Activity, stability, and deactivation behavior of supported Au/TiO₂ catalysts in the CO oxidation and preferential CO oxidation reaction at elevated temperatures

详细信息    查看全文

• 作者：Yvonne Denkwitz ; Birgit Schumacher ; Gabriela Kuč ; erová ; R. Jü ; rgen Behm
• 关键词：Au/TiO₂ catalyst ; CO oxidation ; PROX reaction ; Deactivation ; Mechanism ; Long-term stability ; TEM ; DRIFTS
• 刊名：Journal of Catalysis
• 出版年：2009
• 出版时间：1 October 2009
• 年：2009
• 卷：267
• 期：1
• 页码：78-88
• 全文大小：738 K

文摘

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 °C, both in an idealized, H₂-free reaction atmosphere and in a H₂-rich gas mixture. The results are discussed in a molecular picture. Most important for practical applications (PROX reaction), the selectivity for CO oxidation in H₂-rich gas mixtures decreases sharply with increasing temperature, from 60 % at 80 °C to 15 % at 180 °C. The increasing tendency for H₂ 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 H₂-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.