Investigation of NO and NO₂ adsorption mechanisms on TiO₂ at room temperature

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• 作者：L. Sivach ; iran ; F. Thevenet ; P. Gravejat ; A. Rousseau
• 关键词：Adsorption ; TiO2 ; NO2 ; NO ; NO3
• 刊名：Applied Catalysis B: Environmental
• 出版年：2013
• 出版时间：October-November, 2013
• 年：2013
• 卷：142-143
• 期：Complete
• 页码：196-204
• 全文大小：945 K

文摘

In this study, NO and NO₂ adsorption mechanisms on TiO₂ at room temperature have been investigated separately. Atmospheric pressure gas phase Fourier Transform Infrared Spectroscopy (FTIR) coupled to adsorption and temperature programmed desorption (TPD) experiments have been used to characterize gas phase and adsorbed phase species. TiO₂ coated glass beads packed-bed reactor has been designed and used for NO and NO₂ adsorption and storage capacity under dark and gas-flowing conditions at room temperature. For NO adsorption, experimental data suggests that, at room temperature, NO shows no significant adsorption on TiO₂. On the other hand NO₂ adsorbs in a reactive way by evolving NO in the gas phase. We quantitatively evidenced that, the ratio between consumed NO₂, desorbed NO₂ by TPD after adsorption and produced NO during NO₂ adsorption is 3:2:1, by a qualitative and quantitative analysis performed downstream the reactor. Based on the quantitative analysis, a new NO₂ adsorption mechanism on TiO₂ at room temperature has been proposed, and validated for various NO₂ inlet concentrations. The proposed mechanism is valid on the investigated NO₂ inlet concentration range. In addition, it was found that, NO formation time, during NO₂ adsorption, is rather controlled by TiO₂ surface coverage than NO₂ inlet concentration; similarly, adsorption time i.e. surface coverage, significantly modifies the nature of adsorbed species on TiO₂ surface.