NiY and KNiY were successfully prepared by impregnation method and characterized by X-ray diffraction (XRD), N-2 sorption (BET), scanning electron microscope (SEM), infrared spectrum (IR) and X-ray Photoelectron Spectroscopy (XPS). The competitive adsorption mechanisms of adsorbents were studied by in situ FTIR to explain different desulfurization performance which was evaluated in a miniature fixed-bed flow by gasoline model compounds with 1-hexene or toluene. NiY and KNiY adsorbents showed better desulfurization performance than HY zeolite due to the high selectivity of loaded active metals. Especially, KNiY adsorbent showed its advantages in desulfurization performance with 5 vol% olefins or 5 vol% aromatics involvement. It could be assigned that introduced K cation enhanced dispersion and content of active Ni species on the surface which made Ni species reduce easily. On the other hand, adsorption mechanisms showed that the protonation reactions of thiophene and 1-hexene occurred on the Bronsted acid sites of NiY, which resulted in pore blockage and the coverage of adsorption active centers. By doping K cation on NiY, the amount of the Bronsted acid sites of NiY was decreased and protonation reactions were weaken. Therefore, the negative effects of Bronsted acid sites were reduced. (C) 2016 Elsevier Inc. All rights reserved.