Influence of the Support on the Deactivation of Bifunctional Catalysts (Pt-Pd/support) in the Hydrocracking of LCO

The deactivation of bifunctional catalysts (Pt-Pd/support) has been studied on the hydrocracking of LCO (light cycle oil, which is a highly aromatic byproduct in the FCC unit). The reactions were performed in a fixed bed reactor using a Pt-Pd catalyst prepared with supports of different acidity and pore structure: B (H-beta zeolite), Y-5, Y-12 (H-USY zeolites with SiO2/Al2O3=5 and 12), F (commercial FCC catalyst) and A (gamma-Al2O3). The operating conditions were: 350 degrees C, 50 bar, WHSV= 4 h(-1), H-2/LCO ratio (n(H2),) =8.9 and time on stream (TOS) = 300 min. The results show that, once the initial deactivation has been elapsed, the catalyst reach a pseudo-stable state subsequent to TOS = 250 min, with a considerable residual activity that is maintained constant. This residual activity increases as catalyst acidity is increased.