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

The morphology effect of ZrO 2 –CeO 2 on the performance of MnO x /ZrO 2 –CeO 2 catalyst for the selective catalytic reduction of NO with ammonia was investigated. The catalytic tests showed that the MnO x /ZrO 2 –CeO 2 nanorods achieved significantly higher NO conversions than the nanocubes and nanopolyhedra. The catalytic tests also showed that the MnO x /ZrO 2 –CeO 2 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 ZrO 2 –CeO 2 nanorods had a strong interaction with MnO x species, which resulted in great superiority for the selective catalytic reduction of NO. The excellent catalytic activity of the MnO x /ZrO 2 –CeO 2 nanorods should be attributed to the Mn 4+ species, adsorbed surface oxygen and oxygen vacancies which are associated with their exposed {110} and {100} planes.