1
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Kim S, Chen F, Camaioni DM, Derewinski MA, Gutiérrez OY, Liu Y, Lercher JA. Confined Ionic Environments Tailoring the Reactivity of Molecules in the Micropores of BEA-Type Zeolite. J Am Chem Soc 2024; 146:17847-17853. [PMID: 38888888 PMCID: PMC11228971 DOI: 10.1021/jacs.4c03405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Revised: 05/28/2024] [Accepted: 05/30/2024] [Indexed: 06/20/2024]
Abstract
In the presence of water, hydronium ions formed within the micropores of zeolite H-BEA significantly influence the surrounding environment and the reactivity of organic substrates. The positive charge of these ions, coupled with the zeolite's negatively charged framework, results in an ionic environment that causes a strongly nonideal solvation behavior of cyclohexanol. This leads to a significantly higher excess chemical potential in the initial state and stabilizes at the same time the charged transition state in the dehydration of cyclohexanol. As a result, the free-energy barrier of the reaction is lowered, leading to a marked increase in the reaction rates. Nonetheless, there is a limit to the reaction rate enhancement by the hydronium ion concentration. Experiments conducted with low concentrations of reactants show that beyond an optimal concentration, the required spatial rearrangement between hydronium ions and cyclohexanols inhibits further increases in the reaction rate, leading to a peak in the intrinsic activity of hydronium ions. The quantification of excess chemical potential in both initial and transition states for zeolites H-BEA, along with findings from HMFI, provides a basis to generalize and predict rates for hydronium-ion-catalyzed dehydration reactions in Brønsted zeolites.
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Affiliation(s)
- Sungmin Kim
- Institute for Integrated Catalysis and Physical Science Division, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Feng Chen
- Institute for Integrated Catalysis and Physical Science Division, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Donald M Camaioni
- Institute for Integrated Catalysis and Physical Science Division, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Miroslaw A Derewinski
- Institute for Integrated Catalysis and Physical Science Division, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Oliver Y Gutiérrez
- Institute for Integrated Catalysis and Physical Science Division, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Yue Liu
- Department of Chemistry and Catalysis Research Institute, TU München, Lichtenbergstrasse 4, Garching 85748, Germany
| | - Johannes A Lercher
- Institute for Integrated Catalysis and Physical Science Division, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
- Department of Chemistry and Catalysis Research Institute, TU München, Lichtenbergstrasse 4, Garching 85748, Germany
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2
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Chizallet C, Bouchy C, Larmier K, Pirngruber G. Molecular Views on Mechanisms of Brønsted Acid-Catalyzed Reactions in Zeolites. Chem Rev 2023; 123:6107-6196. [PMID: 36996355 DOI: 10.1021/acs.chemrev.2c00896] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/01/2023]
Abstract
The Brønsted acidity of proton-exchanged zeolites has historically led to the most impactful applications of these materials in heterogeneous catalysis, mainly in the fields of transformations of hydrocarbons and oxygenates. Unravelling the mechanisms at the atomic scale of these transformations has been the object of tremendous efforts in the last decades. Such investigations have extended our fundamental knowledge about the respective roles of acidity and confinement in the catalytic properties of proton exchanged zeolites. The emerging concepts are of general relevance at the crossroad of heterogeneous catalysis and molecular chemistry. In the present review, emphasis is given to molecular views on the mechanism of generic transformations catalyzed by Brønsted acid sites of zeolites, combining the information gained from advanced kinetic analysis, in situ, and operando spectroscopies, and quantum chemistry calculations. After reviewing the current knowledge on the nature of the Brønsted acid sites themselves, and the key parameters in catalysis by zeolites, a focus is made on reactions undergone by alkenes, alkanes, aromatic molecules, alcohols, and polyhydroxy molecules. Elementary events of C-C, C-H, and C-O bond breaking and formation are at the core of these reactions. Outlooks are given to take up the future challenges in the field, aiming at getting ever more accurate views on these mechanisms, and as the ultimate goal, to provide rational tools for the design of improved zeolite-based Brønsted acid catalysts.
