(560ed) Assessment of the Coke Deposited on Lamellar Metal-Modified MFI Zeolite Catalysts in the Transformation of Ethylene to Liquid Aromatics

The effects of zeolite structure and its metal modification on the coke deposition during ethylene conversion reaction to liquid aromatics have been studied by combining the results of multiple analytical and spectroscopic techniques. Gallium or zinc-loaded lamellar MFI zeolites were used as catalysts. The nature, location, and amount of coke in the spent lamellar catalysts were determined by FTIR, UV-Vis, argon adsorption-desorption, and MS-temperature programmed oxidation (MS-TPO) and compared to their commercial microporous zeolite counterparts. FTIR-TPO has also been used to investigate the changes in the nature of the coke during the catalyst regeneration through combustion. The results show that the total amount of coke and the heavy coke fraction are reduced in the lamellar zeolite compared to its solely microporous analogue due to its meso-/microporous structure that provides lower diffusion limitations for bulky coke precursors and facilitates the formation of higher amount of the external coke. Metal-modification of the zeolite changes the acidity properties of the catalyst and as a result decreases the coke deposition rate during the reaction. Therefore, the coke formation on the zeolite catalyst and as a result its regenerability can be tuned by modulating both the textural and acidity properties of the zeolite structure.