Hydrocracking of Vacuum Gasoil over NiMo/ААС-Al2O3 Catalysts Prepared with Citric Acid: The Influence of Temperature of Thermal Treatment of the Catalyst

Abstract

Bimetal Ni-Mo catalysts were prepared by impregnating the support consisting of amorphous aluminosilicate (AAS) and alumina with the solution of Ni, Mo compounds and citric acid; temperature of the thermal treatment was varied from 120 to 550 °C. XPS, TEM and HCNS techniques were used for studying physicochemical properties of the prepared catalysts. The catalysts were tested for hydrocracking of vacuum gasoil. Particles of the active sulfide component (NiMoS phase) were established to reside predominantly on the alumina surface and only partially on the AAS surface. As the temperature of the catalyst calcinations rose, the average number of layers in the NiMoS particles increased due to removal of citric acid that indicated a stronger interaction between the active sulfide component and alumina. The temperature elevation also was accompanied by an increase in the proportion of bulky Ni-Mo particles. The morphology of the active sulfide component was shown to influence the catalyst activity to hydrodesulfurization and hydrodenitrogenation but not to hydrocracking. The optimal temperature of thermal treatment of NiMo/AAS-Al 2 O 3 catalysts prepared with citric acid was 120 °C. Recommendations for the thermal treatment of the catalysts under industrial conditions were provided.