Beckmann-rearrangement of cyclododecanone oxime to ω-laurolactam in the gas phase

The classical route for the industrial production of ω-laurolactam is the homogeneously catalyzed Beckmann-rearrangement of cyclododecanone oxime in the liquid state using fuming sulfuric acid catalyst. Contrary to that, a completely different way is shown in the present work. In addition to the use of a solid acid catalyst, the vapor phase was chosen. From a process technical point of view it is a superior route compared with the classical one. Following intensive investigations of the vapor phase behavior of substrate, product and the main by-products, a catalyst screening of the most promising materials was performed. In addition, a modification of the most active catalysts was carried out to get more information about reaction sites and to optimize the catalyst activity. Using an acid treated [Al,B]-BEA zeolite at a temperature of approx. 320 °C and reduced pressures, complete conversion combined with excellent selectivity of 98% were obtained. The accumulation of reactants in the fixed bed was less than 5 wt%. Furthermore, investigations of deactivation and regeneration behavior of the catalyst were done. It could be demonstrated that the catalytic material could be regenerated under oxidative atmosphere as well as under non-oxidative conditions through thermal desorption of the deactivating compounds without any measurable loss of catalytic performance.

Graphical abstractThis paper investigates the heterogeneously catalysed Beckmann-rearrangement of cyclododecanone oxime to ω-laurolactam in the gas phase. Using an acid treated [Al,B]-BEA zeolite at a temperature of approx. 320 °C and reduced pressures, complete conversion and a selectivity of 98% were achieved.Figure optionsDownload full-size imageDownload high-quality image (47 K)Download as PowerPoint slide