Preparação de catalisadores NiMo/Y para hidrocraqueamento do composto modelo cumeno.

Abstract

The growing demand for middle distillates, together with rigorous specifications directed toward minimizing the environmental impact of automotive fuels, has increased the importance of hydrocracking and hydrotreating processes in modern refineries. Hydrocracking is the most efficient method for producing light fractions from heavy oil. In petroleum refining, this technology has been carried out to produce high quality gasoline, jet fuel, gas oil and lubricants. Most of the conventional hydrocracking catalysts are dual functional catalysts. They have a hydrogenation-dehydrogenation function as well as an acidic function. In this study the hydrocracking experiment was conducted in a high pressure fixed bed reactor and under high temperature. The scheme consisted of four main parts: feeder pump, vaporizer, reactor and a gas analysis unit. In this study, it was prepared NiMosupported zeolite catalysts using HY which was obtained from NaY. The catalysts were characterized with different techniques, and their catalytic properties with respect to the activity, selectivity to hydrocracking and yield of the cracked products were also examined. The physical properties of the catalysts were measured by N2 adsorption and X-ray diffraction (XRD). It was also used energy dispersive X-ray spectrometry – EDX for semi-quantitative characterization of the metals impregnated. Cumene hydrocracking reactions were carried out over zeolite with and without NiMo sulfide. The loading of NiMo was performed by the incipient wetness method using aqueous solutions of ammonium heptamolybdate and nickel nitrate. After impregnation, the catalysts were dried followed by calcinations. In all cases, the loading of NiMo sulfide enhanced catalytic activity. Even so the surface area of the catalysts was very low, the effect of impregnating nickel and molybdenum on the supports was strongly positive, since they all presented significant conversion comparable to the commercial one. The role of NiMo sulfide was found to supply active hydrogen to the hydrocracking active sites on zeolite. Cumene hydrocracking on the sulfided catalysts indicated the supported molybdenum and nickel phase contributed significantly to the cracking functionality of the catalysts