DISINTEGRATION OF MESOPOROUS STRUCTURES OF MCM-41 AND MCM-48 IN WATER

It has been found that mesoporous structures of MCM-41 and MCM-48 disi ntegrate readily in distilled water around 370 K, while the structures can be stable in 100%-steam of 1 atmospheric pressure at much higher temperatures around 820 K. Thus, the structure disintegration is therm odynamically more favorable in water than under the steaming condition . X-ray powder diffraction and magic angle spinning Si-29 NMR spectros copy indicate that the disintegration of the mesoporous structures in water occurs due to silicate hydrolysis.