Reactive adsorption desulfurization of NiO and Ni-o over NiO/ZnO-Al2O3-SiO2 adsorbents: role of hydrogen pretreatment

摘要

Reactive adsorption desulfurization (RADS) of Fluidized Catalytically Cracked (FCC) gasoline on reduced and unreduced NiO/ZnO-Al2O3-SiO2 adsorbents was studied. Various characterizations such as powder X-ray diffraction (XRD), H-2-temperature-programmed reduction (H-2-TPR), the H-2/O-2 pulse titration (HOPT), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) are used to evaluate the effects of hydrogen pretreatment of the adsorbents. XRD and HOPT results indicate that NiO is hard to be reduced to Ni-o under the conditions of RADS. H-2-TPR shows that NiO might be reduced to Ni-o at the temperature of 598 degrees C, much higher than the temperature of RADS. The Ni 2p(3/2) spectrum of Ni-o is not observed for the reduced adsorbent, but the main peak of Ni 2p(3/2) of NiS is found for the spent adsorbent. The unreduced NiO/ZnO-Al2O3-SiO2 adsorbent performs a better desulfurization than the reduced adsorbent at the beginning of desulfurization process. NiO and Ni-o are assumed as the main active components and present a good desulfurization ability in RADS. Finally, a change in the RADS mechanism is presented and discussed.