Activity, stability, and deactivation behavior of supported Au/TiO2 catalysts in the CO oxidation and preferential CO oxidation reaction at elevated temperatures
Activity, stability, and deactivation behavior of supported Au/TiO2 catalysts in the CO oxidation and preferential CO oxidation reaction at elevated temperatures
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DOI：
10.1016/j.jcat.2009.07.018
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发表时间：
2009-10-01
影响因子：
7.3
通讯作者：
Behm, R. Juergen
中科院分区：
文献类型：
--
作者：
Denkwitz, Yvonne;Schumacher, Birgit;Behm, R. Juergen
在80-180 ° C的温度范围内，通过动力学和原位红外测量，研究了在理想的无H2反应气氛和富H2混合气体中，升高反应温度对Au/TiO 2催化剂CO氧化活性、长期稳定性和失活行为的影响。结果在分子图像中进行了讨论。对于实际应用（PROX反应）最重要的是，在富含H-2的气体混合物中CO氧化的选择性随着温度的升高而急剧下降，从80 ℃下的60%下降到180 ℃下的15%。与在无H-2的反应混合物中的反应（30 +/-3 kJ mol（1））相比，在H2存在下CO氧化的表观活化能（18 +/-3 kJ mol（1））明显更低也反映了H-2氧化的增加趋势。在所有情况下，观察到碳酸盐的形成，并提出有助于失活，但根据反应条件的不同程度。(C)2009 Elsevier Inc. All rights reserved.
The influence of elevated reaction temperatures on the activity, long-time stability, and deactivation behavior of Au/TiO2 catalysts for CO oxidation was studied by kinetic and in situ IR measurements in the temperature range 80-180 degrees C, both in an idealized, H-2-free reaction atmosphere and in a H-2-rich gas mixture. The results are discussed in a molecular picture. Most important for practical applications (PROX reaction), the selectivity for CO oxidation in H-2-rich gas mixtures decreases sharply with increasing temperature, from similar to 60% at 80 degrees C to similar to 15% at 180 degrees C. The increasing tendency for H-2 oxidation is reflected also by a distinctly lower apparent activation energy for CO oxidation in the presence of H2 (18 +/- 3 kJ mol (1)) compared to reaction in a H-2-free reaction mixture (30 +/- 3 kJ mol (1)). In all cases, carbonate formation is observed and proposed to contribute to the deactivation, but with different extents depending on the reaction conditions. (C) 2009 Elsevier Inc. All rights reserved.