Epoxidation of castor oil fatty acid methyl esters (COFAME) as a lubricant base stock using heterogeneous ion-exchange resin (IR-120) as a catalyst

Castor oil fatty acid methyl esters (COFAME) epoxide was derived by In-situ epoxidation reaction from COFAME to be used as a bio-lubricant basestock. During the reaction acetic acid was acted as an active oxygen carrier and hydrogen peroxide (H2O2) was an oxygen donor in the presence of strongly acidic cation ion-exchange resin (Amberlite IR 120) as a heterogeneous catalyst. In-situ epoxidation reaction was carried out at H2O2, acetic acid to ethylenic unsaturation molar ratio of 1.5 and 0.5 respectively; catalyst loading 15 wt%, reaction temperature 60 degrees C and reaction time 10 h. The objective of the study was to improve the thermo-oxidative stability of epoxidised COFAME. The resulting products were confirmed by H-1 NMR, FTIR spectroscopy and also analysed for oxirane oxygen content (OOC). Required physico-chemical properties were estimated for unmodified COFAME and epoxidised COFAME. Thermo-oxidative stability of epoxide was determined by thermo gravimetric analysis (TGA) technique in an inert and oxygen atmosphere. Thermo-oxidative stability of COFAME and its epoxide was compared with conventional servo hydraulic lubricant base stock oil. The present work has clearly illustrated significant improvement in the thermo-oxidative stability of COFAME epoxide i.e. after the structural modification.