Catalytic oxidation of polycyclic aromatic hydrocarbons (PAHs) over SBA-15 supported metal catalysts

Naphthalene was chosen as a model reactant of PAHs, and its catalytic destruction aimed to reduce the content of PAHs in diesel fuels was investigated over three different metal (Pt, Ru and Mo) catalysts supported on SBA-15 and γ-alumina. The catalysts were characterized by N2-sorption isotherms, CO and NO chemisorptions, temperature programmed desorption of naphthalene and NH3, and 27Al MAS NMR. The SBA-15 supported metal catalysts showed a better activity at lower reaction temperature than the γ-alumina supported ones, most probably due to higher metal dispersion and enhanced meso-accessibility. Pt/SBA-15 catalyst exhibited the highest activity, corresponded to Ru or Mo/SBA-15 catalyst, as reasoned by the temperature programmed desorption of naphthalene. The improved catalytic performances and thermal stability of catalysts could be achieved by incorporation of Al species into SBA-15. The characteristics of Pt states and complex on the surface of acidic supports could lead to the enhanced catalytic activity of naphthalene oxidation, as well as the limited sintering of Pt particles at high temperature, giving rise to thermal stability of catalysts.