Enlargement of mesopores of 2-D orthorhombic KSW-2 type silica by the addition of poly(oxyethylene) alkyl ether during the mesostructural formation

The size of mesopores in 2-D orthorhombic KSW-2 type silica, derived from a layered silicate kanemite, can be enlarged by the addition of poly(oxyethylene) alkyl ether (C16EO10) during the mesostructural transformation from a lamellar phase to a 2-D orthorhombic one. Precursors for pore-expanded KSW-2 type silica were prepared by an acid treatment of lamellar hexadecyltrimethylammonium-intercalated kanemite (C16TMA-kanemite) in the presence of C16EO10. The acid treatment induces simultaneous reactions of (1) intercalation of C16EO10, (2) deintercalation of C16TMA cations, and (3) mesostructural transformation into a 2-D orthorhombic phase. Depending on the concentration of C16EO10, the d11 spacing of the products after the acid treatment but before calcination varied from 4.0 to 5.4 nm and that of the calcined products varied from 3.5 nm to 4.8 nm. The method provides a precise control in a certain range of the pore size of KSW-2 type mesoporous silica.

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