JPH02218625A - Production of hcfc-134a - Google Patents

Abstract

PURPOSE:To efficiently obtain 1,1,1,2-tetrafluoroethane by reacting dichlorotetrafluoroethane with hydrogen in the presence of a hydrogenation catalyst prepared by a wet reduction method and containing an element of the group VIII as a main ingredient. CONSTITUTION:A dichlorotetrafluoroethane raw material is reacted with hydrogen in the presence of a hydrogenation catalyst prepared by wet reduction method and containing an element of the group VII as a main ingredient in a vapor phase at 120-450 deg.C for 2-60sec to provide the title substance. An element of platinum group such as Ru, Rh, Pd or Pt is preferably used from the viewpoint of an acid resistance and hydrogen reducing activity as the catalyst ingredient and active carbon, alumina, zirconia, etc., is preferably used as a carrier. A method dipping the carrier into a solution obtained by dissolving a salt of the above-mentioned element of platinum group in water or organic solvent to impregnate the salt of the above-mentioned element into the carrier, charging a reducing agent (e.g. formalin) thereto and reducing the salt of the above- mentioned element of platinum group can be applicable as the carrying method.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is directed to HCFC134a (CF3CH2F: 1.
1,1,2-tetrafluoroethane).

[Prior Art and Problems] For the production of HCFC134a (CF3CH2F), the formula CF2XCFYZ (wherein X is fluorine or chlorine; when X is fluorine, Y, Z is chlorine, fluorine or hydrogen, When one of Y and Z is fluorine, the other of Y and Z is hydrogen or chlorine. When X is chlorine, one of Y and Z is fluorine, and Y
, the other of Z is chlorine or hydrogen. One such method is a method in which a heloethane raw material having 4 or 5 fluorine atoms represented by the following formula is reacted with hydrogen in the presence of a hydrogenation catalyst. Here, a typical haloethane raw material is 1,1-dichloro-1,2,2,2-tetrafluoroethane (CF30C12F: R-114a
).

In this method, two chlorine atoms are removed from the haloethane feedstock and replaced with hydrogen.

In this reduction reaction, hydrogen chloride is produced as a by-product, so the catalyst is required to have acid resistance. Therefore, a platinum group element or an alloy catalyst containing a platinum group element as a main component can be used. However, 1,1-dichloro-1,2,2,2-tetrafluoroethane does not necessarily have high activity for gas phase hydrogen reduction and requires a relatively high reaction temperature, but in that case, the selectivity of by-products is high. It has the problem of becoming.

Platinum group catalysts are usually prepared by a method in which ions containing catalyst components are adsorbed onto a carrier by an impregnation method and then reduced, and the properties of the catalyst vary greatly depending on the method of reduction. Broadly speaking, there are so-called wet reduction, in which a carrier adsorbed with catalyst components is reduced in a solution at around room temperature, and so-called gas-phase reduction, in which the adsorbent is reduced in a hydrogen stream after drying. In gas-phase reduction, the catalyst component is usually supported on a carrier, free ionic components are removed by washing with water, and then dried and hydrogen reduction is performed at a relatively high temperature.For this reason, the catalyst component is adsorbed in a highly dispersed state. However, it has the disadvantage that the catalyst components tend to re-agglomerate during washing, drying, and reduction. In addition, the density of adsorbed species on the support surface is considerably lower than in the case of liquid phase reduction, and the ratio of crystal grain growth to nucleation during reduction is often high, making it difficult to form fine catalyst particles. be. Further, gas phase hydrogen reduction is not necessarily advantageous as a catalyst manufacturing process in terms of mass productivity and the like.

[Means for Solving the Problems] As a result of intensive research into a method for producing a hydrogenation catalyst based on an acid-resistant element through liquid-phase reduction, the inventor has developed a method for producing a hydrogenation catalyst that has excellent activity and selectivity, and is suitable for mass production. found that it is suitable for HCFC using such a hydrogenation catalyst.
-134a has been provided.

Hereinafter, details of the present invention will be explained together with examples.

That is, the main component of the catalyst component is at least one element selected from group (I) elements, preferably a platinum group element. Among others, ruthenium, rhodium1. It is preferable to include palladium or platinum in terms of acid resistance and hydrogen reduction activity.

