Alkylation desulfurization of FCC gasoline catalyzed by pyridine ionic liquid

Brønsted acidic ionic liquid [BPY]HSO4 was synthesized and characterized by FT-IR and 1H-NMR. [BPY]HSO4 was then used as a catalyst in alkylation desulfurization of FCC gasoline; the effects of the reaction temperature, time and mass ratio of ionic liquid to oil on the desulfurization efficiency and FCC gasoline quality were investigated. The results showed that after reaction for 90 min under 65°C and an ionic liquid to oil mass ratio of 0.09, the sulfur content of FCC gasoline is decreased from 580.0 to 6.4 μg/g, with a desulfurization rate of 98.90%, which can meet the request of Chinese National Standard V for the sulfur content in motor gasoline (< 10 μg/g). A survey on the distribution of sulfur compounds indicated that sulfur compounds are transferred from light fraction (< 170°C) to heavy fraction (> 170°C) with the help of [BPY]HSO4 and the sulfur compounds in heavy fraction can then be removed further by hydrodesulfurization. PONA results indicated that the alkylation desulfurization catalyzed by [BPY]HSO4 has little effect on hydrocarbon composition and octane number of FCC gasoline. Moreover, the [BPY]HSO4 ionic liquid can be recycled through extraction and reused in the alkylation desulfurization.