Investigation of Organosulfur Adsorption Pathways from Liquid Fuels onto Ag/TiOx–Al2O3 Adsorbents at Ambient Conditions

The adsorption mechanisms for aliphatic and aromatic sulfur compounds onto Ag/TiO x –Al 2 O 3 (10 wt % Ag; Ti/Al = 1:4.4 by weight) adsorbent were investigated in this paper. The mesoporous mixed-oxide-supported silver adsorbent demonstrated promising sulfur adsorption capacities (∼10 mg of S/g of adsorbents) from liquid hydrocarbon fuels [JP5, JP8, and off-road diesel (ORD)]. However, its performance was significantly hindered by the presence of non-sulfur aromatics. In situ infrared (IR) spectra of TiO x –Al 2 O 3 and Ag/TiO x –Al 2 O 3 samples treated with various model fuels revealed dissociative chemisorption pathways for different sulfur species. The aliphatic (1-butanethiol and diethyl sulfide) and aromatic (thiophene, benzothiophene, dibenzothiophene, and 4,6-dimethyldibenzothiophene) sulfur compounds underwent dissociative and reactive adsorption on the surface acid sites at room temperature. The surface hydroxyl groups adsorbed the sulfur aromatics primarily via hydrogen bonding (3100–3400 cm –1 ), and possible dissociated products were saturated/partially saturated aliphatic compounds. The presence of non-sulfur aromatics (benzene) reduced the sulfur adsorption capacity (∼18% for Ag/TiO x –Al 2 O 3 ) because of its competitive adsorption on the adsorbent via π interactions.