Construction of unique six-coordinated titanium species with an organic amine ligand in titanosilicate and their unprecedented high efficiency for alkene epoxidation

Xu, Le; Huang, Dading; Li, Chen-Geng; Ji, Xinyi; Jin, Shaoqing; Feng, Zhaochi; Xia, Fei; Li, Xiaohong; Fan, Fengtao; Li, Can; Wu, Peng

doi:10.1039/c5cc02321a

Cited by 123 publications

(91 citation statements)

References 16 publications

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“…S1, ESI †), and a shoulder peak at 459.6 eV and the main peak at 460.2 eV were detected in TS-1 + as the binding energy of Ti 2p 3/2 , indicating that the charge distribution of the Ti ions in TS-1 + was more negative, which provides the possibility of water ligands coordinating directly to the Ti active sites. 12 The results of IR and XPS in TS-1 + further verify the formation of "TiO 6 " octahedron species proposed by Li et al that it is partially coordinated with water and hydroxyl groups shown as Ti(OSi) 2 (OH) 2 (H 2 O) 2 . 9d The proportion of "TiO 6 " species in TS-1 + remained almost unchanged around 20% in various Ti contents via semiquantitative analysis by UV/Vis measurement (Table S1, ESI †).…”

Section: Synthesis Of Highly Active Oxidation Catalyst With Improved supporting

confidence: 70%

Synthesis of a highly active oxidation catalyst with improved distribution of titanium coordination states

Deng

Zhao

et al. 2016

Chem. Commun.

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Section: Synthesis Of Highly Active Oxidation Catalyst With Improved supporting

confidence: 70%

Synthesis of a highly active oxidation catalyst with improved distribution of titanium coordination states

Deng

Zhao

et al. 2016

Chem. Commun.

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“…2-bottom left). The TOF values indicate that the reaction is reasonably fast, in comparison with other non-functionalized titanosilicates, used under similar conditions, for epoxidation of cyclohexene with TBHP [88][89][90][91]. ICP-AES experiments were conducted on samples 1-7 to evaluate the bulk Ti content in the materials (ESI , Table S2).…”

Section: Determining the Factors That Affect Catalytic Activitymentioning

confidence: 99%

Optimization of mesoporous titanosilicate catalysts for cyclohexene epoxidation via statistically guided synthesis

et al. 2018

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An efficient approach to improve the catalytic activity of titanosilicates is introduced. The Doehlert matrix (DM) statistical model was utilized to probe the synthetic parameters of mesoporous titanosilicate microspheres (MTSM), in order to increase their catalytic activity with a minimal number of experiments. Synthesis optimization was carried out by varying two parameters simultaneously: homogenizing temperature and surfactant weight. Thirteen different MTSM samples were synthesized in two sequential 'matrices' according to Doehlert conditions and were used to catalyse the epoxidation of cyclohexene with tert-butyl hydroperoxide. The samples (and the corresponding synthesis conditions) with superior catalytic activity in terms of product yield and selectivity were identified. In addition, this approach revealed the limiting values of each synthesis parameter, beyond which the material becomes catalytically ineffective. This study demonstrates that the DM approach can be broadly used as a powerful and time-efficient tool for investigating the optimal synthesis conditions of heterogeneous catalysts. Abbreviation

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“…The catalytic results revealed that the hierarchical LTS-1 was less active than the conventional TS-1 in the epoxidation of 1-hexene with H 2 O 2 (6.5% for LTS-1 and 25.2% for TS-1, respectively), because LTS-1 contained a large number of silanol groups than TS-1. [ 146 ] Further characterizations indicated that the resulting organic-inorganic layered titanosilicate contained unusual six-coordinated Ti active site with an organic PI ligand. However, the conversion of 1-hexene achieved on LTS-1 indicated that its catalytic behavior was still characteristic of crystalline titanosilicate rather than Ti-containing mesoporous materials.…”

