Síntese de catalisadores á base de Sn1-xSixO2 visando a aplicação na produção de biodiesel

Abstract

The use of solid catalysts, such as simple and/or modified oxides, has been the focus of a variety of research. For example, for application in heterogeneous catalysis in transesterification and esterification reactions in obtaining biodiesel from different oilseeds, aiming to reduce the environmental impacts caused by fossil fuels. In this sense, the present work aims to obtain catalysts based on substituted oxides Sn1-xSixO2 (x=0,05; 0,10; 0,15 e 0,20) obtained by the method of polymeric precursors, in order to evaluate the influence of Si on the structural modifications of SnO2 and on the catalytic effectiveness for the production of biodiesel from the transesterification reaction and simultaneous esterification of acidified soybean oil (85% Soybean Oil + 15% Oleic Acid), simulating the residual oil. The Sn1-xSixO2 systems obtained were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, granulometric distribution, textural analysis by nitrogen adsorption and scanning electron microscopy. Then, the catalytic tests were carried out, using a pressurized system (Par reactor), by ethyl route and under reaction conditions: molar ratio ethanol: oil of 15:1, 4% of catalyst, time 1 h and temperature 180ºC. The catalytic test products were characterized by acid number and gas chromatography. Through the XRD results it was possible to identify the crystalline planes (220), (002) that are related to the formation of tin dioxide, as well as to the respective Sn1-xSixO2 systems. Through the textural analysis it was notable that the Sn0.80Si0.20O2 catalyst has a higher surface area (82.26 m²/g) compared to the other studied samples, confirming that the presence of Si influenced the expansion of the surface area of these materials, confirmed by granulometric and microscopic analysis that highlights the heterogeneous characteristics of micrometric profile particle sizes. And although the catalytic effect of all catalysts averaged only 46.6%, with a deviation of ±1.8%, the synthesis reproducibility tests of the Sn0.80Si0.20O2/6% system and its respective reuse Sn0.80Si0.20O2/6%R indicate the feasibility of its application in catalysis.