关键词: 稻壳灰, 添加剂, 气凝胶, 孔径分布, 超临界CO2干燥

Abstract: Silica aerogel is prepared using rice husk ash as silicon source. Several additives are added into the sol under suitable conditions, through the steps of sol-gel, solvent exchange and supercritical carbon dioxide drying. The added amount 15%~20% of glycerol and ethylene glycol have strongly influence on the pore size distributions (PSD). During this process, silica aerogel with smaller pores, more uniform, higher specific surface area and smaller average pore size is produced. High molecular weight polyethylene glycols can shorten the gelation time and the PSD is relatively uniform. Formamide and dimethylformamide have the most significant effect on the samples with 20~40 nm PSD and high specific surface area above 750 m2/g. Polyvinylpyrrolidone can accelerate polymerization rate and the aerogel has more small pores and dense network structure.

Key words: rice husk ash, additive, silica aerogel, pore size distribution, supercritical carbon dioxide drying