Ultra-low loading of copper modified TiO2/CeO2 catalysts for low-temperature selective catalytic reduction of NO by NH3

- TiO2/CeO2 catalysts are modified by ultra-low loading of copper.
- The NH3-SCR activity of TiO2/CeO2 are strongly influenced by copper content.
- Redox and surface acidic properties are improved by the addition of copper.
- The appearance of CuO weakened the adsorption ability of nitrates.

A series of ultra-low content copper-modified TiO2/CeO2 catalysts were prepared by wet impregnation method and tested for selective catalytic reduction of NO by NH3. The catalyst with a Cu/Ce molar ratio of 0.005 showed the best low-temperature activity and excellent sulfur-poisoning resistance. It was worth noting that the very small amounts of copper addition can lead to three times the activity at low temperature. The prepared catalysts were characterized by XRD, BET, Raman, XPS, NH3-TPD and the results revealed that the introduction of copper increased the amount of surface adsorbed oxygen and Ce3+ species on the catalyst surface and generated more Brønsted acid sites. The redox and surface acidic properties were also improved by the addition of Cu. All these factors played important roles in enhancing NH3-SCR performance of TiO2-CuO/CeO2 catalysts. Furthermore, in situ DRIFT experiments demonstrated that Cu doping enhanced the adsorption capacity of NH3 while the appearance of CuO weakened the adsorption ability of bridging nitrates, both the two factors synergistically facilitated the NH3-SCR reaction proceed smoothly via the Eley-Rideal pathway.

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