Síntese e avaliação de NiMo/Beta e NiMo/SAPO-5 no hidrocraqueamento do cumeno com piridina.

Abstract

Due to the increasing of the heavier crude oil feedstocks production, the oil refining industry has turned to hydrocracking (HCK) processes to provide the lighter basic fuels which modern society demands. The HCK process is generally carried out under high temperatures and pressures in the presence of the hydrogen and a HCK catalyst. The feedstocks of the Brazilian crudes inevitably contain many impurities, such as organic nitrogen compounds. These nitrogen compounds present in the feeds of hydrocracking process act as, temporary poisons to the catalysts, thereby decreasing the catalyst activity. Usually, hydrocracking catalysts comprise of an acidic support plus a hydrogenating component selected from the Group VIB metals and Group VIII metals of the Periodic Table of the Elements, in their oxide or sulfide form. Beta zeolite and SAPO-5 are proposed as acidic support materials for hydrocracking. Regarding the hydrogenation component the combination of the metals used in the form of oxides, was NiO-MoO3. A series of NiMo catalysts supported on Beta zeolite and SAPO-5, of different compositions, were prepared by sequential incipient wetness impregnation of the materials with aqueous solutions of Ni(NO3)2 . 6H2O and (NH4)6 Mo7O24.4H2O. The supports and catalysts were analyzed by several techniques such as: X-ray diffraction (XRD), plasma-emission spectrometry (ICP-AES), N2 physical adsorption by BET method, temperature programmed reduction (TPR), transmission electronic microscopy (TEM), infrared spectroscopy of adsorbed pyridine (IR), diffuse reflectance spectroscopy (DRS) and nuclear magnetic resonance (NMR) spectroscopy. The sulfide NiMo catalysts were evaluated using a continuous-flow tubular reactor by the cumene hydrocracking in the presence and absence of pyridine. It was verified that the NiMo catalysts based on Beta zeolite produced the highest cumene conversion than those based on SAPO-5, particularly the one with Beta zeolite (Si/Al=8,2) containing 4%NiO and 15%MoO3. The presence of nitrogen as pyridine was detrimental for the performance of all catalysts, including the standards one, supplied for the CENPES.