On the transition to gasoline-to-olefins chemistry in the cracking reactions of 1-octene over H-ZSM-5 catalysts

Alexander P. Hawkins; Andrea Zachariou; Stewart F. Parker; Paul Collier; Nathan S. Barrow; Russell F. Howe; David Lennon

doi:10.1016/j.apcata.2023.119442

On the transition to gasoline-to-olefins chemistry in the cracking reactions of 1-octene over H-ZSM-5 catalysts

Alexander P. Hawkins, Andrea Zachariou, Stewart F. Parker^*, Paul Collier, Nathan S. Barrow, Russell F. Howe, David Lennon

^*Corresponding author for this work

Chemistry

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

Abstract

The cracking reactions of 1-octene over H-ZSM-5 zeolite are studied via micro-reactor and off-line spectroscopic techniques for up to 72 h on stream and a temperature range of 473–673 K. 1-Octene is found to react via a two-cycle hydrocarbon pool mechanism, with strong similarities to that reported for methanol-to-hydrocarbons chemistry. This dual-cycle mechanism requires temperatures of 673 K or higher to function with full efficiency, with lower temperatures deactivating portions of the cyclic mechanism, leading to premature deactivation of the catalyst through over-production of coke species. Inelastic neutron scattering is used to study the coke composition, identifying two distinct deactivation mechanisms depending on reaction temperature. The catalyst is also found to slowly progress from an aromatic-heavy to an olefin-heavy product regime even at full efficiency due to progressive blockage of active sites by amorphous carbon-rich coke. Artificial aging of the zeolite, through steam treatment, is found to shift the catalyst lifetime so that it commences at a later stage in this process, resulting in increased light olefin production. The reduced aromatic production also means that deactivation of the catalyst occurs more slowly in steamed catalysts than in fresh ones, after an equivalent time-on-stream. Collectively, these observations connect with the application of ZSM-5 catalysts to facilitate gasoline-to-olefins chemistry in fluidised catalytic cracking unit operations.

Original language	English
Article number	119442
Journal	Applied Catalysis A: General
Volume	667
Early online date	16 Oct 2023
DOIs	https://doi.org/10.1016/j.apcata.2023.119442
Publication status	Published - 25 Oct 2023

Bibliographical note

Funding Information:
Johnson Matthey plc. is thanked for supplying the ZSM-5 zeolite and for financial support through the provision of industrial CASE studentships in partnership with the EPSRC (APH ( EP/P510506/1 , AZ ( EP/N509176/1 )). The resources and support provided by the UK Catalysis Hub via membership of the UK Catalysis Hub consortium and funded by EPSRC grants EP/R026815/1 and EP/R026939/1 are gratefully acknowledged. This research has been performed with the use of facilities and equipment at the Research Complex at Harwell; the authors are grateful to the Research Complex for this access and support. We would like to thank Dr Daniel Nye for help on the Rigaku Miniflex 600 powder X-ray diffractometer in the Materials Characterisation Laboratory at the ISIS Neutron and Muon Source. The ISIS Neutron and Muon Source is thanked for access to neutron beam facilities via beam time allocations (RB2010486 [54 ] and RB2000212 [55] ).

Publisher Copyright:
© 2023 The Authors

Data Availability Statement

Data will be made available on request

Keywords

Hydrocarbon pool mechanism
Inelastic neutron scattering
Octene
Olefin cracking
Steamed zeolite
ZSM-5

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Cite this

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title = "On the transition to gasoline-to-olefins chemistry in the cracking reactions of 1-octene over H-ZSM-5 catalysts",

abstract = "The cracking reactions of 1-octene over H-ZSM-5 zeolite are studied via micro-reactor and off-line spectroscopic techniques for up to 72 h on stream and a temperature range of 473–673 K. 1-Octene is found to react via a two-cycle hydrocarbon pool mechanism, with strong similarities to that reported for methanol-to-hydrocarbons chemistry. This dual-cycle mechanism requires temperatures of 673 K or higher to function with full efficiency, with lower temperatures deactivating portions of the cyclic mechanism, leading to premature deactivation of the catalyst through over-production of coke species. Inelastic neutron scattering is used to study the coke composition, identifying two distinct deactivation mechanisms depending on reaction temperature. The catalyst is also found to slowly progress from an aromatic-heavy to an olefin-heavy product regime even at full efficiency due to progressive blockage of active sites by amorphous carbon-rich coke. Artificial aging of the zeolite, through steam treatment, is found to shift the catalyst lifetime so that it commences at a later stage in this process, resulting in increased light olefin production. The reduced aromatic production also means that deactivation of the catalyst occurs more slowly in steamed catalysts than in fresh ones, after an equivalent time-on-stream. Collectively, these observations connect with the application of ZSM-5 catalysts to facilitate gasoline-to-olefins chemistry in fluidised catalytic cracking unit operations.",

keywords = "Hydrocarbon pool mechanism, Inelastic neutron scattering, Octene, Olefin cracking, Steamed zeolite, ZSM-5",

author = "Hawkins, {Alexander P.} and Andrea Zachariou and Parker, {Stewart F.} and Paul Collier and Barrow, {Nathan S.} and Howe, {Russell F.} and David Lennon",

