2002 Fiscal Year Final Research Report Summary
Study of Capillary Condensation within Ordered Mesoporous Materials
| Project/Area Number |
12440201
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
機能・物性・材料
|
|---|
| Research Institution | Okayama University of Science |
|---|
Principal Investigator |
MORISHIGE Kunimitsu Okayama University of Science, Department of Chemistry, Professor, 理学部, 教授 (30113195)
|
|---|
| Project Period (FY) |
2000 – 2002
|
| Keywords | Capillary Condensation / Adsorption Hysteresis / Porous Materials |
|---|
| Research Abstract |
In order to elucidate s capillary condensation phenomenon, which is one of the long-standing problems in the field of colloid and interface science, we performed measurements of adsorption-desorption isotherms of simple gases on ordered mesoporous materials with well-defined porous structures. First, we constructed a high-pressure adsorption apparatus that enables adsorption measurements in the temperature and pressure ranges of 20-300K and 0-30 atm. At low temperature, the adsorption-desorption isotherms of nitrogen, oxygen, argon, and carbon dioxide on SBA-16 with ink-bottle type pore exhibited large hysteresis loops of type H2 in the IUPAC classification. When the temperature was increased, the hysteresis shrank and eventually disappeared at a hysteresis temperature, well below the bulk critical temperature. The plots of the relative pressures of capillary condensation and evaporation against the reduced temperature for the above four gases conform to a single curve. A phenomenologi
… More
cal model of a gas bubble in a liquid confined to the spherical pore of SBA-16 explains well the temperature dependence of adsorption hysteresis observed experimentally. This clearly indicates that the energy barrier for formation and disappearance of vapor bubbles in the liquid confined to the pores is responsible for the appearance of the adsorption hysteresis and the hysteresis temperature is not concerned with the so-called capillary criticality. At low temperatures, the adsorption-desorption isotherms of nitrogen and carbon dioxide on MCM-41 and SBA-15 with cylindrical pores exhibited relatively small hysteresis loops of type H1 in the IUPAC classification. In the cylindrical pores, however, the temperature dependence of the hysteresis loop for nitrogen was different from that for carbon dioxide. This indicates that the mechanism of the hysteresis in the cylindrical pores differs from that in the ink-bottle pores. The results for MCM-48 ordered mesoporous adsorbent with well-defined three-dimensional networks of cylindrical pores strongly suggests that interconnections among pores of almost the same size and geometry do not have a significant effect on the adsorption hysteresis and pore criticality. Less
|
Research Products
(12 results)
