Selective synthesis of dimethyl ketone oxime through ammoximation over Ti-MOR catalyst

• Dimethyl ketone oxime is synthesized through ammoximation of acetone over titanosilicates.
• Ti-MOR is superior to TS-1 and Ti-MWW in terms of activity and oxime selectivity.
• Ti-MOR suppresses effectively the formation of byproducts due to consecutive oxidation of oxime.
• Desilication corresponds to the main reason for the deactivation in continuous ammoximation on Ti-MOR.

Titanosilicate with the MOR topology (Ti-MOR), postsynthesized from highly dealuminated mordenite and TiCl4 vapor through a solid–gas reaction, was highly active and selective for the liquid-phase ammoximation of dimethyl ketone (DMK) with ammonia and hydrogen peroxide. The parameters effecting the formation of the ammoximation product of dimethyl ketone oxime were investigated systematically in a batch-type reactor, and the optimized conditions were further applied to continuous ammoximation of DMK in a slurry reactor. Ti-MOR was superior to other titanosilicates in terms of activity and lifetime. TS-1 was not suitable for the ammoximation of DMK, whereas Ti-MWW required a higher catalyst loading to reach a reasonable activity, and they both easily produced a main byproduct of oxidative coupling of dimethyl ketone oxime. The deactivation behavior of Ti-MOR was investigated. Ammonia-induced structural desilication and accompanied Ti sites migration altered a more serious influence on the catalyst duration than coke deposition during continuous ammoximation.

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