Esterification of soybean oil using ferrites MnFe₂O₄ e Mn_0.65Zn_0.35Fe2O₄ as catalyst

Full text The use of heterogeneous catalysts for biodiesel production can reduce significantly environmental pollution, compared to the use of homogeneous catalysts. Among the heterogeneous catalysts, it has been highlighted the magnetic materials like ferrite because of its inverse spinel structure which results in excellent properties such as high thermodynamic stability, electrical conductivity, catalytic activity and corrosion resistance. Thus, this paper aims to obtain the ferrite based on MnFe₂O₄ and Mn_0.65Zn_0.35Fe₂O₄ combustion reaction, for their use as catalyst in esterification reaction of soybean oil for biodiesel production. The samples were characterized by X-ray Diffraction (XRD), Infrared Region Spectroscopy by Fourier Transform (FTIR), Transmission Electron Microscopy (TEM), surface area measurement by nitrogen adsorption (BET) and Magnetic Measurements. The catalytic tests were conducted in a stainless steel reactor with magnetic stirring at 180 °C, molar ratio oil/alcohol of 1:12, 2 % of catalyst for 1 hour via methyl route. According to the results, it was found that the samples showed the spinel phase as majority and agglomerated in the form of irregular plate. By analyzing the magnetic hysteresis of the samples studied, we observed the narrow cycles Ms x H, characterizing the material as 'soft' magnetic hysteresis and typical of superparamagnetic materials. The catalytic tests show that samples MnFe₂O₄ and Mn_0.65Zn_0.35Fe₂O₄ are catalytically active for esterification with conversions of 56 % and 52 %, respectively. References: [1] SOUZA, J. K. D.; FILHO, P. F. A.; SILVA, D. I. O.; LIRA, B. F.; SANTOS, I. M. G.; SOUZA, A. G. I Simpósio Internacional de Oleaginosas Energéticas. 2010. [2]SUAREZ, P. A. Z.; MENEGHETTI, S. M. P.; MENEGHETTI, M. R.; WOLF, C. R. Química Nova. 30, pp 667-676, 2007. (author)