Esterification Reaction Of Oleic Acid And Ethanol Intensified By Pervaporation

The crucial step in biodiesel synthesis using waste oil and grease as resource is reducing the feedstock acid value. In this thesis, oleic acid, one of the most common free fatty acid(FFA) in waste oil and grease, was chosed to react with ethanol. And the esterification was intensified by the intensified Process through pervaporation(PV)integrated with fixed-bed reactor(FBR).The properties of the Na A zeolite membrane such as morphological structure and formulation were investigated by scanning electronic microscopy-energy dispersive spectrometry(SEM-EDS) and X-ray diffractometry(XRD). Results showed that the structure of the Na A zeolite membrane was that the dense zeolite layer with a thickness of about 15 μm coated on the porous Al2O3 support. And the component of the zeolite crystals coated on the tubular membrane support was pure without any impurity. The synthetic materials of the top layer was Na2 Si O3 and Al(OH)3. The membrane was used to separate ethanol/water binary mixtures, and the results showed that the membrane was of good separating performance, and the maximum permeation flux and separation factor were separately 0.9 kg.m-2.h-1 and 16000 when ethanol content was under 90%. The membrane separating performance was also studied in esterification system. The membrane showed the maximum permeation flux of 2.0 kg·m-2·h-1 at the operation time of 8 h, and the SEPARATION FACTOR of water/ethanol and water/oleic acid were separately 16000 and8000 at the operation time of 18 h. Moreover, the membrane permeation flux can be enhanced by rising the temperature. After being used for 9 times, the membrane still was of good stability, and the conversion of the oleic acid was always above 85%.The operating conditions of esterifications in the coupled reactor of PV integrated with FBR and the FBR without PV were separately optimized, and the final conversions achieved at the same experimental conditions were compared so as to analyse the influence of the combination of PV with FBR to the esterification. Results showed that the optimized conditions in the FBR were the reaction temperature of 80.0 o C, ethanol to oleic acid molar ratio of 15:1, catalyst bed height of 160 mm and feedstock flow rate of 1.0 ml/min. And the optimized conditions in the coupled reactor were the reaction temperature of 80.0 o C,ethanol to oleic acid molar ratio of 15:1, catalyst bed height of 132 mm, feedstock flow rate of 1.0 ml/min and the optimized membrane area to feed volume ratio of 3.74. The experimental result of these two reactions under the same experimental conditions showedthat compared with the esterification without PV, the time for achieving balance of the PV assisted esterification was shorted by 6 h. The resin exhibited a much high catalytic activity and stability after used for 100 h in the consecutive single pass fixed-bed esterification.The kinetic model of the coupled membrane reactor(MR) of PV with esterification was built, and the accuracy of the kinetic model was verified by comparing the experimental data with the theoretical results. Moreover, the software Fluent 14.5.0 was applied to simulate and predict the flow distribution of the fluid pressure, the fluid viscosity and the flow velocity in the MR. The influence of the temperature on the esterification was illustrated from the aspect of fluid flows.