P. Rayo

Hydrotreating of Maya Crude Oil: I. Effect of Support Composition and Its Pore-diameter on Asphaltene Conversion

Abstract A systematic study for a concept governing support effect in heavy oil hydrotreating (HDT) catalysts is performed. Different Al2O3 and its mixed oxides supports were prepared and CoMo supported catalysts were tested for Maya heavy crude oil hydrotreating. Fresh and spent catalysts are characterized with N2 adsorption-desorption, element analysis, and scanning electron microscopy-energy dispersion analysis by x-ray (SEM-EDAX), which confirms that coke and metals deposition on the surface of catalyst is most probably near the pore mouth. It is also demonstrated from these results that asphaltene conversion depends on the pore diameter of the catalyst, while other hydrotreating conversions (hydrodesulfurization (HDS), hydrodenitogenation (HDN), and in some extent hydrodemetallization (HDM)) are more likely affected by the nature of active metal distribution. The evaluation of alumina mixed oxide (TiO2, ZrO2, B2O3, and MgO) supported catalysts indicates that supports with basic nature have better stability than the acid ones.

Hydrodesulfurization, Hydrodenitrogenation, Hydrodemetallization, and Hydrodeasphaltenization of Maya Crude over NiMo/Al2O3 Modified with Ti and P

Abstract The effect of adding Ti (4.5 wt%) and P (∼1.0 wt%) by several routes to a NiMo/ab Al2O3 catalyst on the hydrodesulfurization (HDS), hydrodenitrogenation (HDN), hydrodemetallization (HDM), and hydrodeasphaltenization (HDAs) of heavy Maya crude was investigated. The results show that not all the catalyst functionalities respond equally well to the addition of Ti and P to the catalyst formulation. There is not a single catalyst formulation that can achieve optimum performance in all the catalyst functionalities. For HDS, Ti incorporation increases activity but the route by which P is added afterwards can improve or be detrimental to HDS activity. For HDN, the incorporation of P to the catalyst can lead to significant improvements in catalytic activity and catalyst stability. Ti increases HDM activity but the addition of P to the catalyst is detrimental to this functionality. For the elimination of asphaltenes, the catalyst supported on pure alumina is the best. So for HDAs, no benefit is obtained by the addition of Ti or P to the catalyst. Textural properties are important and HDM and HDAs increase with catalyst average pore diameter. Hydrodemetallization activity increases with the acidity of the catalyst.

Hydrotreating of maya crude oil: II. Generalized relationship between hydrogenolysis and HDAs

Abstract Studies of hydrodeasphaltenization (HDAs) and hydrodemetallization (HDM) of Maya heavy crude oil at temperature of 380°C and pressure of 5.4 MPa have been carried out in a high pressure microreactor. Different pore diameter alumina CoMo-supported catalysts were prepared and their catalytic effect is estimated. The fresh and spent catalysts were characterized by textural properties; and the average pore diameter of a fresh catalyst was found to be proportional to the HDM and HDA conversions. The hydrogen elemental analysis of reactant and products indicated that asphaltene conversion is a combination of cracking and hydrogenation (HYD), since HDM correlated well with HDAs, which is due to the complex nature of both molecules (asphaltene and metals).