AN INFRARED STUDY OF THE ADSORPTION OF BUTENES ON SURFACES OF POROUS VYCOR GLASS

1961 ◽  
Vol 39 (1) ◽  
pp. 42-60 ◽  
Author(s):  
L. H. Little ◽  
H. E. Klauser ◽  
C. H. Amberg
Keyword(s):  
Room Temperature ◽  
Acid Leaching ◽  
Hydroxyl Groups ◽  
Infrared Study ◽  
Vycor Glass ◽  
Surface Hydroxyl ◽  
Pure Silica ◽  
Porous Vycor Glass ◽  
Initial Adsorption ◽  
Low Coverage

The adsorption and reactions of the four butenes on porous Vycor glass at room temperature have been studied by infrared spectroscopy. Initial adsorption was rapid and was found to perturb the surface hydroxyl groups of the glass. In the case of the n-butenes rapid isomerization took place at room temperature. In addition to this the adsorbate spectra showed the occurrence of a slower reaction which led to an increase in saturated C—H groupings. C8 and higher compounds were shown to have formed; on outgassing at room temperature small amounts of cracking products were collected. The polymerization of isobutene was particularly rapid. Experiments at low coverage (θ ∼ 0.001–0.002) gave identical initial spectra for the n-butenes. These were discussed in terms of possible models for butene adsorption. A reduction in the alumina and zirconia content of the glass by acid leaching resulted in decreased rates of isomerization and polymerization, suggesting that one or both of these oxides are at least partially responsible for the activity of the glass. A pure silica aerogel was almost completely inactive. Quantitative measurements of the spectra of several monoolefins in solution were made for comparison with the surface species, in particular with respect to their molar intensities of absorption.

AN INFRARED STUDY OF THE ADSORPTION OF AMMONIA ON POROUS VYCOR GLASS

1964 ◽  
Vol 42 (4) ◽  
pp. 802-809 ◽  
Author(s):  
N. W. Cant ◽  
L. H. Little
Keyword(s):  
Hydrogen Exchange ◽  
Lone Pair ◽  
Acid Sites ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Infrared Study ◽  
Vycor Glass ◽  
Oh Groups ◽  
Surface Hydroxyl ◽  
Adsorption Sites

The infrared spectrum of ammonia adsorbed on porous glass at 20 °C and 150 °C has been studied in the region 1450–4000 cm−1. No absorption band due to the asymmetric bending mode of ammonia was observed but in the NH stretching region, bands occurred at 3280 cm−1, 3320 cm−1, 3365 cm−1, and 3400 cm−1. The bands at 3320 cm−1 and 3400 cm−1 were easily removed by evacuation and are due to ammonia molecules hydrogen bonded through the nitrogen atom to surface hydroxyl groups. The bands at 3280 cm−1 and 3365 cm−1 were not removed by evacuation even at 150 °C and are due to ammonia molecules held to surface Lewis acid sites by the nitrogen lone-pair electrons. The site for this adsorption is not a surface hydroxyl group. These results are further evidence for the existence of the two adsorption sites proposed by Folman and Yates. Deuteration of the surface OH groups was easily accomplished with D2O vapor at 300 °C and the rate of hydrogen exchange between adsorbed ammonia molecules and surface OD groups was found to be rapid.

Role of surface hydroxyl groups in promoting room temperature CO sensing by Pd-modified nanocrystalline SnO2

2010 ◽  
Vol 183 (10) ◽  
pp. 2389-2399 ◽  
Author(s):  
Artem V. Marikutsa ◽  
Marina N. Rumyantseva ◽  
Lada V. Yashina ◽  
Alexander M. Gaskov
Keyword(s):  
Room Temperature ◽  
Hydroxyl Groups ◽  
Surface Hydroxyl ◽  
Surface Hydroxyl Groups

Sensitivity of titania(B) nanowires to nitroaromatic and nitroamino explosives at room temperature via surface hydroxyl groups

2011 ◽  
Vol 21 (20) ◽  
pp. 7269 ◽  
Author(s):  
Danling Wang ◽  
Antao Chen ◽  
Sei-Hum Jang ◽  
Hin-Lap Yip ◽  
Alex K.-Y. Jen
Keyword(s):  
Room Temperature ◽  
Hydroxyl Groups ◽  
Surface Hydroxyl ◽  
Surface Hydroxyl Groups

Interactions of formic acid, formaldehyde, and methanol with germania surfaces

1969 ◽  
Vol 47 (6) ◽  
pp. 1077-1083 ◽  
Author(s):  
J. C. McManus ◽  
Kun-Ichi Matsushita ◽  
M. J. D. Low
Keyword(s):  
Formic Acid ◽  
Room Temperature ◽  
High Pressures ◽  
Hydroxyl Groups ◽  
Surface Hydroxyl ◽  
Surface Hydroxyl Groups ◽  
Treated Sample ◽  
Covalently Bonded ◽  
Surface Hydroxyls ◽  
Surface Formate

Infrared studies of the interaction of, respectively, formic acid, formaldehyde, and methanol with hydroxylated germania gel surfaces were made. Formic acid was dissociatively adsorbed to give covalently bonded formate species and new surface hydroxyl groups. Monomeric formic acid could not be observed. Degassing the treated sample at 246° removed most of the surface formate and the perturbing effects on the surface hydroxyls were also decreased. Two adsorbed species were observed when germania was exposed to high pressures (~10 Torr) of formaldehyde at room temperature. One species was very weakly bonded; it was removed by degassing at room temperature and its structure is tentatively taken as formaldehyde hydrogen-bonded to the surface hydroxyl groups. The other species had a spectrum very similar to polyoxymethylene, and it is proposed that it was in fact a surface polymer formed through the catalytic effect of the surface hydroxyl groups. Methanol was dissociatively adsorbed on germania surfaces. A species attributed to surface methoxide was formed and the concentration of the surface hydroxyl groups increased. Also, small concentrations of two other species were observed which gave absorptions at 2195 and 1727 cm−1, respectively. The band at 2195 cm−1 is assigned to a Ge—H species formed, possibly, at non-stoichiometric portions of the surface, while the latter species is tentatively ascribed to a surface formate species.

Magnetic Properties of Nanoscale Iron Particles Photodeposited in Glass

1995 ◽  
Vol 405 ◽  
Author(s):  
D. Sunil ◽  
H. D. Gafney ◽  
C. Tsang ◽  
M. H. Rafailovich ◽  
J. Sokolov ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Magnetic Properties ◽  
Magnetization Curve ◽  
Room Temperature ◽  
Iron Particles ◽  
Vycor Glass ◽  
Porous Vycor Glass ◽  
Transmission Electron ◽  
Nanoscale Iron Particles

AbstractTransmission Electron Microscopy(TEM) and magnetization measurements were used to study the correlation between size of the iron particles precipitated in glass and their magnetic properties. The iron particles les s than 40 Å in diameter photodeposited in porous Vycor glass(PVG) show superparamagnetic behavior at room temperature. As the size of the particles increases and reaches about 100 Å in diameter, the magnetization curve shows minor hysteresis with a very large coercivity.

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