Simple and controllable preparation of SBA-15 microspheres by poly(vinyl alcohol)-assisted P123 templating system

This work reports a simple two-step synthesis method for the preparation of SBA-15 microspheres using poly (vinyl alcohol) (PVA) as a solo additive based on classic P123 templating system. Both spherical particle morphology and long-range 2D-hexagonally ordered mesostructures can be achieved. It is demonstrated that the particle sizes and mesopore sizes of SBA-15 microspheres can be facilely tuned by varying synthesis parameters, including standstill temperatures, hydrothermal treatment temperatures, etc. It is proposed that the addition of PVA in combination with the standstill step at low temperatures (1st step) suppress the rapid growth and aggregation behavior of silicate/P123 primary particles and favor their aggregation into spherical SBA-15 particles, while the meso-ordering and particle uniformity are improved by stirring step at relatively high temperatures (2nd step). This two-step synthesis method based on the PVA-assisted TEOS/P123/HCl(aq.) templating system thus represents a novel and simple pathway to preparing SBA-15 microspheres. Instead of HCl, other mineral acids, including sulfuric acid and nitric acid, can also be used to prepare SBA-15 microspheres. Via sulfuric acid catalyzed system, the carbonization of P123 also enables more direct preparation of mesoporous carbon microspheres.