采用量子化学密度泛函理论(DFT)研究了负载型催化剂Ni/ZrO2(111)的CO甲烷化活性和选择性.结果表明:CO→CHO→CH2O→CH2→CH3→CH4是Ni4-ZrO2(111)面上CH4形成的有利路径,CO→HCO→CH→CH2→CH3→CH4是Ni13-ZrO2(111)面上CH4形成的有利路径,这两种催化剂具有相似的CH4生成活性,Ni13-ZrO2(111)比Ni4-ZrO2(111)具有明显高的CH4选择性.Ni4·ZrO2(111)能较好地抑制积碳.
The density functional theory(DFT)method has been used to reveal the underlying mechanism of Ni cluster supported on ZrO2(111)as well as the activity and selectivity of CO methanation.CO→HCO→CH2O→CH2→CH3→CH4is mainly responsible for CH4 formation on Ni4-ZrO2(111),while CH4 is mainly formed via the path of CO→ HCO→CH→CH2 →CH3 →CH4 on Ni13-ZrO2(111).Ni4-ZrO2(111)and Ni13-ZrO2(111)exhibit similar activity for CH4 formation with the free energy barrier of 2.38 eV and 2.26 eV,respectivley.In addition,Ni13-ZrO2(111)displays a remarkable high selectivity to CH4 comparing with Ni4-ZrO2(111).Moreover,Ni4-ZrO2(111)exhibits high resistance to carbons,while Ni13-ZrO2(111)surface is much sensitively to form deposition carbon.