The synthesis, characterization and catalytic activity of the hierarchical TS-1 with the intracrystalline voids and grooves

Review and perspectives on TS-1 catalyzed propylene epoxidation

Titanium silicate zeolite (TS-1) is widely used in the research on selective oxidations of organic substrates by H2O2. Compared with the chlorohydrin process and the hydroperoxidation process, the TS-1 catalyzed hydroperoxide epoxidation of propylene oxide (HPPO) has advantages in terms of by-products and environmental friendliness. This article reviews the latest progress in propylene epoxidation catalyzed by TS-1, including the HPPO process and gas phase epoxidation. The preparation and modification of TS-1 for green and sustainable production are summarized, including the use of low-cost feedstocks, the development of synthetic routes, strategies to enhance mass transfer in TS-1 crystal and the enhancement of catalytic performance after modification. In particular, this article summarizes the catalytic mechanisms and advanced characterization techniques for propylene epoxidation in recent years. Finally, the present situation, development prospect and challenge of propylene epoxidation catalyzed by TS-1 were prospected.

Enhanced anisole hydroxylation over a hierarchical micro/mesoporous TS-1 catalyst

Micro/mesoporous DTS-1 showed enhanced catalytic activity for anisole hydroxylation showing 54% conversion with 55% selectivity towards p-methoxyphenol.

Synthesis and Characterisation of Hierarchically Structured Titanium Silicalite-1 Zeolites with Large Intracrystalline Macropores

The successful synthesis of hierarchically structured titanium silicalite-1 (TS-1) with large intracrystalline macropores by steam-assisted crystallisation of mesoporous silica particles is reported. The macropore topology was imaged in 3D by using electron tomography and synchrotron radiation-based ptychographic X-ray computed tomography, revealing interconnected macropores within the crystals accounting for about 30 % of the particle volume. The study of the macropore formation mechanism revealed that the mesoporous silica particles act as a sacrificial macropore template during the synthesis. Silicon-to-titanium ratio of the macroporous TS-1 samples was successfully tuned from 100 to 44. The hierarchically structured TS-1 exhibited high activity in the liquid phase epoxidation of 2-octene with hydrogen peroxide. The hierarchically structured TS-1 surpassed a conventional nano-sized TS-1 sample in terms of alkene conversion and showed comparable selectivity to the epoxide. The flexible synthesis route described here can be used to prepare hierarchical zeolites with improved mass transport properties for other selective oxidation reactions.

An efficient hydrophobic modification of TS-1 and its application in the epoxidation of propylene

Hydrophobic TS-1 was synthesized through resole resin precursor modification. Hydrophobic TS-1 can avoid by-product generation.

Direct Hydroxylation of Benzene to Phenol over TS-1 Catalysts

We synthesized a TS-1 catalyst to directly hydroxylate benzene to phenol with H2O2 as oxidant and water as solvent. The samples were characterized by FT-IR (Fourier Transform Infrared), DR UV-Vis (Diffused Reflectance Ultraviolet Visible), XRD (X-ray diffraction), SEM(scanning electron microscope), TEM (Transmission Electron Microscope), XPS (X-ray photoelectron spectroscopy), ICP (inductively coupled plasma spectrum), and N2 adsorption-desorption. A desirable phenol yield of 39% with 72% selectivity was obtained under optimized conditions: 0.15 g (0.34 to the mass of benzene) TS-1, 5.6 mmol C6H6, reaction time 45 min, 0.80 mL H2O2 (30%), 40.0 mL H2O, and reaction temperature 70 °C. The reuse of the TS-1 catalyst illustrated that the catalyst had a slight loss of activity resulting from slight Ti leaching from the first run and then kept stable. Almost all of the Ti species added in the preparation were successfully incorporated into the TS-1 framework, which were responsible for the good catalytic activity. Extraframework Ti species were not selective for hydroxylation.

Inter-connected and open pore hierarchical TS-1 with controlled framework titanium for catalytic cyclohexene epoxidation

A post-synthesis method was developed to reduce the extra-framework titanium in TS-1 zeolites in which TPAOH was used to convert amorphous Ti to zeolitic phases.

Improvement of the selectivity to aniline in benzene amination over Cu/TS-1 by potassium

Two different methods of introducing potassium into Cu/TS-1 were conducted and the catalysts obtained showed a rather different catalytic activity in the ammoxidation of benzene to aniline.

Effect of calcination temperature on the structure and catalytic performance of copper–ceria mixed oxide catalysts in phenol hydroxylation

We report on highly active CuO@CeO₂ catalysts prepared by the surfactant-template method and calcined at different temperatures.

Hierarchical TS-1 synthesized effectively by post-modification with TPAOH and ammonium hydroxide

Hierarchical TS-1 with intracrystalline voids could be synthesized by post-modification with tetrapropyl ammonium hydroxide (TPAOH), however the process was supposed to be restrained by the charge balance effect.