Performance of TS-1-Coated Structured Packing Materials for Styrene Oxidation Reaction

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.

Exploiting the Potential of Biosilica from Rice Husk as Porous Support for Catalytically Active Iron Oxide Nanoparticles

Biomass-derived materials are put forward as eco-friendly alternatives to design heterogeneous catalysts. To contribute in this field, we explored the potential of mesoporous biogenic silica (RH-Silica) obtained from lignocellulosic waste, in particular from rice husk, as an inorganic support to prepare heterogenized iron oxide-based catalysts. Mechanochemistry, considered as a green and sustainable technique, was employed to synthetize iron oxide nanoparticles in pure hematite phase onto the biosilica (α-Fe₂O₃/RH-Silica), making this material a good candidate to perform catalyzed organic reactions. The obtained material was characterized by different techniques, and its catalytic activity was tested in the selective oxidation of styrene under microwave irradiation. α-Fe₂O₃/RH-Silica displayed a good catalytic performance, achieving a conversion of 45% under optimized conditions, and more importantly, with a total selectivity to benzaldehyde. Furthermore, a good reusability was achieved without decreasing its activity after multiple catalytic cycles. This work represents a good example of using sustainable approaches and green materials as alternatives to conventional methods in the production of high-added value products.

The synthesis of pure and uniform nanosized TS-1 crystals with a high titanium content and a high space–time yield

Concentrated basic MFI building unit species played a key role in the crystal synthesis of uniform nanosized anatase-free titanium-rich TS-1.

Synthesis of Titanium Silicalite-1 with High Catalytic Performance for 1-Butene Epoxidation by Eliminating the Extraframework Ti

Titanium silicalite-1 (TS-1) with little extraframework Ti was hydrothermally synthesized in a tetrapropylammonium hydroxide system using starch as the additive. The influences of the amount of starch added on the coordination states of titanium ions and the functional mechanism of starch were studied by various characterization means. The addition of starch slowed the crystallization rate of TS-1 so that the insertion rate of titanium to the framework matched well with that of silicon. Therefore, the generation of extraframework Ti, including the anatase TiO2 and octahedrally coordinated titanium, was eliminated. The catalytic performances of the TS-1 samples were evaluated in the epoxidation of 1-butene to produce butene oxide. The catalytic activity of TS-1 was improved significantly due to the increasing amount of framework Ti.

One-Pot Synthesis of Zeolitic Strong Solid Bases: A Family of Alkaline-Earth Metal-Containing Silicalite-1

Fabricating stable strong basic sites in well-preserved crystallized zeolitic frameworks still remains a difficult issue. Here, we reported a family of MFI-type metallosilicate zeolites, AeS-1 (Ae: alkaline-earth metal ions of Mg, Ca, Sr or Ba; S-1: silicalite-1) through a direct one-pot hydrothermal method involving the acidic co-hydrolysis/condensation of the silica precursor with the Ae salts. Step-by-step full characterizations were designed and conducted for in-depth discussion of the Ae status in AeS-1. Strong basicity (H_≈22.5-26.5) was detected in AeS-1. The basicity was further confirmed by CO2 sorption measurements, (13) C NMR spectra of chloroform-adsorbed samples, and (1) H→(13) C and (1) H→(29) Si cross-polarization magic-angle spinning NMR spectra of ethyl cyanoacetate-adsorbed samples. The results of Knoevenagel condensations demonstrated the excellent solid base catalysis of AeS-1, which showed high activity, reusability, and shape-selectivity, all of which are explained by Ae-derived zeolitic intracrystalline strong basic sites.