Abstract

In the past two decades, we studied the synthesis, modification, and application of titanium silicalite-1 (TS-1) systematically with the goal of exploring its role as a catalyst for industrial selective oxidation reactions. Three factors were primarily considered for catalytic performance: the coordination states of titanium ions, locations of titanium ions, and diffusion properties. The coordination state of Ti, which was the most important of all the three factors, was tuned by controlling the synthesis conditions and posttreating with organic bases. Spectroscopy was used to help establishing the relationship between catalytic activity and coordination state. More active titanium species were located on the external surface by posttreatment, so the catalytic performance for larger molecules was improved significantly. The diffusion properties can be enhanced by posttreatment with organic bases. Furthermore, meso−/microporous titanium silicalite was synthesized by one-pot synthesis with cetyltrimethyl ammonium bromide (CTAB) as a mesoporous porogen. The TS-1 plate with a short b-axis length was also provided.

Highlights

  • Zeolites are a microporous material. Due to their high hydrothermal stability, simple synthesis process, strong adsorption properties, adjustable acidity and alkalinity, and pore shape selectivity, they are widely used in petroleum refining, the chemical industry, and separations [2]

  • We studied the treatment of small-crystal titanium silicalite-1 (TS-1) with different organic bases, including ethylamine (EA), diethylamine (DEA), tetramethylammonium hydroxide (TMAOH), and tetrapropylammonium hydroxide (TPAOH) solutions [33]

  • We found that pentahedrally coordinated Ti existed in the Tetrapropylammonium hydroxide (TPAOH)-treated TS-1, but it was absent in the other samples

Read more

Summary

Introduction

Natural zeolites are a kind of hydrated crystalline silica-aluminate with specific pore structure. It has attracted much attention due to its excellent catalytic activity for selective oxidation with H2O2, such as alkene epoxidation [4–9], aromatics hydroxylation [10–12], ketone ammoximation [13–15], alkane oxidation [16, 17], and so on [18, 19]. It is considered a milestone in the field of zeolitic catalysis. We describe our recent progress on controlling Ti coordination states, design of porosity, and applications of TS-1 We hope that this summary will help in understanding the developing process and our contribution to research on TS-1

Tuning of synthesis conditions
Usage of additives
Posttreatment with organic bases
Reducing of particle size in TPABr system
Design of hollow TS-1 materials
Preparation of plate-like TS-1
One-pot synthesis of meso−/microporous titanium silicalite
Industrial application of HPPO route
Findings
Conclusions
Full Text
Paper version not known

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.