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In this work, the effect of adding alkaline-earth metals (Mg, Ca, Sr, and Ba) to the ZrO 2 support on the activity of Cu/ZrO 2 catalyst for selective catalytic reduction (SCR) of NO x with C 3 H 6 was investigated. The catalytic activity of Cu/ZrO 2 was greatly enhanced by the addition of 5% all of the four alkaline-earth metals to the ZrO 2 support. The highest promotional effect was observed over the Ca-modified Cu/ZrO 2 catalyst. BET, H 2 -TPR and DRIFTS results revealed that the Cu/CaZrO 2 catalyst had a better metal dispersion and metal–support interaction than Cu/ZrO 2 catalyst. This feature inhibited the direct oxidation of C 3 H 6 and improved the C 3 H 6 selectivity for the reduction of NO. On the other hand, NO x -TPD and DRIFTS results showed that Cu/CaZrO 2 catalyst could adsorb much more nitrate species than Cu/ZrO 2 catalyst under both static room temperature adsorption and the real reaction conditions, while nitrate species was an important intermediate in the C 3 H 6 -SCR. |
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