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Affiliation(s)
- Céline Chizallet
- IFP Energies nouvelles, Rond-Point de l'Echangeur de Solaize, BP 3, Solaize 69360, France
| | - Christophe Bouchy
- IFP Energies nouvelles, Rond-Point de l'Echangeur de Solaize, BP 3, Solaize 69360, France
| | - Kim Larmier
- IFP Energies nouvelles, Rond-Point de l'Echangeur de Solaize, BP 3, Solaize 69360, France
| | - Gerhard Pirngruber
- IFP Energies nouvelles, Rond-Point de l'Echangeur de Solaize, BP 3, Solaize 69360, France
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3
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Liu Q, Pfriem N, Cheng G, Baráth E, Liu Y, Lercher JA. Maximum Impact of Ionic Strength on Acid-Catalyzed Reaction Rates Induced by a Zeolite Microporous Environment. Angew Chem Int Ed Engl 2023; 62:e202208693. [PMID: 36317985 PMCID: PMC10107796 DOI: 10.1002/anie.202208693] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 10/14/2022] [Accepted: 10/28/2022] [Indexed: 11/07/2022]
Abstract
The intracrystalline ionic environment in microporous zeolite can remarkably modify the excess chemical potential of adsorbed reactants and transition states, thereby influencing the catalytic turnover rates. However, a limit of the rate enhancement for aqueous-phase dehydration of alcohols appears to exist for zeolites with high ionic strength. The origin of such limitation has been hypothesized to be caused by the spatial constraints in the pores via, e.g., size exclusion effects. It is demonstrated here that the increase in turnover rate as well as the formation of a maximum and the rate drop are intrinsic consequences of the increasingly dense ionic environment in zeolite. The molecularly sized confines of zeolite create a unique ionic environment that monotonically favors the formation of alcohol-hydronium ion complexes in the micropores. The zeolite microporous environment determines the kinetics of catalytic steps and tailors the impact of ionic strength on catalytic rates.
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Affiliation(s)
- Qiang Liu
- Department of Chemistry and Catalysis Research CenterTechnical University of MunichLichtenbergstrasse 485747GarchingGermany
| | - Niklas Pfriem
- Department of Chemistry and Catalysis Research CenterTechnical University of MunichLichtenbergstrasse 485747GarchingGermany
| | - Guanhua Cheng
- Department of Chemistry and Catalysis Research CenterTechnical University of MunichLichtenbergstrasse 485747GarchingGermany
| | - Eszter Baráth
- Department of Chemistry and Catalysis Research CenterTechnical University of MunichLichtenbergstrasse 485747GarchingGermany
| | - Yue Liu
- Department of Chemistry and Catalysis Research CenterTechnical University of MunichLichtenbergstrasse 485747GarchingGermany
- Shanghai Key Laboratory of Green Chemistry and Chemical ProcessesSchool of Chemistry and Molecular EngineeringEast China Normal University200062ShanghaiP. R. China
| | - Johannes A. Lercher
- Department of Chemistry and Catalysis Research CenterTechnical University of MunichLichtenbergstrasse 485747GarchingGermany
- Institute for Integrated CatalysisPacific Northwest National LaboratoryP.O. Box 999RichlandWA 99352USA
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4
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A critical assessment of the roles of water molecules and solvated ions in acid-base-catalyzed reactions at solid-water interfaces. CHINESE JOURNAL OF CATALYSIS 2022. [DOI: 10.1016/s1872-2067(21)64032-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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5
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Gešvandtnerová M, Bučko T, Raybaud P, Chizallet C. Monomolecular mechanisms of isobutanol conversion to butenes catalyzed by acidic zeolites: alcohol isomerization as a key to the production of linear butenes. J Catal 2022. [DOI: 10.1016/j.jcat.2022.07.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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6
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Chen W, Yi X, Liu Z, Tang X, Zheng A. Carbocation chemistry confined in zeolites: spectroscopic and theoretical characterizations. Chem Soc Rev 2022; 51:4337-4385. [PMID: 35536126 DOI: 10.1039/d1cs00966d] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Acid-catalyzed reactions inside zeolites are one type of broadly applied industrial reactions, where carbocations are the most common intermediates of these reaction processes, including methanol to olefins, alkene/aromatic alkylation, and hydrocarbon cracking/isomerization. The fundamental research on these acid-catalyzed reactions is focused on the stability, evolution, and lifetime of carbocations under the zeolite confinement effect, which greatly affects the efficiency, selectivity and deactivation of zeolite catalysts. Therefore, a profound understanding of the carbocations confined in zeolites is not only beneficial to explain the reaction mechanism but also drive the design of new zeolite catalysts with ideal acidity and cages/channels. In this review, we provide both an in-depth understanding of the stabilization of carbocations by the pore confinement effect and summary of the advanced characterization methods to capture carbocations in zeolites, including UV-vis spectroscopy, solid-state NMR, fluorescence microscopy, IR spectroscopy and Raman spectroscopy. Also, we clarify the relationship between the activity and stability of carbocations in zeolite-catalyzed reactions, and further highlight the role of carbocations in various hydrocarbon conversion reactions inside zeolites with diverse frameworks and varying acidic properties.
