Lindgrenite as an efficient heterogeneous catalyst to obtain biodiesel

Abstract

Lindgrenite, Cu3MoO42OH2, presents considerable potential to be used as a catalyst for obtaining biodiesel from soybean oil and methanol. Lindgrenite samples were obtained using conventional coprecipitation and ultrasound-assisted coprecipitation methods. Several catalytic tests were performed to reach the optimal conditions (methanol/oil molar ratio: 45/1, catalyst mass: 1%, reaction time: 4 h, reaction temperature: 180 °C) for obtaining biodiesel, with a 96% yield in the first catalytic cycle and 85% yield in its tenth catalytic cycle. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) of the biodiesel obtained by catalytic method revealed negligible amount of leached metal ions (less than 1 ppm of Cu2+ and less than 3 ppm of Mo6+) with the catalyst obtained by ultrasound-assisted coprecipitation method. The similarity between the FTIR spectra of industrial biodiesel and that obtained in this work confirms the effectiveness of using lindgrenite as an efficient catalyst for the transesterification reaction. Biodiesel synthesis was also confirmed by Nuclear Magnetic Resonance (1H and 13C NMR). The results obtained from Gas Chromatography-Mass Spectrometry (GC-MS) indicate methyl linoleate is the main component of the biodiesel, corresponding to approximately 50.50%. In addition to being easily obtained, lindgrenite is thermally stable and efficient under the applied conditions. The 96% yield after the fifth catalytic cycle is above the catalytic performance commonly observed in the literature. These characteristics indicate that lindgrenite has enormous potential to be used as a new heterogeneous catalyst to obtain biodiesel.