A new concept in high performance ceria-zirconia oxygen storage capacity material with Al2O3 as a diffusion barrier
A new concept in high performance ceria-zirconia oxygen storage capacity material with Al2O3 as a diffusion barrier
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DOI：
10.1016/j.apcatb.2007.09.013
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发表时间：
2008-02-07
影响因子：
22.1
通讯作者：
Shinjo, Hirofumi
中科院分区：
文献类型：
--
作者：
Morikawa, Akira;Suzuki, Tadashi;Shinjo, Hirofumi
CeO2-ZrO2固溶体（(Ce,Zr)O-2）是汽油汽车排放控制中不可缺少的储氧材料。本研究开发的高性能OSC材料由作为“扩散屏障”的Al2O3和中间层的（Ce,Zr）O-2粒子组成，在纳米尺度上，简称为“ACZ”。在1000℃空气中进行耐久性试验后，ACZ的比表面积（BET）为20 m(2)/g，高于不含Al(2)O(3)的由（Ce,Zr）O-2组成的常规CZ （2 m(2)/g）。在1000℃空气中热处理后，ACZ中（Ce,Zr）O-2的粒径约为10 nm，不含Al2O3的ACZ的粒径为纯CZ的一半。用总容量（OSC-c1）和氧释放速率（OSC-r）粗略表征盐含量。在新鲜催化剂中，ACZ和CZ的OSC-c1几乎相同；ACZ的OSC-r比CZ快2倍。耐久性试验后，ACZ和CZ的OSC-r均显著降低，但ACZ的OSC-r速度约为CZ的5倍。支架上的（Ce,Zr）O-2晶粒尺寸和Pt晶粒尺寸对OSC-c1的影响不大，而OSC-r则同时受到这两个参数的影响。通过引入Al2O3作为扩散屏障，抑制ACZ中（Ce,Zr）O-2的颗粒生长，从而抑制Pt颗粒的烧结，从而改善了新催化剂中OSC-r的性能，并抑制了耐久性测试后OSC-r的下降。(c) 2007 Elsevier B.V.版权所有
CeO2-ZrO2 solid solution ((Ce,Zr)O-2) is an indispensable oxygen storage capacity (OSC) material for emission control in gasoline-fuelled automobiles. The high performance OSC material developed in this study is composed of Al2O3 as "a diffusion barrier" and (Ce,Zr)O-2 Particles in intervening layers on a nanometer scale, and is abbreviated as "ACZ". The Brunauer-Emmett-Teller (BET) specific surface area (SSA) of ACZ after durability testing in air at 1000 degrees C was 20 m(2)/g, which is higher than that of conventional CZ (2 m(2)/g) composed of (Ce,Zr)O-2 without Al(2)O(3)After heat treatment at 1000 degrees C in air, the particle size of (Ce,Zr)O-2 in ACZ was about 10 nm and that without Al2O3 was one-half of the size in pure CZ. The OSC was roughly characterized by the total capacity (OSC-c1) and the oxygen release rate (OSC-r). In a fresh catalyst, ACZ and CZ had almost the same OSC-c1; however, the OSC-r of ACZ was twice as fast as CZ. After durability testing, the OSC-r of both ACZ and CZ were reduced significantly, but the OSC-r of ACZ was about five times as fast as CZ. While the OSC-c1 was hardly influenced by the (Ce,Zr)O-2 crystallite size and Pt particle size on the supports, the OSC-r was influenced by both of these parameters. The improvement of the OSC-r in the fresh catalyst and inhibition of the decrease in the OSC-r after durability testing were achieved by suppression of particle growth of (Ce,Zr)O-2 in ACZ by introducing Al2O3 as a diffusion barrier with resultant inhibition of sintering of Pt particles. (c) 2007 Elsevier B.V. All rights reserved.