Thiophene adsorption onto metal–organic framework HKUST-1 in the presence of toluene and cyclohexene

Abstract

Adsorption desulfurization is one of the most promising ways to reduce the sulfur content of gasoline at deeper level. In this work, thiophene (TP) adsorption capacity in cyclohexane onto [Cu3(BTC)2(H2O)3] (HKUST-1) was measured by batch method, and the effect of cyclohexene and toluene on sulfur capacity was investigated. Adsorption isotherms of TP, cyclohexene, and toluene in cyclohexane onto HKUST-1 were conducted at 298.15–313.15 K to explicate the different extent of influence by cyclohexene or toluene addition. The results showed that, compared with cyclohexene, the addition of toluene in model gasoline led to a moderate decline in sulfur capacity of HKUST-1. The isotherm data of TP adsorption were well-correlated using Langmuir equation, while those of cyclohexene or toluene adsorption fitted Freundlich model, indicating different adsorption mechanisms between TP and competitors. The adsorption capacities followed the order of toluene < cyclohexene ≪TP at the same equilibrium concentrations, implying the order of the adsorption affinities, which is in good agreement with the different extent of influence by cyclohexene and toluene. The excellent regeneration performance of HKUST-1 in TP adsorption benefits from the physical adsorption mechanism, which was hinted by the enthalpy of TP adsorption (−37.31 ± 2.04 kJ mol−1) and no detection of new sulfur species.