Combination of Experimental and Theoretical Investigations of MnOx/Ce0.9Zr0.1O2 Nanorods for Selective Catalytic Reduction of NO with Ammonia

Manganese oxides (MnOx) supported on Ce0.9Zr0.1O2 (MnOx/Ce0.9Zr0.1O2) nanorods were synthesized and tested for low-temperature selective catalytic reduction of NO with ammonia. The catalysts were characterized by transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, X-ray photo-electron spectroscopy, and hydrogen temperature-programmed reduction. The structure and morphology results show that the MnOx was highly dispersed on the surface of Ce0.9Zr0.1O2 nanorods. Various species, such as Mn2+, Mn3+, and Mn4+, were exposed due to a strong interaction between manganese and cerium oxides. Thus, the MnOx/Ce0.9Zr0.1O2 nanorods exhibited a better catalytic performance (90% NO conversion at 150 degrees C) compared with that of the as-prepared Ce0.9Zr0.1O2 nanorods. Density functional theory (DFT) calculations clearly demonstrated that the MnOx on the surface of supporting nanorods or Mn@ CeO2(110) could easily form an oxygen vacancy distortion. Furthermore, the Mn@CeO2(110) Model in the DFT analysis showed a prominent effect on the NO and NH3 adsorption which resulted in a stronger nitrite intermediate (NOO*) formations and more attractive interaction with the NH3 gas compared with those observed, with the CeO2(110) model. Therefore, a thorough understanding of the structure and catalytic performance of MnOx/Ce0.9Zr0.1O2 nanorods was successfully achieved by a combination of experimental and theoretical studies.