Synthesis of New Sn-Incorporated Layered Double Hydroxides and Their Thermal Evolution to Mixed Oxides

Abstract

A new series of Mg II Al III Sn IV 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 physicochemical properties of both as-synthesized and their thermally decomposed products were investigated in detail by various analytical and spectroscopic methods such as powder X-ray diffraction (PXRD), chemical analysis, scanning electron microscopy (SEM), FT-IR spectroscopy, 119 Sn and 27 Al MAS NMR, simultaneous TG/DTA, and N 2 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, the MgSn(OH) 6 phase also was formed. The 119 Sn NMR showed a broad signal in the range -525 to -660 ppm for Sn atoms existing in a distorted octahedral environment. Thermal calcination of MgAlSn-LDHs at 450 or 700 °C resulted in the formation of MgO-like solid solution, in which both Al 3+ and Sn 4+ were dissolved. The surface area and pore volume had decreased with increasing Sn content for both assynthesized and calcined samples. Calcination at 1100 °C yielded a mixture of wellcrystallized phases corresponding to MgO, MgAl 2 O 4 , and Mg 2 SnO 4 "inverse spinel".

Preparation, characterization and thermodynamic properties of Zr-containing Cl-bearing layered double hydroxides (LDHs)

“…To investigate the incorporation of tetravalent cations into the LDH structure is interesting task because there is no clarity concerning incorporation of tetravalent metals in LDHs. Some of studies reported the possibility of synthesizing LDHs containing M(IV) ions [5,[19][20][21][22][23][24]. Another authors based on results of X-ray absorption spectroscopy (XAS) and Mössbauer spectroscopy [25] concluded that the M(IV) cations are segregated from LDH structure and may form amorphous M(IV) oxide-like particles.…”

Structure and Energetics of Biocompatible Polymer Nanocomposite Systems: A Molecular Dynamics Study

“…[7][8][9][10][11] Mg/Alhydrotalcite (HT) is biocompatible 6 and has found pharmaceutical applications as antacid, 12 an ingredient in sustained-release pharmaceuticals containing nifedipine, 13 pharmaceutical compositions stabilizer, and in the preparation of aluminummagnesium salts of antipyretic, analgesic, and antiinflammatory drugs. As already mentioned above, hydrotalcite is also a potential host structure for intercalation of different kinds of NSAID molecules, thus exerting a controlled-drug release function.…”

Functional Materials - Syntheses, Characterisation and Catalytic Applications

“…SEM images also indicated the layered structure for both chosen samples ( Figure 18 for Mg 4 Fe-LDH, Figure 19 for Ca 3 Fe-LDH). This is fortunate, since arrangement at the atomic level is not always reflected in the morphology of the materials.…”

“…1 It has the formula of Mg 6 Al 2 (OH) 16 3 Tetravalent cations such as Zr 4+ and Sn 4+ can also be incorporated into the layers. 4 Only one example is known of LDH structure with monovalent cation, the LiAl 2 -LDH that is. It has been speculated that the ionic radii of M(II) and M(III) and the difference between them, 5,6 as well as the solubility products 7 of M(II)(OH) 2 and M(II)CO 3 , play roles in defining the boundaries of the range of metal cations that can form LDHs.…”