Morphology-Dependent Properties of MnOx/ZrO2 CeO2 Nanostructures for the Selective Catalytic Reduction of NO with NH3

The morphology effect of ZrO2-CeO2 on the performance of MnOx/ZrO2-CeO2 catalyst for the selective catalytic reduction of NO with ammonia was investigated. The catalytic tests showed that the MnOx/ZrO2-CeO2 nanorods achieved significantly higher NO conversions than the nanocubes and nanopolyhedra. The catalytic tests also showed that the MnOx/ZrO2-CeO2 nanorods achieved a significantly higher rate constant with respect to NO conversion than that of the nanocubes and nanopolyhedra. On the nanorods, the apparent activation energy is 25 kJ mol(-1,) which was much lower than the values of nanocubes and nanopolyhedra (42 and 43 kJ mol(-1)). The high resolution transmission electron microscopy showed that the nanorods predominately exposed {110} and {100} planes. It was demonstrated that the ZrO2-CeO2 nanorods had a strong interaction with MnOx species, which resulted in great superiority for the selective catalytic reduction of NO. The excellent catalytic activity of the MnOx/ZrO2-CeO2 nanorods should be attributed to the Mn4+ species, adsorbed surface oxygen and oxygen vacancies which are associated with their exposed {110} and {100} planes.