Synthesis brucite

Co-precipitation is also applied in the synthesis of hydrotalcite-like precursors (HTlcs) for catalysts e.g. based on Cu-Zn-Al, or Co-Al catalysts. Synthetic HTlcs, with a general formula (OHjg] [A ] nHgO, are hydrated hydroxycarbonates of a random lamellar structure. These materials can be visualized as brucite-type octahedral layers, in which cations partially substitute for cations (x = The cations are located in the center of... 

For the formation of LDHs many divalent and trivalent cations can be used in the brucite-like layer with the only requirement being that their radii in the case of octahedral coordination does not largely differ from those of Mg" and Al "[H]. Table 20.2. Although different combinations of divalent and trivalent metal ions have been constantly used for the LDH synthesis, the possibility of incorporating tetravalent cations in the brucite-like layer is recently often mentioned [4,11,12]. So far, there is no generally accepted opinion about this possibility, although there has been published work on this subject. 

A series of magnesium silicates has been prepared according to the general recipe of hydrothermal synthesis, with 3Si/Mg ratios variing from 0 (brucite) to 4 (talc) with intermediate ratios corresponding to mixtures of brucite, chrysotile and talc structure as reported in table 3. The various Mg silicates... 

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