Nowadays, there are two major methods to obtain gasoline composition, which are experimental method (GC-FID or GC-MS) and computer-aid reconstruction method based on bulk property data. Computer-aid reconstruction method transforms bulk properties to virtual molecular composition in a rapid way. However, the previous work in our lab has proved that composition produced by this method is unstable. Unstable composition will result in unstable prediction of properties, especially octane number. Experimental method is capable of obtaining more accurate result with good consistency. Although the composition analyzed by GC-FID is much more accurate than simulation method until carbon number reaches 8, the amount of isomers increases exponentially and exceed the separation capacity of gas chromatography column for C8+ components. Here, a new method is proposed to solve this problem. Firstly, molecules in gasoline were categorized into different chemical families based on their structure. In the same chemical family, molecules with the same carbon number will be lumped together. Lump composition below C8 (C8-) can be directly obtained from GC FID while that of C8+ is incomplete. On the basis of the hypothesis that the content of each chemical family against carbon number in gasoline follows a certain statistic distribution, the parameters of the distribution was tuned by fitting C8- component distribution curve. Content of C8+ is used as constraint during this optimization process and new composition was obtained. The method that combines GC-FID and computer-aid reconstruction shows better accuracy and wider application than merely GC-FID method. Several gasoline samples had been tested by this method. The predictions are in good agreement with experimental data.

Computer-aid gasoline molecular composition reconstruction on the basis of GC-FID data

253rd National Meeting (2017)

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