Effect of Addition of Divalent Transition Metal Chlorides on the Structure and Thermal Stability of Lamellar Silica Synthesized by the Neutral Amine Route

The addition of divalent metal chlorides MCl2 (M=Mn, Co, Ni, Cu, Zn, Cd, Hg) drastically affects the structure and thermal stability of lamellar silica obtained through the neutral amine route using 1,12-diaminedodecane as template molecule. These changes in properties are related to the coordination features, as well as the amount of cation employed. The enhancement of the thermal stability of the modified lamellar silica is always independent of the cation added. On the other hand, the thermal stability of the hexagonal phase decreased. The occurrence of structural changes can be attributed to the reorientation of 1,12diaminedodecane chains to allow cation coordination through nitrogen atoms.