Preparation Of Palm Oil Lubricant

The C=C double bonds in the unsaturated fatty acid and theβ-H in the glycerol molecule make palm oil have poor oxidation stability. In this paper, through epoxidation and ring-opening reaction, the C=C was removed, and through transesterification, theβ-H was removed. After chemical modification, the oxidation stability of palm oil was greatly improved. Three kinds of lubricant base oils: epoxy palm oil, acetic acid isomer-ester and trimethylolpropane tri-ester were prepared in this paper. Then, the base oils were compounded with additives to prepare three different viscosity grades of green food machinery lubricants.The epoxy palm oil was prepared using peracetic acid and peroxyformic acid. Adopting single-factor experiments, orthogonal experiments and response surface methodology, and comparing of the two preparation methods, the epoxy palm oil which was prepared using peroxyformic acid had a higher epoxy value. The optimum conditions were determined as follows: mass ratio of palm oil to formic acid to hydrogen peroxide (concentration 30%) to concentrated sulfuric acid 30:6:43:0.3, reaction time 6h, temperature 65℃, and in this condition, its epoxy value was 3.89%. The structural confirmation of the epoxy palm oil was done by FT-IR.The epoxy palm oil prepared using peroxyformic acid was reacted with acetic acid to prepare acetic acid isomer-ester through ring opening reaction. By experimental design and data processing, the rate equation of oxirane cleavage was found to be satisfied with r= k[Ep][CH₃COOH]^1.6, [Ep] was the molar concentration of oxiranes; [CH₃COOH] was the molar concentration of acetic acid and k was the rate constant. The study also showed that, k and the reaction temperature T followed the Arrhenius equation, and the higher the reaction temperature, the faster the oxirane cleavage reaction. The activation energy of oxirane cleavage was 40.28KJ·mol-1. According to the kinetic study, selecting the molar ratio of acetic acid to oxiranes 5:1, reaction temperature 90℃, reaction time 3h, in this condition, the residual epoxy value of the acetic acid isomer-ester was 0.09%, and the structural confirmation was done by FT-IR.The palm oil was also reacted with methanol to prepare palm oil methyl ester, then the palm oil methyl ester was reacted with trimethylolpropane to synthesize trimethylolpropane tri-ester. Adopting the single-factor experiments and response surface methodology, the optimum conditions were determined as follows: the molar ratio of palm oil methyl ester and trimethylolpropane was 7.3:1, amount of sodium methoxide 0.86%, reaction for 7h at temperature of 168℃, and the production rate of tri-ester was up to 88.75%. After purification with molecular distillation, the purity of tri-ester was 98.6%. The structural confirmation was done by FT-IR and MS.Then, the epoxy palm oil, acetic acid isomer-ester and trimethylolpropane tri-ester were compounded with PB-1300 (polyisobutylene), T803B (poly-α-olefin), BHT (2,6-Di-tert-butyl-4-methylphenol) and S-80(sorbitol monoglycerides) to prepare green food machinery lubricants of different viscosity grades of 68, 220 and 150. The three kinds of lubricants all had good viscosity-temperature performances, outstanding security stability and excellent biodegradability, and their color, acid value, sulfate ash, moisture, mechanical impurities and other properties were also better than commercial petroleum-based lubricants.