摘要
采用一次浸渍法分别制备了Pd/Ce0.8Zr0.15La0.05Oδ及Pd/Ce0.8Zr0.2O2整体式蜂窝陶瓷催化剂,考察了不同温度焙烧的两类整体催化剂甲苯催化燃烧性能。通过X射线粉末衍射(XRD)、比表面积、拉曼光谱(Raman)、程序升温还原(H2-TPR)、PdO分散度等表征结果与催化活性进行关联。结果表明,随着焙烧温度升高,催化剂比表面积下降,Raman图谱CeO2及PdO峰强度增加,H2-TPR中Ce4+还原峰向高温方向移动,同时PdO分散度下降,相应甲苯催化氧化活性下降。与Ce0.8Zr0.2O2涂层催化剂相比,La3+掺杂催化剂在高温焙烧时,其比表面积下降较小,Raman光谱表明其氧缺位比铈锆涂层催化剂多,H2-TPR谱图中Ce4+还原峰低约60～80℃,PdO分散度亦比未掺杂催化剂高。1000℃焙烧下的甲苯氧化反应活性远高于未掺杂催化剂,说明镧的掺杂提高了铈锆涂层催化剂的高温反应活性及热稳定性。
Pd/Ce0.8 Zr0. 15 La0.05 Oδand Pd/Ce0 .8 Zr0. 2 O2 monolithic catalysts were prepared by an impregnation method, by which the active component （Pd） and CeO2-ZrO2-La2O3 （ CeO2-ZrO2 ） coat simultaneously impregnated on the corderite substrate. Combining with X-ray diffraction （XRD）, Raman spectroscopy, Brunauner-Emmett-Teller （BET）, and H2-temperature programmed reduction （H2-TPR） characterization techniques, the two kinds of catalysts were systematically investigated. It was found that the BET surface area and PdO dispersion degree decreased with the increase of calcinated temperature, while the peaks of CeO2 and PdO in the Raman spectroscopy, as well as the reduction temperature of Ce^4＋ , increased with increasing calcination temperature. Consistent with the characterization results, it was found that the reactivities of toluene combustion also decrease for both catalysts. It was very interesting to note that the oxygen vacancies of the catalyst doping with La^3＋ into CeO2-ZrO2 solid solution was more than that of the CeO2-ZrO2 coat when calcinated at 1000℃, and the corresponding BET surface area and PdO dispersion degree were all higher than that of Pd/Ce0.8 Zr0.2 O2 nated above 800℃. Correspondingl catalyst when calciy, the toluene combustion conversion of Pd/Ce0.8Zr0.15 La0.05 Oδwas much higher than that of Pd/Ce0.8 Zr0.2 O2 catalyst calcinated at 1000 ℃, indicating the doping with La^3＋ ion greatly improved the reactivity and thermal stability of the monolithic catalyst at high calcinated temperature. Therefore the Pd/Ce0.8Zr0.15 La0.05 Oδ monolithic catalysts had potentially industrial applications to eliminate volatile organic compounds （VOCs）.
出处
《中国稀土学报》
CAS
CSCD
北大核心
2009年第3期327-333,共7页
Journal of the Chinese Society of Rare Earths
基金
浙江省自然科学基金项目(203147
Y407163)
国家自然科学基金项目(20473075)资助
