JPH01319438A - Production of r-134a - Google Patents

Abstract

PURPOSE:To obtain the subject compound which is a promising candidate of a substitute for CCl2F2 in high selectivity by reacting R-114a (CF3CCl2F) with hydrogen in the presence of a specific catalyst having excellent durability and selectivity and containing a group VIII element as a main component and a group IB element as an additive component. CONSTITUTION:The objective compound can be produced by reacting R-114a (CF3CCl2F) with hydrogen (the amount of hydrogen is preferably more than stoichiometric based on the raw material, e.g., >=4mol) under normal or positive reaction pressure in vapor phase at 120-450 deg.C in the presence of a hydrogenation catalyst containing a group VIII element as a main component and one or more elements selected from group IB elements as an additive component. The amount of the group IB element in the above catalyst is 0.01-90wt.%, preferably 0.1-30wt.%. The carrier of the hydrogenation catalyst is e.g., activated carbon or alumina.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing R134a (CFaCHzF), which is considered a promising alternative candidate for R12<CCl2F3).

[Prior art and problems] In the production of R134a (CF3CH2F), the formula CF2XCFYZ (wherein, , if one of Y and Z is fluorine, Y
, the other of Z is hydrogen or chlorine. When X is chlorine, one of Y and Z is fluorine, and the other of Y and Z is chlorine or hydrogen. One method is to react a haloethane raw material having 4 or 5 fluorine atoms represented by the following formula with hydrogen in the presence of a hydrogenation catalyst. Here, typical haloethane raw materials are 1.
1-dichloro-1,2,2,2-tetrafluoroethane (CF3CCl2F). In this method, two chlorine atoms are removed from the haloethane feedstock and these are replaced with hydrogen.

In this reaction, hydrogen chloride is produced as a by-product as shown in the formula below, 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.

CFzCCt2F+H2-CF3CH2F F+HC
1 (R-114a) (R-124)
CFsCHCl F+, H2-CFaCH2F+HC
1 (R-124) (R-134a)
A method using palladium, a relatively low-cost noble metal, as a catalyst has already been reported. (Refer to Japanese Patent Publication No. 56-38131) However, the durability is not necessarily sufficient, and the selectivity of R-134a, which is the target component, is not sufficient.
It has the disadvantage that (CF3CHi) is produced in a relatively large amount.

[Means for Solving the Problems] Palladium has a low melting point among platinum group elements, and therefore the temperature at which atomic movement becomes active is low.

Therefore, sintering of palladium fine particles is considered to be one of the reasons why the catalyst life is not sufficient.

It is known that catalyst sintering can be suppressed by the addition of dissimilar metals, ie, alloying, and oxide dispersion.

On the other hand, this reaction is a sequential reaction as shown in the formula below, and in addition to the target product, R124 (CF 3CHCIF), R14
A considerable amount of 3a (CFsCHi) is also produced. Therefore, R
There is a need for the development of a catalyst with excellent selectivity for 134a. In particular, it is extremely important to suppress the production of R-143a, which is produced by reducing the target product R-134a.

The series of reactions in the above equation are heterogeneous reactions that occur on the catalyst surface, and adsorption of reactive species to the catalyst surface is essential. In other words, although the micromechanism involved in this reaction has not necessarily been clarified, the reduction reaction progresses when hydrogen molecules in the gas phase are adsorbed onto the catalyst surface, and the adsorbed hydrogen atoms that are generated react with heroethane on the catalyst surface. Conceivable. Therefore, in the three stages in the above equation, ■ and ■ are dechlorination and hydrogenation reactions, but stage ■ is a defluorination and hydrogenation reaction, and the reaction activity is lower than in ■ and ■. It is estimated that the oxidation energy is large. Therefore, R
In order to suppress the production of -143a, it is considered effective to suppress the adsorption of R-134a onto the catalyst surface and reduce the average residence time. The adsorption of molecules onto solid surfaces is complicated by various factors, so it is difficult to give a clear interpretation.
-Ultimately, the electronic structure and geometrical factors of the adsorbed species and the solid surface are important factors. The chemisorption energy is related to the number of d-electrons, and d-general unsatisfied transition elements have a large adsorption energy 2. Among transition elements, many have excellent hydrogen reduction activity, such as Pt, Pd, and N.
The number of d-electrons of group II elements such as i, Rh, Co, Ru, etc. is distributed in the range of 6 to 10, and it can be said that the number of d-electrons is specifically satisfied.

