Catalytic cracking of supercritical n-dodecane over meso-HZSM-5@Al-MCM-41 zeolites

• Published in: Chemical engineering science 2015-10, Vol.135, p.452-460
• Main Authors: Diao, Zhenheng, Wang, Li, Zhang, Xiangwen, Liu, Guozhu
• Format: Article
• Language: English
• Subjects: Catalytic cracking; Core-shell; Desilication; Meso-HZM-5 zeolite; Recrystallization; Supercritical n-dodecane
• ISSN: 0009-2509; 1873-4405
• DOI: 10.1016/j.ces.2014.12.048

Meso-HZSM-5@Al-MCM-41 zeolite composites were prepared by sequential desilication and recrystallization of parent HZSM-5 treated with tetramethyl- and tetraethyl-ammonium hydroxide. The as-prepared composites were characterized with XRD, TEM and N2-adsorption-desorption, and found that Al-MCM-41 shell orientedly grows on the meso-HZSM-5 core with thicknesses of 58nm and 27nm. Catalytic cracking of supercritical n-dodecane (500°C, 4MPa) over the zeolite composites shows that meso-HZSM-5@Al-MCM-41 with core-shell structures exhibits the excellent catalytic performance with the highest catalytic activities up to 31% improvement and the lowest deactivation rate (only one fourth) compared with the parent HZSM-5 zeolite, and that the performance enhancement of meso-HZSM-5@Al-MCM-41 is ascribed to the precracking of n-dodecane over the Al-MCM-41 shell and the enhanced diffusion in the meso-HZSM-5 core as evidenced by the product distribution. [Display omitted] •Meso-HZSM-5@Al-MCM-41 zeolites with core-shell structure were prepared.•Core-shell zeolites show excellent supercritical catalytic cracking performance.•Better performance is due to high acid sites accessibility and precracking of shell.