A novel preparation method and performance evaluation of polyacrylic acid high-carbon alkyl esters

Polyacrylic acid high-carbon alkyl esters provide unique advantages in the fields of diesel oil low-temperature flow modification, crude oil demulsification and heavy oil viscosity reduction, so these esters have been widely considered. In this work, a novel method is proposed for preparing polyacrylic high-carbon alkyl esters, which involves an initial polymerization step and a subsequent esterification step, in contrast to the traditional approach, which involves initial esterification and subsequent polymerization. In the initial step, acrylic acid, methyl acrylate, maleic anhydride and methacrylic acid were selected as monomers and prepared separately via polymerization in an aqueous solution. A novel redox initiation system comprising ammonium persulfate (APS) and N,N-diethyl hydroxylamine (DEHA) was established for the first time to regulate the molecular weight distribution of the polymer. In the second step, the polymer was esterified with different high-carbon alcohols under catalysis to obtain products with various ester groups. Notably, the use of poly(tetradecyl acrylate) could reduce the cold filter point of base diesel to 4–5 °C and the freezing point to 1 °C. The application of polyhexadecyl acrylate could reduce the viscosity of a heavy oil, with a viscosity reduction rate of 32.5%, and decrease the pour point of the heavy oil from 5 °C to 3 °C.