Among others, Pd, Pt1. The number of td-electrons is 9 and 10, respectively, and the adsorption energy tends to be particularly low.

Next, consider geometric factors. The above series of molecules have a very stable CF3 group, and when a reaction occurs on the catalyst surface, the CXYZ group on the opposite side of the CF3 group (
It is presumed that the interaction between X, Y, Z: H or Ct or F) and the catalyst surface is important. In the above reaction formula, R-114a and R-124 have two and one large chlorine atoms, respectively, and are large molecules, whereas R-134a and R-1
43a does not contain a chlorine atom, is smaller in size than the above-mentioned heloethane, and allows the reactions of (1) and (2) to proceed rapidly;
In order to suppress the reaction (2), it is considered effective to expand the lattice constant of the catalyst metal in order to suppress the adsorption of R-134a molecules, which are small in size and do not have chlorine atoms. Expansion of the lattice can be achieved by adding an element with low adsorption energy and therefore low catalytic activity and inserting it between catalyst atoms, or by adding metal atoms with a large lattice constant and alloying. As the additive element, an IB group element is selected as an element that has corrosion resistance in the above reaction and does not poison the catalyst among typical elements filled with d-electrons. Based on these basic principles, we have diligently studied the optimization of alloy combinations, composition ratios, catalyst preparation conditions, etc., and as a result, we have been able to provide the present invention using a catalyst with excellent durability and selectivity. It is something that The details will be described below.

-ffi-wise, when a catalyst is alloyed, the characteristics of the component elements often appear depending on the composition. However, when group IB elements are added to group II elements, the reason is not necessarily clear. However, it has been found that high activity can be obtained even in the zero reaction, which is known for the hydrogenation reactions of cyclopropane, acetylene, methylacetylene, etc., and that the reducing activity does not decrease so much.

The amount of the IB group element added is preferably 0.01 to 90% by weight, preferably 0.1 to 30% by weight, in order to take advantage of the hydrogen reduction activity of the group I element.

- In order to effectively suppress sintering, the amount of dissimilar metals is 0.
．． It is said that it is effective when added in an amount of 1% or more. Therefore, from the viewpoint of both lattice expansion and sintering suppression, the addition amount is preferably 0.1 to 30%.

The present invention was completed based on the above findings,
A hydrogenation catalyst made by using R114a raw material as a main component containing one or more elements of Group I elements and adding one or more metals transported from Group IB elements. The present invention provides a new method for producing R-134a, which is characterized by reacting with hydrogen in the presence of R-134a.

In the present invention, examples of the hydrogenation catalyst carrier include:
Activated carbon, alumina, zirconia, etc. are suitable. As the supporting method, a conventional noble metal catalyst preparation method can be applied. In addition, upon use, such metal compounds are at least partially reduced.

The proportions of hydrogen and feedstock can be varied widely. However, stoichiometric amounts of hydrogen are usually used to remove the halogen atoms. Significantly more than stoichiometric amounts of hydrogen can be used, for example 4 moles or more, based on the total number of moles of starting materials. 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.

The present invention provides a production method that has the advantage of producing less R143a (CF3CH3) as a by-product and therefore being able to produce R134a (CF3CH2F) with high selectivity.

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

Preparation Example 1 Coconut shell activated carbon was immersed in pure water to impregnate the inside of the pores with water. To this, an aqueous solution in which palladium chloride and copper sulfate were dissolved in a ratio of 90:10 by weight of each metal component, and the total weight of the metal components was 0.5% based on the weight of the activated carbon, was added dropwise little by little to remove the ionic components. Adsorbed on activated carbon.

After washing with pure water, it was dried at 150° C. for 5 hours, then dried in nitrogen at 550° C. for 4 hours, hydrogen was introduced, and the temperature was maintained at 250° C. for 5 hours for reduction.

