Determination of Carbonyl Functional Groups in Heavy Oil Using Infrared Spectroscopy

In this study, we examined carbonyl functional groups in Canadian oil sand bitumen using Fourier transform infrared spectroscopy (FTIR). FTIR spectra of a bromoform solution of the bitumen fraction showed carbonyl absorption at 1702 cm(-1) which shifted to 1718 cm(-1) following the addition of 1,6-dicyanohexane (DCH) to the bromoform solution. Bromoform solution analyses of model aliphatic and aromatic carboxylic acids and ketones showed carbonyl absorption values of 1704-1702 and 1691-1680 cm(-1), respectively, for the aliphatic and aromatic compounds. When DCH was added to the bromoform solution, aliphatic and aromatic carboxylic acid carbonyl absorption shifted to higher wavenumbers, whereas no equivalent shift was observed in ketones. Therefore, we conclude that the bitumen fraction contained aliphatic carboxylic acids. The FTIR area ratio of carbonyl to C-H of bromoform, at 3020 cm(-1) in the model carboxylic acids and ketones, increased in proportion to their mole ratios. The amount of carbonyl in the bitumen fraction was estimated at 0.026 mol/kg based on the relationship between the area ratio and mole ratio.