JPH0597725A - Fluorination of tetrachloroethylene - Google Patents

Abstract

PURPOSE:To provide a high-performance catalyst effective for the production of 2,2-dichloro-1,1,1-trifluoroethane, 2-chloro-1,1,1-2-tetrafluoroethane and pentafluoroethane by the fluorination of tetrachloroethylene. CONSTITUTION:The single pass conversion rate of tetrachloroethylene, the selectivity of the objective compound and the life and durability of catalyst can be improved compared with conventional catalyst by using a catalyst produced by supporting at least one kind of element selected from Mn and an iron-group element as main component and at least one kind of element selected from alkaline-earth element and lanthanoid element as a subsidiary component to an alumina containing halogen substituting for a part of oxygen. The alumina preferably has a pore volume of >=0.6mL/g and a surface area of >=150m<2>/g and contains pores having an average pore diameter of 100-1,000Angstrom accounting for >=50% of the total pore.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to monohydrohalogenoethanes (general formula C ₂ HF _x Cl _y , 1 ≦ x ≦ 5, x + y = x) by fluorination of tetrachloroethylene (hereinafter abbreviated as TCE).
5), especially 2,2-dichloro-1,1,1-trifluoroethane (HCFC-123), 2-chloro-1,1,1,2-tetrafluoroethane (HCFC-124), and pentafluoroethane (HFC-12
5) on the method of manufacturing.

[0002]

2. Description of the Related Art Generally, hydrogen-containing saturated halogenated hydrocarbons (HCFCs, HFCs) have extremely low possibility of depleting the ozone layer. It is attracting attention as a substitute for hydrocarbons. Monohydrohalogenoethanes (general formula C ₂ HF _x C
l _y , 1 ≦ x ≦ 5, x + y = 5) is expected to be used as a foaming agent, a refrigerant, a cleaning agent, or the like. Many of these are gases and liquids which are inert and have low toxicity at normal temperature and pressure, and are useful.

Of these, 2,2-dichloro-1,1,1-
Trifluoroethane (HCFC-123), 2-chloro-1,1,1,2-
Tetrafluoroethane (HCFC-124) and pentafluoroethane (HFC-125), respectively, are trichloromonofluoromethane (CFC-1), which are suspected of depleting the ozone layer.
1), dichlorotetrafluoroethane (CFC-114) and chloropentafluoroethane (CFC-115) are being studied for use as CFC alternatives.

Conventionally, as a method for producing the above-mentioned monohydrohalogenoethanes, a gas phase fluorination reaction of TCE or the like using a chromium oxide catalyst has been widely known (for example, USP.4843181, EP. For example, see .0403108). However, conventional chromium-based catalysts have problems such as environmental influences due to handling of chromium and the like, and the adoption of non-chromium-based catalysts is desired. In addition, since chromium oxide-based catalysts have high fluorination ability, it is difficult to suppress the formation of high-order fluorinated compounds, and HCFC-123, HCFC-124, HFC-
It is difficult to make 125.

Further, in order to maintain the activity of the gas phase fluorination catalyst, it is known that oxygen, chlorine or the like is supplied together with the reaction raw material to suppress the deterioration of the catalytic activity due to the adhesion of heavy substances to the catalyst. .. In the production of monohydrohalogenoethanes, when chlorine is added, the monohydrohalogenoethane is chlorinated and a large amount of perchlorofluoroethanes (specific CFCs) are by-produced. On the other hand, when oxygen is added, hydrogen chloride generated in the fluorination reaction reacts with oxygen on the chromium oxide-based catalyst to produce chlorine and water as by-products (oxychlorination). As a result, as with chlorine addition, perchlorofluoroethanes (specific CFCs) are by-produced. That is, when a catalyst containing chromium as an active species is used, the target compound is not always obtained selectively,
Moreover, it is difficult to maintain the activity of the catalyst for a long period of time.

Further, monohydrohalogenoethanes (general formula C ₂ HF _x Cl _y , 1 ≦ x ≦ by the gas phase fluorination reaction of TCE)
5, x + y = 5), a metal-supported alumina catalyst is known to be effective (for example, USP.47.
See 66260, etc.). However, when TCE is used as the raw material, the amount of fluorine introduced into the molecule is as large as 3 to 5, so in order to maintain a high conversion rate of TCE, the feed molar ratio of HF / TCE is about 6 to 10. Need to However, even if the supply molar ratio of HF / TCE was increased, TCE was as expected.
It was found that the conversion rate was not achieved. Due to the adsorption characteristics of HF and TCE on the metal-supported alumina catalyst, HF is preferentially adsorbed on the catalyst surface, so even if a large excess of HF is supplied to TCE, a substantial improvement in the conversion rate of TCE is observed. It is thought that it cannot be done. In addition, industrially, there are problems that large amounts of unreacted HF and TCE need to be recovered and reused, and the catalyst life is relatively short.

