催化裂化汽油组成对其储存安定性的影响

EFFECTS OF COMPONENTS OF FCC GASOLINE ON ITS STORAGE STABILITY

通过对催化裂化(FCC)汽油组成、诱导期、吸光度等性质指标的跟踪测试,考察了影响FCC汽油安定性的主要因素。结果表明,FCC汽油中除按产品质量要求严格控制含量的烯烃、总硫及硫醇硫是影响FCC汽油不安定的主要因素外,共轭二烯烃的存在严重影响FCC汽油的储存安定性,含氮化合物是油品变色的关键物质,而大部分酚类化合物具有抗氧化性,它们的存在有利于延长氧化变质诱导期,但对FCC汽油生胶、变色具有酸性催化剂作用。酚含量越多的FCC汽油,其诱导期越长,但油品变色也越快。FCC汽油的酚含量较高(>200μg/g)时,其诱导期随着二烯值的增大而缩短,储存吸光度随着二烯值、碱性氮含量的增大而增加;酚含量较低(<120μg/g)时,汽油颜色稳定,二烯值、碱性氮含量的变化对储存吸光度影响不大,二烯值小至0.7μg/g也可导致诱导期缩短。通过优化催化原料和操作条件、优化调合和添加抗氧防胶剂等措施,可有效地提高FCC汽油的储存安定性。

Based on the test data correlation of the composition, induction period and absorbance of FCC gasoline, the main factors affecting gasoline stability were investigated. Research results showed that the conjugate dienes in FCC gasoline was also main factor affecting stability besides the olefins, sum sulfides and mercaptan, whose contents should be controlled according to gasoline quality claim. Nitrogen containing compounds were key substance causing color change of gasoline. Most of phenols in the FCC gasoline possessed anti-oxidation properties, which could prolong the induction period of FCC gasoline, and could catalyze the formation of color and resins in FCC gasoline by their acidic properties. The more the phenols in the FCC gasoline, the longer the induction period, and the faster the coloration is. When mass fraction of phenols in the FCC gasoline was higher than 200 ug/g, gasoline induction period decreased with the diene value increase, and the storage absorbance increased with both diene value and basic nitrogen increase. When mass fraction of phenols was lower than 120 ug/g, the storage absorbance was not affected by both diene value and basic nitrogen, and gasoline color is was steady. The gasoline induction period could be shortened by the diene with the diene value of 0. 7 ug/g. It is effective to raise gasoline storage stability by adding antioxidant and optimizing operation conditions as well as optimizing the feed for FCC gasoline.