Study On Synthesis And Properties Of Polyme-thacrylates As Cold Flow Improvers For Diesel Fuels

In the cold environment or when the temperature is lowered,the normal paraffins in the diesel are precipitated in the form of crystals and continuously grow and accumulate,thereby forming a three-dimensional network structure to block the filter screen,making the diesel engine unable to operate normally.In order to improve the cold flow properties of diesel,this article uses methacrylate as the core monomer,preferably monomers of different polarities,to synthesize a series of polymethacrylate diesel cold flow improvers（CFIs）with different structures through free radical polymerization.Study the effect of different polar groups in the polymer on the cold flow properties of diesel fuel,and through viscosity-temperature curves,differential scanning calorimetry（DSC）,polarizing optical microscopy（POM）and other test methods to explore the action mechanism of polymethacrylates diesel CFIs.The main content and relevant conclusions of this article are as follows:（1）Using methacrylates(RMC,R=C₁₄,C₁₆ and C₁₈)with different alkyl chain lengths and three polar monomers containing different numbers of benzene rings,N-benzyl methacrylamide（Bn MAM）,N-（diphenylmethyl）methacrylamide（Dp MAM）,N-（triphenylmethyl）methacrylamide（Tr MAM）in different molar ratios（1:1,3:1,6:1,9:1 and12:1）carry out the polymerization reaction to produce a series of copolymers of methacrylate-different methacrylamide compounds with different molar ratios and different numbers of benzene rings.Use it as a CFI of diesel to study the influence of the number of benzene ring groups in the copolymer on the cold flow properties of diesel.The results show that with the gradual increase in the number of benzene rings in the polymer,its depressing effect gradually decreases.Among them,C₁₄MC-Bn MAM（6:1）played the best role when the addition amount was 2000 ppm,reducing the solid point（SP）and cold filter plugging point（CFPP）of diesel by 26°C and 12°C,respectively.The influence of CFI on the viscosity of diesel fuel,the precipitation temperature of wax crystals and the morphology of wax crystals were studied through viscosity-temperature curve,DSC and POM.（2）Tetradecyl methacrylate(C₁₄MC)was optimized to react with two different nitrogen-containing polar monomers,N-benzylmaleimide（BMI）and 4-acryloylmorpholine（ACM）.A series of tetradecyl methacrylate-N-benzylmaleimide copolymers(C₁₄MC-BMI),tetradecyl methacrylate-4-acryloylmorpholine copolymers(C₁₄MC-ACM),and tetradecyl methacrylate-N-benzylmaleimide-4-acryloylmorpholine terpolymer(C₁₄MC-BMI-ACM)with different molar ratios were synthesized by free radical polymerization.The effects of benzene ring and morpholine groups in the polymer on the cold flow properties of diesel fuel were studied by using copolymers and terpolymers of methacrylate-different nitrogen-containing compounds as CFIs.The results show that,compared with the benzene ring and morpholine single polar group in the copolymers C₁₄MC-BMI and C₁₄MC-ACM,the terpolymer C₁₄MC-BMI-ACM contains both benzene ring and morpholine.The two groups act synergistically to improve the cold fluidity of diesel fuel.C₁₄MC-BMI-ACM（9:0.25:0.75）shows the best effect when the addition amount is 1000 ppm,reducing the SP and CFPP of diesel by 22°C and 12°C,respectively.In addition,the use of viscosity-temperature curve,DSC,macrocrystal image and POM research found that C₁₄MC-BMI-ACM delayed the precipitation temperature of wax crystals and modified the morphology of wax crystals,thereby significantly reduced the viscosity of diesel and improved the cold flow properties of diesel.