Adsorption of thiophenes out of hydrocarbons using metal impregnated nanocrystalline aluminum oxide

Adsorption of thiophene and its derivatives was carried out using silver impregnated nanocrystalline metal oxides, with special emphasis on aluminum oxide. A modified nanocrystalline aluminum oxide was prepared by an impregnation method and characterized. The adsorption experiments were carried out for thiophene, benzothiophene, dibenzothiophene and 4,6-dimethyl dibenzothiophene. Incorporation of soft Lewis acid sites such as silver ion is necessary for the adsorption of thiophene related molecules. The modified adsorbent was found to retain its adsorption characteristics even after compaction and it can be used for adsorption again after regeneration by heating at modest temperatures. The adsorption properties of the silver impregnated aluminum oxide (prepared by aerogel procedure) (Ag-AP-Al2O3) were compared with several other high surface area materials (>200 m2/g). Detailed characterization studies showed that the active site in Ag-AP-Al2O3 is the Ag+ ion coordinated to carbonate. Metallic silver nanoparticles do not appear to be effective in thiophene adsorption.