JPH03237014A - Method for producing rare earth element-containing composite oxide - Google Patents

Abstract

PURPOSE:To obtain such a multiple oxide having uniform composition, suitable for catalyst, superconducting material, etc., by mixing rare earth oxides, oxides or/and carbonates of transition metal, and water to produce a multiple hydrate, separating and calcining this hydrate. CONSTITUTION:(A) At least one rare earth element oxide (e.g. La2O3, Nd2O3), (B) oxide of transition metal (e.g. TiO2) or/and carbonate (e.g. MnCO3) and (C) water are mixed to effect hydration and to produce a multiple hydrate containing the components of (A) and (B). Then the produced multiple hydrate is separated by filtering, etc., dried and calcined to obtain the multiple oxide containing rare earth element (e.g. LaMnO3). Since the components (A) and (B) are not simply mixed before calcination but they are subjected to hydration prior to calcination by this method, the obtd. multiple oxide containing rare earth elements has a uniform composition without containing raw material residue.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing a rare earth element-containing composite oxide suitable as a raw material for catalysts, superconducting materials, and fuel cell electrodes.

(Prior Art) Conventionally, as a method for producing rare earth element-containing composite oxides suitable as raw materials for catalysts, superconducting materials, and fuel cell electrodes, rare earth oxides, transition metal oxides, and/or carbonates are mixed in a specified manner. Manufactured by adjusting the particle size and mixing and firing, or by co-precipitating salts such as chlorides or nitrates of the respective metals as hydroxides and oxalates, filtering, drying, and firing. Was. However, when oxides or carbonates are simply mixed and fired, unreacted substances tend to remain, and in order to produce a complete composite oxide, it is necessary to repeat mixing and firing (H, Yohiro and Y, Baba,
J, Electochem, soc, Vol, 135
．． No. 8.2077 (1988)). In addition, in the case of the coprecipitation method, the mixture is homogeneous and highly reactive, and is a desirable method for producing composite oxides. There was a problem in that it was easy to cause a discrepancy between the composition of the raw materials and the composition of the raw materials.

(Problems to be Solved by the Invention) Therefore, the technical problems of the present invention are to improve reactivity without leaving any unreacted materials and to prevent compositional fluctuations of the composite oxide when producing rare earth element-containing composite oxides. The object of the present invention is to provide a manufacturing method that satisfies uniformity at the same time.

(Means for Solving the Problems) In order to solve the problems, the present inventors conducted a comparative study on the raw material powder mixing and sintering method, the coprecipitation method, and the hydration reaction method according to the present invention, and found that the hydration reaction method is The present invention was determined to be the most advantageous, and the present invention was arrived at after intensive research on the hydration reaction conditions.The gist of the invention is as follows: Alternatively, there is provided a method for producing a rare earth element-containing composite oxide powder, which comprises adding water to carbonate and mixing the mixture, followed by separating, drying, and firing the mixture.

The present invention will be described in detail below.

First, to show the scope of application of the present invention, the upper right oxide which is the main raw material is Y, La, Ce, Pr, Nd, P
m, Sm, Eu, Gd, Tb, Dy, Ha
, Er, Tm, Yb and Lu element oxides, and one or more of these may be used. Examples of transition metal oxides and carbonates include metals from groups 4A to 2B of the periodic table, namely Ti, V, (:r, Mn, Fe, Co, Ni
, Cu, Zn and other oxides and carbonates, and specific examples include TiO2, VO□, Cr20a, M
One or more of nCO3, ZnCO3, C:ucO3, etc. is used. Some of these rare earth elements include Mg, Ca, and Sr.
The degree of substitution may vary depending on the properties and uses of the composite oxide, but is generally O to 50 atomic %, preferably O to 20 atomic %. Examples of composite oxide products made of the above metals include LaFe3. LaMnOs, Pr
CoOs, NdCr03. SmNiOs, (
LaCa) Mn0a, (NclSr)Ni03.
GGG etc. are mentioned.

Next, the manufacturing method of the present invention will be explained.

