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Dong S, Liu L, Ling NNA, May EF, Johns ML, Robinson N. Toward Quantifying the Chemical Sensitivity of Nuclear Spin Surface Relaxivity in Mesoporous Media. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:16160-16171. [PMID: 39045723 DOI: 10.1021/acs.langmuir.4c01245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/25/2024]
Abstract
Low-field nuclear magnetic resonance (NMR) relaxation is a promising non-invasive technique for characterizing solid-liquid interactions within functional porous materials. However, the ability of the solid-liquid interface to enhance adsorbate relaxation rates, known as the surface relaxivity, in the case of different solvents and reagents involved in various chemical processes has yet to be evaluated in a quantitative manner. In this study, we systematically explore the surface relaxation characteristics of 10 liquid adsorbates (cyclohexane, acetone, water, and 7 alcohols, including ethylene glycol) confined within mesoporous silicas with pore sizes between 6 and 50 nm using low-field (12.7 MHz) two-dimensional 1H T1-T2 relaxation measurements. Functional-group-specific relaxation phenomena associated with the alkyl and hydroxyl groups of the confined alcohols are clearly distinguished; we report the dependence of both longitudinal (T1) and transverse (T2) relaxation rates of these 1H-bearing moieties on pore surface-to-volume ratio, facilitating the quantification and assignment of surface relaxivity values to specific functional groups within the same adsorbate molecule for the first time. We further demonstrate that alkyl group transverse surface relaxivities correlate strongly with the alkyl/hydroxyl ratio of the adsorbates assessed, providing evidence for a simple, quantitative relationship between surface relaxivity and interfacial chemistry. Overall, our observations highlight potential pitfalls in the application of NMR relaxation for the evaluation of pore size distributions using hydroxylated probe molecules, and provide motivation for the exploration of nuclear spin relaxation measurements as a route to adsorbate identity within functional porous materials.
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Affiliation(s)
- Shuang Dong
- Department of Chemical Engineering, The University of Western Australia, Perth, Western Australia 6009, Australia
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, Dalian University of Technology, Dalian, Liaoning 116024, People's Republic of China
| | - Libin Liu
- Department of Chemical Engineering, The University of Western Australia, Perth, Western Australia 6009, Australia
| | - Nicholas N A Ling
- Department of Chemical Engineering, The University of Western Australia, Perth, Western Australia 6009, Australia
| | - Eric F May
- Department of Chemical Engineering, The University of Western Australia, Perth, Western Australia 6009, Australia
| | - Michael L Johns
- Department of Chemical Engineering, The University of Western Australia, Perth, Western Australia 6009, Australia
| | - Neil Robinson
- Department of Chemical Engineering, The University of Western Australia, Perth, Western Australia 6009, Australia
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2
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Cleary SR, Starace AK, Curran-Velasco CC, Ruddy DA, McGuirk CM. The Overlooked Potential of Sulfated Zirconia: Reexamining Solid Superacidity Toward the Controlled Depolymerization of Polyolefins. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:6612-6653. [PMID: 38509763 DOI: 10.1021/acs.langmuir.3c03966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/22/2024]
Abstract
Closed-loop recycling via an efficient chemical process can help alleviate the global plastic waste crisis. However, conventional depolymerization methods for polyolefins, which compose more than 50% of plastics, demand high temperatures and pressures, employ precious noble metals, and/or yield complex mixtures of products limited to single-use fuels or oils. Superacidic forms of sulfated zirconia (SZrO) with Hammet Acidity Functions (H0) ≤ - 12 (i.e., stronger than 100% H2SO4) are industrially deployed heterogeneous catalysts capable of activating hydrocarbons under mild conditions and are shown to decompose polyolefins at temperatures near 200 °C and ambient pressure. Additionally, confinement of active sites in porous supports is known to radically increase selectivity, coking and sintering resistance, and acid site activity, presenting a possible approach to low-energy polyolefin depolymerization. However, a critical examination of the literature on SZrO led us to a surprising conclusion: despite 40 years of catalytic study, engineering, and industrial use, the surface chemistry of SZrO is poorly understood. Ostensibly spurred by SZrO's impressive catalytic activity, the application-driven study of SZrO has resulted in deleterious ambiguity in requisite synthetic conditions for superacidity and insufficient characterization of acidity, porosity, and active site structure. This ambiguity has produced significant knowledge gaps surrounding the synthesis, structure, and mechanisms of hydrocarbon activation for optimized SZrO, stunting the potential of this catalyst in olefin cracking and other industrially relevant reactions, such as isomerization, esterification, and alkylation. Toward mitigating these long extant issues, we herein identify and highlight these current shortcomings and knowledge gaps, propose explicit guidelines for characterization of and reporting on characterization of solid acidity, and discuss the potential of pore-confined superacids in the efficient and selective depolymerization of polyolefins.
