Strong or weak acid, which is more efficient for Beckmann rearrangement reaction over solid acid catalysts?
The effects of Brønsted acid strength and pore confinement on the Beckmann rearrangement (BR) reaction over solid acid catalysts have been explored. With the help of catalytic evaluation experiments, it is demonstrated that oximes with different size (cyclohexanone oxime and acetoxime) exhibit quite different BR reactivity dependence on the acid strength over microporous and mesoporous zeolites. In order to reveal the origin of such a difference, electronic structure calculations and kinetic analysis were performed. It was theoretically found that the confinement effect from the microporous zeolite framework has a more significant influence on the rate-determining step of the BR reaction when the oxime reactant is well-confined inside the microporous voids, which in turn controls the BR reactivity.