过渡金属替代的CeO_2(111)表面上NO+CO反应机理的理论研究(英文)  

First-principles study of NO reduction by CO on transition metal atoms-doped CeO_2(111)

作　　者：丁戊辰[1] 李微雪[1] 

机构地区：[1]中国科学院大连化学物理研究所,辽宁大连116023

出　　处：《催化学报》2014年第12期1937-1943,共7页

基　　金：supported by the National Natural Science Foundation of China(21173210,21225315);the National Basic Research Program of China(973 Program,2013CB834603);the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA09030000)~~

摘　　要：采用DFT+U方法研究了过渡金属替代的CeO2(111)表面上的NO+CO反应机理,以探求不同过渡金属对N2选择性的影响.结果表明,在反应过程中,反应活性中心由过渡金属单原子与其最近邻的氧空位组成.NO在过渡金属-氧空位上发生N–O断键,不同过渡金属上该还原步骤的难易程度不同.计算发现,右过渡金属Rh,Pd和Pt替代的CeO2(111)表面可以与吸附物之间形成较强的吸附作用,进而可以达到较高的N2选择性.其主要原因是右过渡金属具有较多的d电子,可以与吸附小分子之间形成有效的反馈键.而左过渡金属拥有较少的d电子,难以有效抓住吸附物,最终导致较低的N2选择性.We present here a density functional theory plus U study of NO reduction with CO, catalyzed by a single transition metal atom （TM1=Zr1, Tc1, Ru1, Rh1, Pd1, Pt1）‐doped CeO2（111）. The catalytic cen‐ter was identified as the TM dopant in combination with lattice oxygen. The investigation into N2 selectivity focused on three key elementary steps： gaseous N2O formation, subsequent re‐adsorption, and N–O bond scission to produce N2. In these steps, Rh1, Pd1, and Pt1/CeO2（111） exhibit a higher selectivity, whereas the other systems （Zr1, Tc1, Ru1） TM1/CeO2 show a lower selec‐tivity. The higher selectivity displayed by Pt1, Pd1, and Rh1 dopants arises from the availability of valence d electrons, which permit the formation of strong chemical bonds with the reactants and intermediates. Calculated results agree well with experimental findings, and the insights gained can be used to guide the rational design of the doped oxides for catalysis.

关 键 词：一氧化氮消除 选择性 单原子 单过渡金属原子/氧化铈 密度泛函理论+U 

分 类 号：O643.12[理学—物理化学]