Preparation of porous SiO2 monoliths with high porosity and high temperature stability

Porous SiO2 powder was synthesized from Tetraethylorthosilicate (TEOS) using triblock copolymer P123 as template and 1,3,5-trimethylbenzene (TMB) as swelling agent. SiO2 monoliths were prepared from the synthesized SiO2 powders by gelcasting followed by sintering. Porous SiO2/Al2O3 monoliths were prepared from porous SiO2 powders coated with boehmite sol. XRD, SEM, TEM, N-2 adsorption and Archimedes method were employed to characterize the phase, microstructure, porosity of the prepared powder and monoliths respectively. The thermal stability of the monoliths was studied by sintering the monoliths at 600 - 1000 degrees C. Both SiO2 monoliths and SiO2/Al2O3 monoliths with a porosity of >= 90% were obtained. The porosity of the monoliths decreases with sintering temperature increasing from 600 to 1000 degrees C. The porosity of the monolith sintered at 1000 degrees C is more than 80%. The evolution of the pores in the monoliths with sintering temperature was investigated.