Study On The Chemical Modification Of Vegetable Oil To Prepare Low Pour Point Polyol Ester Lubricant Base Oil

Vegetable oil has the advantages of green renewable,good environmental compatibility,low volatility,easy degradation,high lubrication,etc.It is often used to synthesize bio-based lubricants.However,because vegetable oil contains a large amount of C=C,it is easily oxidized and deteriorated;and the unique triglyceride structure of vegetable oil,which contains ?-H,is unstable and easily decomposed at high temperature,which greatly limits the direct use of natural vegetable oil as a lubricant.Therefore,modifying the chemical structure of vegetable oil can improve its oxidation stability,low-temperature fluidity and thermal stability to varying degrees.At present,the main modification method of vegetable oil is to keep the carbon chain length of branched fatty acid unchanged,and simply modify its structure(such as:transesterification,epoxidation,branching,isomerization,etc.).It can improve its low temperature fluidity and oxidation stability to a certain extent,but it is still difficult to obtain ultra-low pour point lubricating base oil(pour point below-40?)by this method.To this end,this paper proposes a brand-new solution,that is,a two-step synthesis of polyol ester lubricant base oil:(1)Using free fatty acid methyl ester as raw material,oxidative cracking to prepare medium chain fatty acids nonanoic acid(PA)and methyl azelate(AA);(2)Using biological enzymes as catalysts to catalyze the esterification of PA and trimethylolpropane(TMP)to prepare TMP trinonanoate.On this basis,by blending the ratio of nonanoic acid to oleic acid,TMP nona/oleate in different ratios was prepared,and the performance parameters of each mixed ester were determined.