Physicochemical properties of Ce-containing three-way catalysts and the effect of Ce on catalyst activity
Physicochemical properties of Ce-containing three-way catalysts and the effect of Ce on catalyst activity
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DOI：
10.1016/0021-9517(92)90242-a
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发表时间：
1992-02
影响因子：
7.3
通讯作者：
J. Nunan;H. Robota;M. J. Cohn;S. Bradley
中科院分区：
文献类型：
--
作者：
J. Nunan;H. Robota;M. J. Cohn;S. Bradley
在由 H2、CO、C3H6、C3H8、NO、O2、N2、CO2、H2O 和 SO2 组成的全合成废气混合物中研究了 Pt,Rh,Ce/γ-Al2O3 和 Pt,Rh/CeO2 催化剂的活性。研究表明，Pt 和 CeO2 之间的直接相互作用可在合成废气中的催化剂活化后显着提高催化剂性能。催化剂的活化被证明是由于贵金属和表面 Ce 的还原，并且发现催化剂的这种状态对于 CO 氧化特别有效。负责激活的关键成分被证明是 H2；即使废气中氢气含量较低（≤.26 vol%），还原也非常容易。催化剂活化后，Pt/Ce 相互作用的程度以及由此产生的活性可以通过改变 CeO2 晶粒尺寸来控制。 TPR 和 STEM 分析表明，减小 CeO2 晶粒尺寸会导致更大的 Pt/Ce 相互作用，并导致新鲜催化剂和实验室老化催化剂的活性更高。 Pt/Ce 的直接相互作用还导致 Pt 和表面 Ce 的协同还原，我们发现这与活化后的催化剂性能定性相关。
The activity of Pt,Rh,Ce/γ-Al2O3and Pt,Rh/CeO2catalysts has been studied in a full complement synthetic exhaust gas mixture consisting of H2, CO, C3H6, C3H8, NO, O2, N2, CO2, H2O, and SO2. Direct interaction between Pt and CeO2was shown to lead to large improvements in catalyst performance after activation of the catalyst in the synthetic exhaust gas. Catalyst activation was shown to be due to reduction of the noble metals and surface Ce and this state of the catalyst was found to be particularly effective for CO oxidation. The key component responsible for activation was shown to be H2; even at the low H2level present in the exhaust gas (≤.26 vol%), reduction is shown to be very easy. The degree of Pt/Ce interaction, and thus activity, after catalyst activation could be controlled by varying the CeO2crystallite size. Decreasing the CeO2crystallite size led to greater Pt/Ce interaction as shown by TPR and STEM analysis and resulted in greater activity for both fresh and laboratory aged catalysts. Direct Pt/Ce interaction also led to a synergistic reduction of Pt and surface Ce which we found to qualitatively correlate with catalyst performance after activation.