Controllably Confined ZnO on USY Zeolites (USY@ZnO/Al2O3) as Efficient Lewis Acid Catalysts for Baeyer–Villiger Oxidation

Bo Wang; Hao Xu; Yu Ding; Zhiguo Zhu; Darui Wang; Yejun Guan; Haihong Wu; Peng Wu

Index: 10.1002/asia.201800218

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Abstract

A ZnAl‐LDHs (layered double hydroxides) phase was readily formed on the surface of a USY zeolite through a distinctive in situ growth method that benefitted from the interaction of the added Zn source and aluminum species extracted from the Al‐rich USY zeolite crystals. The migration of aluminum and simultaneous interaction with the external Zn source took place in one pot to form a ZnAl‐LDHs phase coated on the surface of the USY crystals. Upon calcination, the ZnAl‐LDHs phase was transformed into a ZnO/Al2O3 composite that was still firmly anchored on the USY zeolite, without sacrificing the core–shell structure. The resultant USY@ZnO/Al2O3 materials gave rise to unique Lewis acidity and hierarchical porosity, which endowed the catalyst with promising performance in the Baeyer–Villiger oxidation of ketones with H2O2 or bulky tert‐butyl hydroxide as an oxidant.