哈油FCC汽油硫及烯烃含量分布特征研究

Study on sulfur and olefin distribution of FCC gasoline from Kazakhstan crude oil

我国每年要从哈萨克斯坦进口原油约10Mt/a,进口哈油大部分是在中国石油天然气股份有限公司独山子石化分公司加工,其中二次加工生产的FCC汽油硫质量分数为600～1000μg/g。在生产国Ⅳ和国Ⅴ成品汽油时,需要对哈油FCC汽油进行选择性深度加氢精制,加氢精制时有部分烯烃被加氢饱和,降低了成品汽油的辛烷值。研究表明：将硫质量分数为686μg/g、烯烃质量分数为47.60%的哈油FCC汽油切割成不同温度段的窄馏分,随着切割温度的提高,各窄馏分硫质量分数由170μg/g逐步增加到1360μg/g,而烯烃质量分数由75.51%逐步降低到30.93%。因此FCC汽油硫含量和芳烃含量主要集中在重汽油馏分中,烯烃含量主要集中在轻汽油馏分中,40℃以前轻汽油馏分中的硫有近50%的是硫醇硫。

China has to import over 10 million tons of crude oil from Kazakhstan each year,and most of the imported crude oil is processed by Dushanzi Petrochemical Company. The sulfur in FCC gasoline of Kazakhstan crude oil in downstream processing is about 1 000 ppm. Therefore,the FCC gasoline has to be deeply hydrotreated to produce gasoline of Guo Ⅳ and Guo Ⅴ specifications. In hydrotreating of FCC gasoline,some olefins are saturated by hydrogenation,which reduces the octane number of gasoline. The study shows that,when the FCC gasoline of Kazakhstan crude with 686 ppm sulfur and 47. 60% olefins are cut into narrow fractions,the content of sulfur in each narrow fraction increases with rising cutting temperature from 170 μg / g to1 360 μg / g,while the olefin content gradually goes down from 75. 51% to 30. 93%. The sulfur and olefins contents in FCC gasoline of Kazakhstan crude are relatively high. The sulfur and aromatics are mainly concentrated in the heavy gasoline fractions and olefins are mainly concentrated in light gasoline fractions. Nearly 50 percent of sulfur of light gasoline fractions under 40 ℃ is the mercaptan sulfur.