EPOXIDATION OF PALM OIL CATALYZED BY VANADYL(IV)- PHENOXYIMINES WITH TERTIARY BUTYL HYDROPEROXIDE

• Main Author: Aini Maulida Zahro, Rifa
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/82760
• Institution: Institut Teknologi Bandung

Indonesia is the largest producer of palm oil. Palm oil has numerous applications due to its versatility. Epoxidized palm oil (EPO) is a valuable derivative with a higher economic value compared to palm oil (PO). EPO can be used directly as a plasticizer or as an intermediate in the synthesis of lubricants, adhesives, and coating materials. Additionally, EPO can replace phthalates, which are restricted in the United States and Europe due to their carcinogenic properties. EPO is produced by oxidizing the carbon-carbon double bonds in the triglyceride chain of palm oil to form an oxiran ring. The conventional method of EPO synthesis involves the use of hydrogen peroxide and mineral acid, which is an exothermic process resulting in low selectivity and corrosive effects on the reactor. The epoxidation reaction can be catalyzed by transition metals using oxygen sources such as tertiary butyl hydroperoxide (TBHP). The complex of MoO2(acac)2 was reported to produce 54% epoxide at 110 °C for 2 h. However the reactions used toluene as solvent, which requires separation of product after the reaction is complete. Recent studies show the activity of vanadium Schiff base in the epoxidation reaction. Phenoximine is one of the Schiff base ligands. To the best of our knowledge, there is no report of palm oil epoxidation using vanadyl(IV) phenoxyimine thus far. This study evaluates the activity of vanadyl(IV) phenoxyimines in the palm oil epoxidation in the absence of solvents and mineral acids. The electronic character of vanadium is modified by a nitro moiety in the phenoxyimine ligand. The synthesis of the vanadium(IV)-phenoximine complex is done by reacting vanadium sulfate with the phenoximine ligand. The results show that the solid complex is green. The synthesized complexes were characterized using P-XRD, MS, FTIR, and MSB. The vanadium(IV)-phenoxyimine complex is used for the epoxidation of palm oil with TBHP as the oxidant. The product of epoxidation is analyzed using 1H-NMR. The catalytic activity test shows that the complex VO(FI-1c)2 produces the highest yield of epoxide, 57%, compared to VO(FI-1a)2 and VO(FI-1b)2, which are 54% and 16%, respectively, under conditions of 70 °C, 3 meq TBHP, 0.3 mol% catalyst, and 7 h. The optimization of reaction parameters for the complex VO(FI-1c)2 shows that 68% epoxide (TOF 76 h?1) can be produced when the reaction at 80 °C, 7 h, 0.1 mol% catalyst, and 3 meq TBHP. The kinetic study at 60, 70, and 80 °C shows that the vanadium(IV) phenoxymine catalyzed epoxidation is pseudo second-order. The values of activation energy is 65 kJ/mol while enthalpy, entropy, and Gibbs free energy of activation at 80 °C are 62 kJ/mol, ?83 J/mol K, and 92 kJ/mol, respectively. The reaction without a catalyst does not produce epoxide, thus the use of a catalyst is necessary for epoxidation. The epoxidation reaction is proposed to occur through the Sharpless mechanism. The complex VO(FI-1c)2 produces the highest yield of epoxide which may indicate that the key step in the epoxidation reaction is the single electron transfer step.