HPM-2, the Layered Precursor to Zeolite MTF

Rojas, Alex; Camblor, Miguel Á.

doi:10.1021/cm403527t

Cited by 45 publications

(61 citation statements)

References 50 publications

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“…44−48 Also, the topotactic phase transition from a two-dimensional layered structure to a three-dimensional framework material is classic to the area of zeolite syntheses. 49 65 ) from their layered precursors (e.g., MCM-22P, 55 PREFER, 51 NU-6(1), 60 66 To the best of our knowledge, the conversion from ZIF-L to ZIF-8 is the first example of a topotactic transition of porous ZIF, from a 2D layered structure to a 3D structure.…”

Section: ■ Introductionmentioning

confidence: 98%

Crystal Transformation in Zeolitic-Imidazolate Framework

Low

Yao

Liu

et al. 2014

Crystal Growth & Design

183

118

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The phase transformation of a zinc-2-methylimidazole-based zeolitic-imidazolate framework (ZIF), from a recently discovered ZIF-L to ZIF-8, was reported. ZIF-L is made up of the same building blocks as ZIF-8, having two-dimensional crystal lattices stacked layer-by-layer. Results indicated that the phase transformation occurs in the solid phase via the geometric contraction model (R2), a kinetic model new to ZIF. The phase transformation was monitored by means of ex situ powder X-ray diffraction, nitrogen sorption, Fourier transform infrared spectroscopy, selected-area electron diffraction, scanning electron microscopy, and in situ nuclear magnetic resonance spectroscopy. This work also demonstrates the first topotactic phase transformation in porous ZIFs, from a 2D layered structure to a 3D structure, and provides a new insight into metal−organic framework crystallization mechanisms.

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Section: ■ Introductionmentioning

confidence: 98%

Crystal Transformation in Zeolitic-Imidazolate Framework

Low

Yao

Liu

et al. 2014

Crystal Growth & Design

183

118

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“…The different behavior of 10BDMI at various temperatures, especially at the high temperatures of 175 and 190 °C successfully rendering MWW zeolites, might cast doubts about the integrity of the organics. High temperatures may cause degradation, and the degraded organic species might have worked as effective SDAs towards target products, as has been reported previously . In this regard, it is important to know whether the organic is occluded intact in the MWW zeolite.…”

Section: Resultsmentioning

confidence: 87%

“…High temperatures may cause degradation, and the degraded organic speciesm ight have worked as effective SDAs towards target products,a sh as been reported previously. [19] In this regard, it is important to know whether the organic is occluded intact in the MWW zeolite.T he CHN elemental analysiso ft he as-made MWW was carriedo ut and the resultsa re shown in Ta ble 2. The C/N ratio is close to the stoichiometric expectationf or 10BDMI,a nd the Np ercentage and thermogravimetric (TG) residues uggest that there are about three cation-like species per unit cell of the MWW framework.…”

Section: Characterizationmentioning

confidence: 99%

Synthesis of Pure Silica MWW Zeolite in Fluoride Medium by Using an Imidazolium‐Based Long Dication

Lü

Gómez‐Hortigüela

Camblor

2018

Chemistry A European J

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As the spacer length in 1,2‐dimethylimidazolium‐based dications increases beyond a specific point (six methylene units), they fail in structure‐directing towards STW zeolites in any synthetic conditions. These dications can instead produce, under fluoride concentrated conditions, either *BEA [in the case of the eight‐methylene‐unit structure‐directing agent (SDA)] or MWW (ten methylene units) zeolites. For any length of the dication, the default zeolite (MTW) is a relatively dense zeolite containing a unidimensional channel, whereas the zeolite demanding most specificity (STW, *BEA or MWW) is more porous, affording a larger concentration of the dication to be occluded. This work provides the first reported fluoride synthesis of pure silica MWW zeolites. Charge balance of the organic dications in this zeolite was achieved by combining “structural” silanolates, regular “connectivity defects” and occluded fluoride. Molecular mechanics calculations showed a perfect fit of the decamethylenebis(dimethylimidazolium) dication in the sinusoidal intralayer pore system of MWW. The calculations showed also that the dication is able to stabilize the interlayer space without disturbing the hydrogen‐bonding system that holds the layers together in the as‐made material. The 19F magic‐angle spinning (MAS) NMR presented two distinct resonances at −71 and −83 ppm, which, on the basis of DFT calculations, we tentatively assigned to fluoride occluded in [4662] and [415262] cages of the MWW structure, respectively. The same DFT study determines a different chemical shift of one methyl 13C nuclear magnetic resonance according to the imidazolium ring residing in the sinusoidal channels or in the large cup cavities, thus explaining an experimentally observed splitting of that resonance.

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“…Rojas and Camblor have developed a new organosilicate layered material, HPM-2 [ 85 ]. Upon calcination, HPM-2 transforms into the pure silica MTF zeolite by topotactic condensation.…”

Section: Other Examples Of Interlayer-expanded Zeolitesmentioning

confidence: 99%

“…But the silanol condensation between the newly incorporated silicon species occurs across the main window producing narrower (6 MR) rather than wider (10MR) windows (Fig. 3.15 ) [ 85 ]. However, this structural change may contribute to the development of zeolitic materials with new pore structure.…”

Section: Other Examples Of Interlayer-expanded Zeolitesmentioning

confidence: 99%

Interlayer Expansion of the Layered Zeolites

Yokoi

Tatsumi

2016

Green Chemistry and Sustainable Technology

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Zeolites with three-dimensional (3D) open-framework structures are generally crystallized under hydrothermal conditions. In addition to this conventional route, the formation of the 3D structures can be achieved by the structural conversion of zeolitic hydrous layer silicates (HLSs) through topotactic dehydration-condensation of silanols on the HLSs. The interlayer spacings can be expanded by the interlayer silylation of zeolitic HLSs, forming interlayer-expanded zeolite (IEZ) materials. The IEZ materials are crystalline and show similar physical and chemical properties to the conventional 3D zeolites. Creating larger interlayer space will provide more open entrance for reactants and decrease the diffusion constrains in catalytic reaction. In this chapter, recent developments of the IEZ materials, in particular interlayer-expanded MWW-, FER-, and CDO-type zeolites, are featured.

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HPM-2, the Layered Precursor to Zeolite MTF

Cited by 45 publications

References 50 publications

Crystal Transformation in Zeolitic-Imidazolate Framework

Crystal Transformation in Zeolitic-Imidazolate Framework

Synthesis of Pure Silica MWW Zeolite in Fluoride Medium by Using an Imidazolium‐Based Long Dication

Interlayer Expansion of the Layered Zeolites

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