Synthesis of new Sn incorporated layered double hydroxides and their evolution to mixed oxides

A new series of MgIIAlIIISnIV hydrotalcite (HT)-like layered double hydroxides (LDHs) with Mg/Al/Sn = 3:1:0 to 3:0:1 were synthesized for the first time by a simple coprecipitation method at room temperature. The incorporation of Sn4+ in the HT-like layer was investigated by powder X-ray diffraction (PXRD), chemical analysis, simultaneous thermogravimetric/differential thermal analysis (TG/DTA), and N2 adsorption–desorption experiments. A single phase corresponding to LDH could be obtained in the composition range Mg/Al/Sn = 3:1:0 to 3:0.7:0.3. Above this composition, in addition to LDH, a MgSn(OH)6 phase was formed. Thermal calcination of these MgAlSn-LDHs at 45°C resulted in the formation of MgO solid solutions in which both Al3+ and Sn4+ were dissolved. The surface area and pore volume decreased with increasing Sn content for as-synthesized as well as for calcined samples. Calcination at 1100°C offered a well-crystallized phase corresponding to Mg2SnO4 "inverse spinel" in addition to the less crystalline MgO and MgAl2O4 phases.