Analysis of gasolines with low and high octane ratings by gas chromatography/mass spectroscopy

CHED 1093

Danijela Smiljanic, baird@wju.edu, James Coffield, and Michael J. Baird, Baird@WJU.edu. Department of Chemistry, Wheeling Jesuit University, 316 Washington Ave., Wheeling, WV 26003
Gasolines are a mixture of hydrocarbons having carbon numbers ranging from 5 to 12 and total approximately 200 compounds. An important property for gasoline is efficient combustion which is indicated by an octane number. The octane number of a gasoline is determined by comparing the antiknock properties of a gasoline blend to that of gasoline standards. At petroleum refineries, the reforming process is used to convert low octane compounds, such as n-alkanes and cycloalkanes, to higher octane compounds, such as iso-alkanes and aromatics. These higher octane hydrocarbons are blended into gasoline resulting in octane numbers ranging from 86 to 94. It is postulated that gasolines with higher octane ratings (93 or 94) should contain more aromatic and branched-hydrocarbons than gasolines with lower octane ratings. In this presentation, the results from analyzing low and high octane gasolines by gas chromatography/mass spectroscopy will be discussed.