Determination of the Lamellar Phase Content in MCM-41 Using X-ray Diffraction, Nitrogen Adsorption, and Thermogravimetry

Self-consistent approaches for quantification of the phase composition of ordered mesoporous materials (OMMs) are proposed on the basis of powder X-ray diffraction (XRD), and, for the first time, on the basis of gas adsorption and thermogravimetry (TGA). A series of hexagonal MCM-41 samples containing different amounts of the lamellar phase was synthesized and characterized using XRD, nitrogen adsorption, and high-resolution TGA. To quantify the phase composition of these samples, pure hexagonal and lamellar materials with appropriate structural properties were prepared, and used to calibrate the quantitative XRD analysis and to develop a new methodology for the phase-composition determination on the basis of gas adsorption and TGA. The phase-composition determination from gas adsorption data was based on the mutual independence of adsorption on different components of mixtures. The relative amounts of components of the mixed phases were obtained by fitting the adsorption isotherms measured on the calcine...