Understanding the mechanism of N coordination on framework Ti of Ti-BEA zeolite and its promoting effect on alkene epoxidation reaction

Liang, Xiaohang; Peng, Xinxin; Liú, Dan; Xia, Changjiu; Luo, Yibin; Shu, Xingtian

doi:10.1016/j.mcat.2021.111750

Cited by 4 publications

(5 citation statements)

References 50 publications

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“…Affected by reaction conditions, compound 12 readily opened the ring to form 2,3-dihydroxybutanoic acid (13), which further broke bonds to form formic acid (14) and propionic acid (15). 62 Compounds 12 and 13 were not detected given their instability under this reaction condition. ② Crotonic acid cleavage reaction: crotonic acid broke the double bond to form acetate acid (16) and formic acid (14).…”

Section: ■ Results and Discussionmentioning

confidence: 96%

“…Crotonic acid could also react with O 2 to form compound 12 . Affected by reaction conditions, compound 12 readily opened the ring to form 2,3-dihydroxybutanoic acid ( 13 ), which further broke bonds to form formic acid ( 14 ) and propionic acid ( 15 ) . Compounds 12 and 13 were not detected given their instability under this reaction condition.…”

Section: Resultsmentioning

confidence: 99%

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Continuous Flow Synthesis of Crotonic Acid from Crotonaldehyde

Yu,

Cao,

Zhao

et al. 2024

Org. Process Res. Dev.

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At present, crotonic acid is mainly produced by oxidation of crotonaldehyde with O 2 in batch reactors. This process suffers from poor selectivity, low yields, and safety hazards. An expeditious and highly efficient continuous-flow process has been developed for the production of crotonic acid from crotonaldehyde with air. Compared with the batch process, the continuous flow process has significant advantages such as higher yields and shorter residence time. The flow protocol in this work provided the desired product with over 91% yield and 99.5% purity. Moreover, the recovery of raw materials ensures high utilization of reagents. The process is safe, efficient, and low-cost, which has the potential for industrial production of crotonic acid.

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Section: ■ Results and Discussionmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

Continuous Flow Synthesis of Crotonic Acid from Crotonaldehyde

Yu,

Cao,

Zhao

et al. 2024

Org. Process Res. Dev.

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“…In Ti-beta catalysts, the abundance of open Ti(OH)(OSi) 3 sites facilitates the easy formation of Ti-η 1 (OOH) species (Ti-OOH/Ti ratio: 13.3) compared to other Ti species. This initiation takes place through the reaction between Ti–OH and H 2 O 2 , demonstrating a remarkably high H 2 O 2 average utilization efficiency of 98.29%. ,, These Ti-η 1 (OOH) species are recognized as the active intermediates in olefin epoxidation. , Subsequently, these active intermediates attack the double bond of 1-hexene via an oxygen atom, leading to the creation of a transition state with a lower apparent activation energy (14.44 kJ mol –1 ) and the subsequent formation of 1,2-epoxyhexane . Due to their ability to activate H 2 O 2 into Ti-η 1 (OOH) species and lower apparent activation energies, Ti(OH)(OSi) 3 sites exhibit superior performance in the epoxidation of 1-hexene.…”

Section: Resultsmentioning

confidence: 99%

“…33,67,68 These Ti-η 1 (OOH) species are recognized as the active intermediates in olefin epoxidation. 69,70 Subsequently, these active intermediates attack the double bond of 1-hexene via an oxygen atom, leading to the creation of a transition state with a lower apparent activation energy (14.44 kJ mol −1 ) and the subsequent formation of 1,2-epoxyhexane. 71 Due to their…”

Section: Active Sites For the 1-hexene Epoxidationmentioning

confidence: 99%

Regulating the Coordination Mode of Ti Atoms in the Beta Zeolite Framework to Enhance the 1-Hexene Epoxidation

Deng,

Xu,

Liu

et al. 2024

Ind. Eng. Chem. Res.

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Regulating the Ti active sites in titanosilicates with different coordination modes is of prime scientific and industrial significance to the rational design of efficient catalysts for olefin epoxidation. In this study, the Ti species in Tibeta zeolite catalysts (open/closed tetra-coordinated Ti sites, hexa-coordinated Ti species, and TiO 2 ) were keenly controlled via the dealumination-metallization approach. By multiple characterizations, kinetics study, and multivariate model analysis, it is found that the open tetra-coordinated framework Ti(OH)(OSi) 3 species contribute more to the catalytic performance for 1-hexene epoxidation with H 2 O 2 . Moreover, the Ti-beta with rich open tetra-coordinated Ti(OH)(OSi) 3 species showed significantly improved reaction performance (TON: 401, conversion: 64%, selectivity: 98%, H 2 O 2 efficiency: 97%) with lower apparent activation energy. This study not only opens up new prospects for the design of efficient titanosilicates by modifying Ti microenvironments but also proposes the strategy to improve the content of open tetra-coordinated Ti sites.

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“… 21 . Xia et al demonstrated that the ammonia (e.g., NH 4 Cl) could coordinate with Ti‐sites to form a bridged Ti‐η 2 (OOH)‐R species, which effectively suppresses the over‐oxidation of the epoxides 34 . Hence, developing a universal strategy to locally modify external environment of Ti‐sites is highly required to boost the catalytic performance.…”

Section: Introductionmentioning

confidence: 99%

Silica islands regulated external Ti‐site environment of TS‐1 for enhanced performance of 1‐hexene epoxidation

Yuan

Fan

et al. 2022

AIChE Journal

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Rational regulation of the local environment of Ti-sites in TS-1 harbors tremendous industrial and scientific significance to epoxidation reactions. Herein, we report a facile and environment-friendly strategy to boost catalytic selectivity by covering the Tisites on an external surface of TS-1 (ITS-1) without sacrificing activity of internal Ti sites. By a quantitative analysis of d 3 -acetonitrile and quinoline-DRIFTS, 1 H MAS NMR and XPS, it is found that the percentage of external Ti-sites decreased from 11% to 6% after depositing surface silica islands. This successfully inhibits ringopening reaction of 1,2-epoxyhexane on catalyst surface, as demonstrated by slower kinetic decomposition rate of 1,2-epoxyhexane. Compared with conventional TS-1 catalyst, selectivity of 1,2-epoxyhexane over ITS-1 catalyst significantly increased from 83.5% to 98.5% while maintaining high 1-hexene conversion. Furthermore, overmuch surface silica coverage only leads to extremely low conversion (2%) due to inhibition of mass transfer. This work paves the way for rational construction of Ti-containing catalysts for 1-hexene epoxidation.

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Understanding the mechanism of N coordination on framework Ti of Ti-BEA zeolite and its promoting effect on alkene epoxidation reaction

Cited by 4 publications

References 50 publications

Continuous Flow Synthesis of Crotonic Acid from Crotonaldehyde

Continuous Flow Synthesis of Crotonic Acid from Crotonaldehyde

Regulating the Coordination Mode of Ti Atoms in the Beta Zeolite Framework to Enhance the 1-Hexene Epoxidation

Silica islands regulated external Ti‐site environment of TS‐1 for enhanced performance of 1‐hexene epoxidation

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