JP2000354770A - Method for depositing active component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively utilize an active component and to reduce a catalyst manufacturing cost by spraying a surface of a catalyst carrier with a solution containing the active component or an active component precursor while the catalyst carrier heated at a prescribed temperature is rolled. SOLUTION: A surface of a catalyst carrier is sprayed with a solution containing an active component or an active component precursor while the particulate carrier heated at a prescribed temperature is rolled. The surface of the carrier is heated preferably at >=50 deg.C. The aqueous solution sprayed onto the surface of the carrier penetrates into an inner part of the carrier and at the same time water as a solvent of the solution is vaporized the moment the solution is brought into contact with the carrier because the carrier is heated at a high temperature. Therefore, the active component is not deposited into the central part of the carrier, which has hardly any contribution to reaction, and accordingly a useless active component can be reduced. As the active component or the active component precursor, inorganic or organic salts, e.g. nitrates, chlorides or acetates, etc., of an active metal, or the active component precursors, e.g. amine compounds, various complex compounds, etc., are used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for supporting an active component on the surface of a particulate catalyst carrier.

[0002]

BACKGROUND OF THE INVENTION An active ingredient such as a metal or a metal oxide is supported on a catalyst carrier in which a porous material typified by a heat-resistant inorganic oxide such as silica and alumina is formed into a particulate form. These catalysts are used in many catalytic reactions. For these catalysts, for example, first, an aqueous solution of a metal salt which is a precursor of an active metal component is impregnated into a catalyst carrier formed by molding a porous inorganic oxide or the like into particles, and then the solvent water is removed and dried. Thereafter, the composition can be prepared by carrying out a treatment such as calcination or reduction, if necessary, to carry the desired active ingredient.

In such a conventional active ingredient supporting method, the active metal component penetrates into the inside of the catalyst carrier particles, and as a result, the active ingredient may be carried on the entire catalyst carrier particles. However, depending on the type of the reaction, the contact reaction occurs only by the active component on or near the surface of the catalyst particle, and the active component near the center inside the catalyst particle hardly contributes to the reaction. In such a case, useless active components not involved in the reaction exist in the catalyst particles. In particular, when the active component is an expensive noble metal or the like, reducing the active component in the catalyst particles not participating in such a reaction as much as possible is an important issue from the viewpoint of reducing the catalyst production cost.

[0004] Therefore, the present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, in the method for supporting the active component on the particulate catalyst carrier by the above-mentioned conventional impregnation method, the particles have been reduced. Active components are concentrated on the surface of or near the surface of the catalyst carrier, and by controlling the thickness of the active component-supporting layer from the surface, the active components can be used effectively and the catalyst production cost can be reduced. And completed the present invention.

[0005]

An object of the present invention is to provide a method for supporting an active component which can effectively utilize the active component when the active component is supported on a particulate catalyst carrier by a so-called impregnation method and which can reduce the cost for producing the catalyst. It is intended to be.

[0006]

SUMMARY OF THE INVENTION According to the present invention, when an active ingredient is supported on a particulate catalyst support, an active ingredient or an active ingredient precursor-containing solution is applied to the surface of the catalyst support while rotating the catalyst support heated to a predetermined temperature. It is characterized by spraying and impregnating. In this method, when spraying the solution containing the active ingredient or the active ingredient precursor on the surface of the heated catalyst carrier, the spraying is interrupted when the temperature of the catalyst carrier decreases, and after the temperature is restored to a predetermined temperature, the spraying is performed again. It is preferable to continue.

[0007]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the method for supporting an active ingredient according to the present invention will be specifically described. As the catalyst carrier used in the present invention, a carrier composed of a known heat-resistant inorganic compound such as silica, alumina, titania, zirconia or activated carbon is used. In the present invention, a carrier obtained by molding the above heat-resistant inorganic compound into an arbitrary shape is used, and the shape of these particulate carriers can be used without particular limitation as long as they are particulate. Specific examples thereof include a molded body usually used as catalyst carrier particles such as a sphere, a column, and a ring.

