Novel Synthetic Route to the Model Sorbent Ag-TiO2 and Sample Characterization: towards Studies of Adsorption/Desorption and Surface Reactivity of Sulfur-Containing Polyaromatic Hydrocarbons (S-PAHs) Representing Components of Petroleum-Derived Fuels

The novel synthetic route employing the in-house developed pneumatic-driven spray deposition technique was applied towards preparation of model adsorbent specimens Ag-TiO2. Molecular films of silver nitrate precursor were spray-deposited under controlled atmosphere conditions onto thin films of titania, that were thermally grown on titanium metal foils. The amount of the spray-deposited silver and the deposition rate were determined by the gravimetric calibration technique. The subsequent calcination at 350 C formed titania-supported metal silver. Surface morphology, spatial dispersion and chemical form of the titania-supported silver was studied by SEM in the Energy Dispersive X-Ray Spectroscopy (SEM-EDS) mode and by X-Ray Diffraction (XRD). Chemical composition of the specimens was determined by X-Ray Photoemission Spectroscopy (XPS). The adsorption of model S-aromatic compound Thiophene onto model sorbent Ag-TiO2 was carried out from solution in toluene, representing chemical composition of sulfur-containing liquid fuels. Adsorption was performed ex-situ at room temperature under controlled atmosphere conditions. The Temperature-Programmed Desorption (TPD) of the Thiophene-treated model sorbents suggest that C-S chemical bond cleavage of the surface species occurs upon heating the sample, leading to the low molecular weight hydrocarbon (C4H6).