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Campbell E, Sazanovich IV, Towrie M, Watson MJ, Lezcano-Gonzalez I, Beale AM. Methanol-to-Olefins Studied by UV Raman Spectroscopy as Compared to Visible Wavelength: Capitalization on Resonance Enhancement. J Phys Chem Lett 2024; 15:6826-6834. [PMID: 38916593 PMCID: PMC11229064 DOI: 10.1021/acs.jpclett.4c00865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 05/21/2024] [Accepted: 05/29/2024] [Indexed: 06/26/2024]
Abstract
Resonance Raman spectroscopy can provide insights into complex reaction mechanisms by selectively enhancing the signals of specific molecular species. In this work, we demonstrate that, by changing the excitation wavelength, Raman bands of different intermediates in the methanol-to-hydrocarbons reactions can be identified. We show in particular how UV excitation enhances signals from short-chain olefins and cyclopentadienyl cations during the induction period, while visible excitation better detects later-stage aromatics. However, visible excitation is prone to fluorescence that can obscure Raman signals, and hence, we show how fast fluorescence rejection techniques like Kerr gating are necessary for extracting useful information from visible excitation measurements.
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Affiliation(s)
- Emma Campbell
- Cardiff
Catalysis Institute School of Chemistry, Cardiff University, Cardiff CF10 3AT, U.K.
- Research
Complex at Harwell (RCaH), Harwell, Didcot, Oxfordshire OX11
0FA, U.K.
| | - Igor V. Sazanovich
- Central
Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratories, Harwell
Campus, Didcot OX11 0QX, U.K.
| | - Michael Towrie
- Central
Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratories, Harwell
Campus, Didcot OX11 0QX, U.K.
| | - Michael J. Watson
- Johnson
Matthey Technology Centre, P O Box 1, Belasis Avenue, Billingham TS23 1LB, U.K.
| | - Ines Lezcano-Gonzalez
- Department
of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K.
- Research
Complex at Harwell (RCaH), Harwell, Didcot, Oxfordshire OX11
0FA, U.K.
| | - Andrew M. Beale
- Department
of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K.
- Research
Complex at Harwell (RCaH), Harwell, Didcot, Oxfordshire OX11
0FA, U.K.
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2
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You X, Zhang X, Ye Y, Zhou H, Jiang S, Zhou X, Dutta Chowdhury A. Evaluating the efficacy of zeolites synthesized from natural clay for the methanol-to-hydrocarbon process. Dalton Trans 2023; 52:14390-14399. [PMID: 37781869 DOI: 10.1039/d3dt02131a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/03/2023]
Abstract
Introducing sustainability into advanced catalytic material design is essential to address growing environmental concerns. Among them, synthesizing inorganic zeolite materials from non-traditional sources (like natural clay) offers several advantages, contributing to sustainability and environmental stewardship. With this objective, we used kaolin to synthesize zeolites with different topologies: SSZ-13 (8-MR with CHA topology), ZSM-5 (10-MR with MFI topology), and Beta (12-MR with BEA topology) (MR: member ring), where a simple and flexible synthetic protocol was adopted without any significant changes. All these zeolites were subjected to catalytic performance evaluation concerning the industrially relevant methanol-to-hydrocarbon (MTH) process. Herein, the kaolin-derived zeolites, especially ZSM-5, led to superior performance and demonstrated enhanced catalyst deactivation-resistant behavior compared to their zeolite counterparts prepared from traditional synthetic routes. Various characterization tools (including under operando conditions) were employed to understand their reactions and deactivation mechanisms. Overall, making zeolites from non-traditional sources presents a pathway for sustainable and environmentally friendly material production, offering benefits such as reduced resource dependence, lower energy consumption, and tailored physicochemical properties beneficial to catalysis. In a broader context, such a research approach contributes to the transition toward a more sustainable and circular economy.
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Affiliation(s)
- Xinyu You
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, Hubei, China.
| | - Xin Zhang
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, Hubei, China.
| | - Yiru Ye
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, Hubei, China.
| | - Hexun Zhou
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, Hubei, China.
| | - Shican Jiang
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, Hubei, China.
| | - Xue Zhou
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, Hubei, China.
