Study On The Synthesis Of Mesoporous Alumina

This paper established a set methods including Dynamic Light Scattering DLS, Thermal Analysis TG, X-ray diffraction XRD, Transmission Electron Microscopy TEM and N2 adsorption isotherms. And the synthesis of mesoporous alumina molecular sieve process was investigated and characterized by means associated with these methods. Surfactants, sol pH, crystallization methods and ways of calcination as well as other influencing factors were taken into consideration about the structure and properties of mesoporous alumina molecular sieve. Our main effort is on the investigation of the hydrolysis process, including the non-ionic surfactant Pluronic 123 block copolymer (P123) in micelle concentration of their colloidal size and the size in reaction system as well as the affection on structure of mesoporous alumina properties. We achieved the following results after efforts to explore:This study shows that there is an optimal value of P123 concentration, which is 0.15mol/L or so (use isopropanol as a solvent). This will result in the optimal structure and properties of mesoporous alumina. Finally, the mesoporous alumina with high BET surface area and Narrow pore size distribution was prepared (358.55m2/g).By changing the type of surfactant or crystallization method, a reasonable choice calcination temperature, we can effectively control the structural properties of mesoporous alumina, and make the pore structure of mesoporous alumina adjustable. With Tween-80 as the template, the mesoporous alumina has the largest BET surface area of 432.26m2/g, and with hexadecyl trimethyl ammonium bromide (CTAB) as the template, the mesoporous alumina can have maximum aperture (15.50nm) and pore volume (1.66cm3/g), as well as high specific surface area of 390.25m2/g.During the process of preparing, the decrease of acidity value of the sol-gel (from 12mol/L to 0.lmol/L) not only makes the surface area lower (from 310.30m2/g to 261.35m2/g), but also makes the acid sites lower, which means reducing the activity of mesoporous alumina. Low acidity value is not conducive to the synthesis of mesoporous alumina, but the reasonable control of acidity value can be adjusted within the range substantially pore size (7-18nm) and pore volume (0.6-1.2cm3/g), which provided favorable conditions for the preparation of large pore size and pore volume of mesoporous alumina.