Thermal stability and behavior of platelet-shaped SBA-15 containing Zr

SBA-15 with a platelet shape, containing Zr(IV), (Zr-SBA-15) was prepared to characterize its thermal stability and thermal behavior in comparison with conventional, rod-shaped SBA-15. The small angle X-ray diffraction (SAXRD) lines of Zr-SBA-15 and SBA-15 disappeared at 1,373 and 1,273 K, respectively. The pore diameter of the Zr-SBA-15 was almost constant from 773 to 1,073 K and decreased above 1,173 K, whereas the SBA-15 pore diameter decreased with increasing calcination temperature from 773 to 1,173 K. Therefore, the thermal stability of the Zr-SBA-15 was higher than that of SBA-15. Zr(IV) distributed within the framework prevents the pores from shrinkage by heating, and the Zr(IV) forms a ZrO₂ crystalline phase above 1,273 K. When calcined at 1,873 K, the Zr-SBA-15 mesostructure collapsed while maintaining its hexagonal platelet shape. The collapse of the mesostructure at 1,373 K, caused the Zr-SBA-15 to shrink in the width direction by approximately 40% compared with that calcined at 773 K, although the dimension hardly changed in the thickness direction.