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3
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Liu C, Uslamin EA, Pidko EA, Kapteijn F. Revealing Main Reaction Paths to Olefins and Aromatics in Methanol-to-Hydrocarbons over H-ZSM-5 by Isotope Labeling. ACS Catal 2023. [DOI: 10.1021/acscatal.3c00168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
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4
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Liutkova A, Zhang H, Simons JFM, Mezari B, Mirolo M, Garcia GA, Hensen EJM, Kosinov N. Ca Cations Impact the Local Environment inside HZSM-5 Pores during the Methanol-to-Hydrocarbons Reaction. ACS Catal 2023; 13:3471-3484. [PMID: 36970466 PMCID: PMC10028611 DOI: 10.1021/acscatal.3c00059] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 02/10/2023] [Indexed: 02/25/2023]
Abstract
The methanol-to-hydrocarbons (MTH) process is an industrially relevant method to produce valuable light olefins such as propylene. One of the ways to enhance propylene selectivity is to modify zeolite catalysts with alkaline earth cations. The underlying mechanistic aspects of this type of promotion are not well understood. Here, we study the interaction of Ca2+ with reaction intermediates and products formed during the MTH reaction. Using transient kinetic and spectroscopic tools, we find strong indications that the selectivity differences between Ca/ZSM-5 and HZSM-5 are related to the different local environment inside the pores due to the presence of Ca2+. In particular, Ca/ZSM-5 strongly retains water, hydrocarbons, and oxygenates, which occupy as much as 10% of the micropores during the ongoing MTH reaction. This change in the effective pore geometry affects the formation of hydrocarbon pool components and in this way directs the MTH reaction toward the olefin cycle.
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Affiliation(s)
- Anna Liutkova
- Laboratory of Inorganic Materials and Catalysis, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Hao Zhang
- Laboratory of Inorganic Materials and Catalysis, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Jérôme F. M. Simons
- Laboratory of Inorganic Materials and Catalysis, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Brahim Mezari
- Laboratory of Inorganic Materials and Catalysis, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Marta Mirolo
- ESRF, The European Synchrotron, 71 Avenue des Martyrs, CS40220, 38043 Grenoble, Cedex 9, France
| | - Gustavo A. Garcia
- Synchrotron SOLEIL, L’Orme des Merisiers, St Aubin, B.P. 48, 91192 Gif sur Yvette, France
| | - Emiel J. M. Hensen
- Laboratory of Inorganic Materials and Catalysis, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Nikolay Kosinov
- Laboratory of Inorganic Materials and Catalysis, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
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5
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Wang C, Chu Y, Hu M, Cai W, Wang Q, Li S, Xu J, Deng F. Influence of zeolite confinement effects on cation-π interactions in methanol-to-hydrocarbon conversion. Chem Commun (Camb) 2022; 58:9242-9245. [PMID: 35899845 DOI: 10.1039/d2cc02216h] [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
By using 2D 13C-13C correlation MAS NMR spectroscopy and DFT calculations, the nature of cation-π interactions between cyclopentenyl cations and benzene was clarified over H-ZSM-5, H-β and H-SSZ-13 zeolites. The cation-π interactions are favored over H-β and H-SSZ-13 with large channels or cages. The zeolite structure is identified to affect the arrangements of cyclopentenyl cations and benzene in the confined environment, leading to different extents of overlapping of positive-negative charge centers and cation-π interaction strength. The stronger cation-π interactions facilitate the bimolecular reactions between cyclopentenyl cations and benzene and the formation of coke species.
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Affiliation(s)
- Chao Wang
- National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China.
| | - Yueying Chu
- National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China.
| | - Min Hu
- National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China. .,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wenjin Cai
- National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China. .,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qiang Wang
- National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China.
| | - Shenhui Li
- National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China.
| | - Jun Xu
- National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China.
| | - Feng Deng
- National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China.