Preparation Example 2 Coconut shell activated carbon was immersed in pure water to impregnate the inside of the pores with water. To this, an aqueous solution in which palladium sulfate and silver nitrate were dissolved at a weight ratio of 90:10 and only 0.5% of the total weight of the metal components relative to the weight of the activated carbon was added little by little to remove the ionic components from the activated carbon. was adsorbed to.

After washing with pure water, it was dried at 150° C. for 5 hours, then dried in nitrogen at 550° C. for 4 hours, hydrogen was introduced, and the temperature was maintained at 250° C. for 5 hours for reduction.

Preparation Example 3 Coconut shell activated carbon was immersed in pure water to impregnate the inside of the pores with water. An aqueous solution in which palladium chloride and chloroauric acid were dissolved in a ratio of 90:10 by weight of each metal component, and 0.5% of the total amount of metal components based on the weight of activated carbon was added dropwise little by little to ionize. The components were adsorbed onto activated carbon. After washing with pure water, it was dried at 150° C. for 5 hours, then dried in nitrogen at 500° C. for 4 hours, hydrogen was introduced, and the temperature was maintained at 250° C. for 5 hours for reduction.

Preparation Example 4 Coconut shell activated carbon was immersed in pure water to impregnate the inside of the pores with water. To this, palladium chloride, chloroplatinic acid and chloroauric acid were added in a weight ratio of each metal component of 90:2+
At a ratio of 8, the total weight of metal components to the weight of activated carbon is 0.
．． 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 500° C. for 4 hours, hydrogen was introduced, and the temperature was maintained at 250° C. for 5 hours for reduction.

Preparation Example 5 Coconut shell activated carbon was immersed in pure water to impregnate the inside of the pores with water. To this, palladium chloride, rhodium chloride and chloroauric acid were added in a weight ratio of each metal component of 90:1:
An aqueous solution containing only 0.5% of the total weight of metal components dissolved in the weight of the activated carbon was dropped little by little at a ratio of 9 to 9 to adsorb the ionic components onto the activated carbon. After washing with pure water,
It was then dried at 150℃ for 5 hours at 500℃ in nitrogen.
After drying at 250°C for 4 hours, hydrogen was introduced and
It was retained and reduced.

Preparation Example 6 Coconut shell activated carbon was immersed in pure water to impregnate the inside of the pores with water. To this, palladium chloride, iridium chloride and chloroauric acid were added in a weight ratio of each metal component of 90:1.
:'9, an aqueous solution in which only 0.5% of the total weight of the metal components was dissolved in the weight of the activated carbon was dropped little by little to cause the ionic components to be adsorbed onto the activated carbon. After washing with pure water,
It was then dried at 150℃ for 5 hours at 500℃ in nitrogen.
After drying at 250°C for 4 hours, hydrogen was introduced and
It was retained and reduced.

Preparation Example 7 Coconut shell activated carbon was immersed in pure water to impregnate the inside of the pores with water. To this, an aqueous solution in which rhodium sulfate and silver nitrate were dissolved at a ratio of 90:10 by weight of each metal component, Q, 5% of the total weight of the metal components relative to the weight of the activated carbon, was added little by little to remove the ionic components from the activated carbon. was adsorbed to. After washing with pure water, it was dried at 150°C for 5 hours.
Next, after drying in nitrogen at 550°C for 4 hours, hydrogen was introduced and the mixture was maintained at 300°C for 5 hours for reduction.

Preparation Example 8 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 and chloroauric acid were dissolved in a ratio of 90:10 by weight of each metal component, and the total weight of the metal components was 0.5% based on the weight of the activated carbon, was added little by little to the ionic components. was adsorbed on activated carbon.

After washing with pure water, it was dried at 150°C for 5 hours, then dried in nitrogen at 550°C for 4 hours, then hydrogen was introduced and kept at 300'C for 5 hours for reduction.

Preparation Example 9 Coconut shell activated carbon was immersed in pure water to impregnate the inside of the pores with water. To this, rhodium chloride, cobalt chloride and copper sulfate were added in a weight ratio of each metal component of 45:45:
An aqueous solution containing only 0.5% of the total weight of metal components dissolved in the weight of the activated carbon was dropped little by little at a ratio of 10:10 to adsorb the ionic components onto the activated carbon. After washing with pure water, it was dried at 150° C. for 5 hours. Next, after drying in nitrogen at 550°C for 4 hours, hydrogen was introduced and the mixture was maintained at 300°C for 5 hours for reduction.

