Preparation and evaluation of polymeric additives based on poly(styrene-co-acrylic acid) as pour point depressant for crude oil

Abstract

The low-temperature flow properties of waxy crude oils are considered the determining factor in pipeline transportation. Polymeric additives known as pour point depressants (PPDs) have been developed to control the growth habits of wax crystals to improve the cold flowability of waxy crude oils. In the present article, a copolymer of poly(styrene-co-acrylic acid) was synthesized by batch emulsion polymerization of styrene (St) and acrylic acid (AA). Further, it was esterified with N,N-dimethylethanolamine, then its quaternization had done by dodecyl and hexadecyl bromide. The prepared compounds are characterized by Fourier transform infrared (FTIR), transmission electron microscopy (TEM), and x-ray diffraction (XRD). The efficiencies of the prepared compounds as PPDs and flow improvers were investigated. From the results, it is found that the quaternized ester of the copolymer with hexadecyl bromide (PPD4) exhibited the maximum pour point depression (ΔPP = 18 °C) at1000 ppm. The XRD of asphaltene in the absence and presence of investigated additives were studied. Photomicrography analysis showed a clear effect of the additives on the wax crystal modification.