MCM-41 AS-SYNTHESIZED AND CALCINED MATERIALS - TEMPORAL DEVELOPMENT OF X-RAY REFLECTION INTENSITY AND PORE VOLUME

The comparison of the temporal development of the X-ray reflection int ensities of as-synthesized and calcined MCM-41 materials demonstrates that 90% of the hexagonal channel arrangement is formed after 5-6 h wh ereas the fully developed mesopore structure requires 72 h. The progre ss of the reaction can be quantified by reference to the maximum pore volume that can be obtained from adsorption isotherms or from model ca lculations based on the packing density of the surfactant and the pore wall thickness of ca. 1 nm. For low critical micelle concentrations t he maximum amount of MCM-41 formed can be calculated and used as a ref erence in order to follow quantitatively the progress of the MCM-41 fo rmation.