Effect of support calcination temperature on Ag structure and catalytic activity for CO oxidation

SiO2 with different nanostructures, namely hexagonal mesoporous silica(HMS), and three unordered commercial silica, were used as supports to fabricate silver catalysts using an incipient wetness impregnation method. It was found that Ag/HMS catalyst showed a high catalytic activity. Next, the HMS support was calcined at different temperatures before impregnation of AgNO3. The effect of calcination temperature of HMS support was investigated in terms of structure and catalytic activity of Ag catalysts. The support and catalysts were characterized by N2 adsorption-desorption isotherms, Thermogravimetric-differential thermal analyzer, X-ray diffraction, H2-temperature program reduction and transmission electron microscopy. The results showed that calcination of HMS at an appropriate temperature(750 °C) before catalyst preparation would benefit the formation of highly dispersive small sized Ag particles on the HMS support and markedly enhance the catalytic activity of Ag/HMS catalyst toward CO oxidation.