Comparative Catalytic Study for Upgrading Mexican Heavy Crude Oil

Abstract

In this work, the study of three transition metal mixtures: cobalt-molybdenum (CoMo), nickel-molybdenum (NiMo), and nickel-cobalt-molybdenum (NiCoMo) with phosphorus supported on a γ-Al2O3 were studied for the hydroprocessing of heavy crude oil. The different metallic compositions were incorporated on gamma-alumina support by incipient wetness impregnation. The materials obtained were dried at 110°C and calcined to 450°C (4 h). The catalysts were evaluated using a Parr stainless steel batch reactor at 10.6 MPa and 380°C, for one hour. Mexican heavy crude oil named Ku-Ma-Loob Zaap was used and characterized according to its chemical composition: saturates, asphaltenes, resins, and aromatics (SARA). Sulfur and nitrogen were also determined by chemiluminescence techniques. The physical measurements for qualifying the transport properties were API gravity and kinematic viscosity. Among the tested catalysts, NiCoMoP/γ-Al2O3 presented the highest activity, increasing the API gravity from 12.6 to 24.5°API and decreasing the kinematic viscosity from 9.896 to 45 cSt at 25°C. The increasing activity was strongly related to the reducibility of the metals and weakly to the metals content. The surface area and pore volume did not change with the amount of metal, so no effect related to these properties was observed. Phosphorus presence was not discussed, since approximately the same amount was used in the three samples. However, it is known that phosphorus increased the hydrotreating activity due to the increased acidity of the catalyst, making trimetallic catalysts more active than bimetallic ones. In terms of the chemical composition of the upgraded crude oil, it was evident that the asphaltenes, sulfur, and nitrogen contents decreased sharply.