Unconventional coke composition during high temperature anisole disproportionation on zeolites

• Published in: Applied catalysis. A, General Vol. 682; p. 119808
• Main Authors: Pichot, N., Chaouati, N., Lemaitre, T., Fahda, M., Valtchev, V., Mintova, S., Gilson, J.-P., Dufour, A., Pinard, L.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 25-07-2024; Elsevier
• Subjects: Anisole; Catalysis; Chemical Sciences; Coke; Organic chemistry; Phenolic compounds; Zeolite; Zeolite pore size; Zeolite pore size; Zeolite; Phenolic compounds; Anisole; Coke; coke; phenolic compounds
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/j.apcata.2024.119808

Catalyst deactivation and shape selectivity in evolved products and retained coke are studied on medium, large and extra-large pore zeolites with varying Si/Al ratios in the disproportionation of anisole. Deactivation modelling as a function of time on stream highlights the key role of the catalyst pore volume. Changes in selectivity between the primary (methylanisole) and secondary (cresol) products are due to the overtaking of one path over a second for the production of cresol. The nature of the products (methyl phenols) inhibits the formation of “usual” polyaromatic and non-oxygenated coke via the Sullivan mechanism, leaving only adsorbed oxygenated monoaromatics, available for transalkylation reactions with the feed, having adsorbed and fouled most of the available surface in the catalyst channels.
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•Pore shape and size has not impact on coke nature for anisole disproportionation.•MOR, FAU, *BEA and JZO zeolites yield to the same oxygenated coke molecules: methyl-phenolics.•Phenolic function blocks the ring contraction/expansion mechanism responsible for coke growth.•Deactivation is by fouling and depends mainly on the pore volume and channel interconnectivity.