Preparation Of Nitrogen-Containing PPD And Their Effects On Diesel Cold Flow Properities

Diesel is a light petroleum product with a high wax content and is commonly used as a transportation fuel.At low temperatures,the solubility of n-alkanes in diesel decreases and crystallizes,which lead to a decrease in the fluidity of diesel and blocks pipelines and equipment.The weak cold flow performance of diesel is one of the key factors limiting its cold flow properties.In this paper,for the purpose of improving the low-temperature fluidity of diesel,we design and synthesize nitrogen-containing methacrylate pour point depressants（PPDs）with different structures and polarities.The crystallization behavior and crystal morphology of the treated diesel fuel were discussed by differential scanning calorimeter（DSC）,polarized optical microscope（POM）and rheological analysis.The main research contents are as follows:（1）Through free radical polymerization,tetradecyl methacrylate(C₁₄MC)and tetradecyl methacrylate-N-α-methacrylamide were polymerized in different ratios,and a series of tetradecyl methacrylate-N-α-methacrylamide copolymer(C₁₄MC-NMLR)high-efficiency pour point depressant（PPD）was synthesized.The results showed that diesel treated with 2000 ppm of C₁₄MC-NML-phenyl（9:1）and C₁₄MC-NML-14a（6:1）showed better solid point（SP）and cold filter plugging point（CFPP）,respectively.Mixing them with 1:4,At a dose of 1000 ppm,ΔSP andΔCFPP reached 25°C and 11°C,respectively.（2）The combined-PPD has shown application potential in improving the cold flow properties of diesel.In this study,a series of methacrylate-acrylamide copolymers（RMC-AM）were polymerized with different molar ratios of polymerized methacrylate（RMC）and acrylamide（AM）using radical polymerization.The effects of different chain lengths and different monomer molar ratios on the SP and the CFPP were explored.Among RMC-AM,C₁₄MC-AM（9:1）shows relatively good cold flow properties（ΔSP=25°C,ΔCFPP=10°C）.Subsequently,ethylene-vinyl acetate copolymer（EVA）materials with different VA contents were introduced.Diesel treated with 1000 ppm EVA-2（VA=28%）showed relatively good cold flow properties（ΔSP=18°C,ΔCFPP=10°C）.Mixing C₁₄MC-AM（9:1）and EVA-2 with 1:2,only 500 ppm is used for treatment,ΔSP andΔCFPP of diesel can reach 28°C and 23°C respectively.The diesel shows excellent cold flow properties.