Uncovering the catalytic mechanism of titanium zeolites
What is it about?
Aqueous hydrogen peroxide oxidizes hydrocarbons in very mild conditions when Ti-zeolites are used as catalysts. This is at the basis of important, widespread and environmentally friendly large-scale industrial processes, such as the epoxidation of olefins with Ti-silicalite zeolite. In spite of the relevance of this process, the role and the behavior of the titanium active centers in the oxidative cycle were still unknown in microscopic detail. Therefore, we modeled a titanium zeolite, simulated the epoxidation reaction with an accurate methodology and validated results against a broad set of experimental data obtained with different techniques. Our work uncovered the mechanism of the catalytic action and provided a consistent picture of the complex behavior of such a relevant class of materials.
Why is it important?
We explained the full catalytic oxidation cycle of an olefin inside a Ti-zeolite in the presence of aqueous hydrogen peroxide. At the end of the cycle, ethylene epoxide and water (a sustainable by-product, indeed!) are obtained, and the catalyst is recovered. One of the novelties of our study is that we predicted the active, oxidizing intermediate to be a peroxo species actually inserted in the zeolite framework. This means that the true catalyst is the whole zeolite, not only its titanium sites, because the framework truly plays a key active role in the catalytic process.
The following have contributed to this page: Gloria Tabacchi