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6
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Spectro-kinetics in the methanol to hydrocarbon reaction combining online product analysis with UV-vis and FTIR spectroscopies in the analysis of the space time. J Catal 2022. [DOI: 10.1016/j.jcat.2022.02.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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7
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Airi A, Damin A, Xie J, Olsbye U, Bordiga S. Catalyst sites and active species in the early stages of MTO conversion over cobalt AlPO-18 followed by IR spectroscopy. Catal Sci Technol 2022. [DOI: 10.1039/d2cy00303a] [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
Reaction-time resolved IR spectroscopy highlights the role of CO and surface –OCH3 in the MTO conversion catalysed by CoAPO-18 with maximised concentration of acidic sites.
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Affiliation(s)
- Alessia Airi
- Department of Chemistry, NIS, and INSTM Reference Centre, University of Turin, Via Quarello 15/A, 10135, Turin, Italy
| | - Alessandro Damin
- Department of Chemistry, NIS, and INSTM Reference Centre, University of Turin, Via Quarello 15/A, 10135, Turin, Italy
| | - Jingxiu Xie
- Centre for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo, Oslo N-0315, Norway
| | - Unni Olsbye
- Centre for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo, Oslo N-0315, Norway
| | - Silvia Bordiga
- Department of Chemistry, NIS, and INSTM Reference Centre, University of Turin, Via Quarello 15/A, 10135, Turin, Italy
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8
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Minova IB, Bühl M, Matam SK, Catlow CRA, Frogley MD, Cinque G, Wright PA, Howe RF. Carbene-like reactivity of methoxy groups in a single crystal SAPO-34 MTO catalyst. Catal Sci Technol 2022. [DOI: 10.1039/d1cy02361f] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
In situ synchrotron infrared microspectroscopy on single crystals of SAPO-34 reveals that a carbene insertion mechanism is responsible for the first carbon–carbon bond formation from surface methoxy groups.
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Affiliation(s)
- Ivalina B. Minova
- EastCHEM School of Chemistry, University of St Andrews, St Andrews KY16 9ST, UK
| | - Michael Bühl
- EastCHEM School of Chemistry, University of St Andrews, St Andrews KY16 9ST, UK
| | - Santhosh K. Matam
- UK Catalysis Hub, Research Complex at Harwell, Rutherford Appleton Laboratory, Oxford, OX11 0FA, UK
- Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Cardiff CF10 3AT, UK
| | - C. Richard A. Catlow
- UK Catalysis Hub, Research Complex at Harwell, Rutherford Appleton Laboratory, Oxford, OX11 0FA, UK
- Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Cardiff CF10 3AT, UK
- Department of Chemistry, University College London, London WC1E 6BT, UK
| | - Mark D. Frogley
- MIRIAM beamline B22, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK
| | - Gianfelice Cinque
- MIRIAM beamline B22, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK
| | - Paul A. Wright
- EastCHEM School of Chemistry, University of St Andrews, St Andrews KY16 9ST, UK
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9
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Hernandez ED, Manookian B, Auerbach SM, Jentoft FC. Shape-Selective Synthesis of Alkylcyclopentenyl Cations in Zeolites and Spectroscopic Distinction of Constitutional Isomers. ACS Catal 2021. [DOI: 10.1021/acscatal.1c03039] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Eric D. Hernandez
- Department of Chemical Engineering, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
| | - Babgen Manookian
- Department of Chemistry, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
| | - Scott M. Auerbach
- Department of Chemistry, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
| | - Friederike C. Jentoft
- Department of Chemical Engineering, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
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10
