EXPLANATION
Aromatic content is a key property of hydrocarbon oils and can affect a variety of properties including boiling range, viscosity, stability, and compatibility of oils with polymers. Existing methods for this work use physical measurements and need suitable standards. This method does not need such standards and is applicable to a wide range of hydrocarbon oils that are completely soluble in chloroform and carbon tetrachloride at ambient temperature. The data obtained by this method can be used to evaluate changes in aromatic contents of hydrocarbon oils due to process changes. Applicable samples include kerosenes, gas oils, mineral oils, lubricating oils, coal liquids, and other distillates. The detection limit is about 0.1 mol % for aromatic hydrogen and 0.5 mol % for aromatic carbon atoms using pulse Fourier transform spectrometers. Continuous wave spectrometers measure only aromatic hydrogen content with a detection limit of 0.5 mol %. This test method is not applicable to samples containing more than 1 mass % olefinic or phenolic compounds.
TEST SUMMARY
Hydrogen NMR spectra are obtained on sample solutions in either chloroform or carbon tetrachloride using a continuous wave or pulse FT high resolution NMR spectrometer. Carbon NMR spectra are obtained on the sample solution in chloroform-d using a pulse FT high resolution NMR. Tetramethylsilane is preferred as an internal reference.
TEST PRECISION
For pure hydrocarbon compounds analyzed by this test method no bias was found.