Superior Silver Sorbents for Removing 2-Vinyl Thiophene from Styrene by π-Complexation

Styrene made from raw pyrolysis gasoline contains sulfur impurities such as 2-vinyl thiophene. We prepared three sorbents, namely, AgY, AgNO₃/γ-Al₂O₃, and AgNO₃/SiO₂, to remove 2-vinyl thiophene from styrene. All three sorbents showed good desulfurization performance while AgY had the highest sulfur capacity. This was due to π-complexation, where the silver cations in AgY can bond 2-vinyl thiophene more strongly than styrene. The desulfurization capacity of AgNO₃/γ-Al₂O₃ was better than that of AgNO₃/SiO₂ when taking its lower silver loading and surface area into consideration. Moreover, prewetting the sorbents was critical for desulfurization but can cause polymerization. Comparison between desulfurization of gasoline and styrene, using AgY, shows its superior sulfur adsorption capacity for desulfurization of styrene. A possible mechanism on the preferential adsorption for 2-vinyl thiophene over styrene by Ag⁺ is given via the comparison between thiophene and benzene.