Product selectivity controlled by manganese oxide crystals in catalytic ammoxidation

The performances of heterogeneous catalysts can be effectively tuned by changing the catalyst structures. Here we report a controllable nitrile synthesis from alcohol ammoxidation, where hydration side reaction could efficiently prevented manganese oxide catalysts. α-Mn2O3 based are highly selective for synthesis, but MnO2-based including α, β, γ, and δ phases favour amide production tandem ammoxidation steps. Multiple structural, kinetic, spectroscopic investigations reveal that water decomposition is hindered on α-Mn2O3, thus to switch off hydration. In addition, selectivity-control feature mainly related their crystalline nature rather than morphology, although morphological issue usually regarded as crucial factor in many reactions.