Date of Award

1997

Degree Name

Chemistry

College

College of Science

Type of Degree

M.S.

Document Type

Thesis

First Advisor

J. Graham Rankin

Second Advisor

Lawrence Schmitz

Third Advisor

Michael Norton

Abstract

An analytical method was developed to quantitatively determine the asphaltene content in petroleum crude oils by Fourier transform infrared spectroscopy (FT-IR). Asphaltenes are a solubility class of compounds found in crude oils. They are black to dark brown solids defined by their insolubility in n-alkane solvents. The structure of asphaltene molecules is polynuclear aromatic rings with alkyl side chains and heteroatoms, such as nitrogen, oxygen, and sulfur attached. Asphaltenes are known to cause oil well plugging and irreversible catalyst deactivation in refineries. The asphaltene content of 50 crude oils from a wide array of geochemical conditions was determined by the standard n-pentane insolubles method. FT-IR spectra of the 50 crude oils were collected using an attenuated total reflectance (ATR) cell. A partial least squares (PLS) model was generated to predict the amount of asphaltenes from 42 of the crude oils. The model was shown to have an R2 value of 0.95 and a standard error of estimate (SEE) of 0.92 wt%. An independent prediction set of eight crude oils was used to test the validity of the model. The prediction set was shown to have an R2 value of 0.96 and a standard error of prediction (SEP) of 0.99 wt%. The FT-IR method compares favorably with the current laboratory method in terms of results, is faster, and uses no solvents.

Subject(s)

Asphaltene.

Petroleum -- Analysis.

Chemistry, Analytical.

Tourier transform infrared spectroscopy.

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