制备了一系列不同Mn/(Mn+Ce)质量比的MnOx-CeO2/WO3-ZrO2整体式催化剂用于富氧条件下的NH3选择性催化还原NOx(NH3-SCR),并采用N2吸脱附、储氧量、X射线衍射、X光电子能谱、NH3/NO程序升温脱附以及H2程序升温还原等手段对催化剂进行表征.结果表明,当Mn/(Mn+Ce)质量比为0.5时,整体式催化剂具有较好的NH3-SCR性能,在空速10000h-1和173~355oC条件反应下,NOx转化率达90%以上.这是由于该MnOx-CeO2/WO3-ZrO2催化剂具有更高的NO氧化活性、更高的表面Ce和Mn原子浓度以及Ce3+/Ce值较低的NH3和NO脱附温度以及优异的氧化还原性能所致.
A series of monolith MnOx-CeO2/WO3-ZrO2 catalysts with different mass ratios of Mn/(Mn+Ce) were prepared and used for the selective catalytic reduction (SCR) of NOx with NH3 in the presence of excess O2. The catalysts were characterized by N2 adsorption, oxygen storage capacity, X-ray diffraction, X-ray photoelectron spectroscopy, NH3/NO temperature-programmed desorption, and H2 temperature-programmed reduction. The best catalyst had the mass ratio of Mn/(Mn+Ce)=0.5. It gave 90% NOx conversion in the range of 173?355 oC at the gas hourly space velocity of 10000 h?1, and characterization results showed that a higher oxidation activity of NO to NO2, more surface Ce and Mn with a larger Ce3+/Ce4+ ratio, lower NH3 and NO desorption temperatures, and excellent redox ability were together responsible for its best NH3-SCR performance.