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Affiliation(s)
- Scott R Cleary
- Department of Chemistry, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Anne K Starace
- National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Caleb C Curran-Velasco
- Department of Chemistry, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Daniel A Ruddy
- National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - C Michael McGuirk
- Department of Chemistry, Colorado School of Mines, Golden, Colorado 80401, United States
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3
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Wu X, Wang X, Zhang L, Wang X, Song S, Zhang H. Polyethylene Upgrading to Liquid Fuels Boosted by Atomic Ce Promoters. Angew Chem Int Ed Engl 2024; 63:e202317594. [PMID: 38183405 DOI: 10.1002/anie.202317594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Revised: 12/28/2023] [Accepted: 01/05/2024] [Indexed: 01/08/2024]
Abstract
Hydrocracking catalysis is a key route to plastic waste upgrading, but the acid site-driven C-C cleavage step is relatively sluggish in conventional bifunctional catalysts, dramatically effecting the overall efficiency. We demonstrate here a facile and efficient way to boost the reactivity of acid sites by introducing Ce promoters into Pt/HY catalysts, thus achieving a better metal-acid balance. Remarkably, 100 % of low-density polyethylene (LDPE) can be converted with 80.9 % selectivity of liquid fuels over the obtained Pt/5Ce-HY catalysts at 300 °C in 2 h. For comparison, Pt/HY only gives 38.8 % of LDPE conversion with 21.3 % selectivity of liquid fuels. Through multiple experimental studies on the structure-performance relationship, the Ce species occupied in the supercage are identified as the actual active sites, which possess remarkably-improved adsorption capability towards short-chain intermediates.
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Affiliation(s)
- Xueting Wu
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, China
- School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei, 230026, China
| | - Xiao Wang
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, China
- School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei, 230026, China
| | - Lingling Zhang
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, China
| | - Xiaomei Wang
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, China
- School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei, 230026, China
| | - Shuyan Song
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, China
- School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei, 230026, China
| | - Hongjie Zhang
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, China
- School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei, 230026, China
- Department of Chemistry, Tsinghua University, Beijing, 100084, China
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4
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Gomes GJ, Zalazar MF, Padilha JC, Costa MB, Bazzi CL, Arroyo PA. Unveiling the mechanisms of carboxylic acid esterification on acid zeolites for biomass-to-energy: A review of the catalytic process through experimental and computational studies. CHEMOSPHERE 2024; 349:140879. [PMID: 38061565 DOI: 10.1016/j.chemosphere.2023.140879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 11/19/2023] [Accepted: 12/01/2023] [Indexed: 01/10/2024]
Abstract
In recent years, there has been significant interest from industrial and academic areas in the esterification of carboxylic acids catalyzed by acidic zeolites, as it represents a sustainable and economically viable approach to producing a wide range of high-value-added products. However, there is a lack of comprehensive reviews that address the intricate reaction mechanisms occurring at the catalyst interface at both the experimental and atomistic levels. Therefore, in this review, we provide an overview of the esterification reaction on acidic zeolites based on experimental and theoretical studies. The combination of infrared spectroscopy with atomistic calculations and experimental strategies using modulation excitation spectroscopy techniques combined with phase-sensitive detection is presented as an approach to detecting short-lived intermediates at the interface of zeolitic frameworks under realistic reaction conditions. To achieve this goal, this review has been divided into four sections: The first is a brief introduction highlighting the distinctive features of this review. The second addresses questions about the topology and activity of different zeolitic systems, since these properties are closely correlated in the esterification process. The third section deals with the mechanisms proposed in the literature. The fourth section presents advances in IR techniques and theoretical calculations that can be applied to gain new insights into reaction mechanisms. Finally, this review concludes with a subtle approach, highlighting the main aspects and perspectives of combining experimental and theoretical techniques to elucidate different reaction mechanisms in zeolitic systems.
