JPH081004A - Zirconium phosphate molded body for catalyst carrier and its production - Google Patents

Abstract

PURPOSE:To obtain a zirconium phosphate molded body having excellent strength characteristics and specific surface area by calcining a mixture molded body comprising a zirconium hydroxide powder, phosphoric acid, and basic zirconium salt. CONSTITUTION:After phosphoric acid and water are added and kneaded with a zirconium hydroxide powder, a soln. of basic zirconium salt is added to the mixture and kneaded till the mixture is plasticized. Then the mixture is molded, dried and calcined at about 400-600 deg.C to obtain the molded body having >=80m<2>/g specific surface area and an absorption peak at 1635cm<-1> in the infrared spectrum. The amt. of phosphoric acid added is 2 to 5wt.% expressed in terms of P2O5 to the amt. of all zirconium expressed in terms of ZrO2 in the molded body. The amt. of basic zirconium salt soln. added is 10-30wt.% expressed in terms of ZrO2 to the zirconium hydroxide powder expressed in terms of ZrO2. Thereby, high specific surface area and excellent rupture strength can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zirconium phosphate molded article excellent as a catalyst carrier for decomposing volatile halogenated organic compounds and a method for producing the same.

[0002]

As a volatile halogenated organic compound,
Freon gas, trichlorethylene, tetrachloroethylene, etc. are available.

Freon gas is widely used not only in the industrial world but also in general because its chemical properties are excellent for applications such as propellants and refrigerants. However, when CFCs are discharged into the atmosphere, they flow into the ozone layer and are decomposed by solar ultraviolet rays to generate chlorine atoms, and the destruction of the ozone layer by these chlorine atoms is a serious problem from the perspective of protecting the global environment. There is. Therefore, when the CFC gas is discharged, it is necessary to perform some harmless treatment without discharging the CFC gas as it is.

Trichloroethylene, tetrachloroethylene and the like are widely used in metal degreasing processes and dry cleaning processes. However, since it was found that chlorine compounds such as trichlorethylene have a carcinogenic effect, their emission into the atmosphere, soil contamination and groundwater contamination due to landfill or illegal dumping have become a problem.

As described above, the volatile halogenated organic compounds and the waste liquid containing them are, from the viewpoint of environmental hygiene,
With the implementation of laws and regulations in various places, it is strongly desired to develop detoxification treatment technology along with strict management.

[0006] Conventionally, as a method for treating volatile halogenated organic compounds such as CFCs, trichloroethylene and tetrachloroethylene, a method of adsorbing and collecting with activated carbon, zeolite or the like has been known. The detoxification treatment method has not been sufficiently developed.

That is, a thermal decomposition method in which a volatile halogenated organic compound is burned at a temperature of 800 ° C. or higher under high pressure, a high-frequency plasma decomposition method in which ultraviolet rays are irradiated for photolysis, and decomposition and combustion are performed in the presence of a catalyst The catalytic decomposition method and the like have been proposed. However, the method of burning under high pressure and the method of decomposing with high-frequency plasma have problems such as large-scale equipment and high processing cost. On the other hand, the catalytic cracking method using a catalyst is a simple method.

Alumina, silica, zeolite, titania, zirconia, zirconium phosphate, etc. have been proposed as the catalyst carrier used in this catalytic cracking method, but titania, zirconia, phosphoric acid having excellent acid resistance is proposed. It is zirconium. And platinum on these catalyst carriers,
It is known that those carrying active metal oxides such as palladium and rhodium are excellent in decomposition activity of volatile halogenated organic compounds.

[0009]

Generally, a method for obtaining a molded product for a catalyst carrier having practical strength in a zirconia system is to use rock wool as a reinforcing agent in zirconia,
A method has been proposed in which a fiber such as alumina or an inorganic substance such as alumina sol or silica sol is added, and water is further added to knead the mixture to obtain a molded body. However, since the reinforcing agent is contained in the zirconia molded body, there is a drawback that the characteristics of zirconia are deteriorated, and particularly when an inorganic substance is added, the acid resistance is significantly decreased.

