Elucidating N2O Formation during the Cyclic NOx Storage and Reduction Process Using CO as a Reductant

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• 作者：Jun Wang ; Xiuting Wang ; Jinxin Zhu ; Jianqiang Wang ; Meiqing Shen
• 刊名：Environmental Science & Technology
• 出版年：2015
• 出版时间：July 7, 2015
• 年：2015
• 卷：49
• 期：13
• 页码：7965-7973
• 全文大小：804K
• ISSN：1520-5851

文摘

The N₂O formation pathway and effect of H₂O on N₂O formation during the NO_x storage and reduction (NSR) process using CO as a reductant were investigated over a Pt鈥揃aO/Al₂O₃ catalyst. The NSR activity measurements and transient in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments were performed to evaluate N₂O evolution and elucidate the N₂O formation mechanism. N₂O is formed in the lean, rich, and delay2 phases. In the lean phase, N₂O formation is related to the reactions between surface isocyanate and gaseous NO/O₂ and NO is more responsible for N₂O formation than O₂. Moreover, N₂O production decreases with H₂O because of the hydrolysis of isocyanate species. In the rich phase, the amount of N₂O formation also decreases in the presence of H₂O at a higher temperature because of the high reduction ability of H₂ generated from the water鈥揼as shift (WGS) reaction. During the delay2 phase, N₂O is mainly formed by nitrite species reacting with Pt⁰鈥揅O. Furthermore, the presence of H₂O decreases the stability of nitrites and results in more N₂O production at a low temperature.