Insight into CH4 dissociation on NiCu catalyst: A first-principles study
Insight into CH4 dissociation on NiCu catalyst: A first-principles study
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深入了解 NiCu 催化剂上 CH4 解离：第一性原理研究
DOI：
10.1016/j.apsusc.2012.05.017
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发表时间：
2012-08-01
影响因子：
6.7
通讯作者：
Xie, Kechang
中科院分区：
文献类型：
--
作者：
Liu, Hongyan;Zhang, Riguang;Xie, Kechang
采用密度泛函理论方法研究了CH 4分子在NiCu（111）表面上的解离.两种型号：建立了均匀表面平板模型（模型A）和富Cu表面平板模型（模型B），用于描述Ni/Cu为单位的NiCu（111）表面。并与纯Ni（111）和Cu（111）的结果进行了比较。结果表明，CHx（x = 1-3）在模型B上的吸附比在模型A上的弱。模型A和B中CH 4解离的速率控制步骤均为CH的解离，相应的活化能垒分别为1.37和1.63 eV。显然，模型A上的能量近似等于纯Ni（111）上的能量[H.柳河，巴西-地张河，巴西-地Yan，B. Wang，K. Xie，Applied Surface Science 257（2011）8955]，而在模型B上比在纯铜上低0.58 eV（111）。因此，富铜表面比均匀表面具有更好的抗碳能力。这些结果很好地解释了NiCu/SiO_2具有优良的催化性能和长期稳定性的实验事实[H. W.陈春Y.王角H.于湖，澳-地T. Tseng，P.- H. Liao，Catalysis Today 97（2004）173]，然而，在甲烷CO2重整中，NiCu/MgO-Al 2 O3上存在严重的积碳[J. Zhang，H. Wang，中国山核桃A. K. Dalai，Journal of Catalysis 249（2007）300]。(C)2012爱思唯尔有限公司版权所有。
A density-functional theory method has been conducted to investigate the dissociation of CH4 on NiCu (111) surface. Two models: uniform surface slab model (Model A) and Cu-rich surface slab model (Model B) have been constructed to represent the NiCu (111) surface, in which the ratio of Ni/Cu is unit. The obtained results on the two models have been compared with those obtained on pure Ni (111) and Cu (111). It is found that the adsorption of CHx(x = 1-3) on Model B are weaker than on Model A. The rate-determining steps of CH4 dissociation on Model A and B both are the dissociation of CH, and the corresponding activation barriers are 1.37 and 1.63 eV, respectively. Obviously, it is approximately equal on Model A to that on pure Ni (111) [H. Liu, R. Zhang, R. Yan, B. Wang, K. Xie, Applied Surface Science 257 (2011) 8955], while it is lower by 0.58 eV on Model B compared to that on pure Cu (111). Therefore, the Cu-rich surface has better carbon-resistance ability than the uniform one. Those results well explain the experimental facts that NiCu/SiO2 has excellent catalytic performance and long-term stability [H.W. Chen, C.-Y. Wang, C.-H. Yu, L.-T. Tseng, P.-H. Liao, Catalysis Today 97 (2004) 173], however, there is serious carbon deposition on NiCu/MgO-Al2O3 in CO2 reforming of methane [J. Zhang, H. Wang, A. K. Dalai, Journal of Catalysis 249 (2007) 300]. (C) 2012 Elsevier B.V. All rights reserved.