Thermal stability of oxygen storage properties in a mixed CeO2-ZrO2 system
Thermal stability of oxygen storage properties in a mixed CeO2-ZrO2 system
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DOI：
10.1016/s0926-3373(97)00060-x
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发表时间：
1998-03-27
影响因子：
22.1
通讯作者：
Belton, D
中科院分区：
文献类型：
--
作者：
Hori, CE;Permana, H;Belton, D
CeO 2和CeO 2/ZrO 2载体通过两种低温（500 ℃）路线制备：氢氧化物沉淀的煅烧和乙酸盐的烧成混合物。载体负载有0.5%Pt，并且表征新鲜和老化（在800和1000 ℃下）。X射线衍射分析表明，CeO 2/ZrO 2固溶体形成在通过沉淀的氢氧化物和煅烧在500 ℃制备的样品中。据我们所知，这是迄今报道的CeO 2/ZrO 2固溶体的最低温度化学路线（不包括高能球磨）。通过烧制乙酸酯混合物制备的样品在分离相中几乎仅具有CeO 2和ZrO 2。储氧测量表明，对于两种制备方法，氧化锆的加入增加了单独的二氧化铈的储氧能力（基于每克催化剂）。在相分离的材料中，每克催化剂的可逆储氧量是仅二氧化铈的1.7-2.5倍。氧化锆的有益效果在具有比二氧化铈高3-5倍的氧储存的固溶体中最显著。当Zr浓度优化时，在1000 ℃下老化的固溶体材料比新鲜CeO 2表现出更高的储氧能力。对于这两种制备方法，发现对于在1000 ℃下老化的样品，最佳（每克催化剂）Zr浓度为25摩尔% Zr，然而，固溶体材料的性能对15至50摩尔% Zr之间的Zr负载量有些不敏感。(C)1998年Elsevier Science B.V.
CeO2 and CeO2/ZrO2 supports were prepared by two low temperature (500 degrees C) routes: calcination of hydroxide precipitates and firing mixtures of acetates. The supports were loaded with 0.5% Pt and characterized both fresh and aged (at 800 and 1000 degrees C). X-ray diffraction analyses show that a CeO2/ZrO2 solid solution is formed in the samples prepared by precipitation of the hydroxides and calcination at 500 degrees C. To our knowledge this is the lowest temperature chemical route (not including high energy ball milling) to CeO2/ZrO2 solid solutions yet reported. Samples prepared by firing the acetate mixtures had almost exclusively CeO2 and ZrO2 in separated phases. Oxygen storage measurements showed that the addition of zirconia increased the oxygen storage capacities (on a per gram of catalyst basis) over ceria alone for both preparation methods. In the phase separated materials the amount of reversibly stored oxygen was 1.7-2.5 times more per gram catalyst than that of ceria only. The beneficial effects of zirconia are most pronounced in the solid solutions which had oxygen storage 3-5 times higher than ceria. When the Zr concentration is optimized, the solid solution materials aged at 1000 degrees C showed higher oxygen storage than fresh CeO2. For both preparation methods, the optimal (per gram catalyst) Zr concentration was found to be 25 mol% Zr for samples aged at 1000 degrees C, however, the performance of the solid solution materials was somewhat insensitive to Zr loading between 15 and 50 mol% Zr. (C) 1998 Elsevier Science B.V.