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Li T, Shoinkhorova T, Gascon J, Ruiz-Martínez J. Aromatics Production via Methanol-Mediated Transformation Routes. ACS Catal 2021. [DOI: 10.1021/acscatal.1c01422] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Teng Li
- King Abdullah University of Science and Technology, KAUST Catalysis Center (KCC), Thuwal 23955-6900, Saudi Arabia
| | - Tuiana Shoinkhorova
- King Abdullah University of Science and Technology, KAUST Catalysis Center (KCC), Thuwal 23955-6900, Saudi Arabia
| | - Jorge Gascon
- King Abdullah University of Science and Technology, KAUST Catalysis Center (KCC), Thuwal 23955-6900, Saudi Arabia
| | - Javier Ruiz-Martínez
- King Abdullah University of Science and Technology, KAUST Catalysis Center (KCC), Thuwal 23955-6900, Saudi Arabia
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11
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Zachariou A, Hawkins AP, Suwardiyanto, Collier P, Barrow N, Howe RF, Parker SF, Lennon D. New Spectroscopic Insight into the Deactivation of a ZSM‐5 Methanol‐to‐Hydrocarbons Catalyst. ChemCatChem 2021. [DOI: 10.1002/cctc.202100286] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Andrea Zachariou
- School of Chemistry University of Glasgow Joseph Black Building Glasgow G12 8QQ UK
- UK Catalysis Hub Research Complex at Harwell STFC Rutherford Appleton Laboratory Chilton, Oxon OX11 0FA UK
| | - Alexander P. Hawkins
- School of Chemistry University of Glasgow Joseph Black Building Glasgow G12 8QQ UK
- UK Catalysis Hub Research Complex at Harwell STFC Rutherford Appleton Laboratory Chilton, Oxon OX11 0FA UK
| | - Suwardiyanto
- Department of Chemistry University of Jember Jember 68121 East Java Indonesia
| | - Paul Collier
- Johnson Matthey Plc. Johnson Matthey Technology Centre Blounts Court Sonning Common Reading RG4 9NH UK
| | - Nathan Barrow
- Johnson Matthey Plc. Johnson Matthey Technology Centre Blounts Court Sonning Common Reading RG4 9NH UK
| | - Russell F. Howe
- Department of Chemistry University of Aberdeen Meston Building Aberdeen AB24 3UE UK
| | - Stewart F. Parker
- School of Chemistry University of Glasgow Joseph Black Building Glasgow G12 8QQ UK
- UK Catalysis Hub Research Complex at Harwell STFC Rutherford Appleton Laboratory Chilton, Oxon OX11 0FA UK
- ISIS Neutron and Muon Source ISIS Facility STFC Rutherford Appleton Laboratory Chilton, Oxon OX11 0QX UK
| | - David Lennon
- School of Chemistry University of Glasgow Joseph Black Building Glasgow G12 8QQ UK
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12
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Valecillos J, Elordi G, Aguayo AT, Castaño P. The intrinsic effect of co-feeding water on the formation of active/deactivating species in the methanol-to-hydrocarbons reaction on ZSM-5 zeolite. Catal Sci Technol 2021. [DOI: 10.1039/d0cy02497j] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Water is formed and added in the conversion of methanol to hydrocarbons, slowing down both the reaction and deactivation rates. The retained species that are reaction intermediates and coke precursors are swept/desorbed, particularly those on silanol sites.
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Affiliation(s)
- José Valecillos
- Department of Chemical Engineering
- University of the Basque Country (UPV/EHU)
- Bilbao
- 48080 Spain
| | - Gorka Elordi
- Department of Chemical Engineering
- University of the Basque Country (UPV/EHU)
- Bilbao
- 48080 Spain
| | - Andrés T. Aguayo
- Department of Chemical Engineering
- University of the Basque Country (UPV/EHU)
- Bilbao
- 48080 Spain
| | - Pedro Castaño
- Department of Chemical Engineering
- University of the Basque Country (UPV/EHU)
- Bilbao
- 48080 Spain
- Multiscale Reaction Engineering KAUST Catalysis Center (KCC)
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13
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Hawkins AP, Zachariou A, Parker SF, Collier P, Howe RF, Lennon D. Studies of propene conversion over H-ZSM-5 demonstrate the importance of propene as an intermediate in methanol-to-hydrocarbons chemistry. Catal Sci Technol 2021. [DOI: 10.1039/d1cy00048a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A role for propene as an intermediate in methanol-to-hydrocarbons chemistry over H-ZSM-5 is considered.