note = "Funding Information: Johnson Matthey plc. is thanked for supplying the ZSM-5 zeolite and for financial support through the provision of industrial CASE studentships in partnership with the EPSRC (APH ( EP/P510506/1 , AZ ( EP/N509176/1 )). The resources and support provided by the UK Catalysis Hub via membership of the UK Catalysis Hub consortium and funded by EPSRC grants EP/R026815/1 and EP/R026939/1 are gratefully acknowledged. This research has been performed with the use of facilities and equipment at the Research Complex at Harwell; the authors are grateful to the Research Complex for this access and support. We would like to thank Dr Daniel Nye for help on the Rigaku Miniflex 600 powder X-ray diffractometer in the Materials Characterisation Laboratory at the ISIS Neutron and Muon Source. The ISIS Neutron and Muon Source is thanked for access to neutron beam facilities via beam time allocations (RB2010486 [54 ] and RB2000212 [55] ). Publisher Copyright: {\textcopyright} 2023 The Authors",

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AU - Zachariou, Andrea

AU - Parker, Stewart F.

AU - Collier, Paul

AU - Barrow, Nathan S.

AU - Howe, Russell F.

AU - Lennon, David

N1 - Funding Information: Johnson Matthey plc. is thanked for supplying the ZSM-5 zeolite and for financial support through the provision of industrial CASE studentships in partnership with the EPSRC (APH ( EP/P510506/1 , AZ ( EP/N509176/1 )). The resources and support provided by the UK Catalysis Hub via membership of the UK Catalysis Hub consortium and funded by EPSRC grants EP/R026815/1 and EP/R026939/1 are gratefully acknowledged. This research has been performed with the use of facilities and equipment at the Research Complex at Harwell; the authors are grateful to the Research Complex for this access and support. We would like to thank Dr Daniel Nye for help on the Rigaku Miniflex 600 powder X-ray diffractometer in the Materials Characterisation Laboratory at the ISIS Neutron and Muon Source. The ISIS Neutron and Muon Source is thanked for access to neutron beam facilities via beam time allocations (RB2010486 [54 ] and RB2000212 [55] ). Publisher Copyright: © 2023 The Authors

PY - 2023/10/25

Y1 - 2023/10/25

N2 - The cracking reactions of 1-octene over H-ZSM-5 zeolite are studied via micro-reactor and off-line spectroscopic techniques for up to 72 h on stream and a temperature range of 473–673 K. 1-Octene is found to react via a two-cycle hydrocarbon pool mechanism, with strong similarities to that reported for methanol-to-hydrocarbons chemistry. This dual-cycle mechanism requires temperatures of 673 K or higher to function with full efficiency, with lower temperatures deactivating portions of the cyclic mechanism, leading to premature deactivation of the catalyst through over-production of coke species. Inelastic neutron scattering is used to study the coke composition, identifying two distinct deactivation mechanisms depending on reaction temperature. The catalyst is also found to slowly progress from an aromatic-heavy to an olefin-heavy product regime even at full efficiency due to progressive blockage of active sites by amorphous carbon-rich coke. Artificial aging of the zeolite, through steam treatment, is found to shift the catalyst lifetime so that it commences at a later stage in this process, resulting in increased light olefin production. The reduced aromatic production also means that deactivation of the catalyst occurs more slowly in steamed catalysts than in fresh ones, after an equivalent time-on-stream. Collectively, these observations connect with the application of ZSM-5 catalysts to facilitate gasoline-to-olefins chemistry in fluidised catalytic cracking unit operations.

AB - The cracking reactions of 1-octene over H-ZSM-5 zeolite are studied via micro-reactor and off-line spectroscopic techniques for up to 72 h on stream and a temperature range of 473–673 K. 1-Octene is found to react via a two-cycle hydrocarbon pool mechanism, with strong similarities to that reported for methanol-to-hydrocarbons chemistry. This dual-cycle mechanism requires temperatures of 673 K or higher to function with full efficiency, with lower temperatures deactivating portions of the cyclic mechanism, leading to premature deactivation of the catalyst through over-production of coke species. Inelastic neutron scattering is used to study the coke composition, identifying two distinct deactivation mechanisms depending on reaction temperature. The catalyst is also found to slowly progress from an aromatic-heavy to an olefin-heavy product regime even at full efficiency due to progressive blockage of active sites by amorphous carbon-rich coke. Artificial aging of the zeolite, through steam treatment, is found to shift the catalyst lifetime so that it commences at a later stage in this process, resulting in increased light olefin production. The reduced aromatic production also means that deactivation of the catalyst occurs more slowly in steamed catalysts than in fresh ones, after an equivalent time-on-stream. Collectively, these observations connect with the application of ZSM-5 catalysts to facilitate gasoline-to-olefins chemistry in fluidised catalytic cracking unit operations.

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KW - Inelastic neutron scattering

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KW - Olefin cracking

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JO - Applied Catalysis A: General

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ER -

On the transition to gasoline-to-olefins chemistry in the cracking reactions of 1-octene over H-ZSM-5 catalysts

Abstract

Bibliographical note

Data Availability Statement

Keywords

Access to Document

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