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Affiliation(s)
- Wei Chen
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, P. R. China.
| | - Xianfeng Yi
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, P. R. China.
| | - Zhiqiang Liu
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, P. R. China.
| | - Xiaomin Tang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, P. R. China.
| | - Anmin Zheng
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, P. R. China. .,University of Chinese Academy of Sciences, Beijing 100049, P. R. China
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7
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Ding M, Shan BQ, Peng B, Zhou JF, Zhang K. Dynamic Pt-OH -·H 2O-Ag species mediate coupled electron and proton transfer for catalytic hydride reduction of 4-nitrophenol at the confined nanoscale interface. Phys Chem Chem Phys 2022; 24:7923-7936. [PMID: 35311880 DOI: 10.1039/d2cp00673a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Generally, the catalytic transformation of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) at heterogeneous metal surfaces follows a Langmuir-Hinshelwood (L-H) mechanism when sodium borohydride (NaBH4) is used as the sacrificial reductant. Herein, with Pt-Ag bimetallic nanoparticles confined in dendritic mesoporous silica nanospheres (DMSNs) as a model catalyst, we demonstrated that the conversion of 4-NP did not pass through the direct hydrogen transfer route with the hydride equivalents being supplied by borohydride via the bimolecular L-H mechanism, since Fourier transform infrared (FTIR) spectroscopy with the use of isotopically labeled reactants (NaBD4 and D2O) showed that the final product of 4-AP was composed of protons (or deuterons) that originated from the solvent water (or heavy water). Combined characterization by X-ray photoelectron spectroscopy (XPS), 1H nuclear magnetic resonance (NMR) and the optical excitation and photoluminescence spectrum evidenced that the surface hydrous hydroxide complex bound to the metal surface (also called structural water molecules, SWs), due to the space overlap of p orbitals of two O atoms in SWs, could form an ensemble of dynamic interface transient states, which provided the alternative electron and proton transfer channels for selective transformation of 4-NP. The cationic Pt species in the Ag-Pt bimetallic catalyst mainly acts as a dynamic adsorption center to temporally anchor SWs and related reactants, and not as the active site for hydrogen activation.
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Affiliation(s)
- Meng Ding
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, College of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, China.
| | - Bing-Qian Shan
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, College of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, China.
| | - Bo Peng
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, College of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, China.
| | - Jia-Feng Zhou
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, College of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, China.
| | - Kun Zhang
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, College of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, China. .,Laboratoire de chimie, Ecole Normale Supérieure de Lyon, Institut de Chimie de Lyon, Université de Lyon, 46 Allée d'italie, 69364 Lyon cedex 07, France.,Shandong Provincial Key Laboratory of Chemical Energy Storage and Novel Cell Technology, School of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng, 252059, Shandong, P. R. China.,Institute of Eco-Chongming, Shanghai 202162, China
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8
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Mendoza Merlano CJ, Zepeda TA, Alonso-Nuñez G, Diaz de Leon JN, Manrique C, Echavarría Isaza A. Effect of crystal size on the acidity of nanometric Y zeolite: number of sites, strength, acid nature, and dehydration of 2-propanol. NEW J CHEM 2022. [DOI: 10.1039/d2nj01530g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Crystallinity damage in acid Y zeolite affects the direct relationship between the number of acid sites or conversion of 2-propanol and the zeolite size and the selectivity of 2-propene in nanosized Y zeolite.
