DETERMINATION OF OCTANE NUMBERS AND REID VAPOR-PRESSURE OF COMMERCIALPETROLEUM FUELS USING FT-RAMAN SPECTROSCOPY AND PARTIAL LEAST-SQUARESREGRESSION-ANALYSIS

A Fourier transform Raman spectrometer was used to collect the Raman s pectra of 208 commercial petroleum fuels. The individual motor and res earch octane numbers (MON and RON, respectively) were determined exper imentally using the industry standard ASTM knock engine method. Partia l least-squares regression analysis was used to build regression model s which correlate the Raman spectra of 175 of the fuels with the exper imentally determined values for MON, RON, and pump octane number (the average of MON and RON) of the fuels. Each of the models was validated using leave-one-out validation, The standard errors of validation are 0.415, 0.535, and 0.410 octane units for MON, RON, and pump octane nu mber, respectively, By comparing the standard error of validation to t he standard deviation for the experimentally determined octane numbers , it is evident that the accuracy of the Raman determined values is li mited by the accuracy of the training set used in creating the models. The Raman regression models were used to predict the octane numbers f or the fuels which were not used to build the models. The results comp are favorably with the leave-one-out validation. Also, it is demonstra ted that the experimentally determined Reid vapor pressures are highly correlated with the Raman spectra of the fuel samples and can be pred icted with a standard error of 0.568 psi.