[0008] The size of such a particulate carrier is not particularly limited, and is appropriately selected according to the intended use.
The active ingredient or active ingredient precursor to be supported on such a particulate carrier is appropriately selected depending on the reaction in which the catalyst is used. For example, an inorganic or organic salt such as a nitrate, chloride or acetate of an active metal is used. Alternatively, active ingredient precursors such as amine compounds and various complex compounds are used. These compounds are preferably water-soluble in terms of handling, and are usually used as an aqueous solution having an appropriate concentration. In addition, those which are hardly soluble in water may be used by dissolving them in organic solvents such as alcohols, ketones and esters.

In the method for supporting an active ingredient according to the present invention, when the active ingredient is supported on the particulate carrier as described above,
The active ingredient or the active ingredient precursor-containing solution is sprayed on the heated particulate carrier surface while rolling the particulate carrier heated to a predetermined temperature. First, in the present invention, a particulate carrier (hereinafter sometimes simply referred to as “carrier”) is heated to a predetermined temperature. Specifically, the carrier is loaded into a rotary heating device such as a rotary kiln or a rotating drum equipped with a suitable heating means, and the carrier is heated while rolling, thereby maintaining the temperature of the carrier uniformly. I do.

The heating temperature at this time varies depending on the type and amount of the active ingredient to be supported, the amount of the support, the thickness of the support layer, and the like.
It is desirably in the range of 0 to 300 ° C, more preferably 80 to 200 ° C. Next, a solution containing the active ingredient or the active ingredient precursor, for example, an aqueous solution is sprayed onto the carrier heated to the above-mentioned constant temperature by an appropriate means such as a spray nozzle. While the aqueous solution containing the active ingredient or the active ingredient precursor is being sprayed, the carrier needs to be tumbled in order to evenly impregnate the entire carrier with the active ingredient and the like.

The aqueous solution sprayed on the surface of the carrier penetrates into the interior of the carrier, and at the same time the carrier is heated to a high temperature, so that the solvent water evaporates at the moment of contact with the carrier. For this reason, since the active ingredient and the like in the aqueous solution permeate only to a certain depth from the surface of the carrier, most of the active ingredient is carried near the surface of the carrier as shown in FIG. In addition, the layer of the active ingredient carried near the surface of the carrier is referred to as “active ingredient carrying layer”.

[0012] The thickness of the active ingredient-supporting layer from the surface of the carrier can be controlled mainly by the temperature of the carrier. That is, the higher the temperature of the carrier, the faster the water of the solvent evaporates, so that the permeation distance of the aqueous solution of the active ingredient into the inside of the carrier is shortened, and the thickness of the active ingredient supporting layer can be reduced. When the solution containing the active ingredient or the precursor of the active ingredient is sprayed as described above, it is preferable to maintain at least the temperature of the surface of the carrier as constant as possible.

Therefore, if the temperature of the carrier drops below a predetermined temperature due to the heat of evaporation of the solvent of the sprayed solution, it is possible to temporarily suspend the spraying and resume the spraying after restoring the temperature of the carrier to the predetermined temperature. preferable. Such an operation may be repeated until a predetermined carrying amount is reached. At this time, it is preferable that the temperature of at least the surface of the carrier during spraying is controlled so as not to be lower than a predetermined temperature by about 10 ° C. or less.

[0014] The holding temperature of at least the surface of the carrier is 5
When the temperature is lower than 0 ° C., the evaporation of the solvent is delayed, so that the active ingredient may penetrate into the vicinity of the center of the carrier. Further, even if the holding temperature is too high, the effect of making the thickness of the support layer thinner is not seen. When two or more active ingredients are supported, a mixed aqueous solution thereof may be sprayed, or each aqueous solution may be sprayed sequentially.

[0015] The carrier impregnated with a predetermined amount of the active ingredient is then subjected to a calcination operation and / or a reduction operation, if necessary, to obtain a desired catalyst. To remove it, it may be dried before the calcination / reduction operation. The drying operation may be performed using the rotary drum or rotary kiln used for the spraying operation, or may be performed after transferring to another drying device. Further, depending on the type of the active ingredient, the above-mentioned drying, calcination and reduction operations are not required, and the desired catalyst may be used as it is.

[0016]

According to the method of the present invention, the active ingredient can be supported on the particulate carrier from the surface to an arbitrary thickness. For this reason, since the active component is not supported even on the central portion of the carrier that hardly contributes to the reaction, useless active components can be reduced, and the cost for producing the catalyst can be reduced.

