The key issue of preparing high pore volume material is strengthening the microscopic supersaturation of precipitation reaction and reducing the particle size.Ultrafine SiO2 was prepared with the fast precipitation method in a membrane dispersion micro-reactor by using sodium silicate and sulfuric acid as raw material.The effects of two-phase flow rates

final pH

salt concentration

aging time

and drying temperature on the specific surface and pore volume were investigated.The results showed that silica powder primary particle size prepared with the membrane dispersion micro-reactor was 10.2 nm

while primary particle size prepared with the stirring method was 20.8 nm

specific surface could be up to 380 m2·g-1 and pore volume was 2.6 ml·g-1 when final pH value was 9.55.Flatting performance test of SiO2 showed that the SiO2 prepared with the membrane dispersion micro-reactor had excellent flatting performance

and extinction index of SiO2 was up to -10.2.