[0007]

DISCLOSURE OF THE INVENTION The object of the present invention is to
-123, HCFC-124, and HFC-125 are manufactured using non-chromium based catalysts that have less impact on the environment, and the conversion rate of TCE in a single flow is higher than that of conventional non-chromium based catalysts. A new and effective TC has been developed by developing a long-life catalyst that is improved and has high selectivity for the target compound and practical problems.
It is to provide a method for fluorinating E 2.

[0008]

Means for Solving the Problems As a result of extensive studies on aluminum oxide and aluminum halide catalysts, the present inventor has found that alumina in which a part of oxygen is replaced by halogen has Mn and iron group elements as main components. At least one element selected from the above, and at least one selected from alkaline earth elements and lanthanoid series elements as accessory components
It has been found that a catalyst carrying a seed element can produce a desired product with high selectivity and maintain its activity for a long period of time.

That is, when fluorinating TCE in the gas phase, it is difficult to suppress the formation of higher fluorinated compounds with a chromium oxide-based catalyst because of its high fluorination ability.
4. It is difficult to suppress the production of HFC-125 and the like, and it is difficult to control the production amount. On the other hand, alumina in which a part of oxygen is replaced with halogen is used as the main component with at least one element selected from Mn and iron group elements. , At least one selected from alkaline earth elements and lanthanoid elements as subcomponents
With the fluorination catalyst supporting various elements, it is possible to selectively produce HCFC-123 under conditions in which the production of HCFC-124 and HFC-125 is suppressed, and under the conditions in which the production of HFC-125 is suppressed,
-123 and HCFC-124 can now be manufactured selectively.

Further, as a catalyst preparation method, by using alumina in which a part of oxygen, that is, 0.01 to 90 mol%, preferably 5 to 60 mol% of oxygen is substituted with halogen in advance, the alumina and the supported active metal species are mixed. By controlling the interaction of TCE, we achieved high dispersion of supported metal species during the reaction and achieved high conversion of TCE.

Further, the pore volume is 0.6 ml / g or more, and the surface area is
It is possible to improve the conversion rate of TCE by selecting alumina that has a pore size of 150m ² / g or more and a pore size of 100 to 1000Å that occupies 50% or more, and by replacing a part of the oxygen of the alumina with halogen. I found it effective.

Next, a method of supporting at least one element selected from Mn and an iron group element as a main component and at least one element selected from an alkaline earth element and a lanthanoid element as a sub-component is adopted. As a result, crystallization of the supported active metal species was suppressed, and it was possible to maintain the activity for a long period of time together with the coexistence of oxygen under the reaction conditions.

That is, the inventors of the present invention have conducted extensive studies on aluminum oxide and aluminum halide catalysts, and as a result, in alumina in which a part of oxygen is replaced by halogen, at least Mn and an iron group element are selected as main components. By fluorinating TCE using a catalyst that supports one element and at least one element selected from alkaline earth elements and lanthanoid elements as a subcomponent, the target product can be obtained with high yield. It has been found that the present invention can be obtained at a high rate and can maintain high activity over a long period of time, and thus completed the present invention.

Thus, according to the present invention, at least one element selected from Mn and an iron group element as a main component, and an alkaline earth element and a lanthanoid-based element as a subcomponent are added to alumina in which a part of oxygen is substituted with halogen. Disclosed is a novel method for fluorinating TCE, which comprises reacting TCE with hydrogen fluoride in a gas phase in the presence of a fluorination catalyst supporting at least one selected element.

The details of the present invention will be described below with reference to examples. The present invention is directed to monohydrohalogenoethanes (general formula) by gas phase fluorination of TCE in the presence of a specific catalyst.
C ₂ HF _x Cl _y , 1 ≦ x ≦ 5, x + y = 5), especially 2,2-dichloro-1,1,1-trifluoroethane (HCFC-123), 2-chloro
The present invention relates to a method for producing -1,1,1,2-tetrafluoroethane (HCFC-124) and pentafluoroethane (HFC-125). More specifically, HCFC-123, HCFC-1
24, HFC-125, and a method for selectively producing a desired product at a high single-flow yield. For example, HF
Conditions that suppress the production of C-125, that is, HCFC-123, HC
It is also possible to selectively produce products such as FC-124 in which the fluorination reaction has not progressed.

