Andrei-Nicolae Parvulescu

Chlorinated impurities in industrial diisocyanates production significantly impact product quality and stability, yet their speciation remains an analytical challenge. This study demonstrates that ³⁵ Cl nuclear quadrupole resonance (NQR) spectroscopy, supported by DFT calculations, provides a powerful framework for identifying byproducts in these processes. We show that NQR frequencies effectively categorize chlorinated species—such as amino hydrochlorides and carbamoyl chlorides—into distinct chemical families, with signal shifts driven by local electronic structure, intermolecular interactions, and conformation. Applied to commercial 4,4'‐MDI, this analytic ruler successfully identifies the presence of specific byproducts and establishes ³⁵ Cl NQR as a uniquely sensitive tool for monitoring byproducts and thereby the quality of industrial diisocyanate streams.

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 TiO ₂ 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.

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 TiO ₂ 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.