Characterization of galloaluminosilicate MCM-41 molecular sieve

Abstract

A series of mesoporous galloaluminosilicate MCM-41 molecular sieves with various compositions have been synthesized. Hexadecyltrimethylammonium bromide was used as an organic surfactant in the synthesis. These materials were characterized with nitrogen sorption, powder X-ray diffraction (XRD), differential thermal analysis (DTA), thermogramitric analysis (TGA) , scanning electron microscope (SEM), transmission electron microscope (TEM) and solid state NMR. The solid products had the MCM-41 structure and contained only atomically dispersed gallium consistent with the framework gallium in MCM-41. Incorporation of either Ga or Al into the framework of MCM-41 affects the long-range order of the mesopores without damaging the essentially mesoporous nature of the materials. Gallium was easier to incorporate into the framework than aluminum. All of the materials had a uniform pore size distribution with pore size around 30 A. The morphologies of [Ga, AL]-MCM-41 were spherical particle packages. A small amount of aluminum had been expelled from the framework of MCM-41 upon calcination at 550°C.