As the gas phase fluorination catalyst, alumina in which a part of oxygen is replaced by halogen is used, at least one element selected from Mn and iron group elements as a main component, and an alkaline earth element as an auxiliary component and A catalyst supporting at least one element selected from lanthanoid elements is used. By using alumina in which a part of oxygen, that is, 0.01 to 90 mol%, preferably 5 to 60 mol%, of oxygen is substituted with halogen, the interaction between the alumina and the supported active metal species is controlled and fluorinated. It is possible to achieve high dispersion of the supported metal that is an active species.

As the raw material alumina whose oxygen is partially replaced by halogen as described above, pores having a pore volume of 0.6 ml / g or more, a surface area of 150 m ² / g or more, and an average pore diameter of 100 to 1000 Å are used.
It is preferable to use an alumina having physical properties that account for 50% or more. That is, it is generally referred to as activated alumina and is amorphous or γ-alumina or η-
A wide range of examples include those containing a structure such as alumina and boehmite, and a mixture of these structures may be used.

Introduction of halogens such as fluorine and chlorine into alumina is carried out by hydrogen fluoride, trichloromonofluoromethane (CFC-11), trichlorotrifluoroethane (CFC-113).
), Etc., can be carried out by contacting with halogenated methane, halogenated ethane or the like containing at least one fluorine atom. For example, with respect to the weight of alumina, a total amount of 0.1 to 2000 times by weight hydrogen fluoride, halogenated methane or the like is caused to flow by a flow method, whereby a part of lattice oxygen in alumina, that is, 0.01 to 90 mol%, preferably Is 5
60 mol% of oxygen can be replaced by halogen.

When introducing halogen into alumina,
It is preferable to use halogenated methane or halogenated ethane containing at least one fluorine atom. Further, the substitution reaction of oxygen with halogen is preferably carried out while appropriately diluting with an inert gas such as nitrogen or helium in order to suppress the temperature rise of the catalyst due to the heat generation of the solid phase reaction.

The amount of metal supported is 0.1 to 20 wt%, preferably 1
~ 10wt% is suitable. The metal to be supported is a group consisting of Mn and an iron group element (Fe, Co, Ni) as a main component, and an alkaline earth element such as Mg and Ca and a lanthanoid element such as La and Ce as a subcomponent. Selected from each. The main component is added as an active species for the fluorination reaction, and the subcomponent is added for suppressing recrystallization of the halogenated oxide and maintaining the activity. The weight ratio of the main component element to the subcomponent element is 50:50 to 99.9: 0.1, preferably 70:30 to 99: 1.

The supporting method is not particularly limited, but usually,
A solution of the supported metal salt in water or an organic solvent,
A method of supporting and then drying by an impregnation method, a spray method, or the like is adopted.

In the present invention, TCE as a raw material used for the gas phase reaction may be an ordinary commercial product. It is preferable to use a high-purity product containing no stabilizer or the like in order to maintain the activity of the catalyst.

The reaction pressure is not particularly limited, and normal pressure or pressurization can be appropriately adopted. It is desirable to select conditions such that the halogenated hydrocarbons and hydrogen fluoride present in the system will not liquefy in the reaction system. The reaction temperature is 150-
It is suitable to select from the range of 550 ° C, preferably 250 to 450 ° C. If the reaction temperature is too high, the catalyst life becomes short, and if the reaction temperature is too low, the reaction rate of TCE decreases.
The contact time is usually 0.1 to 300 seconds, preferably 5 to 60 seconds.

The proportions of hydrogen fluoride and TCE as reactants can be varied considerably. Usually, it is suitable to replace the chlorine atom with a stoichiometric amount to 10 equivalents of hydrogen fluoride for the desired monohydrohalogenoethane. It is possible to use hydrogen fluoride in an amount much higher than the stoichiometric amount with respect to the total number of moles of the starting material, for example, 10 moles or more of hydrogen fluoride per mole of the starting material, but for the efficiency of the reaction, a large excess of hydrogen fluoride was supplied. Even so, substantial improvement in TCE conversion cannot be expected.

In order to maintain the catalytic activity, it is preferable to carry out the reaction in the presence of oxygen in an amount of 0.1 to 10 vol% with respect to TCE.