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Affiliation(s)
- Glaucio José Gomes
- Laboratorio de Estructura Molecular y Propiedades (LEMyP), Instituto de Química Básica y Aplicada Del Nordeste Argentino, (IQUIBA-NEA), Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional Del Nordeste (CONICET-UNNE), Avenida Libertad 5460, 3400, Corrientes, Argentina; Laboratório de Catálise Heterogênea e Biodiesel (LCHBio), Universidade Estadual de Maringá (UEM), Avenida Colombo, 5790, (87020-900), Maringá, Paraná, Brazil; Programa de Pós-Graduação Interdisciplinar Em Energia e Sustentabilidade, Universidade Federal da Integração Latino-Americana (UNILA), Avenida Presidente Tancredo Neves, 3838, (85870-650), Foz Do Iguaçu, Paraná, Brazil.
| | - María Fernanda Zalazar
- Laboratorio de Estructura Molecular y Propiedades (LEMyP), Instituto de Química Básica y Aplicada Del Nordeste Argentino, (IQUIBA-NEA), Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional Del Nordeste (CONICET-UNNE), Avenida Libertad 5460, 3400, Corrientes, Argentina.
| | - Janine Carvalho Padilha
- Programa de Pós-Graduação Interdisciplinar Em Energia e Sustentabilidade, Universidade Federal da Integração Latino-Americana (UNILA), Avenida Presidente Tancredo Neves, 3838, (85870-650), Foz Do Iguaçu, Paraná, Brazil
| | - Michelle Budke Costa
- Universidade Tecnológica Federal Do Paraná (UTFPR), Avenida Brasil 4232, (85884-000), Medianeira, Brazil
| | - Claudio Leones Bazzi
- Universidade Tecnológica Federal Do Paraná (UTFPR), Avenida Brasil 4232, (85884-000), Medianeira, Brazil
| | - Pedro Augusto Arroyo
- Laboratório de Catálise Heterogênea e Biodiesel (LCHBio), Universidade Estadual de Maringá (UEM), Avenida Colombo, 5790, (87020-900), Maringá, Paraná, Brazil
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5
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Samudrala KK, Conley MP. Effects of surface acidity on the structure of organometallics supported on oxide surfaces. Chem Commun (Camb) 2023; 59:4115-4127. [PMID: 36912586 DOI: 10.1039/d3cc00047h] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
Well-defined organometallics supported on high surface area oxides are promising heterogeneous catalysts. An important design factor in these materials is how the metal interacts with the functionalities on an oxide support, commonly anionic X-type ligands derived from the reaction of an organometallic M-R with an -OH site on the oxide. The metal can either form a covalent M-O bond or form an electrostatic M+⋯-O ion-pair, which impacts how well-defined organometallics will interact with substrates in catalytic reactions. A less common reaction pathway involves the reaction of a Lewis site on the oxide with the organometallic, resulting in abstraction to form an ion-pair, which is relevant to industrial olefin polymerization catalysts. This Feature Article views the spectrum of reactivity between an organometallic and an oxide through the prism of Brønsted and/or Lewis acidity of surface sites and draws analogies to the molecular frame where Lewis and Brønsted acids are known to form reactive ion-pairs. Applications of the well-defined sites developed in this article are also discussed.
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Affiliation(s)
| | - Matthew P Conley
- Department of Chemistry, University of California, Riverside, California 92521, USA.
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6
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Synergistic interplay of dual active sites on spinel ZnAl2O4 for syngas conversion. Chem 2023. [DOI: 10.1016/j.chempr.2023.01.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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7
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Peng WL, Liu F, Yi X, Sun S, Shi H, Hui Y, Chen W, Yu X, Liu Z, Qin Y, Song L, Zheng A. Structural and Acidic Characteristics of Multiple Zr Defect Sites in UiO-66 Metal-Organic Frameworks. J Phys Chem Lett 2022; 13:9295-9302. [PMID: 36173737 DOI: 10.1021/acs.jpclett.2c02468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Although defects are prevalent in metal-organic frameworks (MOFs) and usually play a crucial role in modulating their performance in various applications, detailed structural characterizations of various defects remain a challenging task mainly due to their disordered, heterogeneous, and local nature. In this work, by using solid-state nuclear magnetic resonance spectroscopy (SSNMR) techniques in conjunction with density functional theory (DFT) calculations, it is clearly elucidated that the trimethylphosphine (TMP)-assisted 31P NMR strategy is capable of greatly facilitating the qualitative and quantitative description of the detailed structural and acidic characteristics as well as the evolution process of various Zr defects with subtle distinctions in UiO-66 upon moderate thermal treatment, hence surpassing most conventional analytical techniques. These results offer a fundamental understanding of the defect chemistry in MOFs.
