Beckman rearrangement of cyclohexanone-oxime on HNaY zeolites: kinetic and spectroscopic studies

The cyclohexanone-oxime rearrangement catalyzed by a series of HNaY zeolites was studied in a fixed-bed reactor with continuous plug flow at atmospheric pressure and 335°C. Selectivity curves for the different reaction products, viz, ε-caprolactam, 5-cyanopent-1-ene and cyclohexanone, were obtained and from them the reaction mechanism was established. The influence of the level of exchange of Na+ in the HNaY sample on the total conversion of cyclohexanone-oxime, the selectivity for the products and the decay of the catalyst are discussed. It has been found that the formation of ε-caprolactam is catalyzed by Bro¨nsted sites of strength pKa ≦ 1.5, and that 5-cyanopent-1-ene is formed mainly on the Na+ ions of the zeolite.