Room temperature synthesis of mesoporous aluminosilicate materials

Mesoporous aluminosilicate materials with the MCM-41 structure and atomic Si/Al ratio of 8 have been synthesized at room temperature using aluminum chloride hexahydrate and tetraethyl orthsilicate as the sources of materials. The products were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption and 27Al magic-angle-spinning (MAS) NMR. XRD results show that thermal stability of the product can be improved when aluminosilicate MCM-41 is synthesized following a procedure of pH adjustment from 11∼12 to 5∼6 with hydrochloric acid. NMR analysis clearly shows that both 4- and 6-coordinate aluminum is present in the calcined products. High-resolution electron micrograph first exhibits the presence of nanocrystallites, which could be regions of segregated alumina, in amorphous aluminosilicate phase.