Mechanism of methanol synthesis on Cu(100) and Zn/Cu(100) surfaces: Comparative dipped adcluster model study
✍ Scribed by Hiroshi Nakatsuji; Zhen-Ming Hu
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 394 KB
- Volume
- 77
- Category
- Article
- ISSN
- 0020-7608
No coin nor oath required. For personal study only.
✦ Synopsis
The mechanism of methanol synthesis from CO 2 and H 2 on Cu(100) and Zn/Cu(100) surfaces was studied using the dipped adcluster model (DAM) combined with ab initio Hartree-Fock (HF) and second-order Møller-Plesset (MP2) calculations. On clean Cu(100) surface, our calculations show that five successive hydrogenations are involved in the hydrogenation of adsorbed CO 2 to methanol, and the intermediates are formate, dioxomethylene, formaldehyde, and methoxy. The rate-limiting step is the hydrogenation of formate to formaldehyde, and the Cu-Cu site is responsible for the reaction on Cu(100). The roles of Zn on Zn/Cu(100) catalyst are to modify the rate-limiting step of the reaction: to lower the activation energies of this step and to stabilize the dioxomethylene intermediate at the Cu-Zn site. The present comparative results indicate that the Cu-Zn site is the active site, which cooperates with the Cu-Cu site to catalyze methanol synthesis on a Cu-based catalyst. Electron transfer from surface to adsorbates is the most important factor in affecting the reactivity of these surface catalysts.