Comparison of disordered mesoporous alumino silicates 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 surfac e acidity by using a polymer aluminosilicate precursor, and cationic surfac tant cetyltrimethylammonium bromide (CTAB) as the structure-directing agent . The comparison of stability, acidity and catalytic activity for the disor dered mesoporous materials and Al-MCM-41 has been studied by X-ray diffract ion (XRD), transmission electron microscopy (TEM), N-2 adsorption/desorptio n, infrared spectra, NH3-temperature program desorption (NH3-TPD) and Al-27 MAS NMR techniques. The results show that the disordered mesoporous materi als are very similar to mesoporous material MCM-41 as regards its uniform m esopore sizes at the mean value of 3.0 nm, while the mesoporous channel arr angement is fully disordered similar to that for KIT-1 prepared by the addi tive of organic salts. Scanning electron microscopic (SEM) images show that the products have regular microscopic arrays and layer sheet-like morpholo gy. The disordered mesoporous materials are hydrothermally more stable than highly ordered MCM-41. Furthermore, they show stronger acid strength and h igher cracking activities than Al-containing MCM-41. (C) 2001 Elsevier Scie nce B.V. All rights reserved.