Ultrasound‐assisted transesterification reactions for biodiesel production with sodium zirconate supported in polyvinyl alcohol as catalyst

Abstract

This study reports a twofold attempt for biodiesel production in a reactor with ultrasound irradiation and with supported sodium zirconate as solid base catalyst. Kinetic studies showed that the mechanism of this heterogeneously catalyzed transesterification system with ultrasonication is a two‐step reaction in which the mass transfer controlled regime is accompanied by the kinetically controlled regime with both regimes following the pseudo first order reaction kinetic model. Biodiesel yields of ∼80% were achieved after 8 h of reaction at 55°C using 3 wt % of unsupported or supported catalyst and 6:1 of methanol:oil molar ratio for reactions under magnetic stirring or ultrasound irradiation. However, greater reaction times were necessary to achieve the final reaction yield in the reactor with ultrasound irradiation and with the supported catalyst due to the increase in the mass transfer from the reactants to the active sites of the catalyst and to the low applied ultrasound frequency which probably did not promote the complete mixing of the reaction medium. The supported catalyst presented advantages in terms of catalyst reuse compared to the unsupported catalyst. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1262–1267, 2017