Preparation Of SnMCM-41 By Surface Organometallic Chemistry And Study Of Its Performance For Hydroxylation Reaction Of Phenol

Firstly, a mesoporous MCM-41 molecular sieve was synthesized by hydrothermal crystallization, then MCM-41 richened tin on the surface named SnMCM-41 (O) was prepared via surface graft reaction of SnBu4 on surface silanol groups followed by oxidation treatment in oxygen. The structure and performance of SnMCM-41 (O) were characterized by means of XRF, FT-IR, XRD, HTEM, N2 absorption, Raman, UV-Vis, TG and catalytic hydroxylation of phenol. Compared to SnMCM-41 with comparable mole ratio of Si/Sn (Si/Sn≈100) prepared by the mechanical commixture of nanometer SnO2 with MCM-41,the impregnation of MCM-41 with SnCl4 solution as well as the hydrothermal synthesis route,there are differences in the uniformity of pore distributions and sizes, big discrepancy in specific surface areas, and varied coordination forms of surface tin species. The SnMCM-41 (O) with surface stannide existed in tetrahedral coordination exhibits better uniformity of pore distribution, larger specific surface area, more hydrothermal stability and better catalytic properties in the hydroxylation of phenol with H2O2 than that of other containing tin MCM-41 samples.The optimal conditions of the catalytic hydroxylation of phenol on SnMCM-41 (O) were investigated in the thesis, under such conditions, the catalytic performance is correlated with the tin content of the samples, the conversion of phenol, selectivity of produced diphenol reach maxima at Si/Sn=217. As for the SnMCM-41 (O) samples with different tin content, there is a linear relationships between 100Sn/(Sn+Si) and Squrt (r) or area. The reactive activity was investigated primarily, showing that it was related to the dispersion and coordination forms of surface tin species. It is deduced that oxygen-tin on Sn-217 surface maybe the active sites in this reaction.This research provides a possibility in design and synthesis of micro and meso- materials with desired pore sizes and areas, it also provides a new method of preparation new functional films of metal oxide covered the inner surface of zeolites.