On the synthesis and performance of hierarchical nanoporous TS-1 catalysts

Abstract

Hierarchical TS-1 zeolite was successfully prepared using chitosan as a sacrificial template. The X-ray diffraction showed that the presence of chitosan with the synthesis precursor had no deleterious effect on the crystallinity and phase purity of this zeolite. X-ray absorption spectroscopy at the Ti K-edge, FTIR and Raman spectroscopies revealed the titanium ions in the zeolite structure have predominantly tetrahedral coordination. However, it appears that the higher chitosan content in the synthesis gel imparted some hydrophilic character to the TS-1 system. Furthermore, the technique adopted for the preparation of the synthesis gel e e.g partially dried or fully dried e appears to affect the amount of framework titanium in the zeolite structure. The calcined form of the chitosan templated TS-1 zeolites exhibited higher cyclohexene conversion compared to the TS-1 material synthesised without this template , but these catalysts showed lower selectivity for cyclohexene epoxide.

Host–Guest and Photophysical Behavior of Ti8L12 Cube with Encapsulated [Ti(H2O)6] Species

“…X‐ray photoelectron spectroscopy (XPS) studies indicate that PTC‐97 presents multiple Ti III/IV states (Figure S12, Supporting Information). The titanium K‐edge X‐ray absorption near edge structure (XANES) analysis also indicates lower valance states than TiO 2 (Figure S13) . Such partial reduction of the Ti IV ions should be due to the applied solvothermal reaction in DMF.…”

“…The titaniumKedge X-ray absorption near edge structure (XANES) analysis also indicates lower valance states than TiO 2 ( Figure S13). [39] Such partial reduction of the Ti IV ions should be due to the applied solvothermalr eactioni nD MF.T hus, the chargeo ft he Ti 8 L 12 cube in PTC-97 can be proposed as [Ti III 2 Ti IV 6 L 12 ] 6À ,w hich is furtherb alanced by four protons and two [(CH 3 ) 2 NH 2 ] + ions.…”

The effect of T-atom ratio and TPAOH concentration on the pore structure and titanium position in MFI-Type titanosilicate during dissolution-recrystallization process

“…In order to enhance the accessibility of active centres by reacting molecules, hierarchical TS-1 with well-developed secondary porosity has been synthesized by various techniques including desilication [5], silanization [6], dissolutionrecrystallization [2], dry gel conversion [7], soft templating [8] and hard templating [9,10]. Among the variety of strategies in the preparation of hierarchical zeolites, dissolution-recrystallization method is well used in industrial applications [2], as treatment with TPAOH can create voids in TS-1 crystals and reinsert some extra framework titanium into framework position [2].…”

Direct Hydroxylation of Benzene to Phenol over TS-1 Catalysts

“…The FT-IR spectra of TS-1, used TS-1, and commercial TS-1 are shown in Figure 3. Based on the literature [21,[41][42][43][44][45], the band at 550 cm −1 was assigned to the asymmetric framework vibration of double five rings and the characteristics of the MFI structure, and the band at 965 cm −1 was evidence of the isomorphous substitution of Ti in the TS-1 catalyst framework. As shown in Figure 3, the bands at 553 cm −1 and 965 cm −1 demonstrate the successful incorporation of Ti into the MFI framework of both the TS-1 catalyst and the commercial TS-1.…”