MH+(M = Ni, Cu, Zn)和CH4, NH3, H2O等分子在氣相中反應以產生氫氣之理論計算與研究
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2011
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在本文中，我們將藉由密度泛函理論當中的B3LYP方法來探討週期表中第一排過渡金屬的氫化物（[MH]+，M＝Ni、Cu、Zn)，與含氫的小分子(CH4、NH3、H2O)之氣相反應，研究產生氫氣的可能反應機制，以及反應位能與能障的討論。
本實驗共分成三個部分進行研究：（1）MH+(M = Ni, Cu, Zn) + CH4 反應機構的理論探討，（2）MH+(M = Ni, Cu, Zn) +H2O 反應機構的理論探討，（3）MH+(M = Ni, Cu, Zn) + NH3 反應機構的理論探討。結果發現，在過渡金屬離子上加了一個hydrogen ligand的反應物[MH]+（M＝Ni、Cu、Zn），皆會先靠近CH4、NH3、H2O等分子形成複合物，經由相似過渡態TS結構，促使CH4、NH3及H2O等分子中的C-H、N-H、O-H 鍵斷裂，並和金屬上的H結合產生氫氣進而脫除。而我們也觀察到，這三種金屬氫化物(NiH+, CuH+, ZnH+) 以及三種小分子(CH4、NH3、H2O)的反應，在位能曲面圖上出現不同的反應趨勢，針對上述的問題我們也會進行更深入的討論。
We apply density functional theory (B3LYP method) to investigate the possible reaction mechanism of the dehydrogenation process in the reaction of transition metal hydrides ([MH]+, M = Ni, Cu, Zn) with small molecules containing hydrogen atoms (CH4, NH3, H2O) in the gas phase. This paper is divided into three parts to study reaction mechanisms of the reaction (1) MH+ (M=Ni,Cu,Zn) + CH4, (2) MH+ (M=Ni,Cu,Zn) + H2O, and (3) MH+ (M=Ni,Cu,Zn) + NH3. It has been found that the transition metals with an addition hydrogen ligand ([MH]+ ,M＝Ni,Cu,Zn) will firstly attack the CH4, NH3, and H2O molecules respectively to form complexes. Then, through similar transition states (TS), they can induce C-H, N-H, and O-H bond breaking respectively in the CH4, NH3, and H2O molecules, and finally produce hydrogen molecules. We also observe that the potential energy surfaces in reactions of the three metal hydride (NiH+, CuH+, ZnH+) with the three molecules (CH4, NH3, H2O) appear different reaction trend. We will also discuss the related mechanisms in the above reaction systems.
We apply density functional theory (B3LYP method) to investigate the possible reaction mechanism of the dehydrogenation process in the reaction of transition metal hydrides ([MH]+, M = Ni, Cu, Zn) with small molecules containing hydrogen atoms (CH4, NH3, H2O) in the gas phase. This paper is divided into three parts to study reaction mechanisms of the reaction (1) MH+ (M=Ni,Cu,Zn) + CH4, (2) MH+ (M=Ni,Cu,Zn) + H2O, and (3) MH+ (M=Ni,Cu,Zn) + NH3. It has been found that the transition metals with an addition hydrogen ligand ([MH]+ ,M＝Ni,Cu,Zn) will firstly attack the CH4, NH3, and H2O molecules respectively to form complexes. Then, through similar transition states (TS), they can induce C-H, N-H, and O-H bond breaking respectively in the CH4, NH3, and H2O molecules, and finally produce hydrogen molecules. We also observe that the potential energy surfaces in reactions of the three metal hydride (NiH+, CuH+, ZnH+) with the three molecules (CH4, NH3, H2O) appear different reaction trend. We will also discuss the related mechanisms in the above reaction systems.
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DFT計算, MH+, DFT calculation, MH+