Adsorptive Desulfurization with Xerogel-Derived Zinc-Based Nanocrystalline Aluminum Oxide

Adsorption of thiophene from a thiophene-pentane mixture has been investigated using zinc-based nanocrystalline aluminum oxide under ambient conditions. The adsorbents were prepared by a xerogel process, followed by thermovacuum treatment. The adsorptive experiments show that a 20 wt % Zn/Al2O3 adsorbent has the highest capacity, 2.8 mg/g (mg of sulfur per g of adsorbent). Brunauer-Emmett-Teller specific surface area (BET), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) were used to characterize the adsorbents. It was found that a spinel-phase ZnAl2O4 was formed during thermal treatment. The ZnAl2O4 spinel formed by thermal treatment in air was more crystalline, while thermal treatment under vacuum resulted in a defective, less crystalline spinel. Also, the particle size of the adsorbent was smaller and the surface area was higher when thermal treatment was under vacuum. In addition, the prepared adsorbents could be easily regenerated without losing capacity.