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合成了一系列钙钛矿型La_(1-x)Sr_xCoO_(δ-λ)催化剂,研究了它们的晶体结构、氧吸附能力(TPD)、表面状态(XPS)和催化性质。X射线衍射分析证明,样品在x<0.5时出现轻微的畸变,呈菱形结构,在x>0.5时则为立方结构。非计量氧(λ值)随x值从0.045变化至0.389,表明有氧阴离子缺陷生成,这一结果并为XPS研究所确认。根据不同价态的钻离子含量的变化,认为有可能生成两种不同的缺陷:La_(1-x)Sr_xCo_(1-x)~(8+)Co_x~(4+)O和La_(1-x)Sr_xCo~(3+)V_(λ/2O2)O_(δ-λ),而其中Co~(4+)是不稳定的,这类催化剂的活性和热稳定性之所以优于CoCo_2O_4,可归因于CO~(3+)的含量和稳定性。
A series of perovskite La_ (1-x) Sr_xCoO_ (δ-λ) catalysts were synthesized and their crystal structures, oxygen adsorption capacity (TPD), surface state (XPS) and catalytic properties were studied. X-ray diffraction analysis showed that the sample showed a slight distortion at x <0.5, a diamond-shaped structure, and a cubic structure at x> 0.5. The non-metered oxygen (λ value) varied from 0.045 to 0.389 with the value of x, indicating the generation of oxanionic defects, a result confirmed by the XPS study. According to the variation of the content of diamond ions in different valence states, it is considered that it is possible to generate two different kinds of defects: La_ (1-x) Sr_xCo_ (1_x) ~ (8+) Co_x ~ (4 +) O and La_ x) Sr_xCo ~ (3+) V_ (λ / 2O2) O_ (δ-λ), and Co ~ (4+) is unstable. The activity and thermal stability of these catalysts are better than that of CoCo_2O_4 Attributed to the CO ~ (3 +) content and stability.