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Affiliation(s)
- Wen-Li Peng
- 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
| | - Fengqing 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
- University of Chinese Academy of Sciences, Beijing 100049, 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
| | - Shugang Sun
- School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225009, P. R. China
| | - Hui Shi
- School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225009, P. R. China
| | - Yu Hui
- Key Laboratory of Petrochemical Catalytic Science and Technology, Liaoning Petrochemical University, Fushun 113001, P. R. China
| | - 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
| | - Xin Yu
- 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
| | - 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
| | - Yucai Qin
- Key Laboratory of Petrochemical Catalytic Science and Technology, Liaoning Petrochemical University, Fushun 113001, P. R. China
| | - Lijuan Song
- Key Laboratory of Petrochemical Catalytic Science and Technology, Liaoning Petrochemical University, Fushun 113001, 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
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8
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Qiu Y, Yuan B, Mi H, Lee JH, Chou SW, Peng YK. An Atomic Insight into the Confusion on the Activity of Fe 3O 4 Nanoparticles as Peroxidase Mimetics and Their Comparison with Horseradish Peroxidase. J Phys Chem Lett 2022; 13:8872-8878. [PMID: 36125422 DOI: 10.1021/acs.jpclett.2c02331] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Although Fe3O4 nanoparticles were early reported to outperform horseradish peroxidase (HRP), recent studies suggested that this material bears a very poor activity instead. Here, we resolve this disagreement by reviewing the definition of descriptors used and provide an atomic view into the origin of Fe3O4 nanoparticles as peroxidase mimetics. The redox between H2O2 and Fe(II) sites on the Fe3O4 surface was identified as the key step to producing OH radicals for the oxidation of colorimetric substrates. This mechanism involving free radicals is distinct from that of HRP oxidizing substrates with a radical retained on its Fe-porphyrin ring. Surprisingly, the distribution and chemical state of Fe species were found to be very different on single- and polycrystalline Fe3O4 nanoparticles with the latter bearing not only a higher Fe(II)/Fe(III) ratio but also a more reactive Fe(II) species at surface grain boundaries. This accounts for the unexpected gap in the catalytic constant (kcat) observed for this material in the literature.
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Affiliation(s)
- Yuwei Qiu
- Department of Chemistry, City University of Hong Kong, 0000 Hong Kong, Hong Kong SAR, China
| | - Bo Yuan
- Department of Chemistry, City University of Hong Kong, 0000 Hong Kong, Hong Kong SAR, China
| | - Hua Mi
- Department of Chemistry, City University of Hong Kong, 0000 Hong Kong, Hong Kong SAR, China
| | - Jung-Hoon Lee
- Department of Chemistry, Soonchunhyang University, Asan 31538, Korea
| | - Shang-Wei Chou
- Instrumentation Center, National Taiwan University, Taipei 10617, Taiwan
| | - Yung-Kang Peng
- Department of Chemistry, City University of Hong Kong, 0000 Hong Kong, Hong Kong SAR, China
- City University of Hong Kong Shenzhen Research Institute, Shenzhen 518057, China
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9
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Liu P, Liu Q, Liu W, Peng S, Mei D. Mechanistic insights into positional and skeletal isomerization of cyclohexene in the H-BEA zeolite. Phys Chem Chem Phys 2022; 24:18043-18054. [PMID: 35861155 DOI: 10.1039/d2cp02310e] [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
The isomerization of cycloalkenes via the formation of carbenium cations assisted by the Brønsted acid site (BAS) in zeolites is the vital reaction step in hydrocracking and hydroisomerization processes of the petrochemical industry. To understand the acid-catalyzed positional isomerization and skeletal isomerization of cycloalkenes via carbenium intermediates, a series of ab initio molecular dynamics (AIMD) simulations of cyclohexene within the H-BEA zeolite have been carried out. AIMD simulations combined with the enhanced sampling technique reveal that the half-chair conformer is the most stable conformation for cyclohexene within H-BEA. Free energy landscapes characterizing protonation/deprotonation, positional isomerization, and skeletal isomerization of cyclohexene have been mapped out at 413 K. The free energy barrier for the formation of carbenium is calculated to be 44 kJ mol-1. The skeletal isomerization of cyclohexene to methylcyclopentylium via the protonated cyclopropane transition state involves four stages with a total free energy barrier of 134 kJ mol-1. Further geometrical analysis provides additional information about the structural origin of free energy barriers.
