Effect of Pretreatment on the Adsorption Performance of Ni/ZnO Adsorbent for Dibenzothiophene Desulfurization.

Abstract

Ni/ZnO was prepared by co-precipitation and used as adsorbent for reactive adsorption desulfurization (RADS) of dibenzothiophene. The effect of calcination temperature, precipitate washing solvent, and reduction temperature on the adsorption performance of Ni/ZnO was investigated. It is observed that Ni/ZnO adsorbent calcined at 350 °C, washed with ethanol, and unreduced or reduced at low temperature performed best. By the characterization of BET, XRD, TPR, FTIR, and in situ XAFS, the optimal calcination temperature leads to the small crystallite of NiO and ZnO species. Washing with ethanol enhances the surface area of adsorbent and decreases its particle size. The influence of reduction temperature on the RADS performance is stronger than that of calcination temperature, which is ascribed to high-temperature reduction that makes the adsorbent easier to sinter and form a Ni-Zn alloy. The high RADS activity is a result of the adsorbent pretreatment conditions, which can form small Ni and ZnO particles, and the synergism between precursors.