Catalysis Today, Vol.104, No.1, 86-93, 2005
Characteristics of Maya crude hydrodemetallization and hydrodesulfurization catalysts
Hydrotreating of Maya crude is carried out under conditions close to the industrial operation. Various catalysts are prepared in the laboratory and the results are compared with a reference catalyst. Catalysts for such hydrotreating process are designed with high porosity and low active metal content considering metal deposition during the reaction and consequently the stability. Information regarding the activity and deactivation of the catalyst is discussed on the basis of catalyst porosity and deposited metal characterization. It was found that supports prepared by ammonium carbonate and urea hydrolysis methods have macro pore size distribution (PSD) as well as comparatively higher pore volume. The hydrodemetallization (HDM) activity increases while the hydrodesulfurization (HDS) activity decreases with increasing the average pore diameter (APD). The results of HDM and hydrodeasphaltenes (HDAs) activities of catalyst protrude distinct contribution of macro PSD of support which has more capabilities to retain metal deposition and better diffusion of complex organo-chelating metals. The spent catalysts are characterized by PSD, temperature-programmed reduction (TPR), in situ Fourier transform infrared (FT-IR), and transition electron microscopy (TEM). The spent and fresh catalysts characterization results are in well agreement with the activity. It has also been proposed that deposited vanadium sulfide may act as auto-catalytic activity for HDM and HDAs instead of being poison. It is also found that the deposition of metal depends on the porosity and surface area of the catalyst. (c) 2005 Elsevier B.V. All rights reserved.