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Affiliation(s)
- C. J. Mendoza Merlano
- Universidad de Antioquia, Grupo Catalizadores y Adsorbentes, Calle 70 No. 52-21, Medellín, Colombia
| | - T. A. Zepeda
- Universidad Nacional Autónoma de México, Centro de Nanociencias y Nanotecnología(CNyN), Km. 107 Carretera Tijuana-Ensenada Col. Pedregal Playitas, C.P. 22860, Ensenada, Baja California, Mexico
| | - G. Alonso-Nuñez
- Universidad Nacional Autónoma de México, Centro de Nanociencias y Nanotecnología(CNyN), Km. 107 Carretera Tijuana-Ensenada Col. Pedregal Playitas, C.P. 22860, Ensenada, Baja California, Mexico
| | - J. Noe Diaz de Leon
- Universidad Nacional Autónoma de México, Centro de Nanociencias y Nanotecnología(CNyN), Km. 107 Carretera Tijuana-Ensenada Col. Pedregal Playitas, C.P. 22860, Ensenada, Baja California, Mexico
| | - C. Manrique
- Universidad de Antioquia, Grupo Catalizadores y Adsorbentes, Calle 70 No. 52-21, Medellín, Colombia
| | - A. Echavarría Isaza
- Universidad de Antioquia, Grupo Catalizadores y Adsorbentes, Calle 70 No. 52-21, Medellín, Colombia
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9
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Potts DS, Bregante DT, Adams JS, Torres C, Flaherty DW. Influence of solvent structure and hydrogen bonding on catalysis at solid-liquid interfaces. Chem Soc Rev 2021; 50:12308-12337. [PMID: 34569580 DOI: 10.1039/d1cs00539a] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Solvent molecules interact with reactive species and alter the rates and selectivities of catalytic reactions by orders of magnitude. Specifically, solvent molecules can modify the free energies of liquid phase and surface species via solvation, participating directly as a reactant or co-catalyst, or competitively binding to active sites. These effects carry consequences for reactions relevant for the conversion of renewable or recyclable feedstocks, the development of distributed chemical manufacturing, and the utilization of renewable energy to drive chemical reactions. First, we describe the quantitative impact of these effects on steady-state catalytic turnover rates through a rate expression derived for a generic catalytic reaction (A → B), which illustrates the functional dependence of rates on each category of solvent interaction. Second, we connect these concepts to recent investigations of the effects of solvents on catalysis to show how interactions between solvent and reactant molecules at solid-liquid interfaces influence catalytic reactions. This discussion demonstrates that the design of effective liquid phase catalytic processes benefits from a clear understanding of these intermolecular interactions and their implications for rates and selectivities.
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Affiliation(s)
- David S Potts
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
| | - Daniel T Bregante
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
| | - Jason S Adams
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
| | - Chris Torres
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
| | - David W Flaherty
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
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10
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Milaković L, Hintermeier PH, Liu Y, Baráth E, Lercher JA. Influence of Intracrystalline Ionic Strength in MFI Zeolites on Aqueous Phase Dehydration of Methylcyclohexanols. Angew Chem Int Ed Engl 2021; 60:24806-24810. [PMID: 34384139 PMCID: PMC9290721 DOI: 10.1002/anie.202107947] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 07/26/2021] [Indexed: 12/15/2022]
Abstract
The impact of the concentration of hydrated hydronium ions and in turn of the local ionic strength in MFI zeolites has been investigated for the aqueous phase dehydration of 4‐methylcyclohexanol (E1 mechanism) and cis‐2‐methylcyclohexanol (E2 mechanism). The E2 pathway with the latter alcohol led to a 2.5‐fold higher activity. The catalytic activity normalized to the hydronium ions (turnover frequency, TOF) passed through a pronounced maximum, which is attributed to the increasing excess chemical potential of the alcohols in the pores, increasing in parallel with the ionic strength and the additional work caused by repulsive interactions and charge separation induced by the bulky alcohols. While the maximum in rate observed is invariant with the mechanism or substitution, the reaction pathway is influencing the activation parameters differently.
