Hawkins, A. P. , Zachariou, A., Parker, S. F., Collier, P., Barrow, N. S., Howe, R. F. and Lennon, D. (2023) On the transition to Gasoline-to-Olefins chemistry in the cracking reactions of 1-octene over H-ZSM-5 catalysts. Applied Catalysis A: General, 667, 119442. (doi: 10.1016/j.apcata.2023.119442)
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Abstract
The cracking reactions of 1-octene over H-ZSM-5 zeolite are studied via micro-reactor and off-line spectroscopic techniques over a period of up to 72 hours 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 fluidized catalytic cracking unit operations.
| Item Type: | Articles |
|---|---|
| Additional 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. |
| Keywords: | Alkene cracking, ZSM-5, octene, hydrocarbon pool mechanism, inelastic neutron scattering, steamed zeolite. |
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Lennon, Professor David and Zachariou, Miss Andrea and Hawkins, Alexander and Parker, Dr Stewart |
| Creator Roles: | Hawkins, A.Methodology, Investigation, Writing – original draft, Writing – review and editing Zachariou, A.Investigation, Writing – review and editing Parker, S.Supervision, Writing – review and editing Lennon, D.Writing – review and editing, Project administration |
| Authors: | Hawkins, A. P., Zachariou, A., Parker, S. F., Collier, P., Barrow, N. S., Howe, R. F., and Lennon, D. |
| College/School: | College of Science and Engineering > School of Chemistry |
| Journal Name: | Applied Catalysis A: General |
| Publisher: | Elsevier |
| ISSN: | 0926-860X |
| ISSN (Online): | 1873-3875 |
| Published Online: | 08 October 2023 |
| Copyright Holders: | Copyright © 2023 The Author(s) |
| First Published: | First published in Applied Catalysis A: General 667: 119442 |
| Publisher Policy: | Reproduced under a Creative Commons license |
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