SBA-15 is a mesoporous silicon-based molecular sieve with a highly ordered hexagonal straight pore structure (p6mm), the pore size can vary from 5 to 50 nm, and the pore wall is thicker.
XRD test of ordered mesoporous materials
Powder XRD can be divided into wide-angle XRD and small-angle XRD according to the size of the diffraction Angle. In general, the atomic arrangement of crystals is ordered, and most of the crystal face spacing and atomic spacing are an order of magnitude, that is, below 0.2 nm. At present, the atomic arrangement of most mesoporous materials is disordered, and the XRD diffraction peak is based on the order of mesoporous channels.
The position of the pore can be determined from the XRD pattern, and the diffraction intensity reflects the order of the pore and the density of the pore wall in the material. After the material is synthesized, the phase structure of the material is determined by small-angle XRD.
X-ray and SEM tests of ordered mesoporous materials
Due to the large order scale of the ordered mesoporous materials, the ordered arrangement of the pores can be easily seen in the general transmission electron microscope image, and the pore size of the materials can be measured. Through the Fourier transform of TEM image, the diffraction pattern of the material can be obtained, and the crystal phase of the material can be judged.
Nitrogen desorption characterization
Nitrogen deadsorption is an effective method to characterize porous materials. The specific surface area of the material can be obtained by nitrogen adsorption and desorption, and the pore size distribution can be calculated by BJH method. Nitrogen adsorption and desorption of ordered mesoporous materials are generally IV isotherms accompanied by H1 hysteresis loops. And it shows a strong peak in the pore size distribution.
