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Pt/K 2 Ti 2 O 5 is developed as a high-temperature NO x storage and reduction (NSR) catalyst. K 2 Ti 2 O 5 , in place of alkali metals and γ-Al 2 O 3 , works as both support and NO x adsorber; and, unlike alkali-doped NSR catalysts that tend to deactivate at temperature higher than 500 °C, K 2 Ti 2 O 5 shows stable NO x adsorption in a high temperature range of 500–600 °C. The NO x storage and reduction performance over Pt/K 2 Ti 2 O 5 is studied by various means, including temperature-programmed adsorption, isothermal storage, and lean–rich cycling experiments. A maximum value of adsorbed NO x species (close to 1.2 mmol/g catalyst) is achieved at 550 °C. Temperature-programmed de-sorption reveals that the adsorbed NO x on Pt/K 2 Ti 2 O 5 is highly stable, with a peak at 720 °C. Thermal stability investigations indicate Pt/K 2 Ti 2 O 5 has a much higher stability than Pt–K/TiO 2 . Mechanism studies reveal that KNO 3 -like compound is formed after NO x adsorption, and that NO x storage and reduction process on K 2 Ti 2 O 5 is accompanied by a structure transformation between K 2 Ti 2 O 5 and K 2 Ti 6 O 13 . |
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