Highly Ordered Hierarchical Macroporous-Mesoporous Alumina with Crystalline Walls

Abstract

Highly ordered hierarchical macroporous-mesoporous alumina with crystalline walls are synthesized by facial route. The general synthesis strategy is based on a sol–gel process associated with block copolymers as soft templates and polystyrene colloidal crystals as hard template to produce macropore and mesopore structures, respectively. Small-angle XRD, TEM and Nitrogen adsorption and desorption results show that hierarchical macroporous-mesoporous alumina possess highly ordered two-dimensional hexagonal mesostructured and highly ordered face centered cubic macropore arrays structure. The present work reveals that the hierarchical macroporous-mesoporous structure can endure high temperature up to 900 °C. FTIR pyridine adsorption measurements show that the amount of Lewis acid sites provided by hierarchical macroporous-mesoporous alumina is nearly two times more than that for mesoporous alumina, indicating that the open macroporous structure may be in favor of the reactant transfer, and the consequently superior activity. Large surface areas, high thermal stability, uniform pore structures and large amounts of surface Lewis acid sites illustrate that these materials are expected to find wide applications in catalysis realm. The highly ordered hierarchical macroporous-mesoporous alumina with crystalline walls are synthesized by a sol–gel process associated with block copolymers as soft templates and polystyrene colloidal crystals as hard template to produce macropore and mesopore structures, respectively.