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Synthesis of ϵ‐Caprolactam from Cyclohexanone Oxime Using Zeolites Hβ, HZSM‐5, and Alumina Pillared Montmorillonite
Author(s) -
Ouyang KuangHao,
Chen ChihWei,
Ko AnNan
Publication year - 2001
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.200100025
Subject(s) - chemistry , cyclohexanone oxime , caprolactam , catalysis , montmorillonite , acid strength , beckmann rearrangement , lewis acids and bases , brønsted–lowry acid–base theory , calcination , cyclohexanone , oxime , yield (engineering) , zeolite , nuclear chemistry , organic chemistry , materials science , metallurgy
The Beckmann rearrangement of cyclohexanone oxime (CHO) to ϵ‐caprolactam (ϵ‐C) was studied in a plug flow reactor at 300–400°C under atmospheric pressure by using Hβ, ZSM‐5, and alumina pillared montmorillonite. With Hβ(X) Y zeolites, raising the SiO 2 /Al 2 O 3 molar ratio (X) results in the enhancement of catalyst acid strength with concomitant decrease of the total acid amount. In creasing the calcination temperature (Y) causes remarkable diminution of catalyst surface area, acid strength, and acid amount. A similar trend was found for AlPMY catalysts. In there action of CHO, the initial catalytic activity correlates well with the total acid amount of various catalysts except for Hβ(10) Y (Y > 600°C). The reaction proceeds on both Brönsted and Lewis acid sites and the catalyst deactivation most likely occurs at the strong Brönsted acid sites. The effect of solvents in the feed on the catalytic results was also investigated; it was found that polar solvents such as ethanol or n‐butanol give high ϵ‐C yield and longer catalyst life time. In the reaction of CHO/C 2 H 5 OH over Hβ(10)800 at 400°C and W/F 74.6 gh/mol, the CHO conversion and ϵ‐C yield remain 100% and 92%, respectively, for at least 20 h time‐on‐stream. The reaction paths and the mechanism for ϵ‐C formation are proposed.