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Abstract
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Provides
data on the chemical composition of the asphaltene component of Nigerian
crude oils in order to ascertain its properties which can assist in the
refining and processing paths of the oil. Researcher collected crude oil
samples from three major oil fields in Nigeria. They desalted them using
n-pentane. They determined organic characteristics of the precipitated
asphaltenes using Fourier Transform Infrared (FT-IR) Spectrometry. Elemental
contents were measured by Inductively Coupled Plasma Atomic Emission
spectroscopy (ICP-OES) and Carbon and Nitrogen Analyzer. Comparison of the
average content of the Nigerian crude oils asphaltene with that of other
nations shows that the Nigerian crude oil asphaltene content is less than
that of other nations, except for Russian crude oil, but slightly higher than
that of Brazilian crude oil, indicating that asphaltene deposition may pose
less problems during Nigerian crude oil development than most of the crude
oils from other nations.
The
IR spectra of the asphaltenes indicate the presence of alkanes, aromatic
rings, phenyl rings, alcohols, ethers, carboxylic acids, esters, aldehydes,
ketones, anhydrides, organic sulphoxides, sulphate salts and
thiobenzophenones. This confirms that asphaltenes are composed of high
molecular weight polycyclic constituents comprising of nitrogen, sulphur and
oxygen heteroatoms. Ten elements (Cr, Cu, Fe, Mn, Ni, S, V, Zn, C and N) were
examined and their concentrations determined. The results show that the
values of all the elements are comparatively higher in the asphaltenes than
the crude oils due to the presence of comparatively high concentrations of
porphyrins in the asphaltenes than the crude oils.
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