JP2001253714A - High specific surface area zirconium oxide material and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zirconium material having high specific surface area and excellent heat resistance (thermal stability) of the specific surface area. SOLUTION: The high specific surface area zirconium oxide material is an amorphous material consisting essentially of Zr and O and having at least 150 m2/g specific surface area and the manufacturing method is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a high specific surface area zirconium oxide material and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, zirconium oxide has been widely used in various products including catalyst materials and catalyst carriers because of its excellent heat resistance.

For example, zirconium oxide is used in automobile exhaust gas purifying catalysts, which are considered to be the harshest atmospheres, to improve the heat resistance of cerium oxide and to suppress the sintering of precious metals. 8, 566 (1989)).

Further, it is used as a precious metal carrier in a NOx storage-reduction type catalyst for purifying NOx gas contained in exhaust gas from a lean burn engine (Japanese Patent Application Laid-Open Nos. 11-138221 and 11-226404).
No.). It has also been reported that zirconium oxide complexed with sulfuric acid or tungstic acid is useful as a solid acid catalyst (JP-A-9-103681, JP-A-6-21).
0176, JP-A-5-112473, JP-A-61-1
No. 24641).

[0005] The zirconium oxide used in the field of these catalyst supports preferably has as high a specific surface area as possible. Also, when used as a precursor of a composite, it is desired that the specific surface area is high, that is, the reaction activity is high.

[0006]

However, although it has been reported that a high specific surface area can be secured when a composite oxide is formed by adding aluminum, silicon, cerium, etc., pure zirconium oxide (aluminum, aluminum, etc.) can be obtained.
No such examples have been reported for those which do not contain silicon, cerium, etc. and consist essentially of zirconium oxide).

The conventionally known pure zirconium oxide has a specific surface area of at most about 100 m ² / g after being calcined at 400 ° C. Further, the specific surface area when this zirconium oxide is heat-treated at 800 ° C. is about 20 m ² / g, and is significantly deteriorated by heat. Thus, when compared with alumina or the like, the low specific surface area in the middle and high temperature regions is regarded as a major drawback of zirconium oxide.

Therefore, the present invention has a high specific surface area,
Another object of the present invention is to provide a zirconium oxide material having a specific surface area and excellent heat resistance (thermal stability). Another object of the present invention is to provide a method for producing such a material with good reproducibility on an industrial scale.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the problems of the prior art, and as a result, have found that a material obtained by a specific production method has a unique property. The present invention has been completed.

That is, the present invention relates to the following high specific surface area zirconium oxide material and a method for producing the same.

1. An amorphous material containing Zr and O as main components and having a specific surface area of at least 150 m ² / g
High specific surface area zirconium oxide material.

2. A method for producing a high specific surface area zirconium oxide material, which comprises adding at least a diamine compound to the solution when preparing a zirconium oxide material by generating a precipitate from a solution containing zirconium ions.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The high specific surface area zirconium oxide material of the present invention is an amorphous material containing Zr and O as main components, and has a specific surface area of at least 150 m ² / g.

The zirconium oxide material of the present invention essentially requires the presence of zirconium atoms and oxygen atoms, but may contain third components such as unavoidable impurities as long as the effects of the present invention are not impaired. In the present invention, a particularly high specific surface area can be achieved even with a material substantially consisting of only Zr and O.

The zirconium oxide material of the present invention is amorphous. Therefore, the X-ray diffraction image remains broad and there is no clear peak. In particular, the material of the present invention preferably maintains an amorphous state even when heat-treated at least at 400 ° C.

The material of the present invention has a specific surface area of at least 150.
m ² / g (preferably at least 200 m ² / g), and may be appropriately set within the above range according to the use and purpose of the final product. For example, when the material of the present invention is used as a petrochemical catalyst carrier, its specific surface area is usually 20
It is preferably at least 0 m ² / g, particularly preferably at least 250 m ² / g.

Further, the zirconium oxide material of the present invention has a crystal structure containing tetragonal zirconium oxide and has a specific surface area of at least 100 m ² / g after the material is heat-treated at 800 ° C. Is preferred. A material having such properties can be suitably used for applications requiring heat resistance at high temperatures, for example, a catalyst carrier for purifying automobile exhaust gas.

Regarding the crystal structure after heat treatment at 800 ° C.,
It may have a crystal phase other than tetragonal (for example, monoclinic) as long as the effects of the present invention are not impaired. As described above, in the present invention, in the crystal structure after the heat treatment at 800 ° C., other crystal phases may be present together with the tetragonal crystal, but the crystal having a tetragonal crystal ratio of 80% by volume or more, particularly 90% by volume or more is used. It is preferably a structure. This makes it possible to secure a particularly high specific surface area.

