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Nifant'ev I, Komarov P, Sadrtdinova G, Safronov V, Kolosov N, Ivchenko P. Mechanistic Insights of Ethylene Polymerization on Phillips Chromium Catalysts. Polymers (Basel) 2024; 16:681. [PMID: 38475365 DOI: 10.3390/polym16050681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 02/28/2024] [Accepted: 02/29/2024] [Indexed: 03/14/2024] Open
Abstract
Silica-supported chromium oxide catalysts, also named Phillips chromium catalysts (PCCs), provide more than half of the world's production of high- and medium-density polyethylenes. PCCs are usually prepared in the Cr(VI)/SiO2 form, which is subjected to reductive activation. It has been explicitly proven that CO reduces Cr(VI) to Cr(II) species that initiate ethylene polymerization; ethylene activates Cr(VI) sites as well, but the nature of the catalytic species is complicated by the presence of the ethylene oxidation products. It is widely accepted that the catalytic species are of a Cr(III)-alkyl nature, but this common assumption faces the challenge of "extra" hydrogen: the formation of similar species under the action of even-electron reducing agents requires an additional H atom. Relatively recently, it was found that saturated hydrocarbons can also activate CrOx/SiO2, and alkyl fragments turn out to be bonded with a polyethylene chain. In recent years, there have been numerous experimental and theoretical studies of the structure and chemistry of PCCs at the different stages of preparation and activation. The use of modern spectral methods (such as extended X-ray absorption fine structure (EXAFS), X-ray absorption near-edge structure (XANES), and others); operando IR, UV-vis, EPR, and XAS spectroscopies; and theoretical approaches (DFT modeling, machine learning) clarified many essential aspects of the mechanisms of CrOx/SiO2 activation and catalytic behavior. Overall, the Cosse-Arlman mechanism of polymerization on Cr(III)-alkyl centers is confirmed in many works, but its theoretical support required the development of nontrivial and contentious mechanistic concepts of Cr(VI)/SiO2 or Cr(II)/SiO2 activation. On the other hand, conflicting experimental data continue to be obtained, and certain mechanistic concepts are being developed with the use of outdated models. Strictly speaking, the main question of what type of catalytic species, Cr(II), Cr(III), or Cr(IV), comes into polymerization still has not received an unambiguous answer. The role of the chemical nature of the support-through the prism of the nature, geometry, and distribution of the active sites-is also not clear in depth. In the present review, we endeavored to summarize and discuss the recent studies in the field of the preparation, activation, and action of PCCs, with a focus on existing contradictions in the interpretation of the experimental and theoretical results.
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Affiliation(s)
- Ilya Nifant'ev
- A.V. Topchiev Institute of Petrochemical Synthesis RAS, 29 Leninsky Pr., 119991 Moscow, Russia
- Department of Chemistry, M.V. Lomonosov Moscow University, 1-3 Leninskie Gory, 119991 Moscow, Russia
| | - Pavel Komarov
- A.V. Topchiev Institute of Petrochemical Synthesis RAS, 29 Leninsky Pr., 119991 Moscow, Russia
| | - Guzelia Sadrtdinova
- A.V. Topchiev Institute of Petrochemical Synthesis RAS, 29 Leninsky Pr., 119991 Moscow, Russia
- Faculty of Chemistry, National Research University Higher School of Economics, Myasnitskaya St. 20, 101100 Moscow, Russia
| | | | | | - Pavel Ivchenko
- A.V. Topchiev Institute of Petrochemical Synthesis RAS, 29 Leninsky Pr., 119991 Moscow, Russia
- Department of Chemistry, M.V. Lomonosov Moscow University, 1-3 Leninskie Gory, 119991 Moscow, Russia
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Huang C, Liu Z, Liu B, Terano M, Jin Y. Computational Insights into the Multisite Nature of the Phillips CrO x/SiO 2 Catalyst for Ethylene Polymerization: The Perspective of Chromasiloxane Ring Size and F Modification. ACS Catal 2022. [DOI: 10.1021/acscatal.1c04998] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Cuimin Huang
- Key Laboratory for Biobased Materials and Energy of Ministry of Education, College of Materials and Energy, South China Agricultural University, Guangzhou 510630, People’s Republic of China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510630, People’s Republic of China
| | - Zhen Liu
- State Key Laboratory of Chemical Engineering, School of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, People’s Republic of China
| | - Boping Liu
- Key Laboratory for Biobased Materials and Energy of Ministry of Education, College of Materials and Energy, South China Agricultural University, Guangzhou 510630, People’s Republic of China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510630, People’s Republic of China
| | - Minoru Terano
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan
| | - Yulong Jin
- Key Laboratory for Biobased Materials and Energy of Ministry of Education, College of Materials and Energy, South China Agricultural University, Guangzhou 510630, People’s Republic of China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510630, People’s Republic of China
