Determination of the hydroxyl group content in silica by thermogravimetry and a comparison with 1H MAS NMR results

Ek, Satu; Root, Andrew; Peussa, Marko; Niinistö, Lauri

doi:10.1016/s0040-6031(01)00618-9

Cited by 221 publications

(150 citation statements)

References 15 publications

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“…It is well known that alumina dehydroxylates during phase transition from gamma to alpha when temperature increases. In the present study, as shown in Figure 5, 700AlSi exhibits the highest dehydration and dehydroxylation rate and its weight decreases up to 1100 • C. In contrast, the other three samples show a mass loss up to 700 • C and then remained almost constant up to 1100 • C. in the temperature range 130-1100 °C, as reported by Ek et al [33]. It is well known that alumina dehydroxylates during phase transition from gamma to alpha when temperature increases.…”

Section: Hydroxyl Group Content Measurementsupporting

confidence: 86%

“…The previously calcined supports at different temperatures were heated in TGA with a ramp rate of 10 • C/min in an inert gas flow. The weight loss can be divided into two stages: (1) removal of physisorbed water (dehydration) in the temperature range 25-130 • C; and (2) removal of surface hydroxyl groups (dehydroxylation) in the form of water in the temperature range 130-1100 • C, as reported by Ek et al [33]. It is well known that alumina dehydroxylates during phase transition from gamma to alpha when temperature increases.…”

Section: Hydroxyl Group Content Measurementmentioning

confidence: 91%

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Effect of Support Pretreatment Temperature on the Performance of an Iron Fischer–Tropsch Catalyst Supported on Silica-Stabilized Alumina

et al. 2018

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Abstract:The effect of support material pretreatment temperature, prior to adding the active phase and promoters, on Fischer-Tropsch activity and selectivity was explored. Four iron catalysts were prepared on silica-stabilized alumina (AlSi) supports pretreated at 700 • C, 900 • C, 1100 • C or 1200 • C. Addition of 5% silica to alumina made the AlSi material hydrothermally stable, which enabled the unusually high support pretreatment temperatures (>900 • C) to be studied. High-temperature dehydroxylation of the AlSi before impregnation greatly reduces FeO·Al 2 O 3 surface spinel formation by removing most of the support-surface hydroxyl groups leading to more effectively carbided catalyst. The activity increases more than four-fold for the support calcined at elevated temperatures (1100-1200 • C) compared with traditional support calcination temperatures of <900 • C. This unique pretreatment also facilitates the formation of ε -Fe 2.2 C rather than χ-Fe 2.5 C on the AlSi support, which shows an excellent correlation with catalyst productivity.

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Section: Hydroxyl Group Content Measurementsupporting

confidence: 86%

Section: Hydroxyl Group Content Measurementmentioning

confidence: 91%

Effect of Support Pretreatment Temperature on the Performance of an Iron Fischer–Tropsch Catalyst Supported on Silica-Stabilized Alumina

et al. 2018

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“…The second decrease takes place from about 100 to 1000°C and corresponds to 2.2 % mass loss. It is assigned to gradual condensation of the surface silanol groups, described as the process of dehydroxylation [40]. For SBA-15 the analogous mass losses related to dehydration and dehydroxylation were 4.9 and 3.1 %, respectively.…”

Section: Thermal Analysis: Tgamentioning

confidence: 95%

Mesoporous drug carrier systems for enhanced delivery rate of poorly water-soluble drug: nimodipine

et al. 2015

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Two mesoporous silica materials: MCM-41 and SBA-15 were applied as potential nanocarriers for poorly soluble drug-nimodipine. Drug incorporation was performed using modified adsorption from the solution method and loaded samples before and after washing procedure were studied. The physical properties were verified by: differential scanning calorimetry, X-ray powder diffraction, electron microscopies (SEM/TEM) and Fourier-transform infrared spectroscopy (FT-IR). FT-IR results for bulk nimodipine were interpreted on the basis of first principles calculations (DFT). As a result of encapsulation process, in both matrices nimodipine appeared simultaneously in two forms: crystalline and amorphous, but the first one turned out to be easily removable during washing procedure. The in vitro dissolution and release tests were performed with ultra pure water under supersaturating conditions. The release rate of the amorphous nimodipine from mesoporous silica materials was at least 70 times higher than dissolution rate of bulk drug, thus revealed a potential usefulness of such carrier in future pharmaceutical applications in terms of delivery of poorly soluble drugs.

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“…A 2.0 g sample of calcined MCM-41 was pretreated in the ALD reactor in nitrogen atmosphere at 180 °C for 3 h to remove physisorbed water [13]. An amount of 2.5 mL (14. an increase in the final amino group content, indicating that the value of 1.2 mmol/g corresponds to the maximum loading which could be achieved by this deposition method.…”

Section: Vapor Phase Depositionmentioning

confidence: 99%

A comparative study of the functionalization of mesoporous silica MCM-41 by deposition of 3-aminopropyltrimethoxysilane from toluene and from the vapor phase

Ritter

Nieminen²,

Karppinen³

et al. 2009

Microporous and Mesoporous Materials

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Determination of the hydroxyl group content in silica by thermogravimetry and a comparison with 1H MAS NMR results

Cited by 221 publications

References 15 publications

Effect of Support Pretreatment Temperature on the Performance of an Iron Fischer–Tropsch Catalyst Supported on Silica-Stabilized Alumina

Effect of Support Pretreatment Temperature on the Performance of an Iron Fischer–Tropsch Catalyst Supported on Silica-Stabilized Alumina

Mesoporous drug carrier systems for enhanced delivery rate of poorly water-soluble drug: nimodipine

A comparative study of the functionalization of mesoporous silica MCM-41 by deposition of 3-aminopropyltrimethoxysilane from toluene and from the vapor phase

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