Solid-state NMR Studies Of Oxide Catalytic Materials

Oxides are widely used in industrial catalysis.In order to rational design better catalysts,a variety of characterization methods have been applied to investigate the structure and properties of oxide catalysts.Solid-state NMR?ssNMR?is a powerful tool with which to investigate the short range order and local structure of solids.¹⁷O ssNMR spectroscopy can provide the chemical environment information of oxygen atoms,which is the key to the properties of the oxide materials.In this thesis,we use ¹⁷O ssNMR spectroscopy,in combination with various characterization methods as well as theoretical calculations,to develop new ss NMR methods for oxide catalysts and illustrate.By comparing the NMR data of model compounds??-Zn?OH?2?and ¹⁷O isotope labelled ZnO,we distinguished two types hydrogen species with 1H NMR and assigned the two signals to interstitial hydrogen?Hi?bound to an oxygen ion and substitutional hydrogen?HO?at an oxygen vacancy.We used the widely studied and technologically important ceria nanoparticles as an example to illustrate the ¹⁷O NMR approach to study the surface and subsurface structure of nanosized oxides.We show that the ¹⁷O ssNMR resonances arising from the 1st,2nd and 3rd surface layer oxygen ions,hydroxyl sites and oxygen species near vacancies can be distinguished from the oxygen ions in the "bulk".We also investigated the structure and properties of MFI type zeolites and basic metallosilicate zeolites MgS-1 with ssNMR spectroscopy,and gain insight into the structure dependent catalytic performances and the formation mechanism of zeolites.