High-surface-area alumina ceramics with aligned macroscopic pores

High-surface-area alumina with aligned macro- and microscopic pores was synthesized by a single-step processing using freeze-drying. A water-based slurry of Al sub 2 O sub 3 and Al(OH) sub 3 mixture was frozen while controlling the freezing direction. The frozen slurry was dried under reduced pressure and columnar pores were generated after sublimation of ice in the green body. By sintering this green body, we obtained porous alumina with a complex pore structure, where aligned macroscopic open pores contained 10 nm sized pores on their internal walls. These minute pores were formed during thermal decomposition of Al(OH) sub 3 , which consequently resulted in a high surface area.