Synthesis Process And Performance Study Of Bio-based Lubricants

Traditional lubricating oil was mainly obtained from mineral-based oil through petroleum refining,and the production process of mineral-based oil is characterized by high energy consumption,high pollution and poor biodegradability,which has serious pollution to water and land resources in its life cycle.Bio-based lubricant has good biodegradability and excellent lubricating performance,which solves the shortage of mineral-based lubricant with poor environmental compatibility and dependence on petroleum resources,and is considered a green preservation lubricant with broad future.In this thesis,an enzyme-catalyzed process for the synthesis of polyol ester-based bio-lubricants from modified yeast grease was developed.The enzyme was used as a catalyst for the synthesis of bio-based lubricants.The reaction process was optimized in terms of temperature,substrate ratio and enzyme amount,and the final target product yield reached 89.5±1.2%.The model of the effect of variables T,E and R on the response value Y(triglyceride yield)was constructed by Box-benhnken response surface analysis using Design-Expert 12 software,and the accuracy of the model was tested by ANOVA and P-test.The model predicted the best reaction parameters as T=45.106℃,R=3.310,E=10.654%,and the predicted response value Y was 92.55%.The triglyceride yield was 91.53±1.2%verified by three replicate actual experiments,indicating that the established model was accurate and credible.Four process routes were designed with tertiary cottonseed oil and frying waste oil as raw materials by optimizing the process and comparing and evaluating the comprehensive energy consumption and emissions.The optimal conditions were obtained by optimizing the reaction process factors of chemically catalyzed tertiary cottonseed oil:oil-water ratio of 2.5,water-alcohol ratio of 1,alkali amount of 10%excess saponification value,temperature of 40℃,stirring speed of 300 r/min,reaction time of 0.5 hours,and final hydrolysis rate of 98.9%.The optimal conditions were obtained by optimizing the reaction process of enzyme-catalyzed frying:pH 7.5,oil-water ratio 1,40℃,enzyme amount of 10%of the oil amount,stirring speed 400r/min,reaction time 24 hours,and the final hydrolysis rate was 86.6%.The experiments were also carried out for the process 10 times scaling up experimental data with no significant difference from the small test,the scaling up effect is good.The process comparison and evaluation analysis were used to obtain the comprehensive energy consumption and effluent data per unit quality of product for each process.As far as the esterification stage is concerned,enzyme catalysis has a greater advantage over chemical esterification.The energy consumption of enzymatic esterification was 36.4%lower than that of chemical esterification,and zero polluted wastewater discharge was achieved in terms of pollution discharge.In a cross-sectional comparison of the four process routes,the combined chemical and biological method achieves a balance of efficiency and energy consumption,with lower energy consumption and effluent with potential for industrial production applications.The four products prepared were systematically evaluated in comparison with mineral-based base oils of the same viscosity grade.The results show that all the four products reach the standard of ISO-VG46 and have obvious advantages in lubricating performance compared with mineral-based lubricants of the same viscosity.The composite blending results indicate that the products synthesized in this study can be used as a good bio-based green hydraulic fluid base oil.