Preparation Example 10 Coconut shell activated carbon was immersed in pure water to impregnate the inside of the pores with water. To this, rhodium sulfate, cobalt sulfate and silver nitrate were added in a weight ratio of each metal component of 50:40:
An aqueous solution containing only 0.5% of the total weight of metal components dissolved in the weight of the activated carbon was dropped little by little at a ratio of 10:10 to adsorb the ionic components onto the activated carbon. After washing with pure water, it was dried at 150° C. for 5 hours, then dried in nitrogen at 550° C. for 4 hours, hydrogen was introduced, and the temperature was maintained at 300° C. for 5 hours for reduction.

Preparation Example 11 Coconut shell activated carbon was immersed in pure water to impregnate the inside of the pores with water. To this, rhodium chloride, cobalt chloride and chloroauric acid were added in a weight ratio of each metal component of 50:40:
An aqueous solution containing only 0.5% of the total weight of metal components dissolved in the weight of the activated carbon was dropped little by little at a ratio of 10:10 to adsorb the ionic components onto the activated carbon. After washing with pure water,
It was then dried at 150°C for 5 hours at 550°C in nitrogen.
After drying for 4 hours at 300°C for 5 hours, hydrogen was introduced.
Keep it and give it back.

Preparation Example 12 Coconut shell activated carbon was immersed in pure water to impregnate the inside of the pores with water. To this, an aqueous solution in which chloroplatinic acid and chloroauric acid were dissolved in a weight ratio of 90:10 of each metal component, and only 0.5% of the total weight of the metal components to the weight of activated carbon was added dropwise to ionize. The components were adsorbed onto activated carbon. After washing with pure water, it was dried at 150°C for 5 hours.
Next, after drying in nitrogen at 550°C for 4 hours, hydrogen was introduced and the mixture was maintained at 300°C for 5 hours for reduction.

Preparation Example 13 Coconut shell activated carbon was immersed in pure water to impregnate water to the inside of the pores, and palladium chloride, nickel chloride, and copper sulfate were added to this in a weight ratio of 45:45:
An aqueous solution containing only 0.5% of the total weight of metal components dissolved in the weight of the activated carbon was dropped little by little at a ratio of 10:10 to adsorb the ionic components onto the activated carbon. After washing with pure water,
It was then dried at 150°C for 5 hours at 550°C in nitrogen.
After drying for 4 hours at 300°C for 5 hours, hydrogen was introduced.
It was retained and reduced.

Preparation Example 14 Coconut shell activated carbon was immersed in pure water to impregnate the inside of the pores with water. To this, palladium sulfate, nickel sulfate and silver nitrate were added in a weight ratio of 45:45:
An aqueous solution containing only 0.5% of the total weight of metal components dissolved in the weight of the activated carbon was dropped little by little at a ratio of 10:10 to adsorb the ionic components onto the activated carbon. After washing with pure water,
It was then dried at 150°C for 5 hours at 550°C in nitrogen.
After drying for 4 hours at 300°C for 5 hours, hydrogen was introduced.
It was retained and reduced.

Preparation Example 15 Coconut shell activated carbon was immersed in pure water to impregnate the inside of the pores with water. To this, palladium chloride, nickel chloride and chloroauric acid were added in a weight ratio of each metal component of 45:45:
An aqueous solution containing only 0.5% of the total weight of metal components dissolved in the weight of the activated carbon was dropped little by little at a ratio of 10:10 to adsorb the ionic components onto the activated carbon. After washing with pure water, it was dried at 150° C. for 5 hours. Then 550 in nitrogen
After drying at ℃ for 4 hours, hydrogen was introduced and the
It was kept at ℃ and reduced.

Preparation Example 16 Coconut shell activated carbon was immersed in pure water to impregnate the inside of the pores with water. To this, an aqueous solution containing ruthenium chloride and chloroauric acid dissolved in a weight ratio of 90:10 for each metal component and only 0.5% of the total weight of the metal components relative to the weight of the activated carbon was added little by little to form the ionic components. was adsorbed on activated carbon. After washing with pure water, it was dried at 150° C. for 5 hours, then dried in nitrogen at 550° C. for 4 hours, hydrogen was introduced, and the temperature was maintained at 300° C. for 5 hours for reduction.

