JP2621185B2 - Production of metal carbonates as catalyst precursors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention uses copper, zinc,
The present invention relates to a method for producing a metal carbonate used as a precursor of a nickel-based catalyst or the like.

Copper, zinc and nickel carbonates are widely used industrially as important precursors for catalyst production for hydrogenation, oxidation and dehydrogenation, reductive carbonylation and the like.

(Prior Art) In a catalyst such as a copper, zinc, and nickel-based catalyst, a carbonate is often used as a precursor of each metal component constituting the catalyst system. In general, these catalysts are often poisoned by the incorporation of sulfur and alkali metals. Therefore, although sulfates of these metals can be obtained at low cost, they are not used as a raw material for the catalyst. Metal sulfates and metal acetates, which have a low content, are used as raw materials for various catalysts.

Japanese Patent Application Laid-Open No. 60-112725 discloses an example of using a metal sulfate as a catalyst raw material and removing a sulfur content contained therein, for example, a method of washing with a chloride ion-containing aqueous solution such as sodium chloride or sodium carbonate or sodium hydroxide. Add a coprecipitant such as
A method for precipitating with a pH of 9 or more is described.

(Problems to be Solved by the Invention) Metal nitrates, metal acetates, and the like, which are generally used as starting materials for preparing metal carbonates as catalyst precursors, are expensive and increase the catalyst cost.

On the other hand, metal sulfate is generally very inexpensive, and if it can be used as a catalyst raw material, the cost of the catalyst can be significantly reduced. However, when a metal carbonate is prepared from a metal sulfate by an ordinary method or a known method, an excessive amount of an alkaline precipitant is required to reduce the sulfur content as much as possible. May become a new catalyst impurity. Furthermore, there is a lot of industrial uneconomical aspects in that repeated washing with a large amount of pure water is necessary. In practice, it is difficult to reduce the sulfur content and the like below the permissible limit even after such an operation, and an industrial use of metal sulfur salts as a catalyst raw material has not yet been established.

That is, an aqueous solution of a sulfur salt of copper, zinc or nickel is reacted with a precipitant such as an alkali carbonate or an alkali hydrogen carbonate to form a carbonate of the metal, which is filtered and the cake is washed with water. Is obtained,
The metal carbonate obtained by such a usual method has a low sulfur content.
Since it contains 1500 ppm or more and the alkali metal content of the precipitating agent is 500 ppm or more, it is unsuitable as a raw material for preparing a catalyst, and a high-performance catalyst cannot be produced.

Also, in the example of JP-A-60-112725 in which sodium carbonate was used as a precipitant and the pH was set to 9 or more, the sulfur content in the catalyst was 0.1 to 0.5 wt% (1000 to 5000 pp) at the latest.
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(Means for Solving the Problems) As a result of intensive studies on a method for obtaining a metal carbonate as a catalyst precursor from an inexpensive metal sulfur salt, the inventors have found that alkali carbonate or precipitating agent for a metal sulfate aqueous solution is used. The content of the cake or slurry obtained by filtering the resulting precipitate is adjusted to 50 to 95% using alkali bicarbonate. By using a dilute alkali aqueous solution as the washing solution for washing the cake or slurry, the sulfur content can be reduced. The present inventors have found that a metal carbonate having a very low alkali metal content can be obtained, and have reached the present invention.

If the cake or slurry is further washed with pure water or a diluted acid aqueous solution and pure water after washing with a diluted alkaline aqueous solution, a higher effect can be obtained.

That is, in the present invention, an alkali carbonate or an alkali hydrogen carbonate is used as a precipitant of a metal sulfate aqueous solution, and a cake or slurry having a water content of 50 to 95% obtained by filtering the precipitate is washed with a diluted alkaline aqueous solution. A method for producing a metal carbonate as a catalyst precursor, characterized in that, in the method for producing a metal carbonate, washing with a dilute aqueous alkali solution followed by pure water, or washing with a dilute aqueous acid solution and pure water It is.

Metal sulfates used in the present invention are copper sulfate, zinc sulfate, nickel sulfate and the like, and these metal sulfates are
They are used as raw materials for producing catalysts such as copper-based, zinc-based, nickel-based or mixed metal-based catalysts.

The alkali carbonate or bicarbonate used for the precipitant of these metal sulfate aqueous solutions is an alkali metal or ammonium carbonate or bicarbonate, and a combination of alkali hydroxide and carbon dioxide can also be used. The amount of the precipitant used is 1 to the theoretical amount based on the metal sulfate.
It is twice, preferably 1.05 to 1.2 times.

