Synthesis of ordered porous SiO2 with pores on the border between the micropore and mesopore regions using rosin-based quaternary ammonium salt

Abstract

A novel, sustainable, rosin-based quaternary ammonium salt, dehydroabietyltrimethyl ammonium bromine, has been applied for the synthesis of ordered hexagonal supermicroporous silica with nanosheet morphology. Unlike the conventional short chain surfactants, rosin-based surfactant possesses a rigid group of a three-ring phenanthrene skeleton. Such a hydrophobic group gives the surfactant a large total volume and small effective headgroup area, which are beneficial for the formation of 2D hexagonal phase. XRD, N₂ adsorption–desorption, TEM, and SEM are used to characterize the samples. The results indicate that the molar ratios of mixture of silicate source, template agent and inorganic acid in the synthesis system have great effects on the regularity of the pore structure. The synthesized material possesses large surface area (1229 m² g⁻¹), high pore volume (0.59 cm³ g⁻¹) and narrow pore size distribution (centered at about 2.03 nm), which is on the borderline between the micropore and mesopore regions. Such a material will be attractive for applications in separations and catalysis because of its potential shape and size selectivities.