Further, in the zirconium oxide material of the present invention, it is preferable that the crystallite diameter of the material after heat treatment at 800 ° C. is 150 ° or less (particularly 100 ° or less). The material of the present invention can achieve a particularly high specific surface area when the crystal growth is suppressed within the range of the crystallite diameter.

The material of the present invention has a pore volume of usually 0.3 cc.
/ G or more, particularly preferably 0.5 cc / g or more. Further, the pore radius is usually preferably 40 ° or less, particularly preferably 25 ° or less.

The pore volume of this material after heat treatment at 800 ° C. is usually 0.2 cc / g or more, especially 0.1 cc / g.
It is preferably at least 25 cc / g. Similarly, the pore radius after heat-treating this material at 800 ° C. is usually preferably 200 ° or less, particularly preferably 100 ° or less.

Further, the material of the present invention comprises
At least 250 m ² / g after heat treatment at
, Especially at least 300 m ² / g.

800 ° C. (or 400 ° C.) in the present invention
In the heat treatment, for example, 5 g of the above-mentioned material is placed in a crucible and treated in an oxidizing atmosphere at 800 ° C. (or 400 ° C.) for 3 hours in an electric furnace preheated to 800 ° C. (or 400 ° C.). The crucible is taken out from the container and left to cool to room temperature (about 18 ° C.) in a desiccator. Therefore, those exhibiting the above specific surface area or crystallite diameter by at least the above heat treatment are included in the present invention.

The high specific surface area zirconium oxide material of the present invention is obtained by adding at least a diamine compound to the solution when preparing a zirconium oxide material by, for example, forming a precipitate from a solution containing zirconium ions (the present invention). Method).

As the solution containing zirconium ions, for example, a solution obtained by dissolving a zirconium raw material in an appropriate solvent can be used. The zirconium raw material is not particularly limited as long as it can supply zirconium ions. For example, when an aqueous solvent such as water is used as the solvent, zirconium inorganic acid salts such as zirconium oxynitrate and zirconium oxychloride can be used. When an organic solvent such as methanol or ethanol is used, a zirconium organic acid salt such as zirconium tetrabutoxide can be used. In the present invention, it is preferable to use zirconium oxychloride in an aqueous solvent (particularly water) from the viewpoint of productivity on an industrial scale and the like.

The concentration of zirconium ion in the above solution may be appropriately set according to the kind (solubility) of the salt used, etc., but usually about 5 to 200 g, preferably 10 to 80 g as zirconium oxide in 1000 g of solvent.
It is good.

In the method of the present invention, at least a diamine compound is added to the above solution. The diamine compound is not particularly limited as long as it solvates with the solvent used,
A product obtained by a known production method or a commercially available product can be used. For example, diamine compounds such as hydrazine, ethylenediamine, and p-phenylenediamine can be used.

The amount of the diamine compound to be added can be appropriately changed according to the kind (solubility) of the diamine compound to be used, etc., but usually, the pH of the above solution is about 5 to 10, preferably 7 to 9. good.

In the method of the present invention, a precipitate can be formed by adding a diamine compound. However, if necessary, a base can be added to form a precipitate. The base is not particularly limited, and for example, ammonium hydroxide, ammonium bicarbonate, sodium hydroxide, potassium hydroxide and the like can be used.

The amount of the base to be added is not particularly limited as long as a precipitate can be formed from the solution, and the pH of the solution is usually 5 or more, preferably 7 or more.

Further, if necessary, the solution may further contain metal ions or metal particles other than zirconium. One or more of these metal ions can be blended. Thereby, a composite with zirconium can be manufactured. For example, Mg, Al, Si, Ca,
Sc, Ti, Cr, Mn, Fe, Co, Ni, Cu, Z
n, Y, In, Sn, Mo, W, etc., La, Ce,
Lanthanoid elements such as Pr can be added to the above solution.

In the method of the present invention, the temperature of the solution is not particularly limited, and the solution can be carried out at around room temperature. It may be heated to a temperature.

Next, the generated precipitate is recovered by a solid-liquid separation method to obtain a zirconium oxide material. The solid-liquid separation method may follow a known method such as filtration, centrifugation, decantation and the like. After the recovery, the zirconium oxide-based material may be washed with water as needed.

The obtained zirconium oxide-based material may be further dried if necessary. The drying method may be in accordance with a known method, and may be, for example, any of natural drying and heat drying. If necessary, a pulverization treatment, a classification treatment, or the like may be performed after the drying treatment.

If necessary, the zirconium oxide material can be heat-treated. The heat treatment temperature is not particularly limited as long as the zirconium oxide material maintains an amorphous state, but is usually about 400 to 800 ° C., preferably 400 to 800 ° C.
The temperature may be set to ６００600 ° C. The heat treatment atmosphere may be air or an oxidizing atmosphere.

