Coupling membrane pervaporation with a fixed-bed reactor for enhanced esterification of oleic acid with ethanol

Abstract

Process intensification through membrane pervaporation (PV) integrated with a fixed-bed reactor could be successfully applied to the esterification of oleic acid and ethanol, which is a crucial step in the biodiesel synthesis using waste oil and grease as resource. The properties of the NaA zeolite membrane such as structure, formulation and separation were investigated by scanning electronic microscopy–energy dispersive spectrometry (SEM–EDS), X-ray diffractometry (XRD) and PV dehydration. Results showed that the NaA zeolite membrane had good separating property for removing water from the organics mixture. The operating conditions were optimized as the ethanol to oleic acid molar ratio of 15:1, feedstock flow rate of 1.0ml/min, reaction temperature of 80.0°C and catalyst bed height of 132mm. The final conversion of oleic acid increased from 84.23% to 87.18% by PV using the NaA zeolite membrane at 24.0h of operation. The membrane showed good PV performance after used for eight successive runs in the PV-assisted esterification. The resin exhibited a much high catalytic activity and operation stability after used for 100h in the consecutive single pass fixed-bed esterification.