Structure regulation and influence of comb copolymers as pour point depressants on low temperature fluidity of diesel fuel

Adding pour point depressants (PPDs) is a simple and efficient method to remediate the low temperature fluidity of diesel, however, the depressive effects of these polymeric PPDs are always affected by their molecular structure and polarity. In this work, to obtain high-efficiency PPDs for diesel, a series of comb copolymers of tetradecyl methacrylate-benzalacetone (C14MC-BAE), tetradecyl methacrylate-methyl cinnamate (C14MC-MCA) and tetradecyl methacrylate-ethyl 3-benzoylacrylate (C14MC-EBLA) were synthesized by the regulation of molecular structure. The depressive effects of these copolymers on the cold filter plugging point (CFPP) and solid point (SP) of diesel were studied and compared with that in previous reports. Results showed monomers with carbonyl group closer to benzene ring in side chain have better inhibition. As the mole ratio of monomer up to 9:1, these PPDs had the best depressive effect on CFPP and SP of diesel. Thereinto, C14MC-EBLA (9:1) at 2000 ppm decreased the CFPP and SP of diesel by 12 °C and 15 °C, respectively. Furthermore, the morphology and crystallization behavior of wax crystals in diesel before and after adding PPDs were analyzed by polarizing optical microscope, differential scanning calorimeter and viscosity-temperature curves. •A series of methacrylate copolymers were synthesized as PPDs for diesel.•The depressive effect of copolymers can be improved by structure regulation.•C14MC-EBLA (9:1) achieved the greatest reduction on SP and CFPP at 2000 ppm.•The action mechanism of PPDs on diesel were also investigated.