Comparison of disordered mesoporous aluminosilicates with highly ordered Al-MCM-41 on stability, acidity and catalytic activity

A simple procedure has been described to directly synthesize hydrothermally stable, disordered mesoporous aluminosilicate materials with strong surface acidity by using a polymer aluminosilicate precursor, and cationic surfactant cetyltrimethylammonium bromide (CTAB) as the structure-directing agent. The comparison of stability, acidity and catalytic activity for the disordered mesoporous materials and Al-MCM-41 has been studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), N₂ adsorption/desorption, infrared spectra, NH₃-temperature program desorption (NH₃-TPD) and ²⁷Al MAS NMR techniques. The results show that the disordered mesoporous materials are very similar to mesoporous material MCM-41 as regards its uniform mesopore sizes at the mean value of 3.0 nm, while the mesoporous channel arrangement is fully disordered similar to that for KIT-1 prepared by the additive of organic salts. Scanning electron microscopic (SEM) images show that the products have regular microscopic arrays and layer sheet-like morphology. The disordered mesoporous materials are hydrothermally more stable than highly ordered MCM-41. Furthermore, they show stronger acid strength and higher cracking activities than Al-containing MCM-41.