Abstract:

The formation mechanism of mesoporous molecular sieve materials MCM-41 in different synthetic systems has been studied systemically. In the Na2O-(CTMA)2O-SiO2-H2O system, it is found that liquid-crystal templating mechanism should be that silica first forms silicated micelle with surfactant cation, then silica/CTMA+ micelle polymerizes with each other forming the hexagonal mesophase. The experimental results in the TMAOH-SiO2-CTMABr-H2O system supports the mechanism proposed for a surfactant-silica system from the lamellar to the hexagonal mesophase. Therefore, it is found that the formation mechanisms of MCM-41 molecular sieves are not the same under different synthetic conditions and in different synthetic systems.

Key words: Mesopore, Molecular sieve, MCM-41, Formation mechanism