介孔SiO₂包覆Ag/ZIF-8核壳型催化材料的合成

The self-assembly technique was employed to sythesize the Ag nanoparticles on ZIF-8(Ag/ZIF-8). Cetyltrimethyl ammonium bromide(CTAB) was used as the structure-directing agent to facilitate mesoporous silica to coat on the surface of hydrophobic Ag/ZIF-8(Ag/ZIF-8@MS). The prepared Ag/ZIF-8@MS with a core-shell structure was characterized by a series of measurements. The results show that Ag/ZIF-8@MS has a uniform particle size(Ag/ZIF-8@MS: ca. 100 nm, Ag: ca. 15 nm), high specific surface area(539 m²/g) and large pore volume(0.64 m³/g). The TEM images indicate that the thickness of mesoporous silica shell is ca. 20 nm. The structure of catalyst is transformed into Ag/ZnO@MS core-shell structure after calcination at 550℃. Meanwhile, both of the Ag-baesd catalysts were tested for the reaction of 4-nitrophenol to prepare 4-aminophenol. The catalytic results showed that the conversion of 4-nitrophenol catalyzed by Ag/ZIF-8@MS was more than 95%, which proves the advantage of the core-shell structure with ZIF-8 as a carrier.