Ni-Doped Amorphous Al2O3 for One-Pot Synthesis of Azoxybenzene via Nitrobenzene Reduction with Sodium Borohydride

Ni-doped amorphous Al2O3 catalysts were successfully prepared for the one-step reduction of nitrobenzene to azoxybenzene using NaBH4 as hydrogen donors under mild conditions. The amorphous Ni1Al87Ox catalyst achieved a highly efficient azoxybenzene production rate of 1.89 mol·g-Ni−1·h−1, significantly outperforming its Ni/γ-Al2O3 counterpart. On the basis of the MAS NMR and XPS characterization results, the enhanced catalytic performance is associated with Ni incorporation during the preparation of amorphous Ni1Al87Ox, which introduces abundant unsaturated pentacoordinate Al species with oxygen vacancies and stabilizes Niδ+ sites against over-reduction. Notably, Ni1Al87Ox loaded on commercial ZSM-5 supports maintained an azoxybenzene yield of 9.02 mol·g-Ni−1·h−1, highlighting the strong potential for further scalable applications.