Preparation Of Hierarchically Meso-mesoporous Silicas And Mesoporous Organosilicas By Partitioned Coopeartive Self-assembly Process

Ordered mesoporous silicate materials have attracted intense attention for their high surface area, uniform pore size distribution, large pore size, and potential applications,such as catalyst supports, adsorbents and so on.Unfortunately, so far the reports on the tuning of the mesostructures or other physical properties of hierarchically meso-mesoporous silicas and mesoporous organosilicas are rather limited due to the narrow proportion of raw materials and hard controling the mesostructures of conventional cooperative self-assembly process of hierarchically meso-mesoporous silicas and mesoporous organosilicas. So, a new synthesis route of hierarchically meso-mesoporous silicas and mesoporous organosilicas is proposed, called partitioned cooperative self-assembly process (PCSA). It is a facile and versatile synthesis method allowing the physical properties of mesoporous materials to be adjusted by simply partitioning the addition combinations of precursors without using any additives or special synthetic conditions.This work reports using tetraethoxysilane (TEOS) as silica precursors and the nonionic triblock copolymer surfactant(P123) as template, we applied PCSA method to synthesize hierarchically meso-mesoporous silicas, studied the variations of the mesostructres and physical properities of hierarchically meso-mesoporous silicas with different addition combinations, different interval times of precursor and different temperatures in PCSA conditions. The results show that:For hierarchically meso-mesoporous silicas, the PCSA process allows the preparation of hierarchically meso-mesoporous ordered silicas based on tetraethoxysilane under suitable partitioning conditions, in terms of the amounts of sodium silicate in two partitioned additions and interval time between them; Hierarchically meso-mesoporous silicas with the first series of ordered mesoporous can be prepared under certain partitioning conditions (TS5-1.5h-5@43H6.15 and TS4-xh-6@43H5.95); The first level mesoporous of hierarchically meso-mesoporous silicas formation is the result of self-assembly process between silicon species and surfactant P123, the secondary pore is derived from its partitioned cooperative self-assembly process; Using different interval time and interval adding quantity can adjust the secondary level pore size of mesoporous silica materials between 16～32 nm, and the first level of mesoporous (size 7 ～ 10 nm) are not influenced; Temperature and acid adding quantity can influence the properties and structure of hierarchically meso-mesoporous silicas, well hierarchically meso-mesostructure can still be obtained when temperature is 43℃ and acid adding quantity is 12.3g.For mesoporous organosilicas, mesoporous organosilicas using tetraethoxysilane and 3-Aminopropyltriethxysilane as silica precursors can be obtained via partitioned cooperative self-assembly process system and lack of water system; The adding order of silica precursors have little influence on BET and pore volume, but have large influence on mesostructure. For partitioned cooperative self-assembly process system, pore size of mesoporous organosilicas via lack of water system are smaller, but their BET are large.