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シクロヘキサノンオキシムの気相ベックマン転位反応において触媒活性劣化に及ぼす細孔径の影響を明らかにするためMFI構造をもつTS-1およびこれよりも大きな細孔をもつSSZ-31およびSSZ-24を触媒として反応を行った。SSZ-24を用いたときの活性劣化定数は本研究で使用したゼオライトの中で最大になった。さらにε-カプロラクタムの分子径/ゼオライトの細孔径比が1になるとき同程度の酸性度をもつゼオライト間で最大の活性劣化因子をもつことが分かった。これらの結果は細孔内の活性点で生成したε-カプロラクタムが細孔から拡散できないためε-カプロラクタムが長時間にわたり細孔内に滞留し結果としてコークあるいはその前駆体になったことを示唆している。ゼオライトの細孔径はベックマン転位反応の活性劣化に大きな影響を与えた。The vapor phase Beckmann rearrangement of cyclohexanone oxime (CHO) was carried out over TS-1 with an MFI pore structure and  SSZ-31 and SSZ-24 with pore sizes larger than that of MFI to elucidate the effect of the pore size on catalyst deactivation. The deactivation constant over SSZ-24 was the highest among the zeolites used in the study. Furthermore, when the ratio between the molecular size of e-caprolactam (CL) and the pore size of zeolite was unity, the deactivation constant was maximum over the zeolites at similar acidity. These results indicate that since CL produced on the active sites cannot diffuse from the micropores, the CL reacts to form coke or its precursor over a long residence time. The pore size of the zeolite is the main controlling factor of catalyst deactivation during the Beckmann rearrangement

Effect of Micropore Size on Catalyst Deactivation in Vapor Phase Beckmann Rearrangement over Zeolites