Production of alkyl esters as lubricating base oil from palm stearin

Abstract

In this study, the production of alkyl esters from palm stearin for use as lubricating base oil via transesterification reaction with various alcohols as 1-propanol, isopropanol, 1-butanol, 1-hexanol, 1-octanol and 2-ethyl-1-hexanol were investigated. The experiments were conducted in a batch system using sulfuric acid as a catalyst at reaction temperature between 82 degrees Celsius to 130 degrees Celsius. The reaction was carried out at a molar ratio of alcohol to palm stearin of 6:1. The reaction time is 3 hours in each experiment under a continuous stirring. After each experiment, alkyl esters were characterized for their physical and chemical properties. Use of alkyl esters as viscosity index improver was investigated by blending alkyl esters with mineral base oil 150 SN different amounts of alkyl ester. Experimental results show that different types of alcohol affected physical and chemical properties of alkyl esters. Because of different molecular size and molecular structure of each alcohol, the higher molecular size and straight-chain structure provide advantage to alkyl ester properties to have higher kinematic viscosity, higher flash point and lower pour point which are suitable to be used as lubricating base oil. The experimental results also show that 2-ethyl-1-hexyl ester has its properties similar to hydraulic oil. It is also found that viscosity index of each alkyl esters is high enough to be used as viscosity index improver. Blending of mineral base oil 150 SN with alkyl ester shows higher viscosity index of lubricating base oil 150 SN.