Deactivation of a supported zeolite catalyst: Simulation of diffusion, reaction and coke deposition in a parallel bundle

✍ Scribed by R. Mann; G. Thomson

• Publisher: Elsevier Science
• Year: 1987
• Tongue: English
• Weight: 766 KB
• Volume: 42
• Category: Article
• ISSN: 0009-2509
• DOI: 10.1016/0009-2509(87)80017-9

✦ Synopsis

A theoretical framework has been assembled for elucidation of the deactivation of a supported zeolite cracking catalyst used in a fixed bed, plug flow reactor. Intraparticle processes are based upon a parallel bundle model for the macropores and mesopores associated with the sihca alumina support. Zeolite micropores contained within crystallites are assumed to be uniformly distributed along the walls of the support pores. Coke accumulation upon the support is represented by a wedge layering mechanism, which accounts for interactions of the support pore volume and coke deposits, giving rise to possible plugging of support pores. Discrimination of deactivation mechanisms can be achieved by reconciling timewise activity loss with changes in pore structure indicated by adsorption isotherms. The support pore plugging process shows up clearly in the isotherms. Illustrations are provided for a deactivation where the zeolite and support activities are equal. Experimental results for the cracking of cumene at 500°C indicate a rapid loss of zeolite activity followed by a slower support pore deactivation which includes the plugging of pores smaller than 150 A in diameter.