中文摘要：

氮氧化物（NOx）是大气污染的主要因素之一,对其排放的治理成为较为迫切的需求.氨气选择性催化还原法（NH3-SCR）是目前减少NOx排放中应用最为广泛的技术.目前,商业SCR催化剂主要是V2O5（WO3,MO3）/TiO2,但其具有活性温度窗口窄、N2选择性低和对环境影响大等缺点.因此,新型的催化活性高且活性温度窗口宽的环境友好催化剂成为脱硝催化剂的研究热点.CeO2因其独特的氧化还原性能和优异的储释氧能力在催化领域具有广泛应用,在NH3-SCR中也研发出较多类型的铈基催化剂.我们课题组前期研发了具有优异脱硝性能的CeO2（ZrO2）/TiO2催化剂,为拓展其应用范围,需要进行更深入的研究.理论上,Ti^4＋,Ce^4＋以及Zr^4＋离子的价态均高于Er^3＋,且离子半径相近.换言之,Er2O3能够与TiO2以及CeO2产生缺陷反应增大催化剂的缺陷浓度,进而提高催化剂的催化活性.本文以溶胶-凝胶法制备了一系列Er掺杂CeO2（ZrO2）/TiO2催化剂,测试了样品的NH3-SCR催化活性和N2选择性,并且在320℃下连续24h测试了水蒸气、SO2以及两者混合作用对催化剂活性的影响.使用X射线衍射（XRD）、N2等温吸附-脱附（N2-BET）、NH3程序升温脱附（NH3-TPD）、H2程序升温还原（H2-TPR）、光致发光光谱（PL）、电子顺磁共振（EPR）以及X射线光电子能谱（XPS）对催化剂进行了表征.XRD结果显示,Er掺杂后催化剂的结晶程度降低,且图谱中没有出现明显的Er2O3衍射峰,即Er在催化剂上有较好的分散度且掺杂抑制了催化剂的晶化.NH3-TPD和H2-TPR结果表明,Er掺杂降低了酸强且提高了储释氧能力,催化剂的氧化还原能力则有所减弱.PL和EPR测试结果显示,掺杂后的催化剂氧空位浓度和Ti^3＋浓度有所增加,与前期理论设计一致.XPS测试结果表明,掺入Er后催化剂的化学吸附氧含量和Ti^3＋浓度增加,Ce^3＋浓度基本不变,推测是CeO2（ZrO2）/TiO2催化剂

英文摘要：

A series CeO2（ZrO2）/TiO2 catalysts were modified with Er using a sol-gel method.The catalytic activity of the obtained catalysts in the selective catalytic reduction（SCR） of NO with NH3 was investigated to determine the appropriate Er dosage.The catalysts were characterized using X-ray diffraction,N2 adsorption,NH3 temperature-programmed desorption,H2 temperature-programmed reduction,photoluminescence spectroscopy,electron paramagnetic resonance spectroscopy,and X-ray photoelectron spectroscopy.The results showed that the optimum Er/Ce molar ratio was 0.10;this catalyst had excellent resistance to catalyst poisoning caused by vapor and sulfur and gave more than 90% NO conversion at 220–395 ℃ and a gas hourly space velocity of 71 400 h^-1.Er incorporation increased the Ti^3＋ concentrations,oxygen storage capacities,and oxygen vacancy concentrations of the catalysts,resulting in excellent catalytic performance.Er incorporation also decreased the acid strength and inhibited growth of TiO2 and CeO2 crystal particles,which increased the catalytic activity.The results show that high oxygen vacancy concentrations and oxygen storage capacities,large amounts of Ti^3＋,and low acid strengths give excellent SCR activity.