Usually, the practical breaking strength as a catalyst carrier is
A cylindrical molded body having a diameter of 1.5 mm requires 0.5 kg / mm or more. Therefore, zirconia with a high melting point
In order to obtain the required strength, that is, the interparticle bond, firing must be performed at a temperature of 900 ° C. or higher. However, calcination at a high temperature reduces the specific surface area and causes a new problem that the catalyst carrier does not function sufficiently. That is, if the reaction is a gas system, the specific surface area of the catalyst carrier is 50.
m ² / g or more is required, and a specific surface area of 80 m ² / g or more must be realized in order to further improve the catalytic function.

The present invention solves various problems as described above in a molded zirconium phosphate, and provides a molded zirconium phosphate for a catalyst carrier having excellent strength characteristics and specific surface area, and a method for producing the same. With the goal.

[0012]

The zirconium phosphate molded article of the present invention for solving the above problems and achieving the above objects is a mixture of zirconium hydroxide powder, phosphoric acid and a basic zirconium salt. A molded carrier obtained by firing a molded product, having a specific surface area of 80 m ² / g or more,
It has an absorption peak at 1635 cm ^-1 in the infrared spectrum.

Further, in the manufacturing method of the present invention, phosphoric acid and water are added to the zirconium hydroxide powder and kneaded, and then a basic zirconium salt solution is added and kneaded until plasticized and molded. It consists of drying and then calcining in the temperature range from 400 to 600 ° C. The addition amount of phosphoric acid is in the range of 2 to 5% by weight in terms of P ₂ O ₅ equivalent to the ZrO ₂ equivalent amount of all zirconium in the molded body, and the addition amount of the basic zirconium salt solution is hydroxylated. in terms of ZrO ₂ amount to the terms of ZrO ₂ of zirconium powder 10-30
It is added in the range of weight%.

[0014]

The details of the present invention and the operation thereof will be described in more detail below.

That is, the zirconium hydroxide powder is kneaded with an appropriate amount of water and phosphoric acid, and a basic zirconium salt is added to the kneaded product, which is then molded, dried and fired to form a zirconium phosphate molded product. When formed, a molded product having excellent fracture strength can be obtained by firing at a relatively low temperature without adding a reinforcing material that impairs acid resistance. Moreover, the molded product obtained by the low temperature firing in this way has a larger specific surface area than the conventional high temperature baked zirconium phosphate molded product, and can exhibit a sufficient function as a catalyst carrier. It has been confirmed that the specific surface area of the zirconium phosphate molded body having an absorption peak at 1635 cm ^-1 in the infrared spectrum is large.

In the present invention, a zirconium phosphate molding having excellent breaking strength can be obtained at a relatively low temperature by kneading an appropriate amount of water and phosphoric acid with zirconium hydroxide powder and then adding a basic zirconium salt. It is not clear why it is obtained by firing. However, by adding phosphoric acid to the zirconium hydroxide powder and kneading, coarse particles of the zirconium hydroxide powder consisting of secondary and tertiary particles of zirconium are deflocculated and the particles are homogenized, and then basic It is presumed that the particles are fixed and the packing density is increased by the addition of the zirconium salt due to the neutralization reaction. Further, homogenization of zirconia particles is considered to contribute to increase the specific surface area of the molded body.

In the present invention, the phosphoric acid added to the zirconium hydroxide powder includes orthophosphoric acid, phosphorous acid, hypophosphorous acid and the like, and it is preferable to use orthophosphoric acid.

The amount of phosphoric acid added is _{2 to 5 in} terms of P ₂ O _{5 with} respect to ZrO _{2 in} terms of all zirconium in the molded body.
Good results are obtained when added in the range of wt%. When the amount of phosphoric acid added is less than 2% by weight in terms of P ₂ O ₅ , a molded product having an appropriate fracture strength and a high specific surface area cannot be obtained. Conversely, when the amount exceeds 5% by weight, fracture occurs. Although the strength is improved, the presence of P ₂ O ₅ becomes excessive and the specific surface area decreases due to the sintering effect.