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Affiliation(s)
- Peng Liu
- School of Chemical Engineering and Technology, Tiangong University, Tianjin 300387, P. R. China.
| | - Qian Liu
- School of Chemical Engineering and Technology, Tiangong University, Tianjin 300387, P. R. China.
| | - Wei Liu
- SINOPEC Dalian Research Institute of Petroleum and Petrochemicals, Dalian, Liaoning Province, 116045, P. R. China.
| | - Shaozhong Peng
- SINOPEC Dalian Research Institute of Petroleum and Petrochemicals, Dalian, Liaoning Province, 116045, P. R. China.
| | - Donghai Mei
- School of Chemical Engineering and Technology, Tiangong University, Tianjin 300387, P. R. China. .,School of Environmental Science and Engineering, Tiangong University, Tianjin, 300387, P. R. China
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10
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Bekyarova E, Conley MP. The coordination chemistry of oxide and nanocarbon materials. Dalton Trans 2022; 51:8557-8570. [PMID: 35586978 DOI: 10.1039/d2dt00459c] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Understanding how a ligand affects the steric and electronic properties of a metal is the cornerstone of the inorganic chemistry enterprise. What happens when the ligand is an extended surface? This question is central to the design and implementation of state-of-the-art functional materials containing transition metals. This perspective will describe how these two very different sets of extended surfaces can form well-defined coordination complexes with metals. In the Green formalism, functionalities on oxide surfaces react with inorganics to form species that contain X-type or LX-type interactions between the metal and the oxide. Carbon surfaces are neutral L-type ligands; this perspective focuses on carbons that donate six electrons to a metal. The nature of this interaction depends on the curvature, and thereby orbital overlap, between the metal and the extended π-system from the nanocarbon.
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Affiliation(s)
- Elena Bekyarova
- Department of Chemistry, University of California, Riverside, California 92521, USA.
| | - Matthew P Conley
- Department of Chemistry, University of California, Riverside, California 92521, USA.
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11
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Halawy SA, Osman AI, Abdelkader A, Nasr M, Rooney DW. Assessment of Lewis-Acidic Surface Sites Using Tetrahydrofuran as a Suitable and Smart Probe Molecule. ChemistryOpen 2022; 11:e202200021. [PMID: 35324079 PMCID: PMC8944219 DOI: 10.1002/open.202200021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 03/04/2022] [Indexed: 02/03/2023] Open
Abstract
Measuring the Lewis-acidic surface sites in catalysis is problematic when the material's surface area is very low (SBET ≤1 m2 ⋅ g-1 ). For the first time, a quantitative assessment of total acidic surface sites of very small surface area catalysts (MoO3 as pure and mixed with 5-30 % CdO (wt/wt), as well as CdO for comparison) was performed using a smart new probe molecule, tetrahydrofuran (THF). The results were nearly identical compared to using another commonly used probe molecule, pyridine. This audition is based on the limited values of the surface area of these samples that likely require a relatively moderate basic molecule as THF with pKb =16.08, rather than strong basic molecules such as NH3 (pKb =4.75) or pyridine (pKb =8.77). We propose mechanisms for the interaction of vapour phase molecules of THF with the Lewis-cationic Mo and Cd atoms of these catalysts. Besides, dehydration of isopropyl alcohol was used as a probe reaction to investigate the catalytic activity of these catalysts to further support our findings in the case of THF in a temperature range of 175-300 °C. A good agreement between the obtained data of sample MoO3 -10 % CdO, which is characterised by the highest surface area value, the population of Lewis-acidic sites and % selectivity of propylene at all the applied reaction temperatures was found.
