汽油烷基化脱硫中己烯的聚合及对噻吩烷基化的影响

Oligomerization performance of hexene and its influence on olefinic alkylation of thiophenic sulfur in gasoline

以Hβ分子筛作为催化剂,考察了在汽油噻吩烷基化反应脱硫过程中,己烯的聚合对噻吩烷基化反应和Hβ的催化性能的影响。结果表明,在Hβ分子筛上,己烯先与噻吩进行反应,n(己烯)/n(噻吩)=1时,90%以上的己烯与噻吩进行烷基化反应而不发生聚合;当n(己烯)/n(噻吩)≥2时,己烯出现聚合,且反应程度随其含量的增加而近似线性增加,与此同时,该反应维持平衡的时间则逐渐缩短;当n(己烯)/n(噻吩)=9时,己烯聚合量一度达到11%,但3 h后即降低到5%以下;当n(己烯)/n(噻吩)<9时,己烯含量的增加对噻吩烷基化影响不大,在反应时间内噻吩转化率一直维持在99%以上;当n(己烯)/n(噻吩)≤3时,二已基噻吩的含量逐渐升高,说明此时己烯含量增加对噻吩二烷基化有利,但n(己烯)/n(噻吩)≥4之后则相反。在n(己烯)/n(噻吩)从2升到9时,Hβ分子筛的积炭量从5.4%增加到5.9%,其酸性降低程度则没有变化,说明己烯含量的增加没有对Hβ分子筛的性质产生较大影响,其对噻吩烷基化反应的影响主要由于己烯聚合反应引起的与噻吩竞争碳正离子,降低了噻吩烷基化几率。

The influence of hexene concentration on the behavior of thiophene alkylation over HI3 zeolite was investigated. The results show that thiophene had superior reactivity to the hexene oligomerization. When the n（hexene）/n（thiophene） equals 1, over 90% hexene reacts with thiophene while hexene oligomerization doesn＇t happen. When the n（ hexene）/n（thio- phene） is greater than or equals 2, the hexene oligomerization happens, and the dimerie content increased with the hexene concentration increasing linearly, however, the stable period became short. When the n （hexene）/n （thiophene） equals 9, the dimerie content of hexene got to 11% , but after 3 h, it decreased below 5%. When the n（hexene）/n（thiophene） is smaller than 9, the increment of hexene did not influence the thiophene alkylation obviously, the conversion rate of thiophene was kept at above 99% in react time. When the n（hexene）/n（thiophene） is smaller than or equals 3, the increment of hexene was favorable for the thiophene dialkylation and the relative contents of dihexylthiophene increased with the hexene concentration, while the effect was just the reverse when the n （hexene）/n （thiophene） is greater than or equals 4. When n （hexene）/n （thiophene） is from 2 to 9, the hexene oligomerization only increased the carbon deposition from 5.4% to 5.9% , and did not decrease the acidity of the catalyst. As a resuh, the influence of hexene oligomerization on the thiophene alkylation comes from the competition of hexene with thiophene to get C6 ＋ carbonium,lwhieh decreased the probability of thiophene alkylation.