Activated carbon, alumina, zirconia, etc. are suitable as the carrier.

As a supporting method, a method can be applied in which these carriers are impregnated by immersing them in a solution of salts of the above elements in water or an organic solvent, and then a suitable reducing agent is added to carry out reduction. As the reducing agent, formalin, hydrazine, formic acid, sodium borohydride, hydrogen, etc. can be used. Various ion species and molecules are densely adsorbed on the surface of the carrier immersed in the solution, and crystal growth during reduction is suppressed and nucleation becomes dominant, so it is easy to combine this with the low reduction temperature. It is possible to obtain a catalyst having a very fine particle size. It is more effective to add a suitable dispersant. After completion of the reduction, washing and drying are performed to obtain a catalyst.

Although the proportions of hydrogen and dichlorotetrafluoroethane feedstocks can vary widely, stoichiometric amounts of hydrogen are typically used to remove the halogen atoms. Based on the total number of moles of starting materials,
High yields of the desired product can be obtained using significantly higher than stoichiometric amounts, for example 4 moles or more of hydrogen.

As for the reaction pressure, normal pressure or a pressure higher than normal pressure can be used.

The reaction temperature is preferably 120°C or higher, but it is preferable to carry out the reaction in the gas phase at a temperature not exceeding 450°C from the viewpoint of reaction selectivity and catalyst life.

The contact time is usually 0.1 to 0.1 when the reaction is carried out in the gas phase.
300 seconds, especially 2 to 60 seconds.

[Example code] Examples of the present invention are shown below.

Preparation Example 1 Coconut shell activated carbon was immersed in ion-exchanged water to impregnate the inside of the pores with water. After this activated carbon was placed in 0.5% hydrochloric acid, an aqueous solution in which ruthenium chloride was dissolved in an amount of 2.0% of the total weight of metal components based on the weight of the activated carbon was added dropwise little by little to cause the ionic components to be adsorbed onto the activated carbon. After reducing this by adding formalin aqueous solution, it was treated with potassium hydroxide aqueous solution and washed with water.

It was dried at 150°C for 5 hours.

Preparation Example 2 Coconut shell charcoal was immersed in a 0.5% hydrochloric acid aqueous solution to impregnate the inside of the pores with water. To this, ruthenium chloride and silver diammine sulfate were added in a weight ratio of metal components of 90:1.
A catalyst was prepared in the same manner as in Example 1, except that an aqueous solution in which only 5% of the total weight of metal components was dissolved in the weight of activated carbon was used.

Preparation Example 3 Coconut shell charcoal was immersed in a 0.5% hydrochloric acid aqueous solution to impregnate the inside of the pores with water. A catalyst was prepared in the same manner as in Example 5, except that ruthenium chloride and chloroauric acid were used in an aqueous solution in which the weight ratio of the metal components was 90:10, and only 5% of the total weight of the metal components was dissolved in the weight of the activated carbon. was prepared.

Preparation Example 4 Coconut shell activated carbon was immersed in pure water to impregnate the inside of the pores with water. An aqueous solution in which rhodium chloride was dissolved in an amount of 1.0% of the total weight of the metal components based on the weight of the activated carbon was added little by little to make the ionic components adsorbed onto the activated carbon. A solution prepared by adding sodium hydroxide and ethanol to sodium borohydride was added to the solution for reduction. After adding hydrochloric acid to decompose excess sodium borohydride and washing with pure water, it was dried at 150° C. for 5 hours.

Preparation Example 5 Coconut shell charcoal was immersed in a 0.5% hydrochloric acid aqueous solution to impregnate the inside of the pores with water. The catalyst was catalyzed in the same manner as in Example 4, except that rhodium chloride and silver diammine sulfate were used in an aqueous solution in which the weight ratio of the metal components was 90:10, and only 1% of the total weight of the metal components was dissolved in the weight of the activated carbon. was prepared.

Preparation Example 6 Crushed coconut shell charcoal was immersed in a 1% aqueous hydrochloric acid solution to impregnate the inside of the pores with water. A catalyst was prepared in the same manner as in Example 4, except that rhodium sulfate and chloroauric acid were used in an aqueous solution in which the weight ratio of the metal components was 90:10, and only 1% of the total weight of the metal components was dissolved in the weight of the activated carbon. was prepared.

