Goda A M, Barteau M A, Chen J G
Center for Catalytic Science and Technology, Department of Chemical Engineering, University of Delaware, Newark, Delaware 19716, USA.
J Phys Chem B. 2006 Jun 22;110(24):11823-31. doi: 10.1021/jp0554689.
The rate and selectivity of chemical reactions on transition-metal surfaces can be controlled by using different bimetallic combinations. The interaction of bimetallic components leads to a change in the electronic properties of the surface, which in turn produces a change in chemical reactivity. In the current paper, we illustrate the correlation of the electronic properties of bimetallic surfaces with the reaction pathways of C2 hydrocarbons. Density functional theory (DFT) was used to study the binding of hydrogen, ethylene, acetylene, ethyl, and vinyl on monometallic and bimetallic transition-metal surfaces. The binding energies of these species were found to correlate with the d-band centers of these surfaces. The binding energies for hydrogen atoms on bimetallic surfaces were lower than for those on the corresponding parent metal surfaces. This trend was consistent for ethylene and acetylene binding. Comparative studies between acetylene and ethylene revealed that acetylene was more strongly bonded to the monometallic and the bimetallic surfaces than was ethylene. Bond order conservation (BOC) theory was used to calculate the activation barriers for ethyl dehydrogenation to ethylene and vinyl dehydrogenation to acetylene. The activation barriers for these reactions were correlated with the surface d-band center of the substrates.
通过使用不同的双金属组合，可以控制过渡金属表面上化学反应的速率和选择性。双金属组分之间的相互作用会导致表面电子性质发生变化，进而引起化学反应活性的改变。在本文中，我们阐述了双金属表面的电子性质与C2烃反应路径之间的相关性。采用密度泛函理论（DFT）研究了氢、乙烯、乙炔、乙基和乙烯基在单金属和双金属过渡金属表面上的吸附。发现这些物种的吸附能与这些表面的d带中心相关。双金属表面上氢原子的吸附能低于相应母体金属表面上氢原子的吸附能。乙烯和乙炔吸附的情况也是如此。乙炔和乙烯之间的对比研究表明，乙炔比乙烯更强烈地吸附在单金属和双金属表面上。采用键级守恒（BOC）理论计算了乙基脱氢生成乙烯以及乙烯基脱氢生成乙炔的活化能垒。这些反应的活化能垒与底物的表面d带中心相关。
