Preparation of silica aerogel from oil shale ash by fluidized bed drying

The silica aerogel with high specific surface area and large pore volume was successfully synthesized using oil shale ash (OSA) via ambient pressure drying. The oil shale ash was burned and leached by sulfuric acid solution, and then was extracted using sodium hydroxide solution to produce a sodium silicate solution. The solution was neutralized with sulfuric acid solution to form a silica gel. After washing with water, the solvent exchange with n-hexane, and the surface modification with hexamethyldisilazane (HMDZ), the aged gel was dried by fluidization technique and also using a furnace to yield silica aerogels. The physical and textural properties of the resultant silica aerogels were investigated and discussed. The results have been compared with silica aerogel powders dried in a furnace. From the results, it is clear that the properties of silica powders obtained in fluidized bed are superior to that of powders dried in the furnace. Using fluidization technique, it could produce silica aerogel powders with low tapping density of 0.0775 g/cm3, high specific surface area (789 m2/g) and cumulative pore volume of 2.77 cm3/g.

Graphical AbstractA novel method for the production of silica aerogel powders, using oil shale ash as a new silica source by fluidized bed drying technique, has been developed. The aerogel dried by fluidized bed exhibited relatively lower tapping densities (0.0775 g/cm3), higher specific surface (789 cm2/g) and larger cumulative pore volume (2.77 cm3/g) than that of the furnace dried aerogel powders.Figure optionsDownload as PowerPoint slide