Preparation of hexagonal platy particles of nanoporous silica using hydrotalcite as morphology template

Hexagonal platy composite particles with a hydrotalcite core and a nanoporous silica shell with a thickness of ca. 100 nm were synthesized by the reaction of a Mg–Al hydrotalcite with a homogeneous aqueous solution containing tetraethoxysilane, hexadecyltrimethylammonium chloride, ammonia and methanol at 3 °C. The calcination of the products at 500 °C in air led to the composite particle with a Mg/Al mixed oxide core and a nanoporous silica shell. Hexagonal platy particles of nanoporous silica with a pore diameter of 2.3 nm and BET surface area of 700 m2 (g of silica)−1 were obtained by removing the Mg/Al mixed oxide core.

Hexadecyltrimethylammonium cation–silica layers were deposited on a Mg–Al hydrotalcite. A nanoporous silica–Mg/Al oxide composite was obtained by calcination. Nanoporous silica hollow platy particles, which replicated the morphology of hydrotalcite, were obtained by dissolution of the hydrotalcite core.Figure optionsDownload as PowerPoint slide