Adsorptive Removal of Refractory Sulfur Compounds by Tantalum Oxide Modified Activated Carbons

Adsorptive desulfurization of a model diesel fuel consisting of dibenzothiophene (DBT) or 4,6-dimethyldibenzothiophene(4,6-DMDBT) in hexadecane was performed over activated carbons and tantalum oxide modified (Ta-x/ACC, x= 2, 5 or 10 wt % Ta, Activated Carbon Centaur) activated carbons at 50 degrees C. The adsorption isotherm for ACC followed the Langmuir model while the adsorption on Ta-5/ACC fitted the Sips equation indicating more than one type of adsorption sites. Characterization studies indicated new types of adsorption site resulting from the incorporation of Ta oxide into the porous structure of the ACC. XPS data suggested interaction of Ta with the S atom in DBT. The heats of adsorption in the liquid phase determined from micro flow calorimetry for DBT in C16 confirmed the interaction of Ta with DBT. Ta-5/ACC exhibited the highest adsorption capacity for 4,6-DMDBT compared to literature reports. Competitive adsorption experiments showed the adsorption capacity as follows: quinoline> DBT >> naphthalene. (C) 2017 American Institute of Chemical Engineers