[0017]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0018]

EXAMPLE 1 450 g of a spherical silica carrier having a specific surface area of 120 m ² / g and a pore volume of 0.9 ml / g and having a diameter of 2 to 3 mm was loaded on a rotating drum equipped with a heating device and rotated. While rotating the silica carrier, 5
Heated to a temperature of 0 ° C.

13.28 g / liter of Pd (NH ₃ )
450 ml of ₄ (NO ₃ ) ₂ aqueous solution (2.
26 g) was sprayed onto the surface of the tumbling silica support. When the temperature of the silica carrier was lowered by about 5 ° C. from a predetermined temperature (50 ° C.), the spraying was interrupted, and after the temperature was recovered, the spraying operation was continued again. When the entire amount of the aqueous solution was sprayed while repeating this operation, the spraying operation was terminated.

Next, the silica carrier after carrying the active ingredient was taken out of the rotating drum, transferred to a fixed-bed reducing apparatus, and subjected to a reducing operation at 200 ° C. for 1 hour in a hydrogen stream to prepare a target catalyst. The obtained spherical catalyst was divided into two, and the thickness of the active ingredient-supporting layer was measured. The results are shown in Table 1 and FIG.

The thickness of the carrier layer in the carrier after carrying the active ingredient was measured by dividing the dried catalyst into two and observing the cross section with a stereoscopic microscope.

[0022]

Examples 2 to 5 Catalysts were prepared in the same manner as in Example 1, except that the heating temperature of the silica carrier was changed to 90, 120, 160 and 200 ° C. When the temperature of the silica carrier drops by about 5 ° C. from a predetermined temperature (90, 120, 160 and 200 ° C., respectively) as in Example 1, the spraying is interrupted, and after the temperature recovers, the spraying operation is performed again. Continued.

Table 1 and FIG. 2 show the thickness of the active component supporting layer in the obtained catalyst.

[0024]

Example 6: Specific surface area 100 m ² / g, pore volume 0.6
A rotary drum equipped with a heating device is charged with 450 g of a columnar silica carrier having a diameter of 3 mm and a length of 3 to 5 mm having a flow rate of 8 ml / g and heating the silica particles to 120 ° C. while rotating the silica particles to roll the silica particles. did. 360 ml of an aqueous solution of 10.47 g / liter of PdCl ₂ (2.26 g in terms of Pd) was sprayed onto the surface of the tumbling silica carrier. When the temperature of the silica carrier is a predetermined temperature (120
C.), the spraying was interrupted, and after the temperature had recovered, the spraying operation was continued again. When the entire amount of the aqueous solution was sprayed while repeating this operation, the spraying operation was terminated.

Next, the silica carrier after carrying the active ingredient was taken out of the rotating drum, transferred to a fixed-bed reducing device, and subjected to a reducing operation in a hydrogen stream at 200 ° C. for 1 hour to prepare a target catalyst. The obtained columnar catalyst was divided into two, and the thickness of the active ingredient-supporting layer was measured. As a result, about 2
The active ingredient was uniformly loaded to a thickness of 50 μm.

[0026]

[Table 1]

[Brief description of the drawings]

FIG. 1 is a schematic view showing a support layer of an active ingredient.

FIG. 2 is a diagram showing a relationship between a heating temperature of a carrier and a thickness of a carrier layer in Examples.

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Claims (3)

[Claims] 1. A method for spraying an active ingredient or an active ingredient precursor-containing solution onto a surface of a catalyst carrier while rolling the catalyst carrier heated to a predetermined temperature when the active ingredient is supported on a particulate catalyst carrier. A method for supporting an active ingredient, characterized in that: 2. A catalyst carrier having a surface at least 50 ° C.
The method for supporting an active ingredient according to claim 1, wherein the method is heated to the above temperature. 3. When spraying a solution containing an active ingredient or an active ingredient precursor onto the surface of the heated catalyst carrier, if the temperature of the catalyst carrier drops, the spraying is interrupted, and the spray is resumed after the temperature is restored to a predetermined temperature. The method for supporting an active ingredient according to claim 1, wherein the method is continued.