NiO-Doped Mesoporous Silica FDU-12: A High-Performance Heterogeneous Catalyst for Sustainable and Selective Isoamyl Alcohol Oxidation

The selective oxidation of isoamyl alcohol (3-methyl-1-butanol) to isovaleraldehyde under mild and environmentally friendly conditions remains a challenging transformation with significant implications for fine chemical production. Herein, we report the synthesis and systematic evaluation of nickel oxide-loaded mesoporous FDU-12 catalysts, NiO(5 wt %)-FDU-12, NiO(10 wt %)-FDU-12, and NiO(15 wt %)-FDU-12, for this transformation using tert-butyl hydroperoxide (TBHP) as a green oxidant. Among these, NiO(15 wt %)-FDU-12 exhibited benchmark performance, achieving 100% conversion with 91.15% selectivity toward isovaleraldehyde at 80 °C in acetonitrile (ACN) with minimal overoxidation to isovaleric acid (3.13%). Compared with reported catalysts such as ZnO/Co-HMS and Cr-modified ZSM-5, our system operates at lower temperature, under milder conditions, and with superior aldehyde selectivity, thereby overcoming the common limitations of overoxidation and prolonged reaction times. Structural characterization by BET analysis, XRD, and TEM confirmed the uniform dispersion of NiO nanoparticles and the preservation of the mesoporous network after metal incorporation. Importantly, the catalyst retained >95% of its activity over multiple reaction cycles, highlighting its robustness and reusability. These results establish NiO/FDU-12 as a cost-effective, scalable, and environmentally benign catalyst platform for selective alcohol oxidation, with potential applications in industrially relevant oxidation processes.