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Affiliation(s)
- Lara Milaković
- Department of Chemistry and Catalysis Research Center, Technische Universität München, Lichtenbergstraβe 4, 85748, Garching, Germany
| | - Peter H Hintermeier
- Department of Chemistry and Catalysis Research Center, Technische Universität München, Lichtenbergstraβe 4, 85748, Garching, Germany.,Institute for Integrated Catalysis, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA, 99352, USA
| | - Yue Liu
- Department of Chemistry and Catalysis Research Center, Technische Universität München, Lichtenbergstraβe 4, 85748, Garching, Germany
| | - Eszter Baráth
- Department of Chemistry and Catalysis Research Center, Technische Universität München, Lichtenbergstraβe 4, 85748, Garching, Germany
| | - Johannes A Lercher
- Department of Chemistry and Catalysis Research Center, Technische Universität München, Lichtenbergstraβe 4, 85748, Garching, Germany.,Institute for Integrated Catalysis, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA, 99352, USA
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11
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Milaković L, Hintermeier PH, Liu Y, Baráth E, Lercher JA. Influence of Intracrystalline Ionic Strength in MFI Zeolites on Aqueous Phase Dehydration of Methylcyclohexanols. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202107947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Lara Milaković
- Department of Chemistry and Catalysis Research Center Technische Universität München Lichtenbergstraβe 4 85748 Garching Germany
| | - Peter H. Hintermeier
- Department of Chemistry and Catalysis Research Center Technische Universität München Lichtenbergstraβe 4 85748 Garching Germany
- Institute for Integrated Catalysis Pacific Northwest National Laboratory 902 Battelle Boulevard Richland WA 99352 USA
| | - Yue Liu
- Department of Chemistry and Catalysis Research Center Technische Universität München Lichtenbergstraβe 4 85748 Garching Germany
| | - Eszter Baráth
- Department of Chemistry and Catalysis Research Center Technische Universität München Lichtenbergstraβe 4 85748 Garching Germany
| | - Johannes A. Lercher
- Department of Chemistry and Catalysis Research Center Technische Universität München Lichtenbergstraβe 4 85748 Garching Germany
- Institute for Integrated Catalysis Pacific Northwest National Laboratory 902 Battelle Boulevard Richland WA 99352 USA
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12
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Liu P, Yan Z, Mei D. Insights into protonation for cyclohexanol/water mixtures at the zeolitic Brønsted acid site. Phys Chem Chem Phys 2021; 23:10395-10401. [PMID: 33889887 DOI: 10.1039/d0cp06523d] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Proton transfer from Brønsted acid sites (BASs) to alcohol molecules ignites the acid-catalyzed alcohol dehydration reactions. For aqueous phase dehydration reactions in zeolites, the coexisting water molecules around BASs in the zeolite pores significantly affect the alcohol dehydration activity. In the present work, proton transfer processes among the BASs of H-BEA zeolites, the adsorbed cyclohexanol and surrounding water clusters with different sizes up to 8 water molecules were investigated using ab initio molecular dynamics (AIMD) simulations combined with the multiple-walker well-tempered metadynamics algorithm. The plausible proton locations and proton transfer processes were characterized using two/three-dimensional free energy landscapes. The strong proton affinity makes the protonated cyclohexanol stable species until a water trimer is formed. The proton either is shared between protonated cyclohexanol and the water trimer or remains with the water trimer (H7O3+). With a further increase in water concentrations, the proton prefers to remain with the water clusters.
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Affiliation(s)
- Peng Liu
- School of Chemistry and Chemical Engineering, State Key Laboratory of Separation Membranes and Membrane Processes, Tiangong University, Tianjin 300387, P. R. China.
| | - Zhenxin Yan
- School of Chemistry and Chemical Engineering, State Key Laboratory of Separation Membranes and Membrane Processes, Tiangong University, Tianjin 300387, P. R. China.
| | - Donghai Mei
- School of Chemistry and Chemical Engineering, State Key Laboratory of Separation Membranes and Membrane Processes, Tiangong University, Tianjin 300387, P. R. China. and School of Environmental Science and Engineering, Tiangong University, Tianjin 300387, P. R. China
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13
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Bates JS, Gounder R. Kinetic effects of molecular clustering and solvation by extended networks in zeolite acid catalysis. Chem Sci 2021; 12:4699-4708. [PMID: 34168752 PMCID: PMC8179612 DOI: 10.1039/d1sc00151e] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 02/17/2021] [Indexed: 01/06/2023] Open
Abstract
Reactions catalyzed within porous inorganic and organic materials and at electrochemical interfaces commonly occur at high coverage and in condensed media, causing turnover rates to depend strongly on interfacial structure and composition, collectively referred to as "solvent effects". Transition state theory treatments define how solvation phenomena enter kinetic rate expressions, and identify two distinct types of solvent effects that originate from molecular clustering and from the solvation of such clusters by extended solvent networks. We review examples from the recent literature that investigate reactions within microporous zeolite catalysts to illustrate these concepts, and provide a critical appraisal of open questions in the field where future research can aid in developing new chemistry and catalyst design principles.
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Affiliation(s)
- Jason S Bates
- Charles D. Davidson School of Chemical Engineering, Purdue University 480 Stadium Mall Drive West Lafayette IN 47907 USA
| | - Rajamani Gounder
- Charles D. Davidson School of Chemical Engineering, Purdue University 480 Stadium Mall Drive West Lafayette IN 47907 USA
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