The obtained precipitate of metal carbonate is separated by various filters, for example, a filter press, a rotary filter press, an Oliver filter, a Nue type filter, a centrifugal separator and the like. In the present invention, it is important that the water content of the cake or slurry separated by these filters is 50 to 95%, preferably 60 to 90%. If the dehydration rate is increased and the water content is set to 50% or less, the association of the precipitated particles is promoted, and the mother liquor containing a sulfate group or an alkali cation is easily included between the associated particles. It becomes difficult to remove roots and alkali cations. If the dehydration rate is low and the water content is 95% or more,
This is not preferable because a large amount of cleaning liquid is required because the cleaning efficiency is deteriorated. In the case of a cake or slurry having a water content in a preferred range, the precipitated particles can be efficiently washed with a washing liquid.

As the cleaning solution in the present invention, a dilute alkaline aqueous solution is particularly used. Washing with a dilute alkaline aqueous solution has the effect of preventing association of precipitated particles, removing the mother liquor containing sulfate and alkali cation by dispersing the associated portion, and facilitating removal of sulfate adsorbed to the precipitated particles. The alkali component of the washing solution used may be any which has been removed or does not cause harm in the final use form of the catalyst. Ammonia carbonate and the like are used, and in some cases, aqueous solutions of amines, ethanolamines, choline bases and the like are also used.

The concentration of the alkali used varies depending on these compounds, but is in the range of 0.005% to 1.0%, preferably 0.1%.
It is in the range of 01% to 0.5%. The amount of the washing solution to be used depends on the type of the filter, but is 1 to 20, preferably 5 to 15, per mole of the metal carbon salt of the precipitated cake or slurry.

After washing with a basic alkaline aqueous solution, if the cake or slurry is sufficiently dehydrated, a metal carbon salt meeting the purpose can be obtained. It is also effective to further wash with a small amount of pure water after washing with a thin alkaline aqueous solution. Furthermore, if the cake or slurry is lightly washed with a dilute organic acid aqueous solution such as acetic acid or formic acid or a thin aqueous nitric acid solution and then washed with a small amount of pure water, it is particularly effective in reducing the alkali content in the metal carbonate. It is a target. The concentration of the diluted acid aqueous solution depends on the kind of the acid, but is suitably 0.005% to 0.5%.

By the method of the present invention, it is possible to easily achieve a sulfur content of 50 ppm or less and an alkali metal content of 200 ppm or less contained in a metal carbonate as a desired catalyst precursor.

These residual amounts are far below the permissible limit as a catalyst poison, and are not inferior to metal carbonates prepared from raw materials other than metal sulfates, and are sufficiently used industrially as catalyst precursors. What you get.

The method of the present invention can be carried out in any of a batch system and a continuous system.

(Examples) Next, the present invention will be described more specifically with reference to Examples and Comparative Examples.

Ion-exchanged water was used as the washing water in all Examples and Comparative Examples. The obtained metal carbonate of the catalyst precursor was analyzed for the sulfur content by the methylene blue method and the sodium content by the atomic absorption method.

The analytical values of Examples 1 to 5 and Comparative Examples 1 to 4 are shown in Table 1 together with the main preparation conditions of the metal carbonate.

Example 1 Copper sulfate pentahydrate 201.5 g and zinc sulfate heptahydrate 174.5 g were added to water 1.4
And kept at 40 ° C. This solution was added with stirring to a solution of 180 g of sodium carbonate in 40 ° C.
The reaction was carried out at 0 ° C. for 30 minutes, then at 80 ° C. for 30 minutes, and then cooled.

Next, this reaction solution was subjected to suction filtration, and the obtained cake having a water content of 65% was washed with an aqueous solution of 0.1% by weight of an ammonium bicarbonate 8 and squeezed and suctioned to sufficiently dehydrate the cake.
Drying at 15 ° C. for 15 hours gave a copper / zinc-based carbonate catalyst precursor.

Example 2 249.7 g of copper sulfate pentahydrate was dissolved in water 1 at room temperature, and a solution obtained by dispersing 150 g of diatomaceous earth in 0.7 water was added to this solution with stirring. Next, a solution in which sodium carbonate (116.6 g) was dissolved in water (0.4) was added over about 20 minutes, and stirring was continued for another 10 minutes to terminate the reaction. This reaction solution was subjected to suction filtration, and the obtained cake having a water content of 64% was washed with a 0.02% by weight aqueous sodium hydroxide solution 8 and subsequently with water 2. The cake was squeezed and sucked, sufficiently dehydrated, and dried at 90 ° C. for 15 hours to obtain a copper carbonate-supported catalyst precursor.

