Sol-Gel Cu-Al2O3 Adsorbents for Selective Adsorption of Thiophene out of Hydrocarbon

The removal of thiophene from a hydrocarbon mixture by a novel Cu-Al2O3 adsorbent was investigated under ambient conditions. An adsorbent with 5 wt % Cu showed the highest capacity, 1.8 mg/g (milligram of sulfur per gram of adsorbent). A sol-gel process followed by hypercritical drying, calcination, and thermovacuum treatment was successfully used to prepare the adsorbents. The adsorbents were characterized by Brunauer-Emmett-Teller specific surface area (BET), X-ray diffraction (XRD), and UV-vis diffuse reflectance spectroscopy (UV-vis). The characterization results suggested that copper ion with +1 valence was responsible for the adsorptive performance. Metallic copper (Cu0) and Cu2+ were not effective for the adsorption of thiophene. It seemed that Cu+ coordinated to thiophene through the sulfur atom, which was different from the mechanism of (pi)-complexation proposed in the literature.