Sol–gel La2O3–ZrO2 mixed oxide catalysts for biodiesel production

SALINAS, D.; SELPÚLVEDA, C.; ESCALONA, N.; FIERRO, J.; PECCHI, G.:
Journal of Energy Chemistry, 27:2 (2018) 565 – 572.

DOI: 10.1016/j.jechem.2017.11.003

Abstract

Different La₂O₃ contents (0, 1, 2, 3, and 5 wt%) were used to prepared La₂O₃–ZrO₂ mixed oxides calcined at 600 °C by the sol–gel method. The catalytic activity was measured as biodiesel production from canola oil through a transesterification reaction. The characterization results indicate that the La₂O₃ monolayer formation and extent of basicity of m-ZrO₂ have a large influence on biodiesel production. Greater biodiesel conversion (56% at 4  h) was obtained with the 3% La₂O₃–ZrO₂ catalyst in the presence of basic sites and the formation of a monolayer of La₂O₃. The decrease in the catalytic activity for 5% La₂O₃–ZrO₂ resulted from the loss of active sites on the catalyst because of agglomeration, which was suggested by XPS and the isoelectric point. The kinetic data fit to a pseudo-first order constant, and the largest kinetic constant corresponds to 3% La₂O₃–ZrO₂, currently the largest heterogeneous non-alkaline metal catalyst reported for a transesterification reaction.