Synthesis and evaluation of benzyl methacrylate-methacrylate copolymers as pour point depressant in diesel fuel

Abstract

The cold-flow properties of diesel fuel are considered as the determining factors of diesel utilization and popularization. Pour-point depressants (PPDs) are often added to diesel to remediate issues with fluidity in cold climates. In this study, a series of benzyl methacrylate-methacrylate copolymers (MB-R1MC, R1 = C12, C14, C16, C18) and benzyl methacrylate-tetradecyl methacrylate (MB-C14MC) in different molar ratios of the functional monomers (1:1, 1:5, 1:10, 1:15, and 1:20) was synthesized by radical polymerization and characterized by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (1H NMR). The depression effects of these PPDs in diesel were investigated and compared with previous reports. Results showed that diesel treated with 3000 ppm MB-C14MC (1:10) exhibited the best depression on solid point and cold filter-plugging point (CFPP) by 26 and 12 °C, respectively, and the CFPP depression was evidently superior to that in a previous research. Moreover, the action mechanism was explored by differential scanning calorimeter, polarizing optical microscopy and rheology analysis. Results showed that the nonpolar component of PPDs co-crystallized with n-alkanes and provided large number of crystallization sites in diesel, whereas the polar components adsorbed on the wax crystal surface, thereby changing the shape, decreasing the size, and increasing the dispersity of wax crystal. Therefore, MB-C14MC copolymer was confirmed to be an excellent PPD of diesel fuel.