A Study of the Effect of UV Radiation on Resins and Asphaltene Fractions of Crude Oil by IR Spectroscopy

The photochemical stability of resins and asphaltenes during their photolysis under the influence of radiation from a mercury lamp is investigated by IR spectroscopy. It is found that exposure to UV light leads to a change in the band intensities of the absorption spectrum in the range of 400–3400 cm–1. The observed trends are explained on the basis of the transfer of excitation energy from polycyclic aromatic hydrocarbon (PAH) molecules to alkane molecules. From the values of the extinction coefficient and the relative concentration of PAHs in crude oil, the fractions of UV light energy absorption by molecules of individual PAH components are calculated.