The synthesis and characterization of mesoporous molecular sieves MCM-41 with interconnected channels

The mesoporous MCM-41 materials with highly connected nanochannels have been obtained from the aluminosilicate-C_nTMAX-H₂O systems by a delayed neutralization procedure. The N₂ adsorption-desorption isotherm of the materials exhibits a large type B hysteresis at p/p₀∼ 0.5. The hysteresis effect is dependent on the synthetic condition and the Si/Al ratio. In spite of the chain length of the surfactant, this hysteresis takes place around the same p/p₀ value. From the TEM micrographs of the ultrathin section, one can clearly find that these mesoporous materials contain many structure defects, which are irregular shaped and the size distributes between 5.0-30.0 nm. Combining the above two evidences, we interpret the neighboring channels are interconnected through defects in channels walls. The diffusion of molecules inside these highly defective MCM-41 materials becomes more effective. We show that it leads to a better catalyst support material using ethylbenzene dehydrogenation reaction as an illustration.