Datensatz

Zusammenfassung

This work presents the scale-up of room-temperature mechanochemical synthesis of nanocorundum (high-surface-area α-Al₂O₃) from boehmite (γ-AlOOH). This transformation on the 1 g scale using a laboratory shaker mill had previously been reported. High-energy Simoloyer ball mills equipped with milling chambers of sizes ranging from 1 to 20 L were used to scale up the mechanochemical nanocorundum synthesis to the 50 g to 1 kg scale, which paves the way to further increase batch size. Milling chambers made of steel and lined with silicon nitride (Si₃N₄) and milling balls made of steel, zirconia (ZrO₂), and silicon nitride (Si₃N₄) were investigated to address the abrasion problem, leading to contamination of the alumina. Furthermore, several other process parameters, such as ball-to-powder ratio, degree of chamber filling, and milling speed, were optimized to find the conditions for efficient formation of nanocorundum with minimum contamination. Impact forces were found to be decisive in driving the transformation from boehmite to corundum. The nanocorundum produced in the scaled-up experiments has a high specific surface area >110 m²/g with an average particle size of ∼13 nm at a low level of contamination. The optimal sample was also shown to possess improved stability of surface area when exposed to temperatures up to 1200 °C. These results successfully demonstrate the scale-up of 1 g scale results to up to the 1 kg scale and may serve as a blueprint for scaling up also other mechanochemistry processes.