(584ed) Synthesis of a Robust Macroporosity-Free Mesoporous Silica Compacts

Despite the widespread interest in mesoporous materials, large-scale, mechanically robust mesoporous solids are still lacking. This is mainly due to the difficulty of maintaining mesostructural order (at the nanometer) over macroscale ranges (centimeters) using supramolecular self-assembly processes. To overcome this limitation, we developed a multi-step process, involving 1) synthesis of a mesostructured silica powder with an SBA-16 type ordered framework using typical supramolecular assembly methods, 2) consolidation of the powder into an inch-sized robust pellet using spark plasma sintering (SPS), and 3) transformation of the unwanted macroporous network formed during the consolidation process into an ordered mesoporous structure. The last step is done by repeated infiltration of the macropores with a silica solution containing structure-directing polymers, which assemble into the same SBA-16 type cubic mesostructured phase present in the original silica powder. The fabricated monoliths are highly permeable with a surface area exceeding 270 m²/g from a continuous SBA-16 cubic mesoporous matrix. This new type of mesoporous solids exhibits excellent mechanical stability comparable to sedimentary rocks, despite having a low density of only ~1.1 g/cm³.