Extraction of cationic surfactant templates from mesoporous materials by CH3OH-modified CO2 supercritical fluid

摘要

Extraction of cationic surfactant templates from MCM-41, MCM-48, SBA-1 and SBA-3 has been conducted using CH3OH-modified CO2 supercritical fluid. The supercritical fluid extraction (SFE) has been integrated with thermogravimetry (TG), X-ray diffraction (XRD) and N-2 14 adsorption-desorption to evaluate extraction efficiency and structural stability of mesoporous materials. Experiments of optimization indicate that the conditions of 90 bar, 85 degrees C, CH3OH/CO2, = 0.1/1.0 ml/min and 3 h are most suitable for the SFE of cationic templates. 76-95% of the cationic templates can be extracted from the mesoporous materials. XRD and N-2, adsorption-desorption studies illustrate that SFE possesses some advantages over calcination in maintaining mesoporous uniformity and structural stability when used to remove templates. The impact of curing on mesoporous structure is also dealt with. (c) 2005 Elsevier B.V. All rights reserved.