Influence of water on the pillaring of montmorillonite with aminopropyltriethoxysilane

Ahenach, J.; Cool, Pegie; Vansant, Etienne F.; Lebedev, Oleg I.; Landuyt, J. Van

doi:10.1039/a901888c

Cited by 13 publications

(13 citation statements)

References 20 publications

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“…5, these pillared clays had BET surface areas from 160 to 270 m 2 g of which were half that of the other pillared montmorillonite. 6,11,13 This result also conformed to that of fluorine mica. 15,16 This contraction might be due to the insufficiency of the clay delamination.…”

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confidence: 75%

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Preparation of Silica-Pillared Fluorohectorite by Cointercalation of Polysiloxane and Polyvinyl Alcohol

Nakao

Nogami

2005

J. Ceram. Soc. Japan

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Silica-pillared clays with mesopores were prepared from fluorohectorite, aminopropyltriethoxysilane APS and tetraethoxysilane TEOS affected using polyvinyl alcohol PVA. The presence of PVA was important in this synthesis and was effective on the porosity of the obtained silica-pillared clays. Based on the X-ray diffraction measurements, the basal spacings of the silica-pillared clays increased from 1.7 to 5.6 nm with an increase in the PVA concentration. As with the basal spacings, the peaks of the pore size distribution and the average pore diameter shifted up to approximately 3 nm. The pore volumes corresponded to the basal spacings expanded by cointercalation of PVA and polysiloxane. The pore properties and structures of the pillared clays were investigated and the results indicated the relation between the layer structure and pore structure. Key-words : Fluorohectorite, Intercalation, Mesoporous, Pillared clay, Sol-gel method, Polysiloxane IntroductionThe successful intercalations of pillaring species into the interlayer space of clay minerals have led to many attempts to prepare new classes of porous materials, which exhibit interesting properties for adsorption, separation and catalysis. Pillared clays are attracting interest with regard to their use under severe conditions since inorganic materials have better thermal and chemical stabilities than organic materials. Various sizes of inorganic polyhydroxocations have been intercalated as pillaring precursors to control the pore size.1-3 Silica is one of the oxides of interest for obtaining thermally stable and catalytically active pillared clays. Silica pillared clays have been prepared from a titania-silica or iron oxide-silica complex sol because silica precursors are silicate anions, which cannot enter between the clay sheets. [4][5][6] In spite of the large interlayer distance of the sol pillared clay, the obtained pores were mainly micropores due to the multilayer stacking the nanosize sol particles between the silicate layers. The mesoporous sol pillared clays have been synthesized using quaternary ammonium surfactants as templating agents.5,7-10 On the other hand, a silica pillared montmorillonite has been synthesized using ion exchangeable aminopropyltriethoxysilane APS to intercalate the clay sheets in aqueous solution instead of inorganic polyhydroxocations. The polycondensation by APS hydrolysis between the silicate layers was expected to form larger pores.11 However, there was no significant increase in the basal spacing even though the silica content significantly increased with the APS. The pore properties were not increased by the addition of an excess APS for the ion exchange capacity. The pre-intercalation of the alkylammonium ions between the clay layers and the controlled addition of water to the reaction achieved a significant enhancement in the surface area and pore volume. Polysiloxane, which are polycondensation of APS molecules, has been incorporated into

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confidence: 75%

“…The polycondensation by APS hydrolysis between the silicate layers was expected to form larger pores. 11 However, there was no significant increase in the basal spacing even though the silica content significantly increased with the APS. The pore properties were not increased by the addition of an excess APS for the ion exchange capacity.…”

Section: Introductionmentioning

confidence: 86%

Preparation of Silica-Pillared Fluorohectorite by Cointercalation of Polysiloxane and Polyvinyl Alcohol

Nakao

Nogami

2005

J. Ceram. Soc. Japan

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“…The intercalation of APS was expected to expand the interlayer distance due to the polycondensation by hydrolysis. 10 However, there was no significant increase in the basal spacing even though the silica content significantly increased with the APS. The porosities were not increased by the addition of an excess APS for ion exchange capacity.…”

