Magnesium aluminum spinels

A magnesium aluminum coprecipitate comprised of a layered crystallite having the structure ##EQU6## wherein z=equals or is greater than zero but less than 3, and at least one segregated phase of the formula AlO(OH) and/or Al(OH).sub.3 wherein the overall stoichiometry of the precipitate is MgAl.sub.2 (OH).sub.8.

A coprecipitate comprised of a substantially layered crystallite having the structure ##EQU7## wherein M.sup.I represents a cation of a metal or mixture of cations of metals having a valence of 1 or 2, and is selected from the group Li, Fe.sup.++, Mg, Co.sup.++, Ni and Zn;

• M.sup.II represents a cation of a metal or mixture of cations of metals having a valence of 3 and is selected from the group consisting of Al, Fe.sup.+++, Cr.sup.+++ and Co.sup.+++ ;
• X and Y are anions selected from the group consisting of hydroxyl, halogen, sulfate, hydroxycarbonate, chlorohydroxide, dihydrogen phosphate, hydrogen phosphate, nitrate, carbonate, carboxylates and their halogenated derivatives, bicarbonate or mixtures thereof;
• z equals or is greater than zero but less than 3, and sufficient segregated phase of M.sup.II.O.Y and/or M.sup.II Y to produce an overall stoichiometry of M.sup.II Y and M.sup.I X in the ratio of 1.8 to 1 to 2:2 to 1, prepared by coprecipitating from solution the dissolved M.sup.I X and M.sup. II Y at the lowest pH of the solution at which precipitation will occur for the desired components respectively at between about 20.degree. C. and 100.degree. C.

A method for preparing a coprecipitate comprised of a substantially layered crystalite having the structure ##EQU8## wherein M.sup.I represents a cation of a metal or mixture of cations of metals having a valence of 1 or 2, and is selected from the group Li, Fe.sup.++, Mg, Co.sup.++, Ni and Zn;

• M.sup.II represents a cation of a metal or mixture of cations of metals having a valence of 3 and is selected from the group consisting of Al, Fe.sup.+++, Cr.sup.+++ and Co.sup.+++ ;
• X and Y are anions selected from the group consisting of hydroxyl, halogen, sulfate, chlorohydroxide, hydrogen and dihydrogen phosphate, nitrate, carboxylates and their halogenated derivatives, carbonate, bicarbonate or mixtures thereof;
• z equals or is greater than zero but less than 3, and sufficient segregated phase of M.sup.II.O.Y and/or M.sup.II Y to produce an overall stoichiometry of M.sup.II Y and M.sup.I X in the ratio of 1.8 to 1 to 2:2 to 1, which comprises coprecipitating from solution the dissolved M.sup.I X and M.sup.II Y at the lowest ph of the solution at which precipitation will occur for all components respectively at between about 20.degree. C. and 100.degree. C., treating by washing the mother liquor and the precipitate with water or an alkaline solution, separating the precipitate from its mother liquor, washing the so treated precipitate, and drying the precipitate.

A method for preparing a catalyst carrier which comprises shaping the product of claim 22 or claim 26 with or without binders which may be etchable, combustable, meltable, or vaporizable, said shaping being done under pressure, and firing said shaped article at above about 1,500.degree. C., and washing, etching and/or vaporizing said additive if any remains therein, to produce a highly porous shaped article of said spinel, said particles being highly densified and joined to each other.