Synergistic Catalysis of Thermoregulated Ionic Liquid/p-Toluenesulfonic Acid for Alkylation Desulfurization of Fluid Catalytic Cracking Gasoline

Abstract

The olefin alkylation of thiophenic sulfur (OATS) in model fluid catalytic cracking gasoline was carried out using the temperature-responsive catalyst which was prepared by mixing the temperature-responsive ionic liquid (TRIL) and p-toluenesulfonic acid (PTSA) with the mass ratio 1:10 (10% TRIL−PTSA). The liquid−liquid biphasic system was formed during the OATS and returned to the liquid−solid state automatically after completion of the reaction at cooling temperature, which enhanced the mass transfer efficiency and separation ability of oil and the catalyst. As for 10% TRIL−PTSA, the acid strength was adjusted properly by TRIL, and the anionic cluster of [−SO 3 (−SO 3 H) x ]− was also found by Fourier transform infrared, 1 H NMR, and thermogravimetric−differential scanning calorimetry, which displayed a better catalyst performance over PTSA. Moreover, the effects of various factors were fully discussed, including the reaction temperature, reaction time, and catalyst dosage. Under optimal conditions, the conversion of thiophene (T) can reach 100% and it can remain unchanged during 10 recycles. Furthermore, apparent reaction kinetics for OATS was discussed. It suggested that the alkylation of T conformed to the pseudo-first-order kinetic characteristic, and the apparent activation energy was 47.6 kJ/mol. Finally, the synergistic catalysis mechanism was proposed.