Activation Of C-H Bond And N-H Bond Catalyzed By Transition Metal Modified Silicon-based Molecular Sieves

The activation of C-H bond and N-H bond is a very important chemicalreactionprocessinorganicsynthesis.Thedirect functionalization of the C-H bond into an oxygenate is considered to be the best method of atomic economy.At present,the world crude oil reserves contain up to 50%of alkanes,so they can be directly converted into chemical organic products such as alcohols,ketones and organic amines through catalytic processes to achieve their high industrial value.Because organic amines are highly sensitive to oxidation reactions,they are usually not selectively converted to products such as hydrazine,imine,nitrile,amide,etc.,the development of highly active and selective catalysts for one-step directed conversion to terpenoids and the preparation of pharmaceutical and fibrous materials is of great significance.Based on this,the activation of C-H bond and N-H bond were studied in this paper:（1）A titanium-silicon molecular sieve（Mo/HTS）catalyst modified with a transition metal were prepared to catalyze the high-efficiency oxidation of n-hexane to hexanol and ketone by H₂O₂ under acetonitrile as a solvent.Through optimization of experimental conditions,the conversion rate of n-hexane was as high as 94.6%when the hydrogen peroxide utilization rate was the best（87.96%）.The structure and properties of Mo/HTS catalysts were also characterized by FT-IR,UV-vis DRS,Raman,XRD,XPS,TEM and N₂ adsorption and desorption.It was found that the Mo dispersed on the surface of the HTS and the Ti species in the carrier are catalytic activity sites of n-hexane.（2）Nb-modified mesoporous SBA-15 catalyst were prepared for the selective oxidation of various amines using O₂ without solvent.In particular,the selective oxidation of cyclohexylamine to cyclohexanone oxime was further studied,and the structural properties and mechanism of amine oxidation were proposed.The 3%Nb/SBA-15 catalyst exhibited excellent catalytic performance(TOF=469.8 h^-1)and achieved 75%cyclohexylamine conversion and 84%cyclohexanone oxime Selectivity under mild conditions（0.8 MPa O₂,373 K）.As a result,studies on catalyst characterization,detection,and reaction conditions indicated that surface-dispersed Nb species and hydroxyl groups were confirmed as catalytically active sites of cyclohexylamine.