Qualitative and Quantitative Functional Determination in Bitumen Acidic Fractions by 29Si NMR Spectroscopy. Correlation with Bitumen Aging

Knowledge of the chemical functions existing in bitumens represents an important step in the characterization of their aging processes. A new investigation method based on a combination of precipitation and IEC separations followed by both qualitative and quantitative 29Si-NMR spectrocopy is presented. This method is proved to be an efficient procedure for the determination of the acidic fractions of these high-boiling petroleum fractions. It has been demonstrated that phenols, carboxylic acids, and other oxygenated functions were present. A correlation between the acidic character and the aging of bitumens is presented as a prediction of the rate of evolution of these materials.