Next, as the basic zirconium salt to be added to the kneaded product of zirconium hydroxide powder, water and phosphoric acid,
Examples thereof include zirconium carbonate, ammonium zirconium carbonate, potassium zirconium carbonate and the like, and it is preferable to use ammonium zirconium carbonate. The amount of the basic zirconium salt added is such that the zirconium hydroxide powder is added to the basic zirconium salt based on the ZrO ₂ conversion amount.
₂ Add in an amount of 10 to 30% by weight in terms of conversion amount. When the amount of the basic zirconium salt added is less than 10% by weight in terms of ZrO ₂ , a molded body having an appropriate breaking strength cannot be obtained. Conversely, when it exceeds 30% by weight, N
The presence of H ₃ becomes excessive, which reduces the breaking strength of the molded body. In this way, if the addition amount of phosphoric acid or basic zirconium salt is not proper, the object of the present invention is 80.
It becomes impossible to obtain a zirconium phosphate molded product having a specific surface area of m ² / g or more and having sufficient breaking strength. Moreover, the reason why the basic zirconium salt is added and then kneaded by heating is to uniformly disperse the zirconia particles.

In order to obtain the molded zirconium phosphate of the present invention, the zirconium hydroxide powder is kneaded with water and phosphoric acid in the above-mentioned addition amount range, and then the basic zirconium salt solution is added and heated. The kneaded and sufficiently plasticized kneaded product is molded into a desired shape and dried, and this is 400 to 600 ° C.
Firing at a temperature of

Molding of the kneaded product is carried out by using a general extrusion molding machine, a rounding machine or the like. The shape of the molded body may be any shape such as a cylindrical shape, a four-lobed shape, a hollow cylindrical shape, and a spherical shape. The firing temperature is set in the range of 400 to 600 ° C.
1635c at temperatures below and above 600 ° C
No infrared absorption spectrum was observed at m ^-1 and 80 m ² /
This is because a specific surface area value of g or more cannot be obtained.

[0022]

EXAMPLES Examples of the present invention will be described below together with comparative examples.

The specific surface area of the zirconium phosphate molded body was determined by the BET method using nitrogen gas adsorption, the infrared spectrum was determined using Model 1720X manufactured by Perkin Elma Co., and the breaking strength was determined using a Kiya hardness meter.

(Example 1) Zirconium hydroxide powder (Z
1500 g of an industrial reagent containing 65% by weight of rO ₂ ) and 200 g of water and 41 g of orthophosphoric acid (first-grade reagent) were kneaded in a kneader with a heating jacket, and then a zirconium ammonium carbonate solution (containing 65% by weight of ZrO ₂₎ (Industrial reagent) 1220 g was added and kneaded until sufficiently plasticized to obtain a kneaded product. Incidentally, with respect to ZrO ₂ equivalent amount of zirconium hydroxide powder and ammonium zirconium carbonate solution, the amount of orthophosphoric acid is 2% by weight P ₂ O ₅ equivalent amount, in terms of ZrO ₂ of zirconium hydroxide powder On the other hand, the amount of the ammonium zirconium carbonate solution added is _{2 in} terms of ZrO 2.
It is 0% by weight, and the loss on ignition of the kneaded material at 500 ° C. is 48.
%Met. Next, the kneaded product is molded with an extruder having a 1.5 mmφ die and dried at a temperature of 100 ° C. for 15 hours, and the dried product is fired at 500 ° C. for 2 hours to obtain a zirconium phosphate molded body A. Obtained. Obtained molded body A
The specific surface area was 91 m ² /
g, breaking strength was 0.6 kg / mm, and it was also confirmed that the infrared spectrum had an absorption peak at 1635 cm ^-1 . From the results of this example, it can be seen that both the specific surface area and the fracture strength satisfy the values required for the catalyst carrier and are sufficiently applicable as the catalyst carrier.

