NOTE ON THE DETECTION OF AN APPARENT PHASE TRANSITION OF ADSORBED WATER ON POROUS VYCOR GLASS BY MEASUREMENTS OF DIMENSIONAL CHANGES

1959 ◽  
Vol 37 (8) ◽  
pp. 1278-1280 ◽  
Author(s):  
C. Hodgson ◽  
R. McIntosh
Keyword(s):  
Phase Transition ◽  
Volume Ratio ◽  
Adsorbed Water ◽  
Present Form ◽  
Vycor Glass ◽  
Dimensional Changes ◽  
Porous Vycor Glass ◽  
Moderate Sensitivity ◽  
Length Changes ◽  
A New Technique

A new technique is described for detecting possible phase transitions of adsorbates. The method involves the measurement of length changes of the solid, but only solids for which the surface-to-volume ratio is large could be used with the present form of instrument because of its moderate sensitivity. Using this measurement an apparent phase transition for water adsorbed on porous Vycor glass has been detected at approximately −22 °C.

PHASE TRANSITIONS OF WATER AND XENON ADSORBED IN POROUS VYCOR GLASS

1963 ◽  
Vol 41 (12) ◽  
pp. 3095-3107 ◽  
Author(s):  
G. Litvan ◽  
R. McIntosh
Keyword(s):  
Phase Transition ◽  
Capillary Condensation ◽  
Adsorbed Water ◽  
Surface Concentration ◽  
Adsorptive Capacity ◽  
Temperature Cycle ◽  
Length Variation ◽  
Vycor Glass ◽  
Porous Vycor Glass ◽  
Lower Temperature

Measurements of the expansion of porous Vycor glass containing fixed quantities of adsorbed water indicate that in every instance a phase transition starts below −50 °C, with the main change occurring below −160 °C. Two other anomalies of the length variation were observed near −22 °C and −7 °C when the amount of adsorbed water exceeded the value equivalent to two monolayers. The length of the adsorbent after completion of a temperature cycle was different from the initial length. This is thought to be due to damage suffered by the glass and to the fact that the length of the adsorbent is different for adsorption and desorption although the quantity adsorbed may be the same.The phase transition of adsorbed xenon takes place below the normal triple point and is a function of surface concentration as shown by length variations and equilibrium pressures for fixed quantities adsorbed. All transitions are gradual and hysteresis is exhibited by the isosteres. The adsorption isotherms for xenon – Vycor glass show a decreasing adsorptive capacity and a contraction of the hysteresis loop with lower temperature. The inadequacy of the capillary condensation theory of adsorption in relation to these results is discussed.

THE FREEZING OF WATER AND BENZENE IN POROUS VYCOR GLASS

1960 ◽  
Vol 38 (6) ◽  
pp. 958-971 ◽  
Author(s):  
C. Hodgson ◽  
R. McIntosh
Keyword(s):  
Capillary Condensation ◽  
Solid Phase ◽  
Adsorbed Water ◽  
Freezing Process ◽  
Pressure Measurements ◽  
Equilibrium Pressure ◽  
Vycor Glass ◽  
Dimensional Changes ◽  
Porous Vycor Glass

Freezing has been detected in the adsorbed water and benzene of porous Vycor glass at temperatures below that at which the bulk phases freeze. The evidence presented by equilibrium pressure measurements and dimensional changes of the systems is considered in terms of theories of capillary condensation and freezing in cements and soil. Although not all the results can be explained, it is concluded that the freezing process is a gradual one for both adsorbate–adsorbent systems. The evidence further suggests that hysteresis is absent in isotherms if the solid phase has formed.

Small-angle neutron scattering study of adsorbed water in porous Vycor glass: Supercooling phase transition and interfacial structure

1989 ◽  
Vol 39 (1) ◽  
pp. 633-636 ◽  
Author(s):  
M. J. Benham ◽  
J. C. Cook ◽  
J-C. Li ◽  
D. K. Ross ◽  
P. L. Hall ◽  
...  
Keyword(s):  
Phase Transition ◽  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Adsorbed Water ◽  
Interfacial Structure ◽  
Vycor Glass ◽  
Porous Vycor Glass ◽  
Scattering Study ◽  
Neutron Scattering Study

Small angle neutron scattering studies of adsorbed water in porous Vycor glass

1989 ◽  
Vol 156-157 ◽  
pp. 185-188 ◽  
Author(s):  
J.C. Li ◽  
D.K. Ross ◽  
P.L. Hall ◽  
R.K. Heenan
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Adsorbed Water ◽  
Vycor Glass ◽  
Porous Vycor Glass