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Tielens F, Gierada M, Handzlik J, Calatayud M. Characterization of amorphous silica based catalysts using DFT computational methods. Catal Today 2020. [DOI: 10.1016/j.cattod.2019.03.062] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Copéret C. Single-Sites and Nanoparticles at Tailored Interfaces Prepared via Surface Organometallic Chemistry from Thermolytic Molecular Precursors. Acc Chem Res 2019; 52:1697-1708. [PMID: 31150207 DOI: 10.1021/acs.accounts.9b00138] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Heterogeneous catalysts are complex by nature, making particularly difficult to assess the structure of their active sites. Such complexity is inherited in part from their mode of preparation, which typically involves coprecipitation or impregnation of metal salts in aqueous solution, and the associated complex surface chemistries. In this context, surface organometallic chemistry (SOMC) has emerged as a powerful approach to generate well-defined surface species, where the metal sites are introduced by grafting tailored molecular precursors. When combined with thermolytic molecular precursors (TMPs) that can lose their organic moieties quite readily upon thermal treatment, SOMC provides access to supported isolated metal sites with defined oxidation state and nuclearity inherited from the precursor. The resulting surface species bear unusual coordination imposed by the surface that provides them high reactivity in comparison with their molecular precursor. In addition, these molecularly defined species bare strong resemblance with the active sites of supported metal oxides. However, they typically contain a higher proportion of active sites making structure-activity relationship possible. They thus constitute ideal models for this important class of industrial catalysts that are used in numerous applications such as olefin epoxidation (Shell process), olefin metathesis (triolefin process), ethylene polymerization (Phillips catalysts), or propane dehydrogenation (Catofin and related processes). This SOMC/TMP approach can thus provide detailed information about the structure of active sites in industrial catalysts, their mode of initiation and deactivation, as well as the role of the support and specific thermal treatment on the final activity of the catalysts. Nonetheless, these structurally characterized surface sites still exhibit heterogeneous environments borrowed from the support itself, that explain the intrinsic complexity of heterogeneous catalysis. Furthermore, SOMC/TMP can also be used to generate and investigate supported metal nanoparticles. Starting from the well-defined isolated sites, that also contain adjacent surface OH groups, one can graft a second metal and then generate after treatment under hydrogen small and narrowly dispersed alloys or nanoparticles with tailored interfaces that can show improved catalytic performances and are amiable to detailed structure-activity relationships. This approach is illustrated by two case studies: (1) formation of supported copper nanoparticles at tailored interfaces that contain isolated metal sites for the selective hydrogenation of carbon dioxide to methanol, allowing for a detailed understanding of the role of dopants and supports in heterogeneous catalysis, and (2) preparation of highly selective and productive propane dehydrogenation catalysts based on silica-supported Pt xGa y alloy. Overall, this Account shows how the combination of SOMC and TMP helps to generate catalysts, particularly suited for elucidating structural characterization of active sites at a molecular-level which in turn enables structure-activity relationship to be drawn. Such detailed information obtained on well-defined catalysts can then be used to understand complex effects observed in industrial catalysts (effects of supports, additives, dopants, etc.), and to extract information that can then be used to improve them in a more rational way.
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Affiliation(s)
- Christophe Copéret
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir Prelog Weg. 1-5, CH-8093 Zürich, Switzerland
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Bucinsky L, Breza M, Malček M, Powers DC, Hwang SJ, Krzystek J, Nocera DG, Telser J. High-Frequency and -Field EPR (HFEPR) Investigation of a Pseudotetrahedral CrIV Siloxide Complex and Computational Studies of Related CrIVL4 Systems. Inorg Chem 2019; 58:4907-4920. [DOI: 10.1021/acs.inorgchem.8b03512] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Lukas Bucinsky
- Institute of Physical Chemistry and Chemical Physics, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, SK-81237 Bratislava, Slovakia
| | - Martin Breza
- Institute of Physical Chemistry and Chemical Physics, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, SK-81237 Bratislava, Slovakia
| | - Michal Malček
- Institute of Physical Chemistry and Chemical Physics, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, SK-81237 Bratislava, Slovakia
| | - David C. Powers
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Seung Jun Hwang
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - J. Krzystek
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
| | - Daniel G. Nocera
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Joshua Telser
- Department of Biological, Physical and Health Sciences, Roosevelt University, Chicago, Illinois 60605, United States
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Groppo E, Martino GA, Piovano A, Barzan C. The Active Sites in the Phillips Catalysts: Origins of a Lively Debate and a Vision for the Future. ACS Catal 2018. [DOI: 10.1021/acscatal.8b02521] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Elena Groppo
- Department of Chemistry, NIS Centre and INSTM, University of Torino, Via Quarello 15/A, 10125 Torino, Italy
| | - Giorgia Antonina Martino
- Department of Chemistry, NIS Centre and INSTM, University of Torino, Via Quarello 15/A, 10125 Torino, Italy
| | - Alessandro Piovano
- Department of Chemistry, NIS Centre and INSTM, University of Torino, Via Quarello 15/A, 10125 Torino, Italy
| | - Caterina Barzan
- Department of Chemistry, NIS Centre and INSTM, University of Torino, Via Quarello 15/A, 10125 Torino, Italy
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Active sites formation and their transformations during ethylene polymerization by the Phillips CrOx/SiO2 catalyst. J Catal 2017. [DOI: 10.1016/j.jcat.2017.05.025] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Baba R, Thakur A, Chammingkwan P, Terano M, Taniike T. The influence of functional groups on the ethylene polymerization performance of silsesquioxane-supported Phillips-type catalysts. Dalton Trans 2017; 46:12158-12166. [DOI: 10.1039/c7dt02492d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A series of silsesquioxane-supported Phillips-type molecular catalysts for ethylene polymerization were synthesized by introducing various functional groups in proximity to monoalkylated Cr(iii).
