Copper-cerium-zirconium catalysts loaded on Ti02 prepared by a wet impregnation method were investigated for NHz-selective catalytic reduction （SCR） of NOx. The reaction mechanism was proposed on the basis of result...Copper-cerium-zirconium catalysts loaded on Ti02 prepared by a wet impregnation method were investigated for NHz-selective catalytic reduction （SCR） of NOx. The reaction mechanism was proposed on the basis of results from in situ diffuse reflectance infrared transform spectroscopy （DRIFT）. When NH3 is introduced, ammonia bonded to Lewis acid sites is more stable over CuCe0.25Zr0.75/TiO2 at high temperature, while Brensted acid sites are more important than Lewis acid sites at low temperature. For the NH3＋NO＋O2 co-adsorption, NH3 species occupy most of activity sites on CuCe0.25Zr0.75/TiO2 catalyst, and mainly exist in the forms of NH4＋ （at low temperature） and NH3 coordinated （at high temperature）, playing a crucial role in the NHz-SCR process. Two different reaction routes, the L-H mechanism at low temperature （〈 200℃） and the E-R mechanism at high temperature （〉200℃）, are presented for the SCR reaction over C uCe0.25Zr0.75/TiO2 catalyst.展开更多
文摘Copper-cerium-zirconium catalysts loaded on Ti02 prepared by a wet impregnation method were investigated for NHz-selective catalytic reduction （SCR） of NOx. The reaction mechanism was proposed on the basis of results from in situ diffuse reflectance infrared transform spectroscopy （DRIFT）. When NH3 is introduced, ammonia bonded to Lewis acid sites is more stable over CuCe0.25Zr0.75/TiO2 at high temperature, while Brensted acid sites are more important than Lewis acid sites at low temperature. For the NH3＋NO＋O2 co-adsorption, NH3 species occupy most of activity sites on CuCe0.25Zr0.75/TiO2 catalyst, and mainly exist in the forms of NH4＋ （at low temperature） and NH3 coordinated （at high temperature）, playing a crucial role in the NHz-SCR process. Two different reaction routes, the L-H mechanism at low temperature （〈 200℃） and the E-R mechanism at high temperature （〉200℃）, are presented for the SCR reaction over C uCe0.25Zr0.75/TiO2 catalyst.
