Continuous Production of Mesoporous Silica with Controlled Structure via Aerosol-Assisted Evaporation-Induced...

This work demonstrates a viable and attractive continuous synthesis route for spherical SBA-15 mesoporous silica particles using the aerosol-assisted evaporation-induced self-assembly (AA-EISA) technique. This approach integrates aerosol processing with a self-assembly mechanism driven by solvent evaporation, offering distinct advantages over conventional sol-gel and hydrothermal methods. The influence of ethanol content, pH, P123 template amount, and reactor temperature (T _r) on the formation of SBA-15 spheres was systematically investigated using gas physisorption, thermogravimetric analysis (TGA), small-angle X-ray scattering (SAXS), and electron microscopy. In the absence of ethanol, the desired spherical morphology was not obtained; instead, the products consisted of mixed, fiber-like elongated features and bundled aggregates, highlighting ethanol's pivotal role in directing spherical particle formation. An ethanol/tetraethyl orthosilicate (TEOS) molar ratio of 1 was sufficient to maintain a spherical morphology during continuous runs up to 12 h. For production extending beyond 12 h, a ratio of 3 was required to ensure precursor stability and to balance surface area with pore volume. Adjusting the pH to 3 enabled pore expansion to ∼20 nm and a pore volume of 1 cm³/g, with a moderate surface area of 194 m²/g. Lower ethanol and acid usage suggest a more sustainable process. A P123/TEOS molar ratio of 0.015 was sufficient to yield well-ordered mesostructures with minimal reactor fouling. Reducing T _r from 400 to 200 °C decreased energy consumption without sacrificing quality, however, a further reduction to 120 °C compromised the morphology. Key parameters affecting continuous AA-EISA production are given, showing potential for a robust, energy-efficient, and environmentally conscious route to produce mesoporous silica particles.