| 초록 |
Mesoporous silica, SBA-15 with high surface area(713m2g-1) and uniform pore size(6.7nm) has well ordered 2-D hexagonal mesostructure with amorphous mesopore wall. Silica materials with crystalline structure have excellent chemical and mechanical properties such as high thermal stability, strong hardness and unique photonic property than amorphous silica. In this work, we synthesized mesoporous silica with crystalline silica structure from SBA-15 after thermal treatment using alkali metal ions(Na+, K+ and Ca2+). The structural changing of silica in SBA-15 was observed under conditions of different temperature(300-900 oC) and different ratios of Si/alkali metal ion(20-80). The crystalline silica structure(cristobalite and quartz) in SBA-15 was produced after thermal treatment above 700 oC with Si/alkali metal ion ratio below 40. With the increase of alkali metal ion ratio, the mesosturcture has been collapsed and appearing with large pores (90~180 nm) while thermal treatment at 700 oC. |
