Catalysis Today, Vol.220, 124-132, 2014
Composition of stacked bed for VGO hydrocracking with maximum diesel yield
Hydrocracking catalysts prepared by co-impregnation of three different supports with solutions containing Ni, Mo and citric acid were studied. Pure gamma-Al2O3, 30% of zeolite Y/gamma-Al2O3 and 70% of amorphous aluminosilicate ASA ( Si/Al = 0.9)/gamma-Al2O3 were used as supports. All the catalysts were shown to contain the particles of Ni-Mo-S phase with similar morphology after liquid phase sulfidation by DMDS. The active component is uniformly distributed on gamma-Al2O3 and ASA surface in NiMo/Al2O3 and NiMo/ASA-Al2O3 catalysts. The main amount of Ni and Mo is localized on gamma-Al2O3 surface in NiMo/Y-Al2O3 catalyst while the main part of zeolite Y surface is free of supported metals. Testing of stacked beds, which comprise different prepared catalysts, in hydrocracking of vacuum gasoil showed that the NiMo/Al2O3 catalyst had the maximum selectivity to diesel fuel, but its activity was insufficient. Diesel fuel yield did not exceed 50 wt.% for the stacked beds comprising NiMo/Y-Al2O3 independent on the process temperature. NiMo/ASA-Al2O3 had an optimal ratio of activity to selectivity for the production of diesel fuel and provided the diesel fuel yield by over 60 wt.% at 400 degrees C. (C) 2013 Elsevier B.V. All rights reserved.