| The oxidation stability is a very important index for the fuel quality evaluation. The induction period and gum content are often be used for gasoline oxidation stability assessment, which are traditionally determined in GB/T8018-87method and GB/T8019-2008method, respectively. However, the method being very complicated and time-consuming is very difficult to carry out the test of large amount of batch samples and cannot meet the demand of fast and accurate quality supervision of gasoline. Molecular spectroscopic technology has been applied in petrochemical industry for long in the virtue of useful structure information, simple operate step and fast analysis. No relative assess has been found for its use in evaluation of fuel oxidation stability.In this paper, we do lots of research for the feasibility of the application of fourier transform attenuated total reflection infrared spectroscopic (ATR-FTIR) method and Near infrared spectroscopic (NIR) method in oxidation stability evaluation of gasoline. Firstly, a new method is proposed for the fast determination of the induction period of gasoline using fourier transform attenuated total reflection infrared spectroscopy (ATR-FTIR).64different gasoline samples were collected from the Beijing-Tianjin area. The optimum measuring conditions for measuring spectra of gasoline are studied. A PLS calibration model for the induction period was established. The correlation coefficient (R2), standard error of calibration (SEC) and standard error of prediction (SEP) of the model are0.897,68.3and91.9minutes, respectively. The relative deviation of the model meets the requirements of repeatability tolerance in GB/T8018-87method. Moreover, the NIR spectra of61gasoline samples have been collected. And a A PLS calibration model for the induction period has been built which has the Rc, SEC, SEP value of0.9571,72.71min,108.74min,and prediction residual of less than5%which meets the requirements of repeatability tolerance in GB/T8018-87method.Then, four method of ATR-FTIR, NIR, NIR transmission method scanning along sample height direction at a particular wavelength, NIR backscattering method scanning along sample height direction at a particular wavelength are studied in their application in gasoline gum content determination.It has been proved that the NIR method do better in the unwashed gum and washed gum content determination. For a more precise result, more studies should be made by combining the traditional NIR method and the NIR backscattering/transmission method scanning along sample height direction.360gasoline samples in six different additives which were Methyl-tert-butyl ether(MTBE), methanol, ethanol, Dimethyl carbonate(DMC), Sec-butyl acetate(SBA), Methylal are collected. Model using infrared spectra and SIMCA method has been built for purpose of identification of different additives. Result show that six different additives can be discriminated by IR with the recognition rate up to90%.In order to determine the accurate additive content, PLS models for six additives has been built additionally. Prediction residual of DMC, SBA, methylal models were less than0.29%, and that of MTBE, methanol, ethanol models meets the requirements of repeatability tolerance in SH/T0663-1998method. |
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