Catalisadores do tipo SBA-15 e AL-SBA-15 usados na reação de transesterificação do óleo de soja com etanol para produção de biodiesel em reator batelada sem agitação.

Abstract

The present study aimed to prepare mesoporous molecular sieves SBA-15 and AlSBA-15 with Si/Al ratios of 10, 25, 50, 75 and 100 and use them in the transesterification of soybean oil with ethanol for production biodiesel. The catalysts SBA-15 and Al-SBA-15 (Si/Al=10) were selected and tested on reaction to produce ethyl ester, monoglycerides, diglycerides and glycerol. The hydrothermal method under static conditions, was used to synthesize the molecular sieve SBA-15. The mesoporous sieve Al-SBA-15 was prepared by direct synthesis method in SBA-15, and the alumina source used was pseudoboehmite (AlOOH). All samples were characterized in concerning to its structure and texture by XRD and N2 physical adsorption. Moreover, they were characterized by TG/DTA, SEM, FTIR. The acidity generated from aluminum incorporation into the structure of SBA-15 was evaluated by TPD-NH3. The transesterification reaction of soybean oil was carried out in a batch reactor, without stirring, for reaction times of 6, 12, 24 and 48 hours at 200 °C using a 12:1 oil/ethanol relation and 5% of the catalyst (SBA-15 e Al-SBA-15 (10)). The reaction products were characterized by Kinematic Viscosity and Gas Chromatography. The success of the synthesis of molecular sieves SBA-15 and Al-SBA-15 were observed for all the techniques used. All the materials were obtained with a high hexagonal ordering degree, demonstrated by XRD, showed aspects of vermicular type with intertwined necklace appearance, visualized by SEM and showed isotherm with type IV profile, which is a characteristics of mesoporous material. The result of the kinematic viscosity obtained for SBA-15 with 48 hours of reaction (6.49 mm2/s) is close to the range of values obtained by the National Petroleum standard, Natural Gas and Biofuels (ANP) and the international standards of biodiesel ASTM D6751-02 and EN 14214. And the value of kinematic viscosity for Al-SBA-15 (10) with 48 hours of reaction (10.43 mm2/s) is out of the standards range. The selected catalysts (SBA-15 and Al-SBA-15 (10)) was subjected to transesterification reaction of soybean oil with ethanol and the Al-SBA-15 (10) catalyst was more efficient than the SBA-15. The conversion value for the Al-SBA15 catalyst (10) was 96.50%.