Deactivation and Reactivation Behavior of Zeolite Hidrocracking Catalyst for Residual Oil

Abstract Deactivation and reactivation behavior of zeolitic catalyst for residual oil hydrocracking has been studied, and especially the change of the catalyst state in the course of the run was investigated. The hydrodesulfurization activity and the hydrocracking activity decreased with time on stream at 4.00°C for about 500 hours. However after raising the temperature up to 4-10°C, the cracking activity increased gradually for about 1500 hours, while the hydrodesulfurization activity decreased. The behavior of the hydrocracking activity, deactivation and reactivation, had a good agreement with the change of the acidity of the catalyst installed in a zone from the middle to the bottom of the reactor. The carbon to hydrogen atomic ratio, Laser Raman and FT-IR spectra of the used catalysts suggested that the graphitization of the carbonacious species on the used catalysts taken out from the middle and the bottom of the reactor proceeded during the operation at 410°C, and acidic sites was regenerated.