In the present work, two types of relatively low molecular weight styrene-based acidic copolymers were prepared as dispersants for asphaltenes in heavy crude oil. It was observed that when poly(styrene-co-methacrylic acid) copolymer (content of acidic repeat units = ca. 3 mol%) was added to the heavy crude oil to make the weight percentage of dispersant in the crude oil 1%, the acidic copolymer did not affect the dispersion of asphaltenes significantly. Furthermore, the increase in the amount of acidic repeat units from 3 mol% to 15 mol% also did not change the dispersion behavior of the asphaltenes in heavy crude oil. This suggested that the carboxylic acid groups of the copolymers did not interact with asphaltenes strongly enough to enhance the dispersion of the asphaltenes in heavy crude oil. In addition, it was also observed that the dispersion of the asphaltenes was not improved by the addition of poly(styrene-co-styrene sulfonic acid) copolymer (content of acidic repeat units = ca. 11 mol%), which made the weight percentage of dispersant in the crude oil 1%. However, it was found that when the weight percentage of the sulfonic acid copolymer was decreased to 0.1%, the dispersion of the asphaltenes in the heavy crude oil improved noticeably. This indicated that the presence of the sulfonic acid groups, than that of the carboxylic acid groups, was necessary for the asphaltenes to be dispersed in the heavy crude oil. In addition, the relative amount of acidic copolymers in the heavy crude oil was very important for the better dispersion of asphaltenes.

Effects of the addition of relatively low MW acidic copolymers on the dispersion of asphaltenes in heavy crude oil

255th National Meeting (2018)

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