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Affiliation(s)
| | - Andrea Zachariou
- School of Chemistry
- University of Glasgow
- Glasgow G12 8QQ
- UK
- UK Catalysis Hub
| | - Stewart F. Parker
- UK Catalysis Hub
- Research Complex at Harwell
- STFC Rutherford Appleton Laboratory
- UK
- ISIS Neutron and Muon Source
| | - Paul Collier
- Johnson Matthey Technology Centre
- Reading RG4 9NH
- UK
| | | | - David Lennon
- School of Chemistry
- University of Glasgow
- Glasgow G12 8QQ
- UK
- UK Catalysis Hub
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14
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Azarhoosh MJ, Azarhoosh AR. Presenting a Four-Lump Dynamic Kinetic Model for Methanol to Light Olefins Process Over the Hierarchical SAPO-34 Catalyst Using Power Law Models. Comb Chem High Throughput Screen 2020; 24:570-580. [PMID: 32933454 DOI: 10.2174/1386207323666200915092724] [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: 05/12/2020] [Revised: 08/17/2020] [Accepted: 08/17/2020] [Indexed: 11/22/2022]
Abstract
OBJECTIVES A four-lump dynamic kinetic model on the hierarchical SAPO-34 catalyst in the methanol to light olefins (MTO) process has been presented using the power law models. Since decreased catalyst activity in the MTO process is common, for the applicability of the proposed model, the function of catalyst activity was computed as a function of the coke percentage deposited on the catalyst. MATERIALS AND METHODS The reactant and products were divided into four lumps, including methanol and dimethyl ether (DME), light olefins (ethylene and propylene), light paraffin (methane, ethane, and propane) and heavier hydrocarbons from C4. The one-dimensional ideal plug reactor was used for the simulation of the MTO reactor. The kinetic parameters and the catalyst activity function were predicted using the particle swarm optimization (PSO) algorithm. RESULTS The comparison of product distribution in the experimental model and the results of the kinetic model indicated the high accuracy of the presented model. The effect of operational parameters such as temperature and weight hourly space velocity (WHSV) on the mole percent of light olefins was investigated using the proposed kinetic model. The optimized value of temperature and WHSV to reach the maximum yield of light olefins was respectively 460 ˚C and 4.2 h-1. CONCLUSION The passive kinetic coefficients were estimated in the reaction rate constant and catalyst activity function with the help of the PSO optimization algorithm. The mole fraction of different products and the reactant arising from modeling at the reactor outlet was compared with experimental results, which indicated the high accuracy of the presented kinetic model. The results also revealed that the selection of high and low temperatures and WHSV decreases the yield of light olefins and the lifetime of the catalyst.
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15
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Synthesis of HZSM-5 Rich in Paired Al and Its Catalytic Performance for Propane Aromatization. Catalysts 2020. [DOI: 10.3390/catal10060622] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
A series of HZSM-5 catalysts with similar Si/AlF mole ratio, textual properties and morphology, but different contents of AlF pairs, were synthesized by controlling the Na/Al molar ratios in the precursor gel and used for propane aromatization. It is shown that the catalyst with a Na/Al molar ratio of 0.8 in the synthetic gel possesses the highest paired AlF concentration (64.4%) and shows higher propane conversion (38.2%) and aromatics selectivity (19.7 wt.%). Propane pulse experiments, micro reactor activity estimation, Operando diffuse reflectance ultraviolet-visible (DR UV-vis) spectroscopy and Fourier Transform Infrared Spectroscopy (FTIR) analysis of coke species deposited on the catalysts provide evidence that AlF pairs in the ZSM-5 framework promote oligomerization and cyclization reactions of olefins, and then produce more aromatics. Density Functional Theory (DFT) calculations demonstrate that the cyclization of olefins and hydride transfer reaction occurring on AlF pairs in HZSM-5 zeolite show a lower free energy barrier and a higher rate constant than those on single AlF, indicating that the structure of AlF pairs in the HZSM-5 zeolite has a stronger electrostatic stabilization effect on the transition states than that of single AlF.
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