Mechanism of effects of surface acidity on performance of adsorption desulfurization of NiY zeolites

The adsorption behaviors of thiophene, cyclohexene and benzene, and competitive adsorption of thiophene & cyclohexene, and thiophene & benzene over NiY zeolites were studied by in situ Py-FTIR spectroscopy method. The results of single probe molecular adsorption indicate that the Lewis (L) acid sites according to Ni species are the major active centers for the thiophene adsorption, more over the Brönsted (B) acid sites of the NiY and HY are the catalytic active centers of the protonation and oligomerization of thiophene and cyclohexene, while the reaction intensity on NiY is significantly weaker than that on HY zeolite. The competitive adsorption results show that the strongly adsorbed dimeric cyclohexene on B acidic sites in NiY zeolite plays a significant competitive adsorption to thiophene adsorption behavior. The effective solutions to solve the competitive adsorption from olefins and aromatics to thiophene are to reduce the surface B acid centers of the adsorbent and to increase temperature of adsorption system.