Non-oxidative coupling of methane over Mo-doped CeO2 catalysts: Understanding surface and gas-phase processes

Hao Zhang; Yaqiong Su; Nikolay Kosinov; Emiel J.M. Hensen

doi:10.1016/S1872-2067(23)64440-7

Non-oxidative coupling of methane over Mo-doped CeO₂ catalysts: Understanding surface and gas-phase processes

Hao Zhang, Yaqiong Su, Nikolay Kosinov (Corresponding author), Emiel J.M. Hensen (Corresponding author)

Inorganic Materials & Catalysis

Research output: Contribution to journal › Article › Academic › peer-review

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Abstract

Direct catalytic non-oxidative coupling is a promising route for the valorization of abundant methane. Understanding the mechanism is difficult because reactions at the surface of the catalyst and in the gas phase via radicals are important at the high temperatures employed. Herein, a series of Mo-doped CeO₂ samples with isolated Mo sites were prepared by flame spray pyrolysis method and screened for their performance in non-oxidative coupling of methane. The selectivity to value-added C₂ hydrocarbons (ethane and ethylene) among gas-phase products could reach 98%. During the reaction, the isolated Mo-oxo species in the as-prepared catalyst are reduced and convert into Mo (oxy-)carbide species, which act as the active sites for methane activation. By varying the available catalyst-free gas volume along the length of the reactor, we studied the contribution of gas-phase reactions in the formation of different products. Ethane is the primary product of non-oxidative methane coupling and, at least, a part of ethylene and most of benzene is formed through gas-phase chemistry. This work provides insights into the design of efficient catalysts for non-oxidative coupling of methane and highlights the importance of reducing the free volume in the reactor to limit secondary gas-phase reactions.

Original language	English
Pages (from-to)	68-80
Number of pages	13
Journal	Chinese Journal of Catalysis
Volume	49
DOIs	https://doi.org/10.1016/S1872-2067(23)64440-7
Publication status	Published - Jun 2023

Bibliographical note

Funding Information:
This work is supported by the Advanced Research Center for Chemical Building Blocks, ARC CBBC, which is co-founded and co-financed by the Netherlands Organization for Scientific Research (NWO) and the Netherlands Ministry of Economic Affairs. We acknowledge Diamond Light Source for beamtime on beamline B18 under proposal no. SP22225. We acknowledge the European Synchrotron Radiation Facility for provision of synchrotron radiation facilities and we would like to thank Jacub Drnec and Veijo Honkimäki for assistance in using beamline ID31 (DOI: 10.15151/ESRF-ES-432202550) under proposal no. MA4586. We acknowledge MAX IV Laboratory for time on beamline SPECIES-RIXS under proposal no. 20220299. Research conducted at MAX IV, a Swedish national user facility, is supported by the Swedish Research Council under contract 2018-07152, the Swedish Governmental Agency for Innovation Systems under contract 2018-04969, and Formas under contract 2019-02496. We acknowledge Anirudha Ghosh, Conny Såthe, and Ludvig Kjellsson for assistance in using the SPECIES-RIXS beamline. Supercomputing facilities were provided by the NWO and Hefei Advanced Computing Center. We acknowledge Adelheid M. Elemans-Mehring (Eindhoven University of Technology) for the assistance of ICP-OES measurements. Bianca Ligt and Valerii Muravev (Eindhoven University of Technology) are acknowledged for the assistance in the FSP synthesis. Alexander P. van Bavel (Shell Global Solutions International B.V.), Erik Zuidema (Shell Global Solutions International B.V.), and Irina Yarulina (BASF SE) are acknowledged for the fruitful discussions. Boyang Li (Xi'an Jiaotong University) is acknowledged for assistance in the DFT calculations.

Keywords

Active site
CeO
Methane
Mo
Non-oxidative coupling

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Cite this

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title = "Non-oxidative coupling of methane over Mo-doped CeO2 catalysts: Understanding surface and gas-phase processes",

abstract = "Direct catalytic non-oxidative coupling is a promising route for the valorization of abundant methane. Understanding the mechanism is difficult because reactions at the surface of the catalyst and in the gas phase via radicals are important at the high temperatures employed. Herein, a series of Mo-doped CeO2 samples with isolated Mo sites were prepared by flame spray pyrolysis method and screened for their performance in non-oxidative coupling of methane. The selectivity to value-added C2 hydrocarbons (ethane and ethylene) among gas-phase products could reach 98%. During the reaction, the isolated Mo-oxo species in the as-prepared catalyst are reduced and convert into Mo (oxy-)carbide species, which act as the active sites for methane activation. By varying the available catalyst-free gas volume along the length of the reactor, we studied the contribution of gas-phase reactions in the formation of different products. Ethane is the primary product of non-oxidative methane coupling and, at least, a part of ethylene and most of benzene is formed through gas-phase chemistry. This work provides insights into the design of efficient catalysts for non-oxidative coupling of methane and highlights the importance of reducing the free volume in the reactor to limit secondary gas-phase reactions.",

keywords = "Active site, CeO, Methane, Mo, Non-oxidative coupling",

author = "Hao Zhang and Yaqiong Su and Nikolay Kosinov and Hensen, {Emiel J.M.}",

