Investigation of Inorganic and Enzyme Based Materials Oriented to the Generation of Biodiesel

The esterification of oleic acid with methanol was chosen as a reaction test in order to establish the catalytic activity of various inorganic and enzyme based materials such as, bulk H6P2W18O62.xH2O (HPA) and oxide supported Wells Dawson heteropoly acid (HPA/TiO2), a partially substituted cesium salt, Novozym 435, and the lipases from Araujia sericifera (ASL) and Carica papaya (CPL). The reaction was followed through the acidity index of fatty acids and infrared analysis. The IR analysis involved the investigation of two bands centered at 2924 cm and 2854 cm attributed to the stretching vibration of the C-H bonds belonging to the methylene groups. The intensification of such signals and the presence of a new signal centered at 1743 cm attributed to vibrations of the C=O bonds are evidences of the presence methyl oleate (typical component of biodiesel). Additionally, the vibrations at 1242, 1197 and 1172 cm due to the C-O bond belonging to an ester provided further evidence of the presence of methyl oleate. The inorganic materials catalyzed the esterification of oleic acid with methanol in 1:1 molar ratio at 85 °C. In this context, the specific activity of bulk HPA and 18% HPA/TiO2 were 1.10 and 6.40 μmol.mg.h, respectively. The cesium salt Cs2H4P2W18O62 showed inactive.