THE HYSTERESIS LOOP IN ADSORPTION ISOTHERMS ON POROUS VYCOR GLASS AND ASSOCIATED DIMENSIONAL CHANGES OF THE ADSORBENT. II

1957 ◽  
Vol 35 (8) ◽  
pp. 745-756 ◽  
Author(s):  
H. W. Quinn ◽  
R. McIntosh
Keyword(s):  
Adsorption Isotherm ◽  
Hysteresis Loop ◽  
Adsorption Isotherms ◽  
Stable States ◽  
Vycor Glass ◽  
Dimensional Changes ◽  
Porous Vycor Glass ◽  
Porous Adsorbent

The causes of hysteresis in the adsorption isotherms on porous Vycor glass are discussed, employing as ancillary evidence the dimensional changes of the adsorbent. Diagrams of domain complexions for pores of the ink-bottle type are given and used to develop certain of Everett's theorems. Evidence showing the interdependence of domains or voids is given. The compressibility of the porous adsorbent is evaluated and shown to differ with different adsorbates, which suggests distributions of adsorbed matter specific to the adsorbate. A thermodynamic development is given, which indicates that the most stable states of the system are represented along the adsorption isotherm. Finally, certain anomalous findings in the region of low adsorption and within the hysteresis loop are reported and discussed.

ChemInform Abstract: THE PHOTOSENSITIZED ISOMERIZATION OF 2-BUTENES BY SENSITIZERS ADSORBED ON POROUS VYCOR GLASS

1974 ◽  
Vol 5 (49) ◽  
pp. no-no
Author(s):  
KIYOSHI OTSUKA ◽  
AKIRA MORIKAWA
Keyword(s):  
Vycor Glass ◽  
Porous Vycor Glass

scholarly journals Thermal properties of metal-metal bonded Pd(I) complexes supported onto porous Vycor glass

2008 ◽  
Vol 80 (2) ◽  
pp. 263-269
Author(s):  
Iara F. Gimenez ◽  
Oswaldo L. Alves
Keyword(s):  
Solid State ◽  
Thermal Stabilization ◽  
Decomposition Products ◽  
Vycor Glass ◽  
X Ray ◽  
Porous Vycor Glass ◽  
Metal Metal ◽  
Condensed Phosphates ◽  
Diffuse Reflectance Infrared ◽  
Immobilized Complexes

Thermal behavior of the complexes Pd2(dppm)2Cl2, Pd2(dppm)2(SnCl3)Cl and Pd2(dppm)2(SnCl3)2 (dppm = bis[diphenylphosphino(methane)], ((C6H5)2PCH2P(C6H5)2) in the solid state and immobilized onto porous Vycor glass was studied. Similar decomposition mechanisms were observed for the solid and immobilized complexes, with a small thermal stabilization upon immobilization. The decomposition products were characterized by X-ray diffractometry, Raman and diffuse reflectance infrared spectroscopy, which indicated the presence of a mixture of metallic palladium and oxidized species such as PdO,condensed phosphates, SnO2 and SnP2O7. According to X-ray diffractometry, the decomposition products of the immobilized complexes presented higher amounts of PdO than the solid-state residues, probably as an effect of interactions with silanol groups present in the glass surface.

scholarly journals Isomerization ofcis-2-Butene Caused by Electronically-excited Sulfur Dioxide (3B1) Adsorbed on Porous Vycor Glass

1978 ◽  
Vol 51 (2) ◽  
pp. 367-371 ◽  
Author(s):  
Kiyoshi Otsuka ◽  
Masaki Fukaya ◽  
Akira Morikawa
Keyword(s):  
Sulfur Dioxide ◽  
Vycor Glass ◽  
Porous Vycor Glass ◽  
Electronically Excited

Photochemistry of Group 6B hexacarbonyls adsorbed onto porous Vycor glass. Evidence for the formation of methane from carbon species in the glass

1988 ◽  
Vol 27 (15) ◽  
pp. 2733-2742 ◽  
Author(s):  
Robert C. Simon ◽  
Edgar A. Mendoza ◽  
Harry D. Gafney
Keyword(s):  
Vycor Glass ◽  
Carbon Species ◽  
Porous Vycor Glass
Sign in / Sign up

Export Citation Format

Share Document