Titanium mordenite-confined low-loaded Pd for efficient oxime production with H₂ and O₂

The ammoximation of cyclohexanone using a Ti‑zeolite/H₂O₂ system, coupled with a Beckmann rearrangement, is now commercially employed to produce ε‑caprolactam—a critical precursor for the synthesis of Nylon 6. The in situ generation of H₂O₂ integrated with the titanosilicate-catalysed ammoximation of cyclohexanone can eliminate the need for transportation and storage of concentrated H₂O₂, mitigating the economic and environmental costs associated with its production via the conventional anthraquinone process. Here we present a titanium-mordenite‑confined low-Pd-loaded catalyst with subnanometric Pd clusters within specific pores, enabling direct cyclohexanone ammoximation with H₂ and O₂. With only 0.055 wt% Pd, this catalyst maintains exceptional stability for over 4,020 h of continuous ammoximation with H₂ and O₂, achieving 99% oxime selectivity even in H₂O. Our work contributes to the development of an alternative ammoximation route that minimizes precious-metal usage, reducing reliance on both organic solvents and H₂O₂, and paves the way towards a more eco-efficient process for ε-caprolactam production. (Figure presented.)