In order to investigate the rules on preparation of titanium silicalite （TS-1） the ^1H →^13C CP/ MAS NMR spectrometers were applied to track the function of template TPAOH in the process of crystallization of titan...In order to investigate the rules on preparation of titanium silicalite （TS-1） the ^1H →^13C CP/ MAS NMR spectrometers were applied to track the function of template TPAOH in the process of crystallization of titanium silicalite. The research results revealed that at the initial stage of crystallization the TPA＋ ions acting as the template could predominantly absorb the polymers of negatively charged silicatitania sol and the interactions between silica sol and titania sol could gradually lead to the formation of tiny crystal nuclei that could slowly grow up to form molecular sieves. Upon investigating the course of crystallization of titanium silicalite the ^1H →^13C CP/MAS NMR spectrometers were applied to effectively enhance the resolution of 29Si signals in the titanium silicalite. Study results have shown that during the formation of tiny crystal nuclei upon interaction between titania sol and silica sol the influence of titania sol on the silica sol was insignificant. However, when tiny crystal nuclei broke out into molecular sieves the titania sol could enter the zeolite framework that could apparently impose an enhanced effect on the silica sol.展开更多
29Si-NMR and 1H-NMR were used to follow up the basic hydrolysis of tetraethyl orthosilicate （TOES） and the results showed that species of monomer, dimer, trimer, cyclic and polymer silicates were formed. The monomer...29Si-NMR and 1H-NMR were used to follow up the basic hydrolysis of tetraethyl orthosilicate （TOES） and the results showed that species of monomer, dimer, trimer, cyclic and polymer silicates were formed. The monomer and dimer were favorable for the high activity of zeolite. XRD, 13C CP/MAS and 29Si NMR were used to trace the crystallization process of hollow titanium silicalite zeolites （HTS）. The results showed that the induction period of HTS was 80 min, and subsequently it took next 10 min to form HTS and the remaining time of the crystallization period might function for cleaning up the pores and/or washing off the impurities from the HTS zeolite. The catalytic oxidation performance of HTS zeolite is different from that of the acid activity of zeolite in which the conventional definition of crystallinity does not reflect the catalytic oxidation activity proportionally. The synthesized HTS samples were character- ized by XRD, FT-IR, UV-Vis and Raman spectra. It was confirmed that Ti was incorporated into the zeolite framework. The synthesized HTS samples revealed good repeatability and high activity for oxidation of phenol into diphenol.展开更多
文摘In order to investigate the rules on preparation of titanium silicalite （TS-1） the ^1H →^13C CP/ MAS NMR spectrometers were applied to track the function of template TPAOH in the process of crystallization of titanium silicalite. The research results revealed that at the initial stage of crystallization the TPA＋ ions acting as the template could predominantly absorb the polymers of negatively charged silicatitania sol and the interactions between silica sol and titania sol could gradually lead to the formation of tiny crystal nuclei that could slowly grow up to form molecular sieves. Upon investigating the course of crystallization of titanium silicalite the ^1H →^13C CP/MAS NMR spectrometers were applied to effectively enhance the resolution of 29Si signals in the titanium silicalite. Study results have shown that during the formation of tiny crystal nuclei upon interaction between titania sol and silica sol the influence of titania sol on the silica sol was insignificant. However, when tiny crystal nuclei broke out into molecular sieves the titania sol could enter the zeolite framework that could apparently impose an enhanced effect on the silica sol.
基金Project supported by the National Science Foundation of China(2006CB202508)
文摘29Si-NMR and 1H-NMR were used to follow up the basic hydrolysis of tetraethyl orthosilicate （TOES） and the results showed that species of monomer, dimer, trimer, cyclic and polymer silicates were formed. The monomer and dimer were favorable for the high activity of zeolite. XRD, 13C CP/MAS and 29Si NMR were used to trace the crystallization process of hollow titanium silicalite zeolites （HTS）. The results showed that the induction period of HTS was 80 min, and subsequently it took next 10 min to form HTS and the remaining time of the crystallization period might function for cleaning up the pores and/or washing off the impurities from the HTS zeolite. The catalytic oxidation performance of HTS zeolite is different from that of the acid activity of zeolite in which the conventional definition of crystallinity does not reflect the catalytic oxidation activity proportionally. The synthesized HTS samples were character- ized by XRD, FT-IR, UV-Vis and Raman spectra. It was confirmed that Ti was incorporated into the zeolite framework. The synthesized HTS samples revealed good repeatability and high activity for oxidation of phenol into diphenol.
