Estimation of hydrocarbon types in light gas oils and diesel fuels by ultraviolet absorption spectroscopy and multivariate calibration

Abstract

Ultraviolet absorption spectra are used in conjunction with multivariate calibration methods to predict the percent content of saturates (61-99%), monoaromatics (1-34%), diaromatics (0-5%), and polyaromatics (0-1%) in light gas oil and diesel fuel samples. A total of 114 samples taken from three pilot plant studies between 1992 and 1994 were used to develop the calibration models. Supercritical fluid chromatography with flame ionization detection was employed as the reference method for quantifying hydrocarbon types. Several multivariate calibration methods (classical least squares, multiple linear regression, principal components regression (PCR), and partial least squares (PLS)) were examined. PCR and PLS gave the best overall performance, with root-mean-squared errors of prediction (absolute) of 0.9% (saturates), 0.8% (monoaromatics), 0.2% (diaromatics), and 0.05% (polyaromatics) based on 44 prediction samples. Relative errors (absolute × 100/range) for these same species were 2.4%, 2.4%, 3.2%, and 5.3%.Key words: light gas oil, diesel, hydrocarbon content, UV spectroscopy, multivariate calibration, aromatics, petroleum.