Synthesis And Performance Of New PIBSAE Dispersants In Reducing Jet Fuel Thermal Oxidation Deposition

In advanced aircraft,the thermal oxidation stability of jet fuel is of high concern.The use of additives is the most economical and effective method to solve this problem.Additives usually include antioxidants,metal deactivators and dispersants.Among these additives,dispersant is the most demanded one and it can directly work on sediment particles and their precursors to inhibit the formation of thermal oxidation deposits.Commonly used dispersants have disadvantage of complicated preparation process,environmental pollution or poor thermal stability.In this paper,through hydrothermal synthesis,using polyisobutylene succinic anhydride(PIBSA)and polyglycerol,which is non-toxic and environmentally friendly,as raw materials,a new polyisobutylene succinic acid ester(PIBSAE)dispersant was prepared.Its structure and performance in reducing the thermal oxidation deposition of Chinese jet fuel RP-3 was also investigated.First,the effects of reaction temperature,reaction time,different raw material ratios(PIBSA: polyglycerol)and different sizes of polyglycerol on the structure and performance of the dispersant are examined.The results showed that the optimal molar ratio for PIBSA and polyglycerol reaction is 1:1,more PIBSA will cause higher total acid number,more polyglycerol ratio will cause higher amount of hydroxyl groups and di-ester molecules in the product which may cause new coking chain reaction.In addition,using triglycerol as a raw material is more effective than tetraglycerol and hexaglycerol.The dispersant,which obtained from PIBSA reacting with triglycerol at a molar ratio of 1:1 under 180 ℃ for 10 h,reduced 86.4% of the thermal oxidation deposit of RP-3 in electrically heated tube test which has an inlet temperature of 50 ℃ and an outlet temperature of 350 ℃.Then,the obtained ester-type dispersant was compared to commercial dispersant T154 in electrically heated tube test and Jet Fuel Thermal Oxidation Stability Test(JFTOT)under 355 ℃.It was found that although ester-type dispersant had better performance in reducing surface deposition it will cause larger suspended insoluble particles.We modified ester-type dispersant with polyamine which reduced the total acid number and controlled the size of poly-ester molecule.It was found that controlling the amount of added amine is the key to ensure the performance of dispersant under high temperature.The best amine-modified ester-type dispersant reduced 81.2% of the thermal oxidation deposit of RP-3 in electrically heated tube test and the JFTOT result shows that although its ability to reduce thermal oxidation deposition is little bit lower it will not cause larger suspended insoluble particles.