Membrane dehydration-enhanced esterification for biodiesel production from a potential feedstock of Firmiana platanifolia L.f. seed oil

A two-step acid/alkali-catalysis method was developed to produce biodiesel from Firmiana platanifolia L.f. seed oil obtained from continuous-screw squeezing and solvent extraction by absolute ethanol. The esterification of Firmiana platanifolia L.f. seed oil with ethanol was carried out with the strong-acid cation exchange resin to decrease the content of free fatty acids (FFAs) below 1 wt. %. A NaA zeolite membrane was used for dehydration in the coupled reactor. Alkali-catalysis transesterification was performed with 0.08% (m/m oil) of KOH and 6:1 of molar ratio of methanol to oil, reaction time of 30 min, and reaction temperature of 60 degrees C. Results showed that the combination of esterification with vapor permeation (VP) or pervaporation (PV) could greatly shift the reaction equilibrium forward. The FFAs conversion rates higher than 99.0% were obtained under the conditions of ethanol to oil molar ratio of 15:1, catalyst dosage of 40.0 wt.% and temperature of 78 degrees C, and operation time of 7 h. Moreover, the properties of the biodiesel meet the standards of American Society for Testing Material (ASTM), European Norm (EN) and Chinese Standard (GB). (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.