No abstract

Nanostructured porous silica particles with sizes in the micrometer to sub‐micrometer range are of great interest due to their potential applications as catalyst supports and nanocomposite materials. However, if these particles are to be used in industry, a process must be developed to affordably produce them on a large scale. This paper reports on a high‐energy ball‐milling process that has been used to create micrometer‐ to sub‐micrometer‐sized mesoporous silica particles starting from a silica xerogel prepared by a surfactant self‐assembly sol–gel process. We have studied various milling conditions such as milling media (zirconia, stainless steel, or steel‐centered nylon balls), milling time, and the presence of surfactants during milling and the resulting effect on particle size and pore structure. Results from transmission electron microscopy, scanning electron microscopy, X‐ray diffraction, light scattering, and nitrogen adsorption demonstrate the feasibility of producing large quantities of nanostructured particles by this simple milling process.

Aluminum samples were milled in a high-energy ball mill at times ranging from 10 to 500 min in stainless vial/media and nylon vial/media. The crystallite size of aluminum milled in the stainless steel setup reached a plateau at 25 nm around 100 min, whereas the crystallite size of aluminum milled in the nylon setup reached the same plateau at 500 min. Contamination studies were conducted using x-ray fluorescence, hydrogen-carbon-nitrogen analysis, and thermogravimetric analysis. Although organic contamination due to the nylon milling media was high at 12 wt% when milled for 500 min, it is shown that the contaminant could be easily removed by thermal treatment.

Highly ordered mesoporous silica particles with sizes in the micron to sub-micron range are of great interest due to their applications as catalysts and filler materials. Currently, mesoporous silica particles are synthesized using large amounts of solvent, which is impractical for large scale-up in industry. This paper reports on a high-energy ball milling process that has been employed to create micron to sub-micron sized mesoporous silica particles starting from a silica xerogel prepared by a surfactant self-assembly sol-gel process. We have studied the effect of parameters such as milling media (e.g., zirconia, stainless steel, and steel centered nylon balls), milling time, the presence of surfactants during milling, particle size, and pore structure. Results from transmission electron microscopy (TEM), scanning electron microscopy (SEM), Xray diffraction (XRD), and nitrogen adsorption demonstrate the feasibility of producing large quantities of mesostructured particles by a simple milling process.