A hydrothermal post-synthesis route for the preparation of high quality MCM-48 silica with a tailored pore size

Abstract

A post-synthesis hydrothermal restructuring method is introduced as a convenient route to synthesize high quality MCM-48 silica with controllable pore size. Using tetraethyl orthosilicate as the silica source and cetyltrimethylammonium bromide (CTAB) as the template, the pore size could be tailored from 2.6 to 4.2 nm without using organic additives other than CTAB. It was shown by means of nitrogen adsorption, X-ray diffraction, transmission electron microscopy, and scanning electron microscopy that the improved long range structural order and the expanded pore size of the materials depends on the treatment conditions, such as the CTA⁺ concentration, the amount of NH₄OH added, and the aging temperature during the post-synthesis procedure.