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Affiliation(s)
- Samih A. Halawy
- Nanocomposite Catalysts Lab.Chemistry DepartmentFaculty of Science at QenaSouth Valley UniversityQena83523Egypt
| | - Ahmed I. Osman
- Nanocomposite Catalysts Lab.Chemistry DepartmentFaculty of Science at QenaSouth Valley UniversityQena83523Egypt
- School of Chemistry and Chemical EngineeringQueen's University BelfastDavid Keir BuildingBelfastBT9 5AGUK
| | - Adel Abdelkader
- Nanocomposite Catalysts Lab.Chemistry DepartmentFaculty of Science at QenaSouth Valley UniversityQena83523Egypt
| | - Mahmoud Nasr
- Nanocomposite Catalysts Lab.Chemistry DepartmentFaculty of Science at QenaSouth Valley UniversityQena83523Egypt
| | - David W. Rooney
- School of Chemistry and Chemical EngineeringQueen's University BelfastDavid Keir BuildingBelfastBT9 5AGUK
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12
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Zhang W, Lin Z, Li H, Wang F, Wen Y, Xu M, Wang Y, Ke X, Xia X, Chen J, Peng L. Surface acidity of tin dioxide nanomaterials revealed with 31P solid-state NMR spectroscopy and DFT calculations. RSC Adv 2021; 11:25004-25009. [PMID: 35481043 PMCID: PMC9037001 DOI: 10.1039/d1ra02782d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 07/13/2021] [Indexed: 12/29/2022] Open
Abstract
Tin dioxide (SnO2) nanomaterials are important acid catalysts. It is therefore crucial to obtain details about the surface acidic properties in order to develop structure–property relationships. Herein, we apply 31P solid-state NMR spectroscopy combined with a trimethylphosphine (TMP) probe molecule, to study the facet-dependent acidity of SnO2 nanosheets and nanoshuttles. With the help of density functional theory calculations, we show that the tin cations exposed on the surfaces are Lewis acid sites and their acid strengths rely on surface geometries. As a result, the (001), (101), (110), and (100) facets can be differentiated by the 31P NMR shifts of adsorbed TMP molecules, and their fractions in different nanomaterials can be extracted according to deconvoluted 31P NMR resonances. The results provide new insights on nanosized oxide acid catalysts. Facet-dependent acidity of SnO2 nanosheets and nanoshuttles is revealed with TMP-assisted 31P solid-state NMR spectroscopy and DFT calculations.![]()
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Affiliation(s)
- Wenjing Zhang
- Key Laboratory of Mesoscopic Chemistry of MOE, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University 163 Xianlin Road Nanjing 210023 China
| | - Zhiye Lin
- Key Laboratory of Mesoscopic Chemistry of MOE, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University 163 Xianlin Road Nanjing 210023 China
| | - Hanxiao Li
- Chinesisch-Deutsche Technische Fakultät, Qingdao University of Science and Technology 99 Songling Road Qingdao 266061 China
| | - Fang Wang
- Key Laboratory of Mesoscopic Chemistry of MOE, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University 163 Xianlin Road Nanjing 210023 China
| | - Yujie Wen
- Key Laboratory of Mesoscopic Chemistry of MOE, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University 163 Xianlin Road Nanjing 210023 China
| | - Meng Xu
- Key Laboratory of Mesoscopic Chemistry of MOE, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University 163 Xianlin Road Nanjing 210023 China
| | - Yang Wang
- Key Laboratory of Mesoscopic Chemistry of MOE, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University 163 Xianlin Road Nanjing 210023 China
| | - Xiaokang Ke
- Key Laboratory of Mesoscopic Chemistry of MOE, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University 163 Xianlin Road Nanjing 210023 China
| | - Xifeng Xia
- Analysis and Testing Center, Nanjing University of Science and Technology Nanjing 210094 China
| | - Junchao Chen
- Key Laboratory of Mesoscopic Chemistry of MOE, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University 163 Xianlin Road Nanjing 210023 China
| | - Luming Peng
- Key Laboratory of Mesoscopic Chemistry of MOE, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University 163 Xianlin Road Nanjing 210023 China
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Pham TN, Nguyen V, Wang B, White JL, Crossley S. Quantifying the Influence of Water on the Mobility of Aluminum Species and Their Effects on Alkane Cracking in Zeolites. ACS Catal 2021. [DOI: 10.1021/acscatal.1c01138] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tram N. Pham
- School of Chemical, Biological, and Materials Engineering, University of Oklahoma, Norman, Oklahoma 73019, United States
| | - Vy Nguyen
- School of Chemical, Biological, and Materials Engineering, University of Oklahoma, Norman, Oklahoma 73019, United States
| | - Bin Wang
- School of Chemical, Biological, and Materials Engineering, University of Oklahoma, Norman, Oklahoma 73019, United States
| | - Jeffery L. White
- School of Chemical Engineering, Oklahoma State University, Stillwater, Oklahoma 74078, United States
| | - Steven Crossley
- School of Chemical, Biological, and Materials Engineering, University of Oklahoma, Norman, Oklahoma 73019, United States
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