Active Oxygen Vacancy Site for Methanol Synthesis from CO2 Hydrogenation on In2O3(110): A DFT Study

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• 作者：Jingyun Ye ; Changjun Liu ; Donghai Mei ; Qingfeng Ge
• 刊名：ACS Catalysis
• 出版年：2013
• 出版时间：June 7, 2013
• 年：2013
• 卷：3
• 期：6
• 页码：1296-1306
• 全文大小：802K
• 年卷期：v.3,no.6(June 7, 2013)
• ISSN：2155-5435

文摘

Methanol synthesis from CO₂ hydrogenation on the defective In₂O₃(110) surface with surface oxygen vacancies has been investigated using periodic density functional theory calculations. The relative stabilities of six possible surface oxygen vacancies numbered from O_v1 to O_v6 on the perfect In₂O₃(110) surface were examined. The calculated oxygen vacancy formation energies show that the D1 surface with the O_v1 defective site is the most thermodynamically favorable while the D4 surface with the O_v4 defective site is the least stable. Two different methanol synthesis routes from CO₂ hydrogenation over both D1 and D4 surfaces were studied, and the D4 surface was found to be more favorable for CO₂ activation and hydrogenation. On the D4 surface, one of the O atoms of the CO₂ molecule fills in the O_v4 site upon adsorption. Hydrogenation of CO₂ to HCOO on the D4 surface is both thermodynamically and kinetically favorable. Further hydrogenation of HCOO involves both forming the C鈥揌 bond and breaking the C鈥揙 bond, resulting in H₂CO and hydroxyl. The HCOO hydrogenation is slightly endothermic with an activation barrier of 0.57 eV. A high barrier of 1.14 eV for the hydrogenation of H₂CO to H₃CO indicates that this step is the rate-limiting step in the methanol synthesis on the defective In₂O₃(110) surface.

Keywords:

catalytic CO₂ hydrogenation; methanol synthesis; defective In₂O₃ surface; oxygen vacancy; density functional theory