The SMSI between supported platinum and CeO2-ZrO2-La2O3 mixed oxides in oxidative atmosphere
The SMSI between supported platinum and CeO2-ZrO2-La2O3 mixed oxides in oxidative atmosphere
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DOI：
10.1016/j.cattod.2007.06.005
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发表时间：
2007-08
期刊：
影响因子：
5.3
通讯作者：
Jun Fan;Xiaodong Wu;Lei Yang;D. Weng
中科院分区：
文献类型：
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作者：
Jun Fan;Xiaodong Wu;Lei Yang;D. Weng
采用柠檬酸溶胶-凝胶法制备了CeO 2-ZrO 2-La 2 O3（CZL）复合氧化物。将原样凝胶在500、700、900和1050°C下煅烧以分别获得所谓的C5、C7、C9和CK。将C5、C7和C9粉末用H2 PtCl 6浸渍，然后在500°C下煅烧以分别制备P5 C5、P5 C7和P5 C9。将浸渍的CK粉末在500、700和900°C下煅烧以分别制备P5 CK、P7 CK和P9 CK。XRD和XPS分析表明，载体的结构和织构对Pt的表面分布有明显的影响。CO吸附后的FTIR表明，随着焙烧温度的升高，CZL载体的分散度和Pt的化学吸附位减少。CK样品的化学吸附能力甚至完全失活。本文介绍了用于解释还原处理后的强金属-载体相互作用（SMSI）的包封机理，以解释氧化气氛下制备的样品中的异常现象。HRTEM结果也证实了这一解释。讨论了氧空位、Pt表面化学吸附位和Pt/Ce界面位对三效催化活性的影响。
CeO2–ZrO2–La2O3(CZL) mixed oxides were prepared by citric acid sol–gel method. The as-received gel was calcined at 500, 700, 900 and 1050°C to obtain the so-called C5, C7, C9 and CK, respectively. The C5, C7 and C9 powders were impregnated with H2PtCl6and then calcined at 500°C to prepare P5C5, P5C7 and P5C9, respectively. The impregnated CK powders were calcined at 500, 700 and 900°C to prepare P5CK, P7CK and P9CK, respectively. The XRD and XPS analyses show that the surface distribution of Pt is evidently influenced by the structural and textural properties of the support. The CO adsorption followed by FTIR reveals that the dispersion and the chemisorption sites of Pt are reduced as the calcination temperature of CZL support increases. The chemisorption ability of the CK samples is even completely deactivated. The encapsulation mechanism, which has been applied to explain the so-called strong metal–support interaction (SMSI) after reductive treatment, is introduced here to demonstrate the abnormal observations though the samples were prepared in oxidative atmosphere. The HRTEM results also confirm this explanation. The effects of oxygen vacancies, the chemisorption sites on the Pt surface and Pt/Ce interfacial sites on the three-way catalytic activities are discussed.