Fractionation of various heavy oils and bitumen for characterization based on polarity

Abstract

Shale oil, coal liquid, heavy petroleum oil, and oil sand bitumen were separated into four fractions through a silica gel column, with good recovery and repeatability. Structural characterization was performed using elemental analysis i.r., and 1H n.m.r. by the modified Brown-Ladner equations as well as the five-regions method. The structural parameters revealed that coal liquid contained the most polar material while crude oil contained the least. Shale oil had the highest nitrogen content, while oil sand bitumen had the highest sulphur content, and coal liquid had the highest oxygen content. The molecular weight of crude oil was the highest and that of coal liquid was the lowest. The degree of condensation of the aromatic system was as follows: oil sand bitumen > crude oil > coal liquid > shale oil. Coal liquid contained mainly internal olefins while shale oil contained mainly α-olefins. The distribution pattern of the four fractions was different for each fossil fuel studied. This suggests a separation scheme that is a simple, efficient, and rapid technique to fractionate heavy oil and bitumen samples.