A high-performance Ni/ZnO–Al2O3–SiO2 adsorbent was developed for reactive adsorption desulfurization (RADS) of diesel. The desulfurization performance of the prepared adsorbents was evaluated in a fixed-bed reactor for treating a hydrotreated diesel with a sulfur content of 1187 ppm. The preparation conditions were investigated, such as aging time, aging temperature, metallic ion concentration, and precipitation temperature. Results showed that the adsorbents performed at a high desulfurization efficiency under the mild preparation conditions. This indicated that smaller crystalline grains were favorable for desulfurization over the Ni/ZnO–Al2O3–SiO2 adsorbent. The adsorbent attained a high adsorption ability of 38.4 mg/g at a breakthrough sulfur level of 20 ppm. The mechanism of deactivation of the adsorbent was also studied and discussed by various characterizations, such as N2 physisorption, powder X-ray diffraction (XRD), ammonia temperature-programmed desorption (NH3–TPD), transmission electron microscopy (TEM), and scanning electron microscopy/energy-dispersive spectrometry (SEM/EDS). The main reasons of the deactivation of the RADS adsorbent include the carbon deposition, the formation of ZnS, and the sintering of the active and support.

A Ca-doped Ni/ZnO−Al 2 O 3 −SiO 2 adsorbent was prepared for reactive adsorption desulfurization (RADS) of fluidized catalytically cracked (FCC) gasoline. Various characterizations, such as H 2 −temperature-programmed reduction (H 2 -TPR), the H 2 /O 2 pulse titration (HOPT), NH 3 −temperature-programmed desorption (NH 3 -TPD), N 2 physisorption, powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and energy-dispersive spectrometry (EDS), are used to evaluate the sorbent. NH 3 -TPD results showed that Ca loading could reduce the mild and strong acidities of the sorbent surface. HOPT results indicated that Ca doping could promote the dispersity and specific surface area of the nickel component. The adsorbent doped with 1 wt % Ca obtained a higher efficiency of desulfurization and regeneration performance than the undoped one. The breakthrough sulfur capacities of the fresh and the regenerated Ca-doped adsorbents could reach 54.07 mg/g and 46.23 mg/g, respectively, at a breakthrough sulfur level of 10 ppmw with a loss of 0.23 gasoline octane number. The introduction of Ca contributes to the reduction of surface acidity of adsorbent and also reduces the carbon deposition in the process of RADS, improving the desulfurization ability and the regeneration performance of the adsorbent.

A possible reaction mechanism of desulfurization on NiO/ZnO–Al2O3–SiO2 is discussed.

The reactive adsorption desulfurization (RADS) of a model gasoline n-hexane containing thiophene was carried out with a NiO/ZnO-Al2O3-SiO2 adsorbent in N2 and H2, respectively. A declining RADS trend has been observed in N2, without the presence of H2, indicating that NiO is sulfurized and exhibits activity for RADS. TPR and XPS results presented NiO in the adsorbent is hard to be reduced because of the powerful interaction between NiO and the support. The sulfurization of NiO into NiSx is a primary condition for the RADS process, the same as the presulfurization of hydrotreating catalyst, while metallic Ni is an intermediate reduction product of NiSx. Results of a low RADS temperature at 300 °C, much lower than the reduction temperature of NiO, suggest that NiO plays an important role. Based on assumption of NiO as the main active component, the RADS could reduce the reaction temperature and energy consumption significantly. The participation of hydrogen and n-hexane in pretreatment conducted at 420 °C contributes to the activation of adsorbent. Also, these methods of pretreatment improved the desulfurization performance under the reaction temperature of 300 °C.

The effect of nitrogen compounds in FCC gasoline on reactive adsorption desulfurization (RADS)­was investigated over NiO/ZnO-Al2O3–SiO2 adsorbents. On the basis of ammonia temperature-programmed desorption (TPD), pyridine infrared radiation (Py-IR), and X-ray diffraction (XRD), adsorbents calcinated at 500 °C exhibit weak acidity and strong acidity, high Brδnsted acidity, and good dispersion of the active components. High Brδnsted acidity adsorbent presents the best RADS ability, contributing to adsorption and removal of nitrogen compounds. The results show that the basic nitrogen quinoline and pyridine inhibit significantly RADS, but the nonbasic nitrogen carbazole only affects RADS mildly. The order of inhibition is quinoline > pyridine > carbazole.

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Reactive adsorption desulfurization (RADS) has high desulfurization activity and low olefins saturation advantages for upgrading fluidized catalytic cracking gasoline. The effect of reaction temperature on RADS over NiO/ZnO-Al2O3-SiO2 adsorbent was...