Ultralow temperature synthesis of ordered hexagonal smaller supermicroporous silica using semifluorinated surfactants as template.

Abstract

Ordered hexagonal smaller supermicroporous silica (JLU-14L and JLU-11L) has been successfully synthesized at ultralow temperature (0 approximately -20 degrees C) by semifluorinated surfactants, which is extensively investigated by X-ray diffraction, N2 adsorption, and transmission electron microscopy. X-ray diffraction shows that the peak intensity of the samples increases with decreasing synthesis temperatures in the range of 0 approximately -20 degrees C, indicating that the ordering of porous silica improves with decreasing synthesis temperature. N2 adsorption/ desorption isotherms show that JLU-14L has both ordered smaller hexagonal supermicropores (1.27 and 1.28 nm) and disordered micropores (0.67 nm). Such hierarchically porous materials with micro/supermicroporosity should be potentially important for fast diffusion of reactants and products in catalytic reactions. The ultralow temperature synthesis is a crucial factor for the formation of ordered smaller supermicropores and the control of microporosity in JLU-14L.