Section: Wileyonlinelibrarycommentioning

confidence: 99%

“…However, the conversion of 1-hexene achieved on LTS-1 indicated that its catalytic behavior was still characteristic of crystalline titanosilicate rather than Ti-containing mesoporous materials. [ 146 ] Moreover, a family of UTL-type titanosilicates were prepared through the conventional hydrothermal synthesis and the following ADOR process, producing the UTL titanosilicate, Ti-IPC-2, Ti-IPC-4, the silica pillared Ti-IPC-1PISi, and the silica-titania pillared Ti-IPC-1PITi catalysts. Moreover, LTS-1 was immune to Ti leaching and irreversible deactivation in cyclohexene epoxidation with H 2 O 2 compared with the mesoporous Ti-MCM-41, because of the crystalline characteristics of catalyst.…”

Section: Wileyonlinelibrarycommentioning

confidence: 99%

Recent Advances in the Synthesis and Application of Two‐Dimensional Zeolites

Sun

2016

Advanced Energy Materials

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traditional hydrothermal syntheses would produce intermediate materials with 2D feature, such as MCM-22P, [ 7,8 ] PREFER, [ 9 ] which are composed of crystalline zeolite layers with the unit-cell thickness stacking on top of each other in ordered or disordered patterns. [10][11][12][13][14][15] Unlike traditional 3D zeolites, the crystal growth of frameworks in 2D layered zeolites is restricted in one particular direction, leaving lots of hydroxyl groups on layer surface. As zeolites are normally defi ned as 3D materials that possess regular micropore systems and consist of TO 4 tetrahedra, layered zeolite precursors containing silanols could not be regarded as zeolites in the strictest sense, but they are broadly included in the family of zeolite materials. Thus, the as-synthesized 2D zeolites are often denoted as layered zeolite precursors (the typical examples are shown in Table 1 ), [7][8][9] which would transform into their 3D order/disorder counterparts after removing organic molecules and condesation of interlayer silanols via calcination. [ 10 ] In the early research stage, the layered zeolite precursors are discovered accidentally in traditional hydrothermal syntheses, because we have limited control over the traditional synthesis process due to the incomplete understanding of crystallization mechanism. At that stage, one of the most attractive features of 2D zeolites is that they could transform into zeolite materials with hierarchical architectures. In some cases, the traditional synthesis produces hierarchical layered material, such as MCM-56, [ 26 ] in which the crystalline zeolite layers disorderly stacked. Furthermore, the recognition that the obtained layered precursors could be modifi ed into various hierarchical zeolite structures (such as delaminated, pillared, interlayer expanded and others) make them signifi cantly different from conventional 3D zeolite materials with rigid structures. Thus, the construction of hierarchical zeolite materials from the perspective of 2D layered zeolite precursors is an important research aspect during the past few years.With the improved synthetic techniques, layered zeolites are not only increasing in number, but also expanding the notion in composition and structure. One remarkable breakthrough in recent years is the discovery of 2D MFI nanosheets with the single unit-cell thickness (about 2 nm), which is achieved by adopting Gemini-type bifunctional surfactants as organic structure-directing agent (OSDA) in hydrothermal synthesis. [ 49 ] The calcined MFI nanosheets become a special kind of hierarchical zeolites Two-dimensional (2D) zeolites, originating from lamellar precursors, are a special kind of porous materials, in which crystalline zeolite nanolayers are weakly assembled in one particular direction. As there is no covalentbond between layers, the stacking sequences could be manipulated and possibly controlled to derive a family of zeolitic materials with structural diversity. The research on 2D zeolites arises from the primary casual discovery during ...

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Construction of unique six-coordinated titanium species with an organic amine ligand in titanosilicate and their unprecedented high efficiency for alkene epoxidation

Abstract: A novel organic-inorganic layered titanosilicate consisting of Ti-containing MWW-type nanosheets and piperidine ligands was constructed. It exhibited an unprecedented high catalytic activity and recyclability in alkene epoxidation.

Cited by 123 publications

References 16 publications

Synthesis of a highly active oxidation catalyst with improved distribution of titanium coordination states

Synthesis of a highly active oxidation catalyst with improved distribution of titanium coordination states

Optimization of mesoporous titanosilicate catalysts for cyclohexene epoxidation via statistically guided synthesis

Recent Advances in the Synthesis and Application of Two‐Dimensional Zeolites

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