Precipitation and growth of magnesium hydroxide nanopetals on zeolite 4A surfaces

Koh, Pei‐Yoong; Yan, Jing; Teja, Amyn S.

doi:10.1016/j.jcrysgro.2011.07.006

Cited by 10 publications

(6 citation statements)

References 40 publications

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“…In contrast, the MgO-KNaX-1.14 sample, with excess MgO, appears very different ( Figure 1c). The surfaceo ft he sample is covered www.chemsuschem.org by ah igh density of nanostructures, whichr esemble nanopetals, as recently named by Koh et al [35] Similarly,t he MgO-KNaX-1.32 sample with even higher excess MgO also has ah igh density of nanopetals, but this sample also exhibits other plate-like structures ( Figure 1d). As shown below,t his is an indication of MgO nanoparticles coating the surface.…”

Section: Characterization Of Zeolites Mgo-knaxmentioning

confidence: 61%

“…The growth of Mg(OH) 2 nanostructures on zeolite A has been previously reported . For example, Koh et al.…”

Section: Resultsmentioning

confidence: 94%

“…The growth of Mg(OH) 2 nanostructures on zeolite Ah as been previously reported. [35,38] For example, Koh et al found that the precipitation of petal-like nanostructures was controlled by the pH of the solution. [35] If the pH is above the isoelectric point of Mg(OH) 2 ,t he Mg(OH) 2 nuclei are negatively chargeda nd attractN a + ions to decrease the surfacee nergy.…”

Section: Characterization Of Zeolites Mgo-knaxmentioning

confidence: 99%

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Synthesis of C₄ and C₈ Chemicals from Ethanol on MgO‐Incorporated Faujasite Catalysts with Balanced Confinement Effects and Basicity

et al. 2016

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A new type of catalyst has been designed to adjust the basicity and level of molecular confinement of KNaX faujasites by controlled incorporation of Mg through ion exchange and precipitation of extraframework MgO clusters at varying loadings. The catalytic performance of these catalysts was compared in the conversion of C2 and C4 aldehydes to value-added products. The product distribution depends on both the level of acetaldehyde conversion and the fraction of magnesium as extraframework species. These species form rather uniform and highly dispersed nanostructures that resemble nanopetals. Specifically, the sample containing Mg only in the form of exchangeable Mg(2+) ions has much lower activity than those in which a significant fraction of Mg exists as extraframework MgO. Both the (C6+C8)/C4 and C8/C6 ratios increase with additional extraframework Mg at high acetaldehyde conversion levels. These differences in product distribution can be attributed to 1) higher basicity density on the samples with extraframework species, and 2) enhanced confinement inside the zeolite cages in the presence of these species. Additionally, the formation of linear or aromatic C8 aldehyde compounds depends on the position on the crotonaldehyde molecule from which abstraction of a proton occurs. In addition, catalysts with different confinement effects result in different C8 products.

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Section: Characterization Of Zeolites Mgo-knaxmentioning

confidence: 61%

“…The growth of Mg(OH) 2 nanostructures on zeolite A has been previously reported . For example, Koh et al.…”

Section: Resultsmentioning

confidence: 94%

Section: Characterization Of Zeolites Mgo-knaxmentioning

confidence: 99%

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Synthesis of C₄ and C₈ Chemicals from Ethanol on MgO‐Incorporated Faujasite Catalysts with Balanced Confinement Effects and Basicity

et al. 2016

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“…A new morphology that resembled inorganic petals or roughness was formed on the outer surface of the particles. Mg(OH) 2 has a tendency to form hexagonal platelets when crystallized from aqueous solutions because of its layered brucite crystal structure …”

Section: Resultsmentioning

confidence: 99%

Experimental study of the effect of zeolite 4A treated with magnesium hydroxide on the characteristics and gas‐permeation properties of polysulfone‐based mixed‐matrix membranes