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Affiliation(s)
- Ryuki Baba
- Graduate School of Advanced Science and Technology
- Japan Advanced Institute of Science and Technology
- Nomi
- Japan
| | - Ashutosh Thakur
- Graduate School of Advanced Science and Technology
- Japan Advanced Institute of Science and Technology
- Nomi
- Japan
| | - Patchanee Chammingkwan
- Graduate School of Advanced Science and Technology
- Japan Advanced Institute of Science and Technology
- Nomi
- Japan
| | - Minoru Terano
- Graduate School of Advanced Science and Technology
- Japan Advanced Institute of Science and Technology
- Nomi
- Japan
| | - Toshiaki Taniike
- Graduate School of Advanced Science and Technology
- Japan Advanced Institute of Science and Technology
- Nomi
- Japan
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Gierada M, Michorczyk P, Tielens F, Handzlik J. Reduction of chromia–silica catalysts: A molecular picture. J Catal 2016. [DOI: 10.1016/j.jcat.2016.04.022] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Chakrabarti A, Gierada M, Handzlik J, Wachs IE. Operando Molecular Spectroscopy During Ethylene Polymerization by Supported CrO x /SiO2 Catalysts: Active Sites, Reaction Intermediates, and Structure-Activity Relationship. Top Catal 2016. [DOI: 10.1007/s11244-016-0546-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Copéret C, Comas-Vives A, Conley MP, Estes DP, Fedorov A, Mougel V, Nagae H, Núñez-Zarur F, Zhizhko PA. Surface Organometallic and Coordination Chemistry toward Single-Site Heterogeneous Catalysts: Strategies, Methods, Structures, and Activities. Chem Rev 2016; 116:323-421. [PMID: 26741024 DOI: 10.1021/acs.chemrev.5b00373] [Citation(s) in RCA: 497] [Impact Index Per Article: 62.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Christophe Copéret
- Department of Chemistry and Applied Biosciences, ETH Zürich , Vladimir Prelog Weg 1-5, CH-8093 Zürich, Switzerland
| | - Aleix Comas-Vives
- Department of Chemistry and Applied Biosciences, ETH Zürich , Vladimir Prelog Weg 1-5, CH-8093 Zürich, Switzerland
| | - Matthew P Conley
- Department of Chemistry and Applied Biosciences, ETH Zürich , Vladimir Prelog Weg 1-5, CH-8093 Zürich, Switzerland
| | - Deven P Estes
- Department of Chemistry and Applied Biosciences, ETH Zürich , Vladimir Prelog Weg 1-5, CH-8093 Zürich, Switzerland
| | - Alexey Fedorov
- Department of Chemistry and Applied Biosciences, ETH Zürich , Vladimir Prelog Weg 1-5, CH-8093 Zürich, Switzerland
| | - Victor Mougel
- Department of Chemistry and Applied Biosciences, ETH Zürich , Vladimir Prelog Weg 1-5, CH-8093 Zürich, Switzerland
| | - Haruki Nagae
- Department of Chemistry and Applied Biosciences, ETH Zürich , Vladimir Prelog Weg 1-5, CH-8093 Zürich, Switzerland.,Department of Chemistry, Graduate School of Engineering Science, Osaka University, CREST , Toyonaka, Osaka 560-8531, Japan
| | - Francisco Núñez-Zarur
- Department of Chemistry and Applied Biosciences, ETH Zürich , Vladimir Prelog Weg 1-5, CH-8093 Zürich, Switzerland
| | - Pavel A Zhizhko
- Department of Chemistry and Applied Biosciences, ETH Zürich , Vladimir Prelog Weg 1-5, CH-8093 Zürich, Switzerland.,A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences , Vavilov str. 28, 119991 Moscow, Russia
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