Structure Organization of Silicate Polyanions with Surfactants: A New Approach to the Syntheses, Structure Transformations, and Formation Mechanisms of Mesostructural Materials

Fyfe, C. A.; Fu, Geng

doi:10.1021/ja00143a014

Cited by 113 publications

(90 citation statements)

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“…3) exhibit a broad diffraction peak between 15-35 degrees, corresponding to the amorphous SiO 2 of the supports [30,31]. There are no diffraction peaks of CeO 2 were observed indicates that well-dispersed of Ce species in Ce-doped SBA-15, this result in accord with the DRS analysis result.…”

Section: Physicochemical Properties Of Loaded Ptsupporting

confidence: 79%

Preparation of Promoted Pt/SBA-15 and Effect of Cerium on the Catalytic Activity over Carbon Monoxide Oxidation Conversion Reaction

et al. 2009

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Pt/SBA-15 catalysts are modified by cerium dopant and agent. Experimental results show that the catalytic activities of Pt/SBA-15 can be deeply promoted by the introduced cerium species, especially while both cerium dopant and cerium agent are introduced. The promoted catalytic activities are due to the occurrence of new coordination environments, promoted physicochemical properties of Pt loading created by both introduced cerium species, and the strong metal-support interactions created by the cerium loading.

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Section: Physicochemical Properties Of Loaded Ptsupporting

confidence: 79%

Preparation of Promoted Pt/SBA-15 and Effect of Cerium on the Catalytic Activity over Carbon Monoxide Oxidation Conversion Reaction

et al. 2009

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“…Fyfe et al reported a phase transition from a layered complex, which composed of double-four-ring silicates Si 8 O 16 8-and C 16 TMA cations, to cubic MCM-48, to lamellar MCM-50, and to hexagonal MCM-41, in turn by acid treatment. 33 The Q 3 /Q 4 ratios of the products decrease by this transformation; therefore, the charge of the silicate frameworks also decreases. On the basis of both reports, the results obtained in this study are quite reasonable.…”

Section: Effects Of the Synthetic Conditionsmentioning

confidence: 99%

Synthesis and Characterization of Lamellar and Hexagonal Mesostructured Aluminophosphates Using Alkyltrimethylammonium Cations as Structure-Directing Agents

1999

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Lamellar and hexagonal mesostructured aluminophosphates (AlPOs) were prepared and characterized. The lamellar mesostructured AlPO (APW-1) formed hydrothermally and the condensed framework was composed of alternating AlO 4 and PO 4 units. The hexagonal mesostructured AlPO (APW-2) is formed by transformation of a layered precipitate composed of both aluminophosphate oligomers and alkyltrimethylammonium (ATMA) cations. Calcined APW-2 had a mesoporosity with the BET surface area of 980 m 2 g -1 and a pore diameter of 1.8 nm after substantial shrinkage of the framework. Lamellar APW-1 formed under most of the conditions surveyed, while hexagonal APW-2 was obtained under very restricted conditions. In this system, the charge matching in the products is the most important factor, although the assemblies of ATMA cations are essential as the structure-directing agents.

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“…la). The notation Ho is used to represent this mesophase on the basis of the nomenclature by Tiddy for surfactant liquid crystal phases [23] and by Fyfe et al for mesophases [24]. Capital H designates tubular mesophases, L designates lamellar phases, and V designates MCM-48 material, while subscripts are used to distinguish similar phases produced at different reaction times.…”

Section: Xrdmentioning

confidence: 99%

Electron spin resonance and electron spin echo modulation studies of Fe-containing mesoporous MCM-48 molecular sieves

Kevan

2001

Appl. Magn. Reson.

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Through electron spin resonance (ESR) and electron spin echo modulation (ESEM) studies, three Fe(III) species are found in liquid ion-exchanged Fe-MCM-48 and synthesized FeMCM-48. Species A with ESR parameters gA = 4.30 with a line width of 160 G is observed in hydrated samples. This species is accompanied by a shoulder at g = 7.60 and is assigned to distorted tetrahedral Fe(III) likely located at framework defect sites. Species B is a broad peak centered at ga = 2.00 and is assigned to distorted octahedral Fe(III) located at extraframework sites. This species is also observed in dehydrated samples. Species C is a very narrow isotropic signal at gC = 4.30 with a line width of 30 G and is only observed in synthesized mesophase materials. It is consistent with rhombic Fe(III) with zero field parameters D and E corresponding to DIE = 1/3 and is assigned to tetrahedral Fe(III) located at framework sites. Framework Fe(III) in FeMCM-48 is less accessible to ND 3 than is extraframework Fe(III) in Fe-MCM-48. On the basis of deuterium ESEM data, framework Fe(III) in synthesized FeMCM-48 directly coordinates to two D 2 0 or CH3OD molecules and interacts more weakly with two more molecules. However, no deuterium ESEM is observed for extraframework Fe(III) in ion-exchanged Fe-MCM-48 with adsorbed D20 or CH 2 OD. It is also found that Fe(III) is incorporated into the framework of FeMCM-48 at an early stage of the formation of the MCM-48 mesostructure.

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Structure Organization of Silicate Polyanions with Surfactants: A New Approach to the Syntheses, Structure Transformations, and Formation Mechanisms of Mesostructural Materials

Cited by 113 publications

References 0 publications

Preparation of Promoted Pt/SBA-15 and Effect of Cerium on the Catalytic Activity over Carbon Monoxide Oxidation Conversion Reaction

Preparation of Promoted Pt/SBA-15 and Effect of Cerium on the Catalytic Activity over Carbon Monoxide Oxidation Conversion Reaction

Synthesis and Characterization of Lamellar and Hexagonal Mesostructured Aluminophosphates Using Alkyltrimethylammonium Cations as Structure-Directing Agents

Electron spin resonance and electron spin echo modulation studies of Fe-containing mesoporous MCM-48 molecular sieves

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