[0036]

The zirconium-based material of the present invention shows an X-ray diffraction image indicating amorphous. Generally, zirconium oxide is 400
Although it is known to crystallize at <RTIgt; 0 C, </ RTI> the materials of the present invention exist as amorphous up to at least 600C.

In general, after heat treatment at 800 ° C.,
In order to obtain tetragonal zirconium oxide, it is necessary to dissolve a stabilizing agent (for example, yttrium, calcium, magnesium, cerium, etc.) to form stabilized zirconium oxide. On the other hand, since the zirconium oxide of the present invention is composed of fine crystals having a very small crystal diameter, a tetragonal system can be obtained without a stabilizer. This is because the transformation from tetragonal to monoclinic is suppressed by increasing the surface energy as the particles become finer. In order to distinguish a tetragonal crystal in such a state from stabilized zirconium oxide, it may be referred to as meta-stabilized tetragonal zirconium.

Further, the production method of the present invention is characterized in that a diamine compound is added and is present in a solution. As a result, the diamine compound has a zirconium ion (Zr ⁴⁺ or ZrO ₂ ²⁺ ) and a hydroxide ion (O 2
The formation of a hydroxide precipitate polymerized irregularly with H ⁻ ) can be suppressed, and a basic precipitate controlled to a certain polymerization number can be obtained. In addition, since the diamine compound coordinates at the position of hydration water (including coordination water, surface attached water, etc.), aggregation of the precipitate occurs via bidentate of the diamine compound, and sintering occurs during heat treatment dehydration. The effect of suppressing can be exhibited.

[0039]

According to the production method of the present invention, zirconium oxide having a crystal system and specific surface area different from those of conventional zirconium oxide and having a stable specific surface area up to a high temperature range of 800 ° C. or more can be produced on an industrial scale. And can be manufactured with good reproducibility.

Since the zirconium oxide material of the present invention has a large specific surface area, it is useful as a catalyst material (for example, a catalyst, a catalyst carrier, a cocatalyst, etc.), an adsorbent, an ion exchange material and the like. .

In particular, besides a carrier of a noble metal (catalyst carrier) in a catalyst for purifying automobile exhaust gas, a catalyst material for compounding a solid catalyst acid with tungstic sulfate, etc., an application requiring a high specific surface area or a high temperature It can be suitably used in applications used in the region.

[0042]

EXAMPLES Examples and comparative examples are shown below to further clarify the features of the present invention. Note that the present invention is not limited to these embodiments.

Each physical property in the examples was measured by the following methods. In addition, the materials obtained in each of the examples and the comparative examples contain 1.3 to 2.5% by weight of hafnium oxide as an inevitable impurity. (1) X-ray diffraction analysis It was measured using an X-ray diffractometer (“Geigerflex RAD-2C” manufactured by Rigaku). (2) Crystallite diameter It was calculated by the Scherrer method based on the result of measurement using an X-ray diffractometer (“Geigerflex RAD-2C” manufactured by Rigaku). (3) Specific surface area It was measured by a BET method using a specific surface area meter (“Flowsorb-II” manufactured by Micromeritics). (4) Pore volume and pore radius measurement device "Autosorb-1, Quantachrome (MODEL NO.AS1K
R) "by the BJH method.

Example 1 Zirconium oxychloride was converted to zirconium oxide by 20
g and weighed to 500 g
Solution. To this solution was added 95% by weight of ethylenediamine and then 25% by weight of ammonium hydroxide to adjust the pH of the solution to 10 to form a precipitate. The precipitate was collected by filtration and washed with water. next,
The precipitate was calcined at 400 ° C. for 5 hours. The specific surface area of the obtained fired body was 245 m ² / g. Further, X-ray powder diffraction analysis was performed on the fired body. FIG. 1A shows the result.
(Heat treatment at 400 ° C.). From FIG. 1A, it was confirmed that the fired body was amorphous. An X-ray powder diffraction analysis was performed on a sample which was further heat-treated at 800 ° C. The result is shown in FIG. 1A (800 ° C. heat treatment). From FIG. 1A,
The sample was confirmed to be tetragonal zirconium oxide containing monoclinic system (ratio of tetragonal system: about 99% by volume). The specific surface area was 105 m ² / g, and the crystallite diameter was 98 °. Table 1 shows the results. Table 1 shows the pore volume and pore radius of the precipitate,
The pore volume and the pore radius of the sample heat-treated at 0 ° C. are shown.
FIG. 2 shows the result of examining the relationship between the heat treatment temperature and the specific surface area of the precipitate.

