Surface silanol sites in mesoporous MFI zeolites for catalytic Beckmann rearrangement

Park, Han-Young; Bang, Jisuk; Park, Hongjun; Kim, Jaeheon; Kim, Jeong Chul; Park, Jeong Young; Ryoo, Ryong

doi:10.1039/d3cy00543g

Cited by 4 publications

(2 citation statements)

References 64 publications

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“…Park et al [143] reported the use of silanol groups were generated in siliceous MFI zeolite nanosheets, via alkali-free synthesis routes, for catalytic application for gas-phase Beckmann rearrangement. The catalytic conversion by the zeolite nanosheets was investigated at 310 or 350 °C with cyclohexanone oxime, 4phenylcyclohexanone oxime and cyclododecanone oxime.…”

Section: Beckmann Rearrangmnet In Gas Phasementioning

confidence: 99%

Comprehensive updates on Beckmann Rearrangement

Kaushik,

Jain,

Malik

et al. 2024

ChemistrySelect

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Beckmann rearrangement has been quite successful in the preparation of many medicinally potent scaffolds. In synthetic organic chemistry, the Beckmann rearrangement is quite popular, caprolactam is synthesized from cyclohexanone oxime on a large scale for Nylon‐6 production. The function of numerous catalysts and media in the Beckmann rearrangement has been discussed in depth in this review. In the last 20 years, Beckmann rearrangement catalysis has evolved from a potentially hazardous to a more environmentally friendly catalyst, as a result of greater usage. Catalytic performance and synthetic performance of various catalytic systems have been re‐evaluated in the present review article.

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Section: Beckmann Rearrangmnet In Gas Phasementioning

confidence: 99%

Comprehensive updates on Beckmann Rearrangement

Kaushik,

Jain,

Malik

et al. 2024

ChemistrySelect

View full text Add to dashboard Cite

show abstract

“…Afterward, zeolites with a high Si/Al ratio, especially pure-silicon zeolites with silanol active sites, displayed much better catalytic activity and relative longer lifetime − owing to the greater effectiveness of weak acid sites than acidic SiOH[Al] groups which give rise to reduced activity and consecutive reactions in the vapor-phase process. , Meantime, the main reaction mechanism of the vapor-phase BR process from CHO to CPL over silanols has been revealed, , which proceeds with 1, 2 H-shift, rearrangement, and tautomerization reaction steps. , However, there are some certain amount of side-products, such as 5-hexenenitrile, hexanenitrile, cyclohexanone, and 2-cyclohexen-1-one are generated unexpectedly to make the whole reaction network remains unclear. , Hence, further investigation merits to precisely cut off the corresponding side reactions to improve the CPL selectivity. Then, the effects of various silanols, especially the terminal silanols and silanol nests, were investigated, − which point out that silanol nests are more effective to catalyze the vapor-phase BR due to the lower reaction barrier than that of terminal silanols. ,, However, the detailed impacts of terminal silanols are still ambiguous. In addition, introducing mesopores or even macropores into zeolite particles has been proven to be an effective way to promote mass diffusivity, − ascribed to the promoted cooperation between reactivity and mass transfer within the confined space.…”

Section: Introductionmentioning

confidence: 99%

Modulating the Microenvironment of Silanols in Pure-Silicon Zeolites for Boosting Vapor-phase Beckmann Rearrangement of Cyclohexanone Oxime

Zhang,

Wang,

et al. 2023

ACS Appl. Mater. Interfaces

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Vapor-phase Beckmann rearrangement of cyclohexanone oxime (CHO) to ε-caprolactam (CPL) is still difficult to commercialize at the industrial scale due to its relatively low catalytic activity and poor lifetime. Herein, we synthesized a series of pure-silicon zeolites (including MFI, MEL, and −SVR) with three-dimensional 10-member-ring topolgies, diverse silanol status, and hierarchical porosity to investigate the synergistic effects of inner diffusivity and reactivity. S-1 zeolite of MFI-type topology with plentiful silanol nests exhibits a more preferable catalytic performance in terms of CHO conversion (99.7%) and CPL selectivity (89.7%), much higher than those of MEL-and −SVRtype zeolites mainly due to their diverse silanol distribution. With the construction of hierarchical porosity, S-1-P shows improved CPL selectivity of 94.1% owing to the enhanced diffusivity to shorten the retention time of the reactant and product molecules. The reaction mechanism and network have been further revealed by density functional theory (DFT) calculations and experimental designs, which indicate that silanol nests are major active sites due to their suitable interaction with CHO rather than terminal silanols. Particularly, the microenvironments of silanols can be modulated by alcohol solvents, ascribed to their different charge transfer and steric hindrance. Consequently, S-1-P shows superior CPL selectivity of 97.3% in ethonal solvents, which have higher adsorb energy of −0.627 eV with silanol nests than other alcohols. The present study not only provides a fundamental guide for the design of zeolite catalysts but also provides a reference for modulating the microenvironment of active sites according to the catalytic mechanism.

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Application of Mixed Acid-Modified Hollow TS-1 Zeolite to Vapor-Phase Beckman Rearrangement Reaction

Yin,

Nie,

Wen

et al. 2024

Catal Lett

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Surface silanol sites in mesoporous MFI zeolites for catalytic Beckmann rearrangement

Abstract: Silanol groups were generated in siliceous MFI zeolite nanosheets, via alkali-free synthesis routes, for catalytic application for gas-phase Beckmann rearrangement. The catalytic conversion by the zeolite nanosheets was investigated at...

Cited by 4 publications

References 64 publications

Comprehensive updates on Beckmann Rearrangement

Comprehensive updates on Beckmann Rearrangement

Modulating the Microenvironment of Silanols in Pure-Silicon Zeolites for Boosting Vapor-phase Beckmann Rearrangement of Cyclohexanone Oxime

Application of Mixed Acid-Modified Hollow TS-1 Zeolite to Vapor-Phase Beckman Rearrangement Reaction

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