Synthesis, characterization and catalytic activity studies of lanthanum oxide from Thai monazite ore for biodiesel production

Rare earths in Thai monazite ore were separated by chemical process following purification by an ion exchange process technique. They were utilized as raw materials to synthesize solid catalysts for the production of biodiesel. The novel solid catalysts were prepared by the simple oxalic acid precipitation method. The prepared CeO2, La2O3 and Nd2O3 catalysts were employed to catalyze transesterification of palm oil and methanol. They showed high catalytic activity with FAME content over 95%. The catalytic performance of the best available La2O3 catalyst was additionally investigated. It was found that the initial transesterification rate catalyzed by the synthesized La2O3 catalyst was three times higher than its commercial counterpart, which related to its basic strength, high crystallinity, large pore volume and great crystallite size. The highest FAME content of 95% was achieved within 45 min under the optimal conditions of 200 °C reaction temperature, 39 bar reaction pressure, 1:30 molar ratio of oil to methanol, 10 wt% catalyst loading and 600 rpm stirring rate. In addition, the novel La2O3 catalyst was observed to be stable even after four recycle runs with insignificant loss of catalytic activity.