Unprecedented Catalysis of Cs+ Single Sites Confined in Y Zeolite Pores for Selective Csp3–H Bond Ammoxidation: Transformation of Inactive Cs+ Ions with a Noble Gas Electronic Structure to Active Cs+ Single Sites
| Autor: | Takehiko Sasaki, Yasuhiro Iwasawa, Shankha S. Acharyya, Yusuke Yoshida, Shilpi Ghosh, Takuma Kaneko |
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| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
catalysis mechanism
Materials science Hydrogen bond Inorganic chemistry catalytic Csp3−H activation General Chemistry Noble gas (data page) Electronic structure ammoxidation of toluene and its derivatives Catalysis Ion Transformation (genetics) selective nitrile synthesis confined Cs+ single site in Y zeolite pore Zeolite Ammoxidation |
| Zdroj: | ACS Catalysis. 11(11):6698-6708 |
| ISSN: | 2155-5435 |
| Popis: | We report the transformation of Cs+ ions with an inactive noble gas electronic structure to active Cs+ single sites chemically confined in Y zeolite pores (Cs+/Y), which provides an unprecedented catalysis for oxidative cyanation (ammoxidation) of Csp3–H bonds with O2 and NH3, although in general, alkali and alkaline earth metal ions without a moderate redox property cannot activate Csp3–H bonds. The Cs+/Y catalyst was proved to be highly efficient in the synthesis of aromatic nitriles with yields >90% in the selective ammoxidation of toluene and its derivatives as test reactions. The mechanisms for the genesis of active Cs+ single sites and the ammoxidation pathway of Csp3–H bonds were rationalized by density functional theory (DFT) simulations. The chemical confinement of large-sized Cs+ ions with the pore architecture of a Y zeolite supercage rendered the highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gap reduction, HOMO component change, and preferable coordination arrangement for the selective reaction promotion, which provides a trimolecular assembly platform to enable the coordination-promoted concerted ammoxidation pathway working closely on each Cs+ single site. The new reaction pathway without involvement of O2-dissociated O atom and lattice oxygen differs from the traditional redox catalysis mechanisms for the selective ammoxidation. |
| Databáze: | OpenAIRE |
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