Utilização de catalisadores zeolíticos no processo de craqueamento de óleo de soja bruto: avaliação do tratamento de troca iônica

Abstract

As an alternative to oil and its derivatives, it is possible to obtain petrochemical products, such as fuels, from renewable sources. The catalytic cracking process of vegetable oils produces molecules of hydrocarbons similar to petroleum. In this study was evaluated the hydrocracking of crude soybean oil, not treated, which is cheaper and allows the use of low quality oils. The acid catalysts were tested: ZSM- 5, NaY, USY, the catalyst used in the cracking of oil FCC and the exchanged with ammonium HZSM-5 and HY. Their structures were evaluated by diffraction (XRD) X- ray and nuclear magnetic resonance (NMR) 27Al and 29Si, porosity via physisorption of nitrogen, and the measure of the strength of the acid sites by the programmed desorption of ammonia temperature (TPD).The catalytic tests occurred with hydrogen flow in a tubular reactor at 723K. Was evaluated the behavior of the distribution of products throughout the reaction time. The products were analyzed by gas chromatography with mass spectrum and coke by temperature programmed oxidation (TPO). All the catalysts showed great deoxygenation capacity, producing various petrochemical products, mainly gaseous and aromatic hydrocarbons. The reaction time promoted the formation of coke, which modified the distribution of goods, in general, rising the oxigen content. The ion exchange with ammonium was able to increase the acidity of zeolites, promoting an increase in the catalytic activity and the formation of aromatics. The HZSM-5 maintained its high selectivity to hydrocarbons during the process. The change in product profile along the reaction time, indicates the possibility to get different types of molecules through different residence times in other types of reactors.