[0025] Except (Example 2) that the amount of orthophosphoric acid to be added to ZrO ₂ equivalent amount of zirconium hydroxide powder and a zirconium ammonium carbonate solution was 5 wt% in terms of oxide amount, performed A zirconium phosphate molded body B was obtained by a method substantially similar to the method shown in Example 1. When the properties of the obtained molded product B were examined, the specific surface area was 84.
m ² / g, breaking strength is 0.8 kg / mm,
It was also confirmed that the infrared spectrum had an absorption peak at 1635 cm ^-1 .

From the results of Example 1, the amount of orthophosphoric acid added to the ZrO ₂ conversion amount of the zirconium hydroxide powder and the zirconium ammonium carbonate solution was ₂ to the oxide conversion amount.
It can be seen that both the specific surface area and the breaking strength can satisfy the values required as the catalyst carrier within the range of 5% by weight.

(Examples 3 to 4) Except that the amount of zirconium ammonium carbonate solution added was 10% by weight and 30% by weight in terms of ZrO ₂ with respect to the amount of ZrO _{2 in} zirconium hydroxide powder. Zirconium phosphate molded bodies C and D were obtained by a method substantially similar to the method shown in Example 1. When the properties of the obtained molded products C and D were determined, the specific surface areas were 86 m ² / g and 89 m ² / g, respectively, and the breaking strengths were 0.7 kg / mm and 0.5 kg / mm, respectively. It was confirmed that the infrared spectrum also had an absorption peak at 1635 cm ^-1 .

From the results of Examples 3 to 4, the addition amount of the ammonium zirconium carbonate solution to the ZrO ₂ conversion amount of the zirconium hydroxide powder was 10 to 3 in ZrO ₂ conversion amount.
It can be understood that both the specific surface area and the breaking strength can satisfy the values required as the catalyst carrier within the range of 0% by weight.

Comparative Examples 1 and _{2 The} amount of orthophosphoric acid added to the zirconium hydroxide powder and the zirconium ammonium carbonate solution in terms of ZrO ₂ was 1% by weight in terms of oxide, and 7 Example 1 except that the weight percent was used.
Zirconium phosphate molded bodies E and F were obtained by a method substantially similar to the method shown in FIG. When the properties of the obtained molded products E and F were determined, the specific surface areas were 72 m ² / g and 4 respectively.
It is 5 m ² / g and the breaking strength is 0.4 kg / mm.
0 kg / mm, and the infrared spectrum is 16
It was confirmed that there was an absorption peak at 35 cm ^-1 .

From the results of Comparative Examples 1 and 2, ZrO 2 of zirconium hydroxide powder and zirconium ammonium carbonate solution was added.
The addition amount of orthophosphoric acid is _{2 in} terms of oxide in 2 equivalent
When the content is less than 5% by weight, the specific surface area is reduced as compared with the zirconium phosphate molded article A of Example 1, and the breaking strength is remarkably inferior, and it is found that the value required as a catalyst carrier cannot be sufficiently satisfied. When the content is more than 100%, the fracture strength becomes strong, but the specific surface area becomes remarkably small. Therefore, it is clear that both are not suitable as a catalyst carrier.

Comparative Examples 3 to 4 Except that the amount of the zirconium ammonium carbonate solution added was changed to 5% by weight and 40% by weight in terms of ZrO ₂ with respect to the amount of ZrO _{2 in} zirconium hydroxide powder. Zirconium phosphate molded bodies G and H were obtained by a method substantially similar to the method shown in Example 1. The resulting molded mold bodies G, was examined the properties for H, each specific surface area 84m ² / g, a 88m ² / g, breaking strength was 0.4kg / mm, 0.3kg / mm,
It was confirmed that the infrared spectrum also had an absorption peak at 1635 cm ^-1 .

