Challenges and Strategies in the Synthesis of Mesoporous Alumina Powders and Hierarchical Alumina Monoliths

A new rapid, very simple and one-step sol-gel strategy for the large-scale preparation of highly porous gamma-Al2O3 is presented. The resulting mesoporous alumina materials feature high surface areas (400 m(2) g(-1)), large pore volumes (0.8 mL g(-1)) and the gamma-Al2O3 phase is obtained at low temperature (500 degrees C). The main advantages and drawbacks of different preparations of mesoporous alumina materials exhibiting high specific surface areas and large pore volumes such as surfactant-nanostructured alumina, sol-gel methods and hierarchically macro-/mesoporous alumina monoliths have been analyzed and compared. The most reproducible synthesis of mesoporous alumina are given. Evaporation-Induced Self-Assembly (EISA) is the sole method to lead to nanostructured mesoporous alumina by direct templating, but it is a difficult method to scale-up. Alumina featuring macro-and mesoporosity in monolithic shape is a very promising material for in flow applications; an optimized synthesis is described.