Ab initio screening of zeolite Y formulations for efficient adsorption of thiophene in presence of benzene

Abstract

In the context of deep desulfurization of transport fuels, the present work aimed at identifying a suitable material for the selective removal of thiophene from fuels. Dispersion corrected density functional theory (DFT) calculations have been carried out in order to investigate the adsorption of benzene and thiophene in various faujasite zeolite formulations including DAY, HY, LiY, NaY, KY, CsY, Cu(I)Y, Cu(II)Y, Ag(I)Y, Zn(II)Y, and FAU containing Lewis acid sites (LAS) (defect or extra-framework). Bearing-LAS FAU, Cu(I)Y, Cu(II)Y, Zn(II)Y, CsY, and HY showed a higher affinity towards thiophene adsorption. In particular, thiophene is more adsorbed on defect LAS than benzene by 17.7 kJ/mol, suggesting that this zeolite could be chosen as a suitable candidate for the optimal selective adsorption of thiophene in the presence of benzene. In terms of regenerability, all formulations can be safely used (except the one containing extra-framework Lewis acid sites) as they can limit the activation of the C-S bond of thiophene. Considering both adsorption selectivity and sorbent regenerability criteria, faujasites containing defect Lewis acid sites could be chosen as a good compromise to perform a selective adsorption of thiophene in presence of benzene.