From the results of Comparative Examples 3 to 4, the amount of the zirconium ammonium carbonate solution added was 10% by weight in terms of ZrO ₂ with respect to the amount of zirconium hydroxide powder in terms of ZrO _2.
It can be seen that when the content is less than or equal to 30% by weight or more, the breaking strength cannot satisfy the values required as the catalyst carrier.

(Comparative Examples 5 to 6) Almost the same as the method shown in Example 1 except that the zirconium phosphate molded dried product was calcined for 2 hours while changing the calcining temperature to 300 ° C and 700 ° C. Zirconium phosphate molded bodies I and J were obtained. The resulting molded mold bodies I, were examined the properties for J, respectively the specific surface area of 98m ² / g, a 34m ² / g, respectively breaking strength 0.4 kg / mm, 1.2k
It was g / mm, and the absorption peak appearing at 1635 cm ^-1 in the infrared spectrum was confirmed for the zirconium phosphate molded body J, but not for the zirconium phosphate molded body I.

From the results of Comparative Examples 5 to 6, when the calcining temperature of the dried zirconium phosphate molded product is lower than the calcining temperature within the range of the present invention, the specific surface area increases, but the breaking strength is inferior and the infrared spectrum is 1635 cm ^{−. The} absorption peak appearing in ¹ cannot be confirmed, and conversely, when it is increased, the fracture strength is increased, but the specific surface area is remarkably reduced, and it is understood that the value required as the catalyst carrier cannot be satisfied.

Comparative Example 7 Almost the same as the method shown in Example 1 except that water, orthophosphoric acid and ammonium zirconium carbonate solution were added to zirconium hydroxide powder and kneaded in a kneader with a heating jacket. A zirconium phosphate molded body K was obtained by the method. When the properties of the obtained molded body K were determined, the specific surface area was 86 m ² / g, the breaking strength was 0.3 kg / mm, and the infrared spectrum of 16
It was confirmed that there was an absorption peak at 35 cm ^-1 .

From the results of Comparative Example 7, it is clear that the breaking strength is remarkably inferior in the production method in which water, orthophosphoric acid and ammonium zirconium carbonate solution are added all at once to the zirconium hydroxide powder. It is understood that the value required as a carrier cannot be satisfied.

[0037]

As disclosed in the present invention, an appropriate amount of water and phosphoric acid are added to a zirconium hydroxide powder and kneaded, and then a basic zirconium salt is added, followed by molding and drying.
The zirconium phosphate molded product obtained by firing has an absorption peak peculiar to 1635 cm ⁻¹ in the infrared spectrum, without containing a substance such as an inorganic reinforcing material that inhibits acid resistance, and 80 m ² / high specific surface area of not less than g and 0.
It has an excellent breaking strength of 5 kg / mm or more.

Claims (3)

[Claims] 1. A molded product obtained by firing a mixed molded product of zirconium hydroxide powder, phosphoric acid and a basic zirconium salt, and having a specific surface area of 80 m ² / g or more, and an infrared spectrum. A zirconium phosphate molding for a catalyst carrier, which has an absorption peak at 1635 cm ^-1 . 2. Zirconium hydroxide powder is added with phosphoric acid and water and kneaded, then a basic zirconium salt solution is added and kneaded until plasticized, molded and dried, and then 4
A method for producing a zirconium phosphate molded body for a catalyst carrier, which comprises calcination in a temperature range of 00 to 600 ° C. Amount of wherein phosphoric acid is in terms _of P ₂ O ₅ weight relative to ZrO ₂ in terms of total zirconium in the molded materials 25
In the range of weight percent, the claims amount of basic zirconium salt solution, and wherein the relative terms of ZrO ₂ of zirconium hydroxide powder is in the range of 10 to 30 wt% in terms of ZrO ₂ amount 2. The method for producing a zirconium phosphate molded body for a catalyst carrier according to 2.