Example 2 Zirconium oxychloride was converted to zirconium oxide by 20
g and weighed to 500 g
Solution. To this solution, 60% by weight of hydrazine hydrate (N ₂ H ₄ .H ₂ O) was added to adjust the pH of the solution to 8, and a precipitate was formed. The precipitate was collected by filtration and washed with water. Next, the precipitate was calcined at 400 ° C. for 5 hours. The specific surface area of the obtained fired body was 317 m ² / g. Further, X-ray powder diffraction analysis was performed on the fired body. The result is shown in FIG. 1B (heat treatment at 400 ° C.). FIG.
B confirmed that the fired body was amorphous. The sample which was further heat-treated at 800 ° C. was subjected to X-ray powder diffraction analysis. The result is shown in FIG. 1B (800 ° C. heat treatment).
From FIG. 1B, it was confirmed that the sample was zirconium oxide composed of tetragonal crystals including a monoclinic system (ratio of tetragonal crystals: about 99% by volume). The specific surface area was 128 m ² / g, and the crystallite diameter was 98 °. Table 1 shows the results. Table 1 shows the pore volume and pore radius of the precipitate, and the pore volume and pore radius of the sample heat-treated at 800 ° C. FIG. 2 shows the result of examining the relationship between the heat treatment temperature and the specific surface area of the precipitate.

Comparative Example A precipitate was obtained in the same manner as in Example 1 except that ethylenediamine was not used. The precipitate was calcined at 400 ° C. for 5 hours. The specific surface area of the obtained fired body is 107 m ² /
g. Further, X-ray powder diffraction analysis was performed on the fired body. The result is shown in FIG. 1C (heat treatment at 400 ° C.). From FIG. 1C, it was confirmed that the fired body was zirconium oxide composed of a monoclinic crystal containing a small amount of tetragonal crystals. An X-ray powder diffraction analysis was performed on a sample which was further heat-treated at 800 ° C. The result is shown in FIG. 1C (heat treatment at 800 ° C.). From FIG. 1C, it was confirmed that the sample was monoclinic zirconium oxide (ratio of tetragonal: about 3% by volume). The specific surface area was 21 m ² / g, and the crystallite diameter was 211 °. Table 1 shows the results. Also,
Table 1 shows the pore volume and pore radius of the precipitate,
The pore volume and the pore radius of the sample heat-treated at 00 ° C. are shown. FIG. 2 shows the result of examining the relationship between the heat treatment temperature and the specific surface area of the precipitate.

[0047]

[Table 1]

As is clear from the results shown in Table 1, in the comparative example, the precipitate has a specific surface area of 150 m ² / g or less.
m ² / g is greatly reduced.

On the other hand, the precipitates of Examples 1 and 2
It can be seen that a large specific surface area of 100 m ² / g or more can be maintained even after the heat treatment at 800 ° C. The pore volume after heat treatment at 800 ° C. is 0.2 cc /
It can be seen that it has a unique structure of not less than g and not more than 200 ° of the pore radius.

[Brief description of the drawings]

FIG. 1 shows 400 ° C. and 80 ° in each of Examples and Comparative Examples.
It is a figure which shows the X-ray-diffraction analysis result after heating at 0 degreeC.

FIG. 2 is a view showing a result of examining a relationship between a heat treatment temperature and a specific surface area of a precipitate in each of Examples and Comparative Examples.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G048 AA02 AB02 AC08 AD06 AE05 4G069 AA01 AA08 BA05A BA05B CA03 CA09 DA06 EC02Y EC03X EC03Y EC04Y EC05Y EC26 FA01 FC07

Claims (8)

[Claims] 1. A high specific surface area zirconium oxide material having a specific surface area of at least 150 m ² / g, which is an amorphous material containing Zr and O as main constituents. 2. The high specific surface area zirconium oxide material according to claim 1, which has a crystal structure including tetragonal zirconium oxide after heat treatment at 800 ° C. and has a specific surface area of at least 100 m ² / g. . 3. The high specific surface area zirconium oxide material according to claim 1, wherein the crystallite diameter after heating at 800 ° C. is 150 ° or less. 4. A method for producing a zirconium oxide material having a high specific surface area, wherein at least a diamine compound is added to the solution when a precipitate is formed from a solution containing zirconium ions to prepare the zirconium oxide material. . 5. The solution containing zirconium ions having a pH of 5
The diamine compound is added so as to be from 10 to 10.
The manufacturing method as described. 6. The method according to claim 5, wherein the produced precipitate is further heat-treated. 7. The method according to claim 4, wherein the solution containing zirconium ions further contains metal ions or metal particles other than zirconium. 8. A catalyst material comprising the material according to claim 1.