Obtaining multimetallic oxides derived from hydrotalcite type compounds

A procedure for obtaining mixed multimetallic oxides derived from hydrotalcite type compounds, characterized in that the laminar metallic hydroxides obtained are constituted by three or four metallic cations, forming part of the sheets of the hydrotalcite type material represented by the following formula:

• [M(II)1−x−y−zM(II)′xM(III)yM(III)′z(OH)2](An−y+z/n).mH2O, where:
• [M(II)+M(II)′]/[(M(II)+M(III)′], is the molar relationship between the divalent cations and the trivalent cations, and is between 0.5 and 10.
• M(II) represents an element of group 2, 6-12 of the periodic table with valence equal to two.
• M(II)′ represents an element of group 2, 6-12 of the periodic table with valence equal to two or three, and this may be equal to M(II) but with different valence
• M(III) represents an element of group 4-8, 13 with valence equal to 3 and different from M(II) and M(II)′.
• M(III)′ represents an element of group 4-8, 13 with valence equal to 3 and different from M(II) and M(III) or equal to M(III) but with different valence.
• A, represents any anion located between the sheets comprised of the aforementioned cations.
• n−, represents the negative electronic charge of the interlaminar anion, and it may be from −1 to −8);
• x=0.01 up to 0.99;
• y=0.01 up to 0.99 and z=0.01 up to 0.99;
• the process for preparation of the multimetallic hydrotalcites comprises:
• (1) preparing an aqueous or organic solution containing three or more cations from precursor compounds comprising oxides, hydroxides, chlorides, nitrates, and/or acetates or any combination thereof;
• (2) preparing an alkaline solution of 0.5 to 10 molarity of KOH, K2CO3, (NH4)2CO3, NH4(OH), urea or any alkaline compound, except a sodium compound, or a combination thereof;
• (3) slowly combining solutions (1) and (2) to cause the co-precipitation of the cations in the form of hydroxides at a pH between 7 and 12 at a temperature between 293 and 373 K;
• (4) washing the precipitate containing the hydrotalcites with water, until removal of the non-precipitated ions;
• (5) drying between 333 and 473K, with air, oxygen or nitrogen or under vacuum, or any combination thereof;
• (6) calcining the hydrotalcites between 573 and 1273K with a stream of air, oxygen, nitrogen or any combination thereof.