NiMnO_3 perovskite catalysts supported on cordierite modified by Ce_xZr_(1-x)O_2 coatings were prepared using impregnation and sol-gel methods for catalytic combustion of single/double component VOCs at different concentrations and GHSV of 15,000 h^(-1), which were characterized by BET, XRD, SEM, FT-IR, H_2-TPR and O_2-TPD. After coating modification, the specific surface area of catalysts is improved obviously.Among the catalysts, the Ce_(0.75)Zr_(0.25)O_2 coating modified NiMnO_3 catalyst exhibits the best catalytic activity for VOCs combustion with 95.6% conversion at 275 ℃ and has stable activity when catalyst is embalmed at 800 ℃. In addition, the catalyst also presents the excellent water-resistant and conversion stability over time-on-stream condition. The reason is that Ce_(0.75)Zr_(0.25)O_2 coating can promote more lattice distortion and defects and smaller crystal size, which improve oxygen transfer capability and dispersion of active component.
Lei DengChao HuangJiawei KanBing LiYingwen ChenShemin ZhuShubao Shen
A series of MnCeOx catalysts supported on cordierite honeycomb (Cord) were prepared by a combustion synthesis method using Mn(NO3)2 , Ce(NO3 )2·6H2O and citric acid. The effect of the molar ratio of Mn/Ce, calcination time, the amount of citric acid and the effect of water vapor on the catalytic properties for the complete oxidation of benzene were investigated. These catalysts were characterized by X-ray diffraction (XRD), H 2 temperature-programmed reduction (H2 -TPR), O2 temperature programmed desorption (O2 -TPD) and scanning electron microscopy (SEM) techniques. The results indicated that the MnCeOx /Cord catalyst with Mn/Ce molar ratio of 1:1, calcining for 7h and M n+ /(citric acid) molar ratio of 6 exhibited the highest catalytic activity. When the concentration of benzene was 1500 ppm and the gaseous hourly space velocity was 20000h -1 , the conversion of toluene was 99.1% at the reaction temperature of 300 oC.