Example 3 287.6 g of zinc sulfate heptahydrate was dissolved in water 1 at room temperature, and this solution was added to a solution of 116.6 g of sodium carbonate in 0.4 of water.
The mixture was added in 0 minutes, and the mixture was further stirred for 10 minutes to complete the reaction. Next, the reaction solution was subjected to suction filtration to obtain a water content of 65%.
The cake is made from 0.1% by weight aqueous sodium carbonate solution 8 and water 2
And washed. This cake is squeezed and sucked to fully dehydrate,
After drying at 90 ° C. for 15 hours, a zinc carbonate catalyst precursor was obtained.

Example 4 262.8 g of nickel sulfate hexahydrate was dissolved in water 1 at room temperature, and 235 g of diatomaceous earth was added thereto and stirred. Next, sodium carbonate
127.2 g was added to a solution of 0.4 in water in about 20 minutes,
Stirring was continued for another hour to complete the reaction. The reaction solution is filtered by suction, and the obtained cake having a water content of 55% is washed with 0.2 wt% ammonia water 10, and the cake is squeezed and sucked, sufficiently dehydrated, dried at 90 ° C. for 15 hours, and dried with nickel carbonate. A catalyst precursor of salt diatomaceous earth was obtained.

Example 5 The cake having a water content of 65% obtained in Example 1 was mixed with an aqueous solution of ammonium bicarbonate 7 having a concentration of 0.1 wt% and water 1
After washing with 0.01% by weight acetic acid solution 1 and then with water, the acqui is squeezed and sucked to sufficiently dehydrate, and then dried at 90 ° C. for 15 minutes.
After drying for a period of time, a copper / zinc-based carbonate catalyst precursor was obtained.

Comparative Examples 1 to 4 In each of Examples 1 to 4, the cake of each water content obtained by suction-filtration of the reaction solution was washed with water 12 only, and the other conditions were the same as in each Example. I got a body.

Example 6 31.4 kg of copper sulfate pentahydrate was dissolved in water 80 and kept at 40 ° C. This solution was prepared by dissolving 16 kg of sodium carbonate in water 110 at 40 ° C.
To the solution at 40 ° C. for 30 minutes, followed by 80 minutes.
The reaction was carried out at 30 ° C. for 30 minutes to produce basic copper carbonate.

Next, the obtained reaction solution was sent to a rotary filter press, and was continuously filtered and washed. The water content of the slurry at the time of this washing was 86%, and 1 m ^{3 of an} aqueous solution of sodium carbonate having a concentration of 0.025% was used as the washing liquid. After the alkaline cleaning,
Washing was performed with water 400.

Thereafter, the slurry obtained by dehydration was dried at 90 ° C. for 15 hours to obtain a powder of basic copper carbonate. This powder contained 50 ppm of sulfur and 350 ppm of sodium.

(Effect of the Invention) As described above, the metal carbonate catalyst precursor from the metal sulfate obtained by the method of the present invention has a small amount of sulfur and alkali metal added thereto, and has a low content other than metal nitrate and metal acetate. It is used in the production of various catalysts as a catalyst precursor, equivalent to metal carbonates prepared from expensive raw material salts.

According to the present invention, copper, zinc, which occupy an important industrial position,
In addition, metal carbonates, which are precursors for the production of catalysts such as nickel-based catalysts, are easily obtained from inexpensive metal sulfates, and the cost of catalysts is greatly reduced.

Claims (3)

(57) [Claims] An alkali carbonate or an alkali hydrogen carbonate is used as a precipitant for a metal sulfate aqueous solution, and a cake or slurry having a water content of 50 to 95% obtained by filtering a precipitate is washed with a dilute alkaline aqueous solution. A method for producing a metal carbonate as a catalyst precursor, characterized by comprising: 2. The method for producing a metal carbonate as a catalyst precursor according to claim 1, wherein the cake or slurry washed with a diluted alkaline aqueous solution is further washed with pure water. 3. The method for producing a metal carbonate as a catalyst precursor according to claim 1, wherein the cake or slurry washed with a diluted alkaline aqueous solution is further washed with a diluted acid aqueous solution and pure water.