Synthesis, Characterization and Catalytic Performance of Mixed Nanoferrites Submitted to Transesterification and Esterification Reaction Using Methyl and Ethyl Route for Biodiesel Production

ABSTRACT

The mixed nanoferrites of Ni_0.5Zn_0.5Fe₂O₄ and Ni_0.2Cu_0.3Zn_0.5Fe₂O₄ were synthesized by combustion reaction using urea as fuel and a conical reactor as heating source in batches of 10 g, and then tested as heterogeneous nanocatalysts in the transesterification and esterification reaction of soya bean oil using the methyl and ethyl routes to biodiesel production. During the synthesis the time and temperature of the reactions were measured, and the evolved gases and the color of the emitted flames were observed. The samples were characterized by XRD, EDX, FTIR, SEM/EDS, BET and gas chromatography. The reaction tests were carried out with 10 g of oil for 1 h, oil:alcohol molar ratio of 1:12, 2 % (w/w) of catalyst, and conducted at 180 °C. The XRD patterns and the FTIR spectra revealed the presence of the inverse spinel phase type B(AB)₂O₄. The morphology showed the formation of agglomerates with fragile morphology and high surface area. The chromatographic analysis produced excellent results in the esterification reactions for both samples in the tested conditions, with special emphasis on Ni_0.5Zn_0.5Fe₂O₄, whose conversions were of 91.4 % in methyl esters and of 77.8 % in ethyl esters, while the Ni_0.2Cu_0.3Zn_0.5Fe₂O₄ sample showed conversion of 75.1 and 65.1 %, respectively. The conversions in the methyl and ethyl transesterification were of 14 and 2 % of the Ni_0.5Zn_0.5Fe₂O₄ sample, and of 11 and 3 % for the Ni_0.2Cu_0.3Zn_0.5Fe₂O₄ sample.

Keywords:
Mixed ferrites; combustion reaction; nanocatalysts; transesterification; esterification; biodiesel