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

Key words:  hexene oligomerization thiophene alkylation  desulfurization  gasoline

Abstract:

The influence of hexene concentration on the behavior of thiophene alkylation over Hp 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 rt(hexene)/^(thiophene) is greater than or equals 2, the hexene oligomerization happens, and the dimeric content increased with the hexene concentration increasing linearly, however, the stable period became short. When the n( hexene)/n( thiophene) equals 9, the dimeric 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 contwits of dihexylthiophene increased with the hexene concentration ,while the effect was just the reverse when the n ( hexene )/ra (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 result, the influence of hexene oligomerization on the thiophene alkylation comes from the competition of hexene with thiophene to get C6+ carbonium, Iwhich decreased the probability of thiophene alkylation.