CO adsorption, CO dissociation, and C－C coupling on Cu monolayer-covered Fe(100)
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摘要: 采用密度泛函方法研究了Fe(100)表面Cu单层膜上CO的吸附，直接解离，氢助解离以及C－C偶合反应。相比洁净的Fe(100) 表面，在Fe(100)的单层Cu膜上，CO的吸附和活化都减弱了。特别是，相比Fe(100) 上CO的解离能垒1.08eV，铜单层膜上CO解离能垒高达2.4eV。在H原子共吸附的情况下，Fe(100)上CO解离在动力学上更容易了一些，而在Cu单层膜上，CO的解离通过形成甲酰基(CHO)大大的加快了，能垒降低到了0.92eV，接近Fe(100) 上的0.81eV。同时，我们发现Cu单层膜上C－H键C－C键的形成比Fe(100)上能垒低，且放热量更大。Abstract: CO adsorption, CO dissociation and C－H and C－C bond-making reactions on Cu-covered Fe(100) have been computed within the framework of periodic density functional theory. Compared to the clean Fe(100) surface with strong CO activation, Cu monolayer-covered Fe(100) surface has weaker CO adsorption energy, lower CO activation degree; and ultra higher CO dissociation barrier (2.4eV). Under H co-adsorption, CO dissociation is favored kinetically on Fe(100). On the Cu-monolayer covered Fe(100), co-adsorbed H largely facilitates CO dissociation via the formation of CHO. The energy barrier decreases to as low as 0.92eV. It is also found that C－H and C－C bond-making reactions of Cu monolayer-covered Fe(100) surface have lower activation barriers and are more exothermic than on the clean Fe(100) surface.
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Key words:
- Fischer-Tropsch synthesis (FTS) /
- Fe(100) /
- Cu monolayer /
- H-assisted CO dissociation /
- C－C coupling /
- DFT
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