ZSM‐5@KIT‐6‐encapsulated composite molecular sieves for the catalytic cracking of waste cooking oil model compound to produce light olefins

Abstract BACKGROUND A series of ZSM‐5@KIT‐6 composite molecular sieve catalysts was prepared by encapsulating ZSM‐5 as a substrate in the mesoporous material KIT‐6. The intent was to use these catalysts to promote the catalytic cracking of a waste cooking oil model compound (WCOMC) to produce light olefins. RESULTS The morphology, structural characteristics and acidity of each of the resulting catalysts were characterized by X‐ray diffraction, transmission electron microscopy, N 2 ‐Brunauer–Emmett–Teller (N 2 ‐BET) surface area analysis and temperature‐programmed ammonia desorption. The results showed that ZSM‐5 was successfully coated with KIT‐6. The BET surface areas of these catalysts ranged from 345 to 792 m 2 g −1 and the specimens had average pore sizes in the range of 2.37–5.51 nm. Total acidity increased with increases in the mass‐based proportion of ZSM‐5 in the material. CONCLUSION The catalytic cracking of WCOMC was studied in a lab‐scale fixed‐bed apparatus. Trials at a reaction temperature of 600 °C using the material having a mass‐based ZSM‐5 proportion of 80.0% (ZK‐80) gave the highest gas‐phase yield of light olefins of 43.8%. After 6000 min, the catalytic performance of this material remained stable, demonstrating a resistance to carbon deposits. The superior activity of the present composite catalysts can be ascribed to improvements in pore structure and acid strength distribution. © 2023 Society of Chemical Industry (SCI).