Anion-Doped Manganese Oxides Enabling Relay Catalysis for Aerobic Alcohol Ammoxidation.
Аннотация
The development of noble-metal-free heterogeneous catalysts for room-temperature aerobic ammoxidation of alcohols to nitriles represents an enduring challenge, primarily hampered by unselective lattice-oxygen over-oxidation via the classical Mars-van Krevelen (MvK) pathway and strong site-blocking effects. Herein, we report a dual-anion (C/N) doped MnOx (C/N-MnOx) synthesized via a green, solvent-free crystallization strategy, which exhibits excellent catalytic performance (95.3% benzyl alcohol conversion, >99% benzonitrile selectivity) and broad substrate versatility (35 diverse alcohol substrates) under ambient conditions (25°C, 1 atm O2) without external energy inputs. Structural analyses and theoretical calculations demonstrate that N-doping introduces medium-strong Lewis acidic Mn-N sites to capture NH3, while C-doping generates localized oxygen vacancies for O2 activation. Crucially, kinetic isotope effect experiments and density functional theory (DFT) calculations prove that this anion dopant-programmed relay catalysis successfully bypasses the MvK pathway, fundamentally shifting the rate-determining step from initial alcohol dehydrogenation to the homolytic α-C-H bond scission of the aldimine intermediate. This work presents a paradigm shift in designing multifunctional non-precious catalysts for ambient-condition green organic transformations.
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