Study Of Analysis Method Of Sulfur-containing Compounds In Gas Oil

With the increase of domestic demand for fuel oil and chemical products, theimportion of crude oil from abroad increases year by year. Middle East crude oil has astable source and low price, it is also convient to transport. Theses advantages make it anew important crude oil supply base for our country in the future. One of the characteristicsof Middle East oil is its high sulfur content. Refining high sulfur crude oil will not onlyaffect the product quality, sulfur and some sulfur compounds will also cause a corrosion onthe equipment in the process. Therefore it is very important in the crude oil processing tolearn of the distribution law of sulfur and sulfur compounds in the crude oil and itsdistillates.In an acid simulation system that contains mercaptan, silver nitrate potentiometrictitration is used to analyze mercaptan-sulfur. Many factors is respectively considered aboutinfluence on this analysis method, such as the acid value, the existence of olefins, aromaticsand sulfur ether. The detection limit of the method is also determined. The result shows thatnone of the factors, including the acid value and the presence of olefins, aromatics andthioether, affect mercaptan-sulfur analysis with the method of silver nitrate potentiometrictitration; and mercaptan sulfur has a detection limit of7.9mg.L-1with this method.Subtraction method is used to analyze disulfide-sulfur in the acid simulation systemthat contains disulfide. The effect of acid value on disulfide-sulfur analysis is observed, andthe detection limit of disulfide-sulfur with this method is determined. It is found that acidvalue makes little effect on this analysis method, and mercaptan sulfur has a detection limitof20mg.L-1with subtraction method.In an acid simulation system that contains thioether, lead tetraacetate potentiometrictitration is used to analyze thioether-sulfur. The solvent effect on the analysis method is investigated and the detection limit of the method is determined. The result shows thatwhether water-acetic acid or toluene-acetic acid is used as solvent, there is no influence onanalysis method, and the ratio of solvent selection also has little effect on this analysismethod. And thioether sulfur has a detection limit of313μg.g-1with this method.Apply these analysis methods to the0#diesel and the Karamay second vacuumside-stream, the following results can be reached: the content of thioether sulfur in the0#diesel oil is535.5μg.g-1, and it has extremely low content of mercaptan sulfur and disulfidesulfur; the content of mercaptan sulfur in Karamay second vacuum side-stream is27.3μg.g-1,and it also has a content of11950.5μg.g-1thioether sulfur.There has no disulfide in Karamaysecond vacuum side-stream because the silver nitrate potentiometric titration curve leapedover zero.