The greatest feature of the present invention is that the rare earth oxides constituting the rare earth element-containing composite oxide mentioned above take advantage of the property of easily causing a hydration reaction with water and becoming fine. If oxides and/or carbonates are blended in proportions to form a predetermined composite metal oxide, and water is added and wet-mixed, a hydration reaction will proceed, and the rare earth oxide will become fine and composite hydrated. Become a thing. The composition of this composite hydrate is the same as that of the raw material oxide, and there is no change in the composition of the composite oxide obtained by filtering, drying, and calcining, making it possible to easily manufacture composite oxides. Ta. The hydration reaction conditions vary depending on the type of composite metal oxide to be produced, the reaction equipment, etc., but in general, the amount of water is 0.5 to
Added 10 times (by weight) and reacted at a temperature of 0 to 100°C for a reaction time of 0.
．． 5 to 48 hours is appropriate. In the case of carbonate, the same conditions as above may be applied. It depends on the type of composite oxide, but the firing time is 6
00-1.300°C x 0.5-24 hours is common.

Hereinafter, embodiments of the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

(Example 1) 58.6 g of La20s, 1.4 g of MnCO3 and 1 part of water
00 cc was added and mixed with a bladed stirring bar to hydrate and form a slurry. After filtering and drying this, 1200℃
The mixture was fired for 6 hours to obtain a composite oxide of LaMnO3. As a result of measuring this by X-ray diffraction, no unreacted substances were found, and it was found to be a single phase of LaMnO3.

(Example 2) 5924g of La2O and 3148g of SrCO in a ball mill
, 928 g of MnCOa, and 2000 cc of water were added.
Partially hydrated for 1 hour at °C. The resulting mixture was filtered, dried, and fired at 1200° C. for 6 hours to obtain a LaSrMnOx composite oxide powder. As a result of measurement by X-ray diffraction, the presence of LaJs, which is an unreacted substance, was observed, but as a result of quantitative analysis, no compositional deviation was observed.

(Example 3) 20g of Nd 68.8g, 31.2g of Cr2O and 7g of water
0 cc was added, and these were mixed in a mortar and hydrated to form a slurry. After filtering and drying, this was calcined at 1300° C. for 6 hours to obtain a composite oxide powder of NdCrO3. This is X
As a result of measurement by line diffraction, the presence of unreacted substances was not observed.

(Example 4) 200 cc of water was added to 58.9 g of PraOz and 41.1 g of CoCL, stirred and mixed with a magnetic stirrer, filtered and dried, and then calcined at 1,300°C for 6 hours to obtain P
A composite oxide powder of rCo0a was obtained. As a result of measuring this by X-ray diffraction, no unreacted substances were found. Further, as a result of quantitative analysis, no compositional deviation was observed.

(Comparative Example 1) 20 g of La, 58.6 g, and 541.4 g of MnCO were dry mixed in a mortar, and the mixture was fired at 1200° C. for 6 hours. As a result of measuring this by X-ray diffraction, it was found that unreacted La
The presence of 2O5 was observed.

(Comparative Example 2) La20++ 928g, 5rCOs 148g, Mn
928 g of C0a was mixed in a mortar for 15 minutes, and this was baked at 1200°C for 6 hours. Furthermore, as a result of measurement by X41 diffraction, the presence of unreacted La20i was observed.

(Comparative Example 3) Law'358.6g, MnCO341.4g and water 10
After mixing with 0 cc of 12N hydrochloric acid and dissolving it, 15N ammonia water is added to adjust the PL to 9 or more, and coprecipitation is performed. This was filtered, dried, and then calcined at 1,200°C for 6 hours. As a result of measuring this by X-ray diffraction,
Although no unreacted substances were observed, a compositional deviation was observed by quantitative analysis.

(Effect of the invention) There was a problem that unreacted substances remained even if oxides were simply mixed and fired as in the conventional method, but the hydration reaction method of the present invention has a uniform composition without any unreacted substances. It has become possible to produce composite metal oxides containing rare earth elements.

In addition, unlike the coprecipitation method, there is no need for the process of dissolving raw metal salts in water, neutralizing them, and precipitating them as hydroxides, etc. Furthermore, rare earths with a uniform composition that does not deviate from the raw material composition can be produced. It has become possible to produce element-containing composite metal oxides, and the industrial value thereof is extremely high.

Claims (1)

[Claims] A rare earth element-containing composite oxidation characterized by adding water to one or more rare earth oxides and one or more transition metal oxides and/or carbonates, mixing the mixture, and then separating, drying, and baking the mixture. How things are manufactured.