Synthesis Of Oil Pour Point Depressants And Research On The Depression Mechanism

In the season of low temperature, the long chain n-alkanes of oil are easily crystallized and bring great difficulties to the use and transport of oil, so improve the cold flow property of oil plays an important role. Adding pour point depressant(PPD) is an economic and effective way to improve the cold flow property of oil. This paper mainly studied the synthesis of PPDs and the depression mechanism.N-alkyl acrylate-vinyl acetate-maleic anhydride(AVM) and n-alkyl acrylate-vinyl acetate-styrene(AVS) were synthesized by radical polymerization and the alkyl chain length of alkyl acrylate were 12, 14, 16 and 18. The better experimental conditions of the two systems were determined by orthogonal experiment. Finally, the AVM terpolymers AVM-12, AVM-14, AVM-16, AVM-18 and AVS terpolymers AVS-12, AVS-14, AVS-16, AVS-18 were obtained. The synthesized terpolymers were characterized by FTIR, GPC and TG, the results confirmed that the polymerization of monomers occurred preferably, the molecular weight of terpolymers was on the preferred molecular weight range and the terpolymers had a high heat resistance.For 0# diesel oil of Qingdao Refinery Co., the distribution of n-alkanes in diesel fuel was analyzed first, then the effect of AVM terpoymers with different alkyl chain length on solidifying point, cold filter plugging point and viscosity of diesel fuel was determined. Meanwhile, the micrographs of diesel fuel treated with and without PPDs were photographed. Finally, the probable performance mechanism of AVM terpolymers was obtained through a comprehensive analysis of above results. AVS terpolymers were done the same test and the results shown that the effect of AVS terpolymers was worse than the effect of AVM terpolymers and the impact of alkyl chain length on the two systems was inconsistent, this may be because the depression mechanism of the two systems was different.-10# diesel oil of Qingdao Refinery Co. was selected to evaluate the efficiency of compound PPDs. The mixed methods were better PPDs compound with each other, and better PPDs compound with surfactant agents and EVA. AVS terpolymers had better compounding effects wit h the selected objectives, while AVM terpolymers basically had no compounding effects.For Jiudong and Qingxi crude oil, only AVM-18 had good effects on crude oils, thus the effects of AVM-18 on viscosity, colling gelling property, yield value and isothermal structure development of crude oil after static and dynamic cooling were studied. After adding AVM-18, the viscosity and yield value of crude oil was reduced significantly; the cooling gelling property of crude oil had a big change and the gel point moved to lower temperature; the strength of gel structure decreased obviously. The strength of isothermal structure of crude oil treated with and without PPD had a great decrease after dynamic cooling compared with after static cooling. The results suggested that the adding of PPD made the strength of three dimensional network significantly reduced and the shear rate added in cooling process also made the strength of three dimensional network significantly reduced.