Comparative Preparation Example 1 Coconut shell activated carbon 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 0.5% 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 dried at 150 °C for 5 hours. Then, after drying in nitrogen at 550 °C for 4 hours, hydrogen was introduced,
The mixture was maintained at 300° C. for 5 hours for reduction.

Comparative Preparation Example 2 Coconut shell activated carbon was immersed in pure water to impregnate the inside of the pores with water. An aqueous solution in which palladium chloride and nickel chloride (molar ratio 1:1) were dissolved in an amount of 0.5% of the total weight of the metal components based on the weight of the activated carbon was added little by little to the mixture, so that the ionic components were adsorbed onto the activated carbon.

After washing with pure water, it was dried at 150° C. for 5 hours, then dried in nitrogen at 550° C. for 4 hours, hydrogen was introduced, and the temperature was maintained at 300° C. for 5 hours for reduction.

Comparative Preparation Example 3 Coconut shell activated carbon was immersed in pure water to impregnate the inside of the pores with water. An aqueous solution in which ruthenium chloride was dissolved in an amount of 0.5% of the total weight of the metal components based on the weight of the activated carbon was added 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 550° C. for 4 hours, hydrogen was introduced and the temperature was maintained at 300° C. for 5 hours for reduction.

Examples 1 to 16 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.
The prepared reaction tube was immersed in a salt bath furnace.

Hydrogen and dichlorotetrafluoroethane (R-114a purity 95 mol%, remainder is isomer R-114) in 2=
A molar ratio of 1 was introduced into the reaction tube.

The flow rates of hydrogen and starting material were 100 cc/min and 5 cc/min, respectively.
The reaction temperature was 200°C and the contact time was 6 cc/min.
．． It was 7 seconds. The gas composition at the outlet of the reaction tube was analyzed using gas chromatography. As a result, the main reaction product is R-124
, R-134a and R-143a. Among them, the selectivity of R-143a is the first.
Shown in the table.

Comparative Examples 1 to 3 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 are R-124, R13
Among them, the selectivity of R-143a is shown in Table 2.

Table 1 R-143a selectivity The catalyst used in the example showed almost no change in characteristics even after 500 hours from the start of the reaction.

Table 2 R-143a! ! Selectivity [Effects of the Invention] As shown in Examples, the present invention has excellent effects in improving reaction selectivity and durability.

Claims (1)

[Claims] 1. R-114a (CF_3CCl_2F) in the presence of a hydrogenation catalyst containing a group VIII element as a main component and one or more elements selected from group IB elements as an additive component. CF_3CH_ characterized by reacting with hydrogen
A method for producing R-134a represented by 2F. 2. The manufacturing method according to claim 1, wherein at least a stoichiometric amount of hydrogen is used with respect to the raw material. 3. VII in which the proportion of added components is 0.01 to 90% by weight
The manufacturing method according to any one of claims 1 to 2, in which an alloy containing Group I elements as a main component is used as a hydrogenation catalyst. 4. The hydrogenation catalyst according to any one of claims 1 to 3, in which an alloy mainly composed of group VIII elements in which the proportion of added components is 0.1 to 30% by weight is used as a hydrogenation catalyst. Manufacturing method. 5. Claim 1 using a hydrogenation catalyst in which a catalyst containing Group VIII elements as a main component and one or more elements selected from Group I and B elements is supported on an activated carbon carrier. The manufacturing method according to any one of Items 1 to 4. Claim 1 uses a hydrogenation catalyst in which a catalyst containing group VIII elements as a main component and one or more elements selected from group I and B elements is supported on an alumina carrier. The manufacturing method according to any one of Items 1 to 4. 7. Claim 1 using a hydrogenation catalyst in which a catalyst containing a group VIII element as a main component and one or more elements selected from group I and B elements as an additive component is supported on a zirconia carrier. The manufacturing method according to any one of Items 1 to 4. 8. The production method according to any one of claims 1 to 7, wherein the reaction is carried out in a gas phase at a temperature range of 120°C to 450°C.