Characterization of Modified Nanoscale ZSM-5 Catalyst and Its Application in FCC Gasoline Upgrading Process

Abstract

Nanoscale HZSM-5 zeolite was hydrothermally treated with ammonia water at 673 K and then loaded with La2O3 and ZnO. The parent and modified nanoscale HZSM-5 zeolite catalysts were characterized by SEM, XRD, NH3-TPD, IR, and XRF. In the presence of hydrogen, the performance of the modified ZSM-5 catalyst for FCC gasoline upgrading was evaluated in a fixed-bed reactor. The results indicated that the modified catalyst exhibited excellent aromatization activity, isomerization activity, and a strong ability to reduce olefin and sulfur contents in FCC gasoline. Under the given reaction conditions, the average olefin content in FCC gasoline was decreased from 49.6 to 12.8 vol % within 300 h time on stream; the aromatic and paraffin contents in the product were increased from 11.4 and 39.0 vol % to 24.7 and 62.5 vol %, respectively. The modified nanoscale ZSM-5 catalyst reduced sulfur concentration in FCC gasoline by about 78% without gasoline octane number loss.