note = "Funding Information: This work is supported by the Advanced Research Center for Chemical Building Blocks, ARC CBBC, which is co-founded and co-financed by the Netherlands Organization for Scientific Research (NWO) and the Netherlands Ministry of Economic Affairs. We acknowledge Diamond Light Source for beamtime on beamline B18 under proposal no. SP22225. We acknowledge the European Synchrotron Radiation Facility for provision of synchrotron radiation facilities and we would like to thank Jacub Drnec and Veijo Honkim{\"a}ki for assistance in using beamline ID31 (DOI: 10.15151/ESRF-ES-432202550) under proposal no. MA4586. We acknowledge MAX IV Laboratory for time on beamline SPECIES-RIXS under proposal no. 20220299. Research conducted at MAX IV, a Swedish national user facility, is supported by the Swedish Research Council under contract 2018-07152, the Swedish Governmental Agency for Innovation Systems under contract 2018-04969, and Formas under contract 2019-02496. We acknowledge Anirudha Ghosh, Conny S{\aa}the, and Ludvig Kjellsson for assistance in using the SPECIES-RIXS beamline. Supercomputing facilities were provided by the NWO and Hefei Advanced Computing Center. We acknowledge Adelheid M. Elemans-Mehring (Eindhoven University of Technology) for the assistance of ICP-OES measurements. Bianca Ligt and Valerii Muravev (Eindhoven University of Technology) are acknowledged for the assistance in the FSP synthesis. Alexander P. van Bavel (Shell Global Solutions International B.V.), Erik Zuidema (Shell Global Solutions International B.V.), and Irina Yarulina (BASF SE) are acknowledged for the fruitful discussions. Boyang Li (Xi'an Jiaotong University) is acknowledged for assistance in the DFT calculations. ",

year = "2023",

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doi = "10.1016/S1872-2067(23)64440-7",

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journal = "Chinese Journal of Catalysis",

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T2 - Understanding surface and gas-phase processes

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AU - Su, Yaqiong

AU - Kosinov, Nikolay

AU - Hensen, Emiel J.M.

N1 - Funding Information: This work is supported by the Advanced Research Center for Chemical Building Blocks, ARC CBBC, which is co-founded and co-financed by the Netherlands Organization for Scientific Research (NWO) and the Netherlands Ministry of Economic Affairs. We acknowledge Diamond Light Source for beamtime on beamline B18 under proposal no. SP22225. We acknowledge the European Synchrotron Radiation Facility for provision of synchrotron radiation facilities and we would like to thank Jacub Drnec and Veijo Honkimäki for assistance in using beamline ID31 (DOI: 10.15151/ESRF-ES-432202550) under proposal no. MA4586. We acknowledge MAX IV Laboratory for time on beamline SPECIES-RIXS under proposal no. 20220299. Research conducted at MAX IV, a Swedish national user facility, is supported by the Swedish Research Council under contract 2018-07152, the Swedish Governmental Agency for Innovation Systems under contract 2018-04969, and Formas under contract 2019-02496. We acknowledge Anirudha Ghosh, Conny Såthe, and Ludvig Kjellsson for assistance in using the SPECIES-RIXS beamline. Supercomputing facilities were provided by the NWO and Hefei Advanced Computing Center. We acknowledge Adelheid M. Elemans-Mehring (Eindhoven University of Technology) for the assistance of ICP-OES measurements. Bianca Ligt and Valerii Muravev (Eindhoven University of Technology) are acknowledged for the assistance in the FSP synthesis. Alexander P. van Bavel (Shell Global Solutions International B.V.), Erik Zuidema (Shell Global Solutions International B.V.), and Irina Yarulina (BASF SE) are acknowledged for the fruitful discussions. Boyang Li (Xi'an Jiaotong University) is acknowledged for assistance in the DFT calculations.

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N2 - Direct catalytic non-oxidative coupling is a promising route for the valorization of abundant methane. Understanding the mechanism is difficult because reactions at the surface of the catalyst and in the gas phase via radicals are important at the high temperatures employed. Herein, a series of Mo-doped CeO2 samples with isolated Mo sites were prepared by flame spray pyrolysis method and screened for their performance in non-oxidative coupling of methane. The selectivity to value-added C2 hydrocarbons (ethane and ethylene) among gas-phase products could reach 98%. During the reaction, the isolated Mo-oxo species in the as-prepared catalyst are reduced and convert into Mo (oxy-)carbide species, which act as the active sites for methane activation. By varying the available catalyst-free gas volume along the length of the reactor, we studied the contribution of gas-phase reactions in the formation of different products. Ethane is the primary product of non-oxidative methane coupling and, at least, a part of ethylene and most of benzene is formed through gas-phase chemistry. This work provides insights into the design of efficient catalysts for non-oxidative coupling of methane and highlights the importance of reducing the free volume in the reactor to limit secondary gas-phase reactions.

AB - Direct catalytic non-oxidative coupling is a promising route for the valorization of abundant methane. Understanding the mechanism is difficult because reactions at the surface of the catalyst and in the gas phase via radicals are important at the high temperatures employed. Herein, a series of Mo-doped CeO2 samples with isolated Mo sites were prepared by flame spray pyrolysis method and screened for their performance in non-oxidative coupling of methane. The selectivity to value-added C2 hydrocarbons (ethane and ethylene) among gas-phase products could reach 98%. During the reaction, the isolated Mo-oxo species in the as-prepared catalyst are reduced and convert into Mo (oxy-)carbide species, which act as the active sites for methane activation. By varying the available catalyst-free gas volume along the length of the reactor, we studied the contribution of gas-phase reactions in the formation of different products. Ethane is the primary product of non-oxidative methane coupling and, at least, a part of ethylene and most of benzene is formed through gas-phase chemistry. This work provides insights into the design of efficient catalysts for non-oxidative coupling of methane and highlights the importance of reducing the free volume in the reactor to limit secondary gas-phase reactions.

KW - Active site

KW - CeO

KW - Methane

KW - Mo

KW - Non-oxidative coupling

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