The effects on pore size and particle morphology of heptane additions to the synthesis of mesoporous silica SBA-15

Abstract

The effect of heptane on the particle morphology and pore size in the synthesis of SBA-15 is presented. Heptane in the presence of NH 4F works as a pore swelling agent, resulting in 13–18 nm sized pores in 400 nm long and 200–1000 nm wide crystallites. The pores are hexagonally arranged and run through the crystallites. Increasing the heptane to P123 molar ratio changes the morphology of SBA-15 from fibers to sheets when the crystallites rearrange during the synthesis. The pore order in the sheets is controlled by changing the molar ratio of water to P123. The surface areas of these materials are 500–800 m 2/g with pore volumes of 1.2–1.7 cm 3/g. The sheets have accessible pores with a size of 18 nm running parallel to the sheet normal, which makes them suitable for membranes.