Insights into the nature of Zr-species in MFI-type Zr-metallosilicates by using bulk and surface techniques
Bakytzhan Yeskendir, Izabela Kurzydym, Pardis Simon, Nicolas Nuns, Maya Marinova, Hervé Vezin, Christian Courtois, Yannick Lorgouilloux, Izabela Czekaj, Jean‐François Paul, Sébastien Royer, Jean‐Philippe Dacquin, Jérémy Dhainaut
Abstract
The purpose of this study is to prepare Zr-metallosilicates with MFI-type framework via direct hydrothermal approach, by varying Si and Zr precursors. First, a set of routine characterization techniques was applied to confirm the presence of the targeted structure as well as their intrinsic properties. Results suggest the formation of MFI-type materials with large specific surface areas (up to 421 m2 g−1). Then, a combination of advanced spectroscopic techniques (XPS, ToF-SIMS, EPR), high-resolution microscopy, and periodic Density Functional Theory (DFT) calculations were applied to study their bulk and surface properties as well as the nature and localization of Zr-species. It appears that the insertion of zirconium atoms within a MFI framework is energetically unfavorable, leading to the formation of an amorphous silica-zirconia shell coating the zeolite crystals.