以非离子型表面活性剂P123和三甲基苯的微乳液为模板剂合成介孔SiO2粉体. 以此粉体为原料, 经干压成型、烧结制备多孔SiO2块材. 分别用AlOOH溶胶和TiO2溶胶包覆多孔SiO2粉体, 制成多孔SiO2/Al2O3块材和SiO2/TiO2块材. 采用XRD、SEM、TEM、N2吸附法和阿基米德排水法对所制粉体和块材进行了表征, 并研究了块材的热稳定性. 结果表明, 600~700℃烧结的多孔SiO2基块材的孔隙率为74%~76%. 与多孔SiO2块材相比, 在800~1000℃范围内, SiO2/Al2O3块材的热稳定性显著提高, SiO2/TiO2块材的热稳定性在800~900℃范围内有一定改善.
Porous monoliths with high porosity and improved high temperature stability are required in heat insulation. Mesoporous SiO2 powder was synthesized from tetraethyl orthosilicate using oil-in-water microemulsions composed of non-ionic surfactant P123 and 1,3,5-trimethylbenzene as template. Porous SiO2 monoliths were prepared from the mesoporous SiO2 powder by dry pressing followed by sintering. Porous SiO2/Al2O3 monoliths and SiO2/TiO2 monoliths were prepared from mesoporous SiO2 powders coated with boehmite Sol and titania Sol respectively. XRD, SEM, TEM, N2 adsorption and Archimedes method were employed to characterize the powders and the monoliths. The thermal stability of the monoliths was studied. The porosity of the silica-based monoliths sintered at 600-700℃ is about 74%?76%. Compared with SiO2 monolith, porous SiO2/Al2O3 monolith has much better thermal stability at 800-1000℃ and porous SiO2/TiO2 monolith has an improved thermal stability at 800-900℃. It is indicated that alumina coating on porous silica particle surface can improve the high temperature stability of SiO2/Al2O3 monolith.
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