Reactive adsorption desulfurization of NiO and Ni0 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–Al _(2) O _(3) –SiO _(2) 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 ~(0) under the conditions of RADS. H _(2) -TPR shows that NiO might be reduced to Ni ~(0) at the temperature of 598 °C, much higher than the temperature of RADS. The Ni 2p _(3/2) spectrum of Ni ~(0) 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–Al _(2) O _(3) –SiO _(2) adsorbent performs a better desulfurization than the reduced adsorbent at the beginning of desulfurization process. NiO and Ni ~(0) 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.