ABNORMAL ADSORPTION-ISOTHERMS OF MCM-41 M OLECULAR-SIEVE AND CATALYSTS

The adsorption isotherms of mesoporous MCM-41 molecular sieve and supp orted MCM-41 catalysts have been investigated. These isotherms are hig hly abnormal as they not only exhibit two regions in their reversible parts, but also two hysteresis loops. The first discovered low pressur e hysteresis at relative pressure below 0.4 is assigned to the capilla ry condensation in the mesoporous channels, whereas the hysteresis nea r saturation pressure is assigned to the capillary condensation in the mesopores between aggregates of the molecular sieve. The adsorption i sotherms together with the XRD patterns of the samples can be used to characterize the orderliness of the structure and the accessibility of the mesoporous channels of MCM-41 effectively.