Effect of preparation method on the performance of Pd-MnOx/γ-Al2O3 monolithic catalysts for ground-level O3 decomposition

MnOx+gamma-Al2O3 and MnOx/gamma-Al2O3 catalysts were prepared by the sol-gel and sequential precipitation methods, respectively. The same amount of Pd was loaded on these catalysts by incipient wetness impregnation. The two Pd-MnOx/gamma-Al2O3 catalysts with different physicochemical properties were coated on cordierite. The catalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, H-2 temperature-programmed reduction, and N-2 adsorption-desorption measurement. The preparation method and calcination temperature of MnOx have significant impact on the crystalline phase of MnOx, MnOx species and active oxygen species, and textural properties of the catalysts. The experimental results showed that 0.60 mu L center dot L-1 of ozone was completely decomposed on these catalysts in the temperature range of 16 to 90 degrees C at space velocities from 380000 to 580000 h(-1). In particular, the activity for O-3 decomposition was excellent on the Pd/MnOx+Pd/gamma-Al2O3 catalyst that used MnOx prepared by the sol-gel method. Mnn+ is beneficial for O-3 decomposition, and Mn2+, Mn3+, and Mn4+ were presented in a mole ratio of 1.7:1:3 on the surface of the catalyst. (C) 2014, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.