Section: Introductionmentioning

confidence: 86%

Effect of Polyvinyl Alcohol on the Synthesis of Silica-Pillared Clay by Using 3-Aminopropyltriethoxysilane

Nakao

Nogami

2005

J. Ceram. Soc. Japan

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Silica pillared clays with large interlayer distance were synthesized by the simultaneous intercalation of 3-aminopropyltriethoxysilane APS and polyvinyl alcohol PVA . Characterization of the synthetic silica pillared clay was done by X-ray diffraction measurement, nitrogen adsorption-desorption measurement and X-ray fluorescence analysis. The gallery height of the synthesized pillared clay was 1.3 nm in the presence of PVA, and it was found that the gallery height was twice as large as that of the pillared clay synthesized without using PVA. The specific surface area and pore volume of the pillared clay obtained with PVA were larger than those obtained without PVA. It was confirmed that the interlayer distance was enlarged with increase in the amount of pillaring precursors only by using PVA. 1 -3 Silica is one of the oxides of interest to obtain thermally stable and catalytically active pillared clays. Silica-pillared clays have been synthesized from a titania-silica or iron oxide-silica complex sol, because silica precursors are silicate anions which cannot enter between the negatively charged clay sheets. 4 -6 In spite of the large interlayer distance of the sol pillared clay, the pores were mainly micropores due to the multilayer stacking of the nanosize sol particles between the silicate layers. The mesoporous sol pillared clays have been synthesized by using surfactants.5 ,7 -9 On the other hand, a silica-pillared montmorillonite has been synthesized using ion exchangeable aminopropyltriethoxysilane APS instead of inorganic precursors. The intercalation of APS was expected to expand the interlayer distance due to the polycondensation by hydrolysis.10 However, there was no significant increase in the basal spacing even though the silica content significantly increased with the APS. The porosities were not increased by the addition of an excess APS for ion exchange capacity. Kaneko et al. have investigated the structure and the properties of the polysiloxane made from APS.11 The polysiloxane was dispersed in water. Pillared clays having the large surface areas and pore volumes have been prepared by introducing cationic oligomers using polyvinyl alcohol PVA .12 -15 The PVA presence in the interlayer space retained the distance between the silicate layers expanded. PVA was incorporated into the interlayer region

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“…In the case of the mixture of ethanol and water, it is likely that hydrolysis and condensation occurs before intercalation [21]. With the hydrolysis and polymerization, different polymers with various sizes can be formed, such as linear, monocyclic, polycyclic and 'cagelike,' depending on the water amount in the reaction system [22].…”

Section: Powder X-ray Diffractionmentioning

confidence: 99%

Grafting of montmorillonite with different functional silanes via two different reaction systems

Shen

Zhu

et al. 2007

Journal of Colloid and Interface Science

114

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Silane grafted montmorillonites were synthesized by using 3-aminopropyltriethoxysilane and trimethylchlorosilane via two different grafting reaction systems: (a) ethanol-water mixture and (b) vapor of silane. The resulting products were investigated using Fourier transform infrared (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA). XRD patterns demonstrate that silane was intercalated into the montmorillonite gallery, as indicated by the increase of the basal spacing. The product prepared by vapor deposition has a larger basal spacing than that obtained from solution, due to the different extent of silane hydrolysis in various grafting systems. TGA curves indicate that the methyl groups penetrate into the siloxane clay are the primary reason for the decrease of the dehydroxylation temperature of the grafted products. 3-Aminopropyltriethoxysilane in the grafted montmorillonite adopts a bilayer arrangement while trimethylchlorosilane adopts a monolayer arrangement within the clay gallery.

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Influence of water on the pillaring of montmorillonite with aminopropyltriethoxysilane

Cited by 13 publications

References 20 publications

Preparation of Silica-Pillared Fluorohectorite by Cointercalation of Polysiloxane and Polyvinyl Alcohol

Preparation of Silica-Pillared Fluorohectorite by Cointercalation of Polysiloxane and Polyvinyl Alcohol

Effect of Polyvinyl Alcohol on the Synthesis of Silica-Pillared Clay by Using 3-Aminopropyltriethoxysilane

Grafting of montmorillonite with different functional silanes via two different reaction systems

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