Enhancement of the visible light absorption intensity of microporous vanadosilicate AM-6

Guo, Meiling; Li, Guanna; Fan, Fengtao; Feng, Zhaochi; Li, Can

doi:10.1039/c2cc36083g

Cited by 6 publications

(6 citation statements)

References 43 publications

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“…A band at 940 cm À1 was only observed for catalyst A and could similarly be ascribed to the V]O bonds. It is important to note that no crystalline V 2 O 5 phase was detected in the samples, because the fingerprint Raman bands of this phase (at 994, 701, 526, and 284 cm À1 ) were not present [23,29,30]. The DR UV-Vis spectra of the vanadosilicates are shown in Fig.…”

Section: Structural Characterization Of the Catalystsmentioning

confidence: 99%

“…The spectra for catalysts A, B, and C contained similar broad bands centered at around 215, 265, and 545 nm. According to Brandão et al [23] bands near 215 and 265 nm can be explained by O-to-V 4þ charge transfer (CT), while the band centered at 545 nm is due to dd transitions of V 4þ in octahedral VO 6 [30].…”

Section: Structural Characterization Of the Catalystsmentioning

confidence: 99%

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One-step oxidehydration of glycerol to acrylic acid using ETS-10-like vanadosilicates

Paula

Possato

Ratero

et al. 2016

Microporous and Mesoporous Materials

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Vanadosilicates isostructural to ETS-10 and AM-6 microporous materials were synthesized hydrothermally using derivatives of cis-and trans-3,5-dimethyl-piperidine as organic structure directing agents (SDAs) and were subsequently tested as heterogeneous catalysts for the oxidehydration of glycerol to acrylic acid. The best performances were obtained with vanadosilicates prepared with 1,1,3,5-tetramethyl piperidinum cations, which were capable of converting 93.6% of glycerol to acrylic acid in one step, with 85.4% selectivity. Other important chemicals such as acrolein (3.8%), propanal (2.3%), acetaldehyde (3.2%), acetic acid (2.5%), and propionic acid (1.4%) were produced in smaller amounts. The results clearly indicated that these vanadosilicates are potential multifunctional catalysts capable of performing the oxidehydration of glycerol to acrylic acid in a single step. Spectroscopic data obtained from 51 VMAS-NMR, UV-Vis, XPS, and Raman scattering analyses suggested that the selectivity of these vanadosilicates for the oxidative dehydration of glycerol to acrylic acid could be attributed to the capacity of the vanadium species for dynamic adoption of multiple oxidation states during the catalytic reaction.

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Section: Structural Characterization Of the Catalystsmentioning

confidence: 99%

Section: Structural Characterization Of the Catalystsmentioning

confidence: 99%

One-step oxidehydration of glycerol to acrylic acid using ETS-10-like vanadosilicates

Paula

Possato

Ratero

et al. 2016

Microporous and Mesoporous Materials

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“…The DFT/MM hybrid calculation method was also employed to analyze the electronic properties and geometry of transition-metal-doped ETS-10 derivatives. , For this purpose, the structure of the silica framework was fixed, and only the structures of the quantum wires comprised of transition-metal octahedron complexes were optimized using G03. Finally, Guo et al performed DFT calculations on AM-6, which contains VO 4 tetrahedral centers, using a cluster model …”

Section: Introductionmentioning

confidence: 99%

“…To obtain optimal results, QM calculations on ETS-10 (Na 32 Ti 16 Si 80 O 208 ) should utilize the whole unit cell (336 atoms), and periodicity should be allowed in all three dimensions (3D). However, owing to the difficulties that attend calculations on large full unit cells of this type with 3D periodicity, previous QM calculations of ETS-10 and AM-6 have been performed on simplified cluster models and by restricting periodicity to 1D ,− using ab initio or DFT/MM hybrid calculations. In contrast to the previous approaches, we for the first time have carried out first-principles DFT calculations not only on ETS-10 but also on AM-6 and SGU-29 using their full unit cells allowing periodicity to 3D.…”

Section: Introductionmentioning

confidence: 99%

DFT Calculated Structures and Electronic Properties of ETS-10, AM-6, and SGU-29: Structure Stabilization through Periodic Distortions

2016

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ETS-10, AM-6, and SGU-29 are isostructural microporous transition metal silicates that contain TiO6 and VO6 quantum wires and one-dimensional (1D) arrays of CuO4 square planes, within the structures. Owing to their unique structures, these materials commonly have the ability to adsorb large amounts of CO2 from humid flue gases without interference by moisture. Because of this interesting property, a greater understanding of the local structural features of these substances is required so that superior CO2 absorbing materials can be designed. Quantum mechanical (QM) calculations would be ideal for this purpose. Previous QM calculations have been conducted only on ETS-10 and its heteroatom-substituted analogues, employing simple cluster models or restricting periodicity to one dimension. In the current study, we carried out first-principles QM calculations on ETS-10, AM-6, and SGU-29 employing their full unit cells allowing periodicity to all three dimensions. The results show that the symmetries of TiO6 and VO6 octahedron quantum wires and the CuO4 square plane arrays undergo severe distortions with periodic patterns, and as a result, the framework structures become significantly stabilized. The calculated unit cell volume decreases on going from ETS-10 to AM-6 and SGU-29. The calculated band gap energies (E g) decrease in the same order. The band structures suggest that ETS-10 is a p-type wide band gap semiconductor, AM-6 is an n-type narrow band gap semiconductor, and SGU-29 is a semimetal.

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“…This unique structure in AM-6 leads to increased photoreactivity in the visible region. [6,7] Although the specific surface area of AM-6 is large due to its microporosity, the surrounding SiO 2 matrix makes the linear chains mostly isolated from adsorbed molecules. [8] Thus, only a small portion of the AM-6 surface area is reactive in both traditional catalytic and photocatalytic reactions.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Morphology Control of AM‐6 Nanofibers with Tailored ‐V‐O‐V‐ Intermediates

Guo

Feng

Hofmann

et al. 2013

Chemistry A European J

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Microporous vanadosilicates with octahedral VO6 and tetrahedral SiO4 units, better known as AM-6, have been hydrothermally synthesized with different morphologies by controlling the Na/K molar ratio of the initial gel mixtures. The morphology of the AM-6 materials changed from bulky cube to nanofiber aggregates as the Na/K molar ratio decreased from 1.9 to 0.2. Raman spectroscopy revealed that the VO3 (-) intermediate species plays an important role in the formation of the nanofiber morphology. The orientation of -V-O-V- chains in nanofiber aggregates was examined by confocal polarized micro-Raman spectroscopy. It was found that these aggregates are assemblies of short -V-O-V- chains perpendicular to the axis of nanofibers. The obtained AM-6 nanofibers greatly increase the exposed proportion of VO terminals, and thus improve the catalytic performance.

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Enhancement of the visible light absorption intensity of microporous vanadosilicate AM-6

Cited by 6 publications

References 43 publications

One-step oxidehydration of glycerol to acrylic acid using ETS-10-like vanadosilicates

One-step oxidehydration of glycerol to acrylic acid using ETS-10-like vanadosilicates

DFT Calculated Structures and Electronic Properties of ETS-10, AM-6, and SGU-29: Structure Stabilization through Periodic Distortions

Synthesis and Morphology Control of AM‐6 Nanofibers with Tailored ‐V‐O‐V‐ Intermediates

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