Pakizeh

Hokmabadi

2016

J of Applied Polymer Sci

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Nowadays, new methods for gas-separation processes are being quickly developed. The separation of CH 4 /CO 2 and CH 4 /H 2 is usually the subject of most related research studies, especially in the membrane gas-separation process, because of their important role in industry. In this study, we attempted to improve the separation properties of a polysulfone/zeolite 4A mixed-matrix membrane by modifying the zeolite particle surface. The method included a simple ion-exchange reaction of magnesium chloride with ammonium hydroxide that yielded the formation and precipitation of magnesium hydroxide whiskers on the surface of the zeolites. The whiskers could omit most of the nonselective voids by interlocking the polymer chains through them and, consequently, improve the permeability, selectivity, and elastic modulus of the membranes. X-ray diffraction, energy-dispersive X-ray spectroscopy, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, and dynamic mechanical analysis proved all the changes recorded after the particle and membrane treatments. SEM images showed the petal-like morphology of the whiskers that formed on the surface of the particles after the reaction against the smooth surface of the untreated zeolite. At a 30 wt % loading of particles in the polymeric matrix, the selectivities for H 2 /CH 4 and CO 2 /CH 4 increased by 69 and 56%, respectively; in contrast, the H 2 and CO 2 permeabilities decreased by 2.5 and 10%, respectively. The modulus of elasticity for the treated membrane also increased by 14 and 30% compared to those of the pure and untreated membranes, respectively.

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“…However, those researchers mainly focused on the degree of hydration rather than the morphology of MH particle affected by the hydrating agent. The morphology analysis method was usually used when MH was prepared by solution precipitation method . Seawater is a natural solution contains magnesium ions.…”

Section: Introductionmentioning

confidence: 99%

Morphology analysis of magnesium hydroxide prepared by magnesium oxide hydration within seawater

Tang

Guo

Liu

et al. 2015

Crystal Research and Technology

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In order to investigate the microstructure of magnesium oxide hydration product within seawater, two reaction conditions (liquid-solid and gas-liquid-solid) and two solutions (seawater and deionized water) were adopted for magnesium oxide hydration. The characterization of the hydration product using X-Ray diffraction and scanning electron microscope was performed. Experimental results indicate that cations and anions in seawater promote the hydration. Most of the hydration products within seawater system display flower-like morphology, but the agglomeration phenomenon is not obvious within deionized water system, especially for the supernatant layer products within deionized water system under gas-liquid-solid reaction condition. There was no stratification phenomenon occurred when MgO hydrated with seawater under three-phase reaction condition.

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Precipitation and growth of magnesium hydroxide nanopetals on zeolite 4A surfaces

Cited by 10 publications

References 40 publications

Synthesis of C₄ and C₈ Chemicals from Ethanol on MgO‐Incorporated Faujasite Catalysts with Balanced Confinement Effects and Basicity

Synthesis of C₄ and C₈ Chemicals from Ethanol on MgO‐Incorporated Faujasite Catalysts with Balanced Confinement Effects and Basicity

Experimental study of the effect of zeolite 4A treated with magnesium hydroxide on the characteristics and gas‐permeation properties of polysulfone‐based mixed‐matrix membranes

Morphology analysis of magnesium hydroxide prepared by magnesium oxide hydration within seawater

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Precipitation and growth of magnesium hydroxide nanopetals on zeolite 4A surfaces

Cited by 10 publications

References 40 publications

Synthesis of C4 and C8 Chemicals from Ethanol on MgO‐Incorporated Faujasite Catalysts with Balanced Confinement Effects and Basicity

Synthesis of C4 and C8 Chemicals from Ethanol on MgO‐Incorporated Faujasite Catalysts with Balanced Confinement Effects and Basicity

Experimental study of the effect of zeolite 4A treated with magnesium hydroxide on the characteristics and gas‐permeation properties of polysulfone‐based mixed‐matrix membranes

Morphology analysis of magnesium hydroxide prepared by magnesium oxide hydration within seawater

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Synthesis of C₄ and C₈ Chemicals from Ethanol on MgO‐Incorporated Faujasite Catalysts with Balanced Confinement Effects and Basicity

Synthesis of C₄ and C₈ Chemicals from Ethanol on MgO‐Incorporated Faujasite Catalysts with Balanced Confinement Effects and Basicity