Assessment of coke deposits on lamellar metal-modified MFI zeolites in ethylene transformation to aromatic liquids

• Published in: Applied catalysis. A, General Vol. 595; p. 117510
• Main Authors: Emdadi, Laleh, Mahoney, Luther, Lee, Ivan C., Leff, Asher C., Wu, Wei, Liu, Dongxia, Nguyen, Chi K., Tran, Dat T.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 05.04.2020; Elsevier Science SA
• Subjects: Argon; Catalysts; Coke; Coke formation; Deposits; Ethylene; Ethylene conversion; Gallium; Lamellar structure; Lamellar zeolite; Liquids; Metal-modified zeolite; MFI; Oxidation; Regeneration; zeolite; Zeolites; Zinc; Ethylene conversion; MFI; Coke formation; Lamellar zeolite; zeolite; Metal-modified zeolite
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/j.apcata.2020.117510

[Display omitted] •Characteristics of the coke deposits on lamellar metal (Ga or Zn)-modified zeolites were studied.•Mesoporous lamellar structure decreases the coke formation by facilitating the external coke deposition.•Metal modification decreases the coke formation by changing the acidity of zeolite.•Highest fraction of light coke is obtained for Zn-modified lamellar zeolite.•Both zeolite structure and metal-modified acidity affect the coke formation. The effects of meso-/microporous structure and metal-additive (Ga or Zn) of lamellar MFI catalysts on the characteristics of coke deposits during ethylene-to-aromatic liquids conversion were investigated. The nature, composition, and location of coke deposits in spent lamellar catalysts were analyzed and compared to those on the microporous MFI counterparts, using FTIR, UV–Vis, GC–MS, and argon adsorption-desorption. The total amount of coke and the changes in coke nature during catalyst regeneration were studied by MS/FTIR combined with temperature programmed oxidation. The lamellar meso-/microporous structure of MFI reduces the coke quantity and the heavy coke fractions. The coke preferentially deposites on external surface of lamellar zeolite due to the lower diffusion limitation for bulky coke precursors. Metal-additive changes the catalyst acidity and decreases the coke formation rate, especially when zinc is used. Therefore, the coke formation on zeolite can be tuned by modulating the textural and acidity properties of the metal-modified catalyst.