Facile synthesis of highly thermostable mesoporous ZnAl2O4 with adjustable pore size

Abstract

Highly thermostable mesoporous zinc aluminate spinel ZnAl₂O₄ with adjustable textures and unusually high specific surface areas have been synthesized through a co-precipitation method using a mixed structure directing agent of butylamine and alkanols with different lengths of straight carbon chain. Powder X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), thermogravimetric and differential thermal analysis (TG/DTA), high resolution transmission electron microscopy (HRTEM) and nitrogen adsorption–desorption techniques were used to characterize the prepared samples. The results indicate that the pore size for mesoporous ZnAl₂O₄ calcinated at 500 °C was 3.1 nm when butylamine and hexanol were used as the mixed structure directing agent, and it could be enlarged to 4.5 and 5.0 nm through changing the alkanol to decanol and dodecanol, respectively. Correspondingly, the pore volume and surface area also exhibited an augmentation with increasing the carbon chain length of the alkanol from C6 to C12. The specific surface area of ZnAl₂O₄ obtained by using butylamine and dodecanol and calcinating at 500 °C is as high as 298 m² g⁻¹ and its total pore volume reaches 0.54 cm³ g⁻¹.