Post-Synthetic Zinc Modifications to Correct Speciation in Ti-MWW Zeolites for Catalytic Oxidation

Ti-MWW is an important member of Ti-containing zeolites, industrially employed as heterogeneous catalyst for selective oxidations. However, the development of more active variants is often hampered by the lack of characterization methods able to track transformations and interplay between a multitude of species; this is further exacerbated by the use of post-synthetic modifications. Combining microscopy and various spectroscopic techniques show that the promotional role of Zn is closely linked to its healing of hydrophilic silanol nests, while simultaneously generating small TiO_x clusters. Notably, these changes are accompanied by Ti weight loading dependent modifications of the extra-framework TiO₂ and formation of Zn species. Overall, our study not only highlights the interplay between a plethora of species, but enables a more rational development of post-modification of Ti-containing zeolites.