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Manganese oxide octahedral molecular sieves (OMS-2) synthesized from hydrothermal (H-OMS-2), reflux (R-OMS-2), co-precipitation (C-OMS-2), and solid phase (S-OMS-2) methods were impregnated with palladium and used for CO catalytic oxidation. Preparation methods presented an obvious effect on the morphology and catalytic activity of Pd/OMS-2 catalysts for CO oxidation. The hydrothermal synthesized OMS-2 (Pd/H-OMS-2) exhibited more ordered nanorod structure and higher crystallinity than Pd/R-OMS-2, Pd/C-OMS-2, and Pd/S-OMS-2. Further surface analysis indicated that different preparation methods of synthesizing OMS-2 and the impregnation process followed have a significant effect on the chemical states of Mn and O over the final Pd/OMS-2 products. The kinetics studies showed the trend of apparent activation energy (E a) over different catalysts: Pd/H-OMS-2 (18.19 kJ/mol)

The Cu/ZSM-5 catalysts prepared by different copper precursors were used for the selective catalytic reduction (SCR) of NO x with NH3. The Cu/ZSM-5 catalyst prepared by the copper nitrate (Cu/ZSM-5-N) presented the best performance among the Cu/ZSM-5 catalysts and showed above 90 % NO x conversion at 225–405 °C. The average particle size of CuO was 5.82, 9.20, and 11.01 nm over Cu/ZSM-5-N, Cu/ZSM-5-S (prepared by copper sulfate), and Cu/ZSM-5-C (prepared by copper chloride), respectively. The Cu/ZSM-5-N catalyst showed the highly dispersed copper species, the strong surface acidity, and the excellent redox ability compared with the Cu/ZSM-5-C and Cu/ZSM-5-S catalysts. The Cu+ and Cu2+ existed in the Cu/ZSM-5 catalysts and the abundant Cu+ over Cu/ZSM-5-N might be responsible for the superior SCR activity.