Mesoporous molecular sieves of silica, and alumina, and porous materials of titania, zirconia, and niobia were synthesized by cationic and/or neutral templating methods. These porous materials were characterized by powder X-ray diffraction, transmission electron microscopy, N2 adsorption-desorption isotherms and water adsorption-desorption isotherms. Mesoporous molecular sieves of silica with surface areas of 956 and 1072 m2/g and of alumina with surface area of 407 m2/g were synthesized. The Ti, Zr and Nb oxide porous materials, however, showed smaller surface areas of 258, 178, and 77 m2/g, respectively, after calcination at 300°C and exhibited only small peaks for mesopores as determined by the pore-size distributions. Water adsorption-desorption isotherms of silica and alumina mesoporous molecular sieves showed Type V (weak interaction) and Type IV isotherms, respectively. The property of sudden filling of mesopores in the P/P0 range of 0.45 to 0.55 in silica mesoporous molecular sieves with well-defined hysteresis during desorption, can be used in the design of humidity sensors. The titania, zirconia and niobia porous materials showed Type I water adsorption-desorption isotherms which suggests that these are mainly microporous. These results suggest that water adsorption-desorption isotherms provide valuable information about mesoporous molecular sieves for their potential use as humidity sensors.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Mechanics of Materials
- Mechanical Engineering