US 4,060,500 A · Preparation of mixed metal oxides by decomposition of carbonate solid solutions having the calcite structure

Abstract

A process for the preparation of high surface area mixed metal oxides by decomposition of solid solutions of carbonates possessing the calcite structure. Oxide compounds comprising mixtures of Ca, Mn, Fe, Co, Ni, Zn, Cd and Mg can be prepared by this method. For example, CaMnO.sub.3 with a surface area of 11 m.sup.2 /g useful as a battery cathode, has been prepared by the instant method, that is, by decomposition of a CaMn(CO.sub.3).sub.2 precursor. The mixed metal carbonate solid solutions which are used as precursors for the preparation of the mixed metal oxides are themselves prepared by the precipitation from solution of the appropriate metal ions by the addition of an excess of a carbonate ion source (such as (NH.sub.4).sub.2 CO.sub.3). The metal-ion ratio in this solution is adjusted so that the resulting precipitate has the same stoichiometry as the desired oxide. The intimate mixing achieved by using the carbonate precipitation technique allows calcination to metal oxide to be run at lower temperatures for shorter periods of time, thereby achieving higher surface areas.

Claims45

Dependent claims

A method for the preparation of mixed metal oxides of the formula:

Ca.sub.(a) Fe.sub.(b) Co.sub.(c) Zn.sub.(d) Cd.sub.(e) Mg.sub.(f) Mn.sub.(g) [0].sub.Q,
wherein Q is 1, a to g are decimals ranging from 0 to <1 with a minimum, when the metal cation is present at all of 0.01 and wherein the sum of the products of each cation subscript times the respective cation valence equals 2(Q), which method comprises the steps of:
1. dissolving individual metal salts in water to give metal salt solutions;
2. mixing 2 or more of the metal salt solutions of (1) in appropriate molar amounts, provided they do not result in formation of a spontaneous precipitate, to give a solution which when contacted with a source of carbonate ions will yield only a single phase calcite structure carbonate precipitate having the metal ion stoichiometry desired in the final product;
3. mixing the solution of step (2) with a source of carbonate ions thereby yielding a single phase mixed metal carbonate solid solution precipitate having a calcite structure;
4. separating the precipitate from the solution;
5. firing the isolated precipitate under oxidizing conditions for a time at a temperature of from 300.degree. to 900.degree. C thereby yielding the mixed metal oxide.

4 more elements

A method for the preparation of supported mixed metal oxides of the formula:

Ca.sub.(a) Fe.sub.(b) Co.sub.(c) Zn.sub.(d) Cd.sub.(e) Mg.sub.(f) Mn.sub.(g) [0].sub.Q
wherein Q is 1, a to g are decimals ranging from 0 to <1 with a minimum when the metal cation is present at all of 0.01 and wherein the sum of the products of each cation subscript times the respective cation valence equals 2(Q), which method comprises the steps of:
1. dissolving individual metal salts in water to give metal salt solutions;
2. mixing 2 or more of the metal salt solutions of (1) in appropriate molar amounts, provided they do not result in formation of a spontaneous precipitate, to give a solution which when contacted with a precipitating solution will yield only a single phase calcite structure carbonate precipitate having the metal ion stoichiometry desired in the final product;
3. contacting an inert support material with the solution of (2) thereby resulting in a soaked support material;
4. separating the soaked support material of (3) from the excess solution of (2);
5. contacting the soaked support material of (4) with a source of carbonate ions thereby yielding a mixed metal carbonate calcite structure precipitate supported on an inert support material;
6. firing the supported mixed metal carbonate calcite structure precipitate of (5) under oxidizing conditions at a temperature of from 300.degree. to 900.degree. C thereby yielding the supported mixed metal oxide.

5 more elements

A method for the preparation of supported mixed metal oxides of the formula:

Ca.sub.(a) Fe.sub.(b) Co.sub.(c) Zn.sub.(d) Cd.sub.(e) Mg.sub.(f) Ni.sub.(g) [0].sub.Q
wherein Q is 1, a to g are decimals ranging from 0 to <1 with a minimum when the metal cation is present at all of 0.01 and wherein the sum of the products of each cation subscript times the respective cation valence equals 2(Q), which method comprises the steps of:
1. dissolving individual metal salts in water to give metal salt solutions;
2. mixing 2 or more of the metal salt solutions of (1) in appropriate molar amounts, provided they do not result in formation of a spontaneous precipitate, to give a solution which when contacted with a precipitating solution will yield only a single phase calcite structure carbonate precipitate having the metal ion stoichiometry desired in the final product;
3. contacting an inert support material with the solution of (2) thereby resulting in a soaked support material;
4. separating the soaked support material of (3) from the excess solution of (2);
5. contacting the soaked support material of (4) with a source of carbonate ions thereby yielding a mixed metal carbonate calcite structure precipitate supported on an inert support material;
6. firing the supported mixed metal carbonate calcite structure precipitate of (5) under oxidizing conditions at a temperature of from 300.degree. to 900.degree. C thereby yielding the supported mixed metal oxide.

5 more elements

Dependencies are inferred from the claim text.

Preparation of mixed metal oxides by decomposition of carbonate solid solutions having the calcite structure

Life of this patent

Preparation of mixed metal oxides by decomposition of carbonate solid solutions having the calcite structure

Life of this patent

Abstract

Claims45