 99%

The Nature and Catalytic Function of Cation Sites in Zeolites: a Computational Perspective

Pidko

2018

ChemCatChem

100

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Zeolites have a broad spectrum of applications as robust microporous catalysts for various chemical transformations. The reactivity of zeolite catalysts can be tailored by introducing heteroatoms either into the framework or at the extraframework positions that gives rise to the formation of versatile Brønsted acid, Lewis acid and redox‐active catalytic sites. Understanding the nature and catalytic role of such sites is crucial for guiding the design of new and improved zeolite‐based catalysts. This work presents an overview of recent computational studies devoted to unravelling the molecular level details of catalytic transformations inside the zeolite pores. The role of modern computational chemistry in addressing the structural problem in zeolite catalysis, understanding reaction mechanisms and establishing structure‐activity relations is discussed. Special attention is devoted to such mechanistic phenomena as active site cooperativity, multifunctional catalysis as well as confinement‐induced and multisite reactivity commonly encountered in zeolite catalysis.

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Section: Brønsted Acidity Of Zeolitesmentioning

confidence: 99%

The Nature and Catalytic Function of Cation Sites in Zeolites: a Computational Perspective

Pidko

2018

ChemCatChem

100

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“…[4] It has been observed that the hydronium ions strongly affect adsorption properties in the micropore confines. Then, the Brønsted acid sites transform into charged hydrated hydronium ions (H 3 O + hydr.…”

Section: Understandingandcontrollingtheinteractionsofmoleculesmentioning

confidence: 99%

“…[1] Thee nvironment interacts with the sorbed molecules,either via directed bonds that include hydrogen bonding and electron pair donoracceptor interactions or via nondirected dispersion forces. [4] It has been observed that the hydronium ions strongly affect adsorption properties in the micropore confines. Zeolites,which have aw ell-defined three-dimensional pore structure with nonpolar channel walls and polar Brønsted acidic OH groups (Brønsted acid sites,B AS), are ideal systems to explore this complexity.The combination of active sites and pore structure offers au nique way to influence both ground and transition states in catalyzed reaction pathways.…”

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confidence: 99%

Influence of Hydronium Ions in Zeolites on Sorption

et al. 2019

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In the presence of sufficient concentrations of water, stable,hydrated hydronium ions are formed in the pores and at the surface of solid acids such as zeolites.F or am edium-pore zeolite,s uch as zeolite MFI, hydrated hydronium ions consist of eight water molecules and have an effective volume of 0.24 nm 3 .I ntheir presence,larger organic molecules can only adsorb in the portions of the pore that are not occupied by hydronium ions.Asaconsequence,the available pore volume decreases proportionally to the concentration of the hydronium ions.T he higher charge density (the increasing ionic strength) that accompanies an increasing concentration of hydronium ions leads to an increase in the activity coefficients of the adsorbed substrates,t hus,w eakening the interactions between the organic part of the molecules and the zeolite and favoring the interactions with polar groups.T he quantitative understanding of these interactions makes it possible to link ac ollective property such as hydrophilicity and hydrophobicity of zeolites to specific interactions on molecular level. Understandingandcontrollingtheinteractionsofmoleculesin confined space of varying polarity is central to the action of enzymes and to properties that link zeolite catalysis with synthetic mimics of enzyme functions. [1] Thee nvironment interacts with the sorbed molecules,either via directed bonds that include hydrogen bonding and electron pair donoracceptor interactions or via nondirected dispersion forces. [2] Therelative dominance of the two types of interactions in an aqueous environment makes specific regions of the materials hydrophilic or hydrophobic, which is,i nt urn, manifested in colligative properties such as the specific surface tension, wetting, and the enrichment of polar or nonpolar components in complex mixtures.T his classification of interactions is widely used conceptually,but the classifications are empirical ("hydrophobicity scale") [3] and are difficult to extend and transfer between systems.Thes imultaneous presence of polar and nonpolar domains in proximity in catalyst/enzyme environments and its importance for catalytic properties make it imperative to explore the heterogeneity and its impact on interactions with substrates at an atomistic and molecular level. Zeolites,which have aw ell-defined three-dimensional pore structure with nonpolar channel walls and polar Brønsted acidic OH groups (Brønsted acid sites,B AS), are ideal systems to explore this complexity.The combination of active sites and pore structure offers au nique way to influence both ground and transition states in catalyzed reaction pathways.Understanding the influence of such an environment on reacting molecules becomes even more complex, when zeolites are used in the presence of water. Then, the Brønsted acid sites transform into charged hydrated hydronium ions (H 3 O + hydr. ). [4] It has been observed that the hydronium ions strongly affect adsorption properties in the micropore confines. [5] On am acroscopic level, zeolites with very low concentration...

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“…). [4] It has been observed that the hydronium ions strongly affect adsorption properties in the micropore confines. [5] On am acroscopic level, zeolites with very low concentrations of BASd isplay stronger adsorption of less polar organic substrates and are regarded as hydrophobic; [5a-c] zeolites with high concentrations of BAShave higher affinity to water and are considered to be hydrophilic.…”

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confidence: 99%