Abstract
For the Beckmann rearrangement of cyclohexanone oxime into -caprolactam, the monomer of nylon-6 are of great industrial importance. The conventional method uses concentrated sulfuric acid or oleum as a catalyst and produces ammonium sulfate as a by-product. Among solid
acids, zeolites have been found to exhibit superior property for Beckmann rearrangement of cyclohexanone oxime. However, the active sites inside the micropores imposes severe mass transfer constrains. Hierarchical porous zeolite contains micro, meso and macro pores in the same material to
overcome the mass transfer constrains. The present paper aims to synthesize hierarchical nanocrystalline TS-1 using dual template approach for liquid-phase Beckmann rearrangement of cyclohexanone oxime. The catalyst was characterized by several techniques. The reaction parameters such as,
catalyst loading, concentration of cyclohexanone oxime, reaction temperature, influence of solvent and catalyst reusability were studied. The hierarchical nanocrystalline TS-1 catalyst was found to be superior activity (94%) and selective towards the formation of ε-caprolactam (>99%)
at mild reaction condition. In addition, these catalysts have excellent reusability and can be used instead of sulfuric acid for selective production of ε-caprolactam. Finally, the catalyst tested here is suitable for carrying out the Beckmann rearrangement of bulky oximes.