1. Isomorphous incorporation of tin ions into extra-large pore framework with high-stannum content as efficient Lewis acid catalyst.
- Author
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Liu, Xue, Liu, Sen, Yan, Tingyu, Wang, Zhongrui, Gao, Shutao, Gao, Zhuoyou, Nie, Xinhao, and Liu, Zejiang
- Subjects
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BAEYER-Villiger rearrangement , *LEWIS acids , *IONS , *CHEMICAL structure , *HYDROXYL group , *ACID catalysts , *ALLOY plating , *OXIDATION - Abstract
[Display omitted] • Calcined *CTH experienced structural collapse and reconstruction by HNO3 treatment. • Sn-*CTH were post-synthesized via the structural rearrangement and Sn incorporation. • Sn-*CTH exhibited a high catalytic activity in the Baeyer-Villiger oxidation. • High ε-caprolactone selectivity was obtained through controlling reaction parameters. Germanium-rich *CTH zeolite without organic molecules located inside pore channels experienced only partial structural collapse and subsequently repaired to high-silica structure analogous to the original topology in a short time. The surprise acid-hydrolysis process has caused a large amount of framework Ge ions were removed, giving rise to abundant hydroxyl nests. Benefiting from the unexpected variation of framework structure and chemical composition, stannosilicates Sn-*CTH with extra-large pores and various Sn loadings (Si/Sn molar ratio in the range of 30-∞) were post-prepared depending on the reaction between the added (NH 4) 2 SnCl 6 species and the formed silanol groups in the hydroxyl nests. The resultant Sn-*CTH zeolites were able to release significantly the diffusion limitations encountered by the bulky substrates and oxidants, exhibiting promising activities to catalyze the Baeyer-Villiger (B-V) oxidation of ketones with single oxidant either hydrogen peroxide (H 2 O 2) or large-sized tert-butyl hydroperoxide (TBHP). Especially, high ε-caprolactone product selectivity was also obtained in the B-V oxidation of cyclohexanone using H 2 O 2 oxidant through reducing the H 2 O 2 /cyclohexanone molar ratio as well as controlling appropriate reaction time, which was more efficient than the traditional Sn-Beta-F catalyst. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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