水分作用对制备用于乙醇还原NOx的Ag / Al <sub>2</sub> O <sub>3</sub>催化剂的影响,The Journal of Physical Chemistry C

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水分作用对制备用于乙醇还原NOx的Ag / Al ₂ O ₃催化剂的影响
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2016-10-10 00:00:00 , DOI: 10.1021/acs.jpcc.6b08886
Hua Deng ₁ , Yunbo Yu _{1,

2} , Hong He _{1,

2}

Affiliation

研究了湿法浸渍法，半湿法和无水球磨法制得的氧化铝负载银催化剂（Ag / Al ₂ O ₃）对乙醇选择性催化还原NOx的作用。发现可以通过湿法浸渍和半湿法而不是通过无水球磨来获得具有最高NO _x还原效率的Ag / Al ₂ O ₃催化剂。为了优化制备参数并辨别水在生产Ag / Al ₂ O _{3中的作用}作为催化剂，通过XRD，BET，XAS（XANES和EXAFS），原位DRIFTS和NMR对所得的一系列氧化铝负载的银样品进行表征。结果表明，银物种被氧化并高度分散在通过湿法浸渍和半湿法获得的大表面积Al ₂ O _3上。原位DRIFTS显示，在通过这些方法制备的催化剂表面上，重要的中间烯类物质相应地占优势，而在无水球磨制备的Ag / Al ₂ O ₃催化剂上，显着形成了惰性的中间体乙酸盐类。固态¹ H NMR表明，湿法中使用的水可增强Ag的交换⁺带有来自氧化铝表面羟基的质子，这导致银物种高度分散并形成活性的Ag-O-Al实体。

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Water Effect on Preparation of Ag/Al2O3 Catalyst for Reduction of NOx by Ethanol

Alumina-supported silver catalysts (Ag/Al₂O₃) derived from wet impregnation, a semiwet method, and water-free ball-milling were investigated for the selective catalytic reduction of NOx by ethanol. It was found that Ag/Al₂O₃ catalysts with the highest NO_x reduction efficiency can be obtained via wet impregnation and the semiwet method but not by water-free ball milling. To optimize the preparation parameters and discern the effect of water in the production of Ag/Al₂O₃ catalysts, the resulting series of alumina-supported silver samples were characterized by means of XRD, BET, XAS (XANES and EXAFS), in situ DRIFTS, and NMR. The results indicated that silver species were oxidized and highly dispersed on the large surface area Al₂O₃ obtained from wet impregnation and the semiwet method. In situ DRIFTS revealed that the vital intermediate enolic species were correspondingly predominant on the surfaces of catalysts prepared by these methods, while the inactive intermediate acetate species were significantly formed on Ag/Al₂O₃ catalysts prepared by water-free ball milling. Solid state ¹H NMR suggested that the water employed in the wet methods enhances the exchange of Ag⁺ with protons from hydroxyl groups on the alumina surface, which leads to silver species being highly dispersed and forming active Ag–O–Al entities.

更新日期：2016-10-10

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