Green Approach to Beckmann Rearrangement of Cyclohexanone Oxime Using Nanostructured ZSM-5 Zeolite

The catalytic liquid-phase Beckmann rearrangement of cyclohexanone oxime to ε-caprolactam has been effectively achieved using ZSM-5 nanoparticles as catalysts. Comprehensive characterization of the catalysts was performed by utilizing techniques such as DLS, XRD, FT-IR, N2 adsorption–desorption isotherms and NMR analysis. A systematic investigation of key reaction parameters, including the concentration of cyclohexanone oxime, catalyst loading, reaction temperature, and catalyst reusability, was conducted to optimize the catalytic process. The results demonstrate that the ZSM-5 nanoparticles aged at 80°C for 24 h and calcined at 550°C for 5 h (denoted as ZSM-5(50)-24/c) exhibited superior catalytic performance, achieving the highest conversion of cyclohexanone oxime and exceptional selectivity for ε-caprolactam under optimized conditions. The optimum reaction conditions are 0.10 g of ZSM-5(50)-24/c catalyst, cyclohexanone oxime concentration of 100 mmol and the reaction temperature of 120°C. This catalytic system offers notable advantages, including environmental sustainability, straightforward separation, and efficient catalyst recovery and recyclability. These features make it a promising approach for industrial applications in ε-caprolactam production, aligning with the green chemistry principle.