Mastikhin V M, Terskikh V V, Lapina O B, Filimonova S V, Seidl M, Knözinger H
Boreskov Institute of Catalysis, Novosibirsk, Russia.
Solid State Nucl Magn Reson. 1995 Aug;4(6):369-79. doi: 10.1016/0926-2040(95)00020-q.
1H magic-angle spinning nuclear magnetic resonance (MAS NMR) spectra of TiO chi/SiO2 catalysts suggest the interaction of surface TiO chi species with Si-OH groups of the silica. Simultaneously, Ti-OH groups from surface titania species appear. The distribution of TiO chi species over SiO2 is non-uniform, since a considerable part of surface OH groups remains unreacted with supported titania. Supported vanadia species interact both with Si-OH and Ti-OH groups. 51V NMR spectra suggest the interaction of vanadia with supported titania species and show the non-uniform distribution of titania over the SiO2 surface. Deposition of titania as well as vanadia produces strong electron-accepting (Lewis) sites which interact with the terminal N atom of adsorbed N2O molecules, resulting in a downfield shift of the resonance in 15N NMR spectra. The acid strength of electron-accepting sites is similar in both cases. Only about 10% of the total amount of supported titania and vanadia create Lewis sites.
TiOχ/SiO₂催化剂的¹H魔角旋转核磁共振（MAS NMR）光谱表明，表面TiOχ物种与二氧化硅的Si-OH基团发生了相互作用。同时，表面二氧化钛物种的Ti-OH基团出现。TiOχ物种在SiO₂上的分布不均匀，因为相当一部分表面OH基团未与负载的二氧化钛发生反应。负载的钒物种与Si-OH和Ti-OH基团都发生相互作用。⁵¹V NMR光谱表明钒与负载的二氧化钛物种发生了相互作用，并显示了二氧化钛在SiO₂表面的不均匀分布。二氧化钛以及钒的沉积产生了强电子接受（路易斯）位点，这些位点与吸附的N₂O分子的末端N原子相互作用，导致¹⁵N NMR光谱中的共振发生向低场位移。两种情况下电子接受位点的酸强度相似。负载的二氧化钛和钒总量中只有约10%产生路易斯位点。
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