Direct Spectroscopic Evidence of CO Spillover and Subsequent Reaction with Preadsorbed NOx on Pd and K Cosupported Mg鈥揂l Mixed Oxides

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• 作者：Yexin Zhang ; Xiao Wang ; Zhongpeng Wang ; Qian Li ; Zhaoliang Zhang ; Limin Zhou
• 刊名：Environmental Science & Technology (ES&T)
• 出版年：2012
• 出版时间：September 4, 2012
• 年：2012
• 卷：46
• 期：17
• 页码：9614-9619
• 全文大小：400K
• 年卷期：v.46,no.17(September 4, 2012)
• ISSN：1520-5851

文摘

The CO adsorption and subsequent reaction with preadsorbed NO_x on Pd and K cosupported Mg鈥揂l mixed oxides (Pd鈥揔/MgAlO, 1/8/100 w/w) were investigated using in situ FTIR spectroscopy. During CO adsorption, a peculiar and well-defined IR band at 2160 cm^鈥? was observed. Several elaborately designed experiments such as the competitive adsorption of CO and CO₂ demonstrated that the 2160 cm^鈥? band was exclusively assigned to a carbonyl species on K sites due to the CO spillover from Pd to K, which results from a strong Pd鈥揔 interaction based on temperature-programmed reduction with H₂ experiments. Importantly, the spillover of CO is found to be involved in the reduction of preadsorbed NO_x from temperature-programmed surface reactions with CO. Thus, all adsorbed NO_x can be reduced by CO before desorption. Like the process of 鈥減umping鈥?CO by Pd from the atmosphere to 鈥渋rrigate the field鈥?of the nitrates/nitrites, the adsorbed NO_x at not only K sites adjacent to Pd but also at the remote K sites can be reduced into N₂ and N₂O effectively.