Synthesis of large surface area MnOx-CeO2 using CTA and its catalytic activity for soot combustion

Large surface area (n) MnOx-(1-n) CeO2 (0 <= n <= 1) catalysts were synthesized using a hybrid organic/inorganic route and characterized by XRD, N-2 adsorption and catalytic test. The addition of aqueous ammonia to mixed solutions of cerium and manganese nitrates in the presence of CTAB (cetyltrimethyl ammonium bromide) yielded gelatinous hydrous Ce-Mn oxide/CTA composites (MnCeCTA). As calcined MnOx-CeO2 (n = 0.25, 450 degrees C) exhibited a largest surface area of 223 m(2)/g, which is quite larger than 80 m(2)/g for the corresponding oxide prepared from conventional co-precipitation route (MnCeCP). As synthesized MnOx-CeO2 catalysts were tested for soot oxidation by O-2. The catalytic activity of MnCeCP was highest at n = 0.25-0.5, whereas the catalytic activity of MnCeCTA was lower and increased monotonically with an increase of the Mn content (n). The different catalytic behavior seems to be associated with the activity of surface oxygens and lower oxidation state of MnCeCTA.