| 초록 |
The SiO2 is widely used as catalyst supports, because of its high surface area and thermal stability. There are many functional groups on the silica surface. The Silanol group(Si-OH) hinders metal reduction. Because it leads to strong metal oxide-support interaction. The silanol groups are removed by thermal treatment, and this removal results in improvement of the metal dispersion. So we calcined the SiO2 at 300℃ to 1100℃. The Pd/SiO2 is prepared by ion exchange method. From the FT-IR results, the amount of Si-OH was decreased with increasing as calcination temperature. And more than 700℃, Si-OH was disappeared completely. The results of CO-chemisorption indicated that the thermal-treatment(900℃) of SiO2 lead to the highest dispersion of Pd as 7.97%. Therefore, to improve the metal dispersion of Pd/SiO2, the interaction between Pd and silanol should be reduced. The enhancement in the hydrophobicity of the calcined SiO2 supports would be increasing the metal dispersion. |
