Preparation of NbOx/SiO2-coated structured packing material and it's catalytic performance in the gas-phase Beckmann rearrangement of cyclohexanone oxime to ε-caprolactam

Abstract

Potential industrial applicability of a NbOx/SiO2 catalyst material was strongly improved by fixing μm-particles onto a structured packing. The granular catalyst displays a high catalytic performance in producing ε-caprolactam via gas-phase Beckmann rearrangement. However, applicability is strongly hampered because a high linear gas velocity and a small particle size are necessary to avoid diffusion limitations. These requirements would lead to an unacceptably high pressure drop in an industrial reactor. The novel NbOx/SiO2 structured packing catalyst displays, at high WHSV in a tube reactor, a constant high ε-caprolactam yield (96%) for at least 32h time-on-stream, without any indication of deactivation.