| Comprehensive two-dimensional gas chromatography(GC × GC) is a new separation technology with high resolution and sensitivity developed in recent years. Aimimg at separation and characterization of hydrocarbons and sulfur-containing compounds in complex petroleum fractions produced in oil processing, this dissertation conducted work in methodological research and application development as stated below.Firstly, we took light cycle oil (LCO) as a sample and discussed the separation characteristics of GC × GC and optimization of the conditions for separation of a sample with a wide distillation range. Afterwards we established a way to characterize the important target compounds and groups in a petroleum fraction based on two-dimensional retention times of standard substances, the rule of boiling points and structure informations in the two-dimensional chromatograms. Quantification of interested substances and hydrocarbon groups in a complex system was achieved.Then, taking advantage of the sulfur chemiluminescence detector (SCD), a GC/SCD method to characterize the sulfur-containing compounds in a light petroleum fraction was established; and for the first time, a method of separating and quantifying characteristic sulfur-containing compounds and their groups in a medium petroleum fraction with a single injection was established using the GC/SCD technology. The RSD of the group quantification results was not greater than 10%, and the recovery varied between 91.3 to 101.2%. Comparing to the ASTM D 4294 method, the RAD was not greater than 6.02%. With GC × GC/TOFMS, 167 PASHs were primarily determined, including 16 dihydrobenzothiophene and its alkyl-substituted isomers, 3 thiophanthrenes and 3 benzothiophanthrenes. Based on the structure informations provided in the GC × GC/SCD and GC × GC/TOFMS chromatograms, the distribution rule of sulfur-containing compounds in the GC × GC/FID chromatogram of an LCO sample was deduced.Lastly, with the support of the above-introduced technical platform, the distribution rules of hydrocarbons and sulfur-containing compounds in cut fractions of different oil processing units were systematically analyzed and effects of different process parameters upon the distribution rules were studied as well. Making use of changes in hydrocarbon and sulfur-containing compound distribution in the feedstock and products, we studied the effects of process parameters on desulfurization and dearomatization of diesel fractions with upgrading catalysts. The results show that different fractions have largelyvaried group compositions and the sources of crude oil have direct impact upon the group distribution of straight-run distillates. And the compositions of secondary processed diesel fractions from different processing units are significantly different as well. In terms of aromatics with condensed nuclei, RFCC has the highest concentration and has a total aromatic concentration of 75.6-88.3%, followed by 51.7-69.4% of FCC and 23.4-31.2% of the delayed-coking respectively, while the visbreaking fraction has a tricyclic aromatic content of only 0.2-0.9%. The quality of FCC diesel fraction can be optimized by controlling the reaction rate of hydrogen transference of aromatics with condensed rings. Over 80% of the sulfur-containing compounds in FCC diesel exist in the form of polycyclic aromatic sulfur heterocycles (PASHs), while mainly in form of alkyl sulfides in thermal cracking diesel, which are easy to be removed. RN-10 catalyst converts aromatics with condensed nuclei into polycyclic naphthenes through hydrosaturation; while FC-18 catalyst has functions of both hydrosaturation and ring-opening cracking. The reaction mechanism of PASHs includes direct hydrogenolysis and hydrogenation.The results of the study have provided technological support for optimization of feedstock, process parameters and product quality in various oil processing units and research on corrosion protection of equipment and chemical reaction mechanism analysis as well. |
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