Novel heterogeneous denitrification catalyst over a wide temperature range: Synergy between CeO2, ZrO2 and TiO2

A series of CeO2-ZrO2-TiO2 mixed oxide catalysts were synthesized by hydrothermal method. Compared to the pure CeO2 and ZrO2-TiO2 catalysts, the novel 0.3CeO(2)-ZrO2-TiO2 catalyst exhibited good catalytic activity in a wide temperature window (220-400 degrees C) under a gas hourly space velocity (GHSV) of 30,000 h(-1) for the selective catalytic reduction of NOx with NH3. Some analytical techniques were used to study the relationship between the structure, surface properties and catalytic properties of the catalysts. For the 0.3CeO(2)-ZrO2-TiO2 catalyst, the amorphous particles with a broad mesoporous distribution leaded to higher surface area than those of pure CeO2 and ZrO2-TiO2, which was conducive to the adsorption of active gas and the catalytic activity. Also, the catalyst prepared by hydrothermal method produced more Ce3+ ions. The electron redistribution effect arised from the synergistic effect between the different components promoted the formation of Ce3+, oxygen vacancies and active oxygen species. The existence of Ce3+ species can lead to charge imbalance and unsaturated chemical bonds, which futher increase the chemisorbed oxygen or yield active oxygen species and are beneficial to form reactive centers in catalytic reduction of NOx. Moreover, rich surface acidity, strong redox property and active intermediate species are the main contributors to the high DeNO(X) activity of CeO2-ZrO2-TiO2 SCR catalyst.