Preparation Example 7 Crushed coconut husk charcoal was immersed in a 0.5% aqueous hydrochloric acid solution to impregnate the inside of the pores with water. An aqueous solution in which palladium chloride was dissolved in an amount of 2.0% of the total weight of the metal components based on the weight of the activated carbon was gradually added dropwise to this to adsorb the ionic components onto the activated carbon. A 30% aqueous hydrazine solution was added dropwise for rapid reduction. After washing with pure water, it was dried at 150° C. for 5 hours.

Preparation Example 8 Crushed coconut husk charcoal was immersed in a 0.5% aqueous hydrochloric acid solution to impregnate the inside of the pores with water. To this, palladium chloride and chloroplatinic acid were added in a weight ratio of metal components of 99.9: 0.1, respectively.
The total weight of metal components is 1°0% of the weight of activated carbon.
The ionic components were adsorbed onto the activated carbon by dropping an aqueous solution in which the ions were dissolved little by little. A 30% aqueous hydrazine solution was added dropwise for rapid reduction.

After washing with pure water, it was dried at 150° C. for 5 hours.

Preparation Example 9 Molded coconut shell charcoal was immersed in a 1% aqueous hydrochloric acid solution to impregnate the inside of the pores with water. The same procedure as in Example 7 was used except that an aqueous solution containing palladium chloride and rhodium chloride at a metal component weight ratio of 99:1 and only 0.5% of the total weight of the metal components dissolved in the weight of activated carbon was used. A catalyst was prepared.

Preparation Example 10 Crushed coconut husk charcoal was immersed in a 0.5% hydrochloric acid aqueous solution to impregnate the inside of the pores with water. A catalyst was prepared in the same manner as in Example 7, except that an aqueous solution containing palladium chloride and copper sulfate in a weight ratio of metal components of 90:10 and only 1% of the total weight of metal components relative to the weight of activated carbon was used. Prepared.

Preparation Example 11 Coconut shell activated carbon was immersed in pure water to impregnate the inside of the pores with water. After putting this activated carbon into a 1% aqueous hydrochloric acid solution, chloroplatinic acid was added to the activated carbon at a rate of 0.0% by total weight of metal components based on the weight of the activated carbon.
An aqueous solution containing only 5% of the solution was dropped little by little to cause the ionic components to be adsorbed onto the activated carbon.

After adding formalin aqueous solution and cooling with stirring, the mixture was treated with potassium hydroxide aqueous solution. After washing with pure water,
It was dried at 150°C for 5 hours.

Preparation Example 12 Coconut shell charcoal was immersed in a 1.0% hydrochloric acid aqueous solution to impregnate the inside of the pores with water. To this, chloroplatinic acid and diammine silver sulfate were added in a weight ratio of metal components of 90:10, respectively.
A catalyst was prepared in the same manner as in Example 11, except that an aqueous solution containing only 2% of the total weight of metal components dissolved in the weight of activated carbon was used.

Preparation Example 13 Coconut shell charcoal was immersed in a 1% aqueous hydrochloric acid solution to impregnate the inside of the pores with water. The same procedure as in Example 11 was used, except that chloroplatinic acid and chloroauric acid were used in an aqueous solution in which the weight ratio of the metal components was set to 90 = 10, and only 1% of the total weight of the metal components was dissolved in the weight of the activated carbon. A catalyst was prepared.

Comparative Preparation Example 1 Coconut shell molded charcoal (Shirasagi C2X) was immersed in a 0.5% hydrochloric acid aqueous solution to impregnate the inside of the pores with water. Add ruthenium chloride to this, with the total weight of the metal component being 2 times the weight of the activated carbon.
．． An aqueous solution in which only 0% of the ionic components were dissolved was dropped little by little to cause the ionic components to be adsorbed onto the activated carbon. After washing with pure water, it was dried at 150 °C for 5 h and then dried at 250 °C in nitrogen for 4 h.
After drying for an hour, hydrogen was introduced and kept at 350° C. for 4 hours for reduction.

