Application Of Solid-State NMR Techniques To Heterogeneous Catalysts And Catalytic Reaction

In this dissertation, several important solid acid catalysts and non-oxidative methane aromatization reaction were studied by using solid-state NMR techniques, including in situ NMR and probe molecule techniques, and some fruitful results were obtained.Non-oxidative methane aromatization reaction is of scientific importance toward understanding the nature of scission of C-H bond of CH4, which is the most stable molecule in alkenes family. Active metal phase and products and intermediate adsorbed on the surface of the W and Mo /HZSM-5 catalysts were observed in the process of the reaction by in situ ¹³C MAS NMR techniques. In the process of methane aromatization reaction on both W/HZSM-5 and Mo/HZSM-5, a induction period occurs and during this period, Mo and W oxide in/on the surface are reduced by methane to MoCx and the low valent W oxide, respectively, which are responsible for initial activation of methane. For the first time the active metal phase MoCx distributed on the external surface and in the channels of the zeolite HZSM-5 were observed in the process of the reaction. In addition, the structure and the acid sites of W/HZSM-5 catalysts were characterized, and the relationship between the structure of the catalyst and its catalystical performance at the high temperature was revealed.Solid acid catalysts SO₃/Al₂O₃ and BF₃/Al₂O₃ were characterized by multiple resonance,...