Thiophene Adsorption on Microporous Activated Carbons Impregnated with PdCl2

International regulations have established the decrease on sulfur content in fuels down to as low as 10 ppm in a few years from now. Cyclic sulfur compounds are noticeably refractory to hydrodesulfurization (HDS) processes, which are the usual technology found in oil refineries. To meet the increasingly strict environmental requirements, selective physisorption may be a feasible option toward lowering the sulfur content of the outlet streams of current HDS units. The present work investigates the adsorption of benzothiophene (BT) and dibenzothiophene (DBT.) in hydrophobic microporous activated carbons impregnated with PdCl2. The adsorbents used were commercial samples (Norit, Amersfoort, The Netherlands) modified by wet impregnation of PdCl2 in acidic media, followed by drying at 130 degrees C under Fie flow. They were characterized by N-2 adsorption isotherms, transmission electron microscopy (TEM). X-ray diffraction (XRD), and X-ray photoelectronic spectroscopy (XPS). Characterization results provide evidence that palladium was effectively supported on the activated carbon as the chloride itself and as metallic palladium. A total of 20 mL of BT and DBT solutions in hexane (500 ppm) were put in contact with 100 mg of each adsorbent, and the adsorbed capacities were measured by the concentration differences. Additionally. Fourier transform infrared (FTIR) spectra were measured upon adsorption of BT vapors. The impregnation of PdCl2, enhances sulfur adsorption capacity for most studied cases, and sulfur compounds with an increasing number of aromatic rings are preferentially adsorbed.