Comparative Preparation Example 2 Molded coconut shell charcoal (Shirasagi C2X) was immersed in a 0.5% aqueous hydrochloric acid solution to impregnate the inside of the pores with water. Add rhodium chloride to this in a ratio of 1.0% by total weight of metal components to the weight of activated carbon.
An aqueous solution in which only 0% of the ionic components were dissolved was dropped little by little to cause the ionic components to be adsorbed onto the activated carbon. After washing with pure water, it was dried at 150° C. for 5 hours. Next, after drying in nitrogen at 250°C for 4 hours, hydrogen was introduced and the temperature was maintained at 350°C for 5 hours for reduction.

Comparative Preparation Example 3 Coconut shell charcoal (White 51 C2X) was immersed in pure water to impregnate the inside of the pores with water. An aqueous solution in which palladium chloride was dissolved in an amount of 2.0% of the total weight of the metal components based on the weight of the activated carbon was added little by little to make the ionic components adsorbed onto the activated carbon. After washing with pure water, it was heated to 150°C.
After drying in nitrogen for 5 hours at 250° C. for 4 hours, hydrogen was introduced and the mixture was kept at 350° C. for 5 hours for reduction.

Comparative Preparation Example 4 Molded coconut shell charcoal (Shirasagi C2X) was immersed in a 0.5% hydrochloric acid aqueous solution to impregnate the inside of the pores with water. To this, chloroplatinic acid was added in an amount of 0.0% by total weight of the 7 metal components based on the weight of activated carbon.
An aqueous solution containing only 5% of the solution was dropped little by little to cause the ionic components to be adsorbed onto the activated carbon. After washing with pure water, it was dried at 150° C. for 5 hours, then dried in nitrogen at 250° C. for 4 hours, hydrogen was introduced, and the temperature was maintained at 350° C. for 5 hours for reduction.

Examples 1 to 13 Inconel 600 with an inner diameter of 2.54 cm and a length of 100 cm filled with 300 cc of the catalyst prepared as in the preparation example.
Do not immerse the reaction tube in the salt bath furnace.

Hydrogen and starting material (1,1-dichloro-1,2,2,2-
Tetrafluoroethane and 1,2-dichloro-1,1,2
, 2-tetrafluoroethane in a molar ratio of 95:
5) was introduced into the reaction tube in a molar ratio of 2:1. hydrogen,
The flow rates of starting materials were 100 cc/min and 50 cc, respectively.
The zero reaction temperature (Z minute) was 220° C., and the zero contact time was 20 seconds. The gas composition of the nine reaction tube ratios was analyzed using gas chromatography. As a result, the main reaction products were R-124, HC
It was confirmed that they were FC-134a and R-143a. Among them, the reaction rate of R-114a is the first.
Shown in the table.

Comparative Examples 1 to 4 Using the catalysts prepared as in Comparative Preparation Examples, reactions were carried out in the same manner as in Examples, and the gas composition at the outlet of the reaction tube was analyzed. As a result, the main reaction products were R-124, HCF
After confirming that they were C-134a and R-143a, the second reaction rate for R-114a among them was confirmed.
Shown in the table.

Table 1 Table 2 [Effects of the Invention] As shown in Examples, the present invention has the effect of being able to convert dichlorotetrafluoroethane to HFC-134a with high efficiency.

Claims (1)

[Claims] 1. HCF characterized in that dichlorotetrafluoroethane raw material is reacted with hydrogen in the presence of a hydrogenation catalyst whose main component is a group VIII element prepared by a wet reduction method.
Method for producing C-134a (CF_3CH_2F). 2. The manufacturing method according to claim 1, wherein the catalyst component contains a platinum group element as a main component. 3. The manufacturing method according to any one of claims 1 to 2, wherein a hydrogenation catalyst in which the catalyst component is supported on coconut shell activated carbon is used. 4. The manufacturing method according to any one of claims 1 to 2, wherein a hydrogenation catalyst in which the catalyst component is supported on alumina is used. 5. The manufacturing method according to any one of claims 1 to 2, wherein a hydrogenation catalyst in which the catalyst component is supported on zirconia is used. 6. The manufacturing method according to any one of claims 1 to 5, wherein the reaction is carried out in a gas phase at a temperature range of 120°C to 450°C.