Scaling Relations for Acidity and Reactivity of Zeolites

Liu, C Chong; Tranca, Ionuţ; Santen, Rutger A. van; Hensen, Emiel J. M.; Pidko, Evgeny A.

doi:10.1021/acs.jpcc.7b08176

Cited by 81 publications

(89 citation statements)

References 96 publications

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“…The adsorption of reactants is a fundamental step for surface‐catalyzed reactions. Various characteristic properties of the adsorbed species such as bond distances, bond orders, vibrational frequencies are also frequently used as descriptors to rationalize and predict the catalytic activities ,. Therefore, the adsorption properties are very informative and lead to understanding activation of reactants and eventually the catalytic activities.…”

Section: Resultsmentioning

confidence: 99%

Origin of Nb₂O₅ Lewis Acid Catalysis for Activation of Carboxylic Acids in the Presence of a Hard Base

et al. 2018

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The Nb2O5 surface catalyzes the amidation of carboxylic acids with amines through Nb5+ Lewis acid activation of the C=O group. In this work, DFT calculations were applied to theoretically investigate the C=O bond activation of a model carboxylic acid (acetic acid) on θ‐Al2O3(110), anatase TiO2(101), and T‐Nb2O5(100) surfaces. The adsorption sites, adsorption energies, reaction energy barriers, electronic properties, and vibrational frequency of acetic acid were examined in detail. It was found that the bond activation of the carbonyl group is most efficient on Nb2O5, although the adsorption energy is larger on Al2O3 and TiO2. The most efficient C=O bond activation on Nb2O5 results in the lowest energy barrier of C−N bond formation during amidation. The Nb2O5 surface also shows larger tolerance to methylamine and water molecules than Al2O3 and TiO2 surfaces. These crucial factors contribute to the highest amidation catalytic reactivity on Nb2O5. Furthermore, the position of the mean density of states of the d‐conduction band of the active metal site relative to the Fermi energy level correlates well with the efficiency in the C=O bond activation and, consequently, the catalytic activity for amidation. These results suggest that, unlike a classical understanding of strong acid sites of metal oxide surfaces, interaction of a carbonyl HOMO with an unoccupied metal d‐orbital, or, in other words, covalent‐like interaction between a carbonyl group and metal adsorption site, is relevant to the present system.

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Section: Resultsmentioning

confidence: 99%

Origin of Nb₂O₅ Lewis Acid Catalysis for Activation of Carboxylic Acids in the Presence of a Hard Base

et al. 2018

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“…Adsorption energy of ammonia was proposed as a suitable descriptor for constructing scaling laws to estimate activation barriers of elementary steps as well as the reaction rate of alkene methylation ,. It is important to note that such (single) property‐activity scaling relations constructed for one zeolite type may not necessarily hold for other topologies because of the different van der Waals interactions and geometric constraints imposed by zeolite pores with different topologies …”

Section: Brønsted Acidity Of Zeolitesmentioning

confidence: 99%

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

Pidko

2018

ChemCatChem

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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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“…Additionally, the IR spectra of pyridine adsorption on different Y‐zeolites and mordenite showed the characteristic bands of pyridine almost at the same frequency values . It was also shown that the strength in the acidity, which is well described by the adsorption energy of electron donor basic molecules, is more related to the chemical composition of the zeolite than to its morphology …”

Section: Methodsmentioning

confidence: 95%

“…[49] It was also shown that the strength in the acidity, which is well described by the adsorption energy of electron donor basic molecules, is more related to the chemical composition of the zeolite than to its morphology. [50] Calculations were carried out using the Vienna Ab-initio Simulation Package (VASP) considering periodic boundary conditions and pseudo potentials. [51][52][53] The Projected Augmented Wave (PAW) method and the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional were chosen for performing all the calculations.…”

Section: Dft Calculation Of the Frequencies Of Organonitrogen Compounmentioning

confidence: 99%

In Situ IR‐ATR Study of the Interaction of Nitrogen Heteroaromatic Compounds with HY Zeolites: Experimental and Theoretical Approaches

et al. 2019

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In the present work, the liquid‐solid interaction of liquid N‐heteroaromatic compounds, commonly present in the petroleum feedstocks of the refineries, with Y zeolites used as hydrocracking catalysts was followed using IR‐ATR spectroscopy. The inhibition of the zeolitic acid sites by strongly basic pyridine and weakly basic indole was highlighted using a continuous flow IR‐ATR cell. Results were assessed by Density Functional Theory calculations to compute the vibrational frequencies of pyridine and indole according to the nature of the interaction sites: silanol groups or acidic OH groups. The study points out that IR‐ATR spectroscopy opens the way for investigating the interaction modes of low vapor pressure molecules (e. g. indole) that present an inherent difficulty to be operated in the gas phase. Moreover, the IR‐ATR makes possible the analysis of the little‐explored low wavenumber zone (<800 cm−1), that presents informative vibrational modes on the adsorption mode of N‐molecules. Hence, this work points out that for pyridine, the bands at 686 and 727 cm−1 are characteristic of pyridinium species formed over zeolitic OH groups, meanwhile, the signals at 703 and 750 cm−1, are associated to pyridine in interaction with silanol groups. The IR‐ATR study reveals that indole, a weakly basic compound, can be protonated on acidic Y zeolites as unambiguously evidenced by the formation of the bands at 1617, 1608, 1543 and 705 cm−1. Findings here exposed are crucial for studying inhibitory effects exerted by weak nitrogenated compounds on acidic materials during hydrocracking processes.

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Scaling Relations for Acidity and Reactivity of Zeolites

Cited by 81 publications

References 96 publications

Origin of Nb₂O₅ Lewis Acid Catalysis for Activation of Carboxylic Acids in the Presence of a Hard Base

Origin of Nb₂O₅ Lewis Acid Catalysis for Activation of Carboxylic Acids in the Presence of a Hard Base

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

In Situ IR‐ATR Study of the Interaction of Nitrogen Heteroaromatic Compounds with HY Zeolites: Experimental and Theoretical Approaches

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Scaling Relations for Acidity and Reactivity of Zeolites

Cited by 81 publications

References 96 publications

Origin of Nb2O5 Lewis Acid Catalysis for Activation of Carboxylic Acids in the Presence of a Hard Base

Origin of Nb2O5 Lewis Acid Catalysis for Activation of Carboxylic Acids in the Presence of a Hard Base

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

In Situ IR‐ATR Study of the Interaction of Nitrogen Heteroaromatic Compounds with HY Zeolites: Experimental and Theoretical Approaches

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Origin of Nb₂O₅ Lewis Acid Catalysis for Activation of Carboxylic Acids in the Presence of a Hard Base

Origin of Nb₂O₅ Lewis Acid Catalysis for Activation of Carboxylic Acids in the Presence of a Hard Base