[0026]

EXAMPLES Examples of the present invention will be shown below, but it goes without saying that the present invention is not limited to these examples.

Preparation Examples 1 to 6 Pore volume 0.63 ml / g, surface area 310 m ² / g, average pore size 1
After drying 1000 g of alumina whose pores of 00 to 1000 Å occupy 61% to remove water, in a mixed gas stream of HF / N ₂ ,
After being fluorinated at 300 to 450 ° C, it was further chlorinated and fluorinated at 250 to 300 ° C in a mixed gas stream of trichloromonofluoromethane (hereinafter abbreviated as CFC-11) / HF. This was immersed in an aqueous solution prepared by dissolving both reagents shown in Table 1 in 2 liters of water, and then dried and removed of water. CFC-11 again
It was activated by chlorination and fluorination at 250-300 ° C in the / HF / N ₂ mixed gas stream.

[0028]

[Table 1]

[0029] Comparative Preparation Example 1 special grade Al (NO ₃₎ of 1100g ₃ · 9H ₂ O, 125g of Cr (NO _{3) 3} · 9
H ₂ O and 40 g of Mg (NO ₃ ) ₂ .6H ₂ O were dissolved in 2.5 liters of water, and this was mixed with 28 wt% ammonium hydroxide solution 20
While stirring, 00 g was added to 4 liters of heated water to obtain a hydroxide precipitate. The hydroxide was filtered off, washed with pure water, and dried, and then baked at 450 ° C. for 5 hours to obtain an oxide powder. This was molded into a cylindrical shape having a diameter of 5 mm and a height of 5 mm using a tablet molding machine. Before the reaction, the catalyst thus obtained was heated in a mixed gas stream of HF / N ₂ at 300-450
After fluorination at ℃, it was further activated by chlorinated fluorination at 250 to 300 ℃ in a mixed gas stream of CFC-11 / HF / N ₂ .

Comparative Preparation Examples 2 to 3 Pore volume 0.63 ml / g, surface area 310 m ² / g, average pore size 1
After drying 1000 g of alumina whose pores of 00 to 1000 Å occupy 61% to remove water, in an HF / N ₂ mixed gas stream
After being fluorinated at 300 to 450 ° C, it was further chlorinated and fluorinated at 250 to 300 ° C in a CFC-11 / HF mixed gas stream. This chlorinated fluorinated alumina was mixed with 50 g of CrCl ₃ .6H ₂ O (Comparative Preparation Example 2) or 50 g of CoCl ₂ .6H ₂ O (Comparative Preparation Example 2).
After immersing in an aqueous solution dissolved in liter of water, drying and water removal were performed. Further, it was activated by chlorination and fluorination at 250 to 300 ° C. in a mixed gas flow of CFC-11 / HF / N ₂ .

Comparative Preparation Example 4 Pore volume 0.63 ml / g, surface area 310 m ² / g, average pore diameter 1
1000 g of alumina, which occupies 61% of pores of 00 to 1000 Å,
After being immersed in an aqueous solution prepared by dissolving ₂ g of CoCl ₂ .6H ₂ O and 5 g of CeCl ₃ in 2 liters of water, drying and water removal were performed. CF
It was activated by chlorination and fluorination at 250 to 300 ° C in a mixed gas stream of C-11 / HF / N ₂ .

Example 1 A U-shaped reaction tube made of Inconel 600 having an inner diameter of 2.54 cm and a length of 100 cm was filled with 200 ml of the catalyst prepared as in Preparation Example 1. Gasified TCE, oxygen and hydrogen fluoride are supplied at 50 ml / min, 2 ml / min and 300 ml / min respectively, and 360
Hold at 0 ° C. The gas composition after removing the acid content was analyzed by gas chromatography. Table 2 shows the reaction results 3 days after the reaction was started and the reaction results after the reaction was continued for 150 days under the same conditions.

In Table 2, R-110S is chloropentafluoroethane (CFC-115), tetrafluorodichloroethane (CFC-114, CFC-114a), trichlorotrifluoroethane (CFC-113, CFC-113a), tetrachlorodifluoroethane (CFC-113a). This refers to the sum of perhalogenoethanes such as chlorodifluoroethane (CFC-112, CFC-112a). HCFC-122m is 1,2,2-trichloro
The sum of isomers of -1,1-difluoroethane (HCFC-122) and 1,1,2-trichloro-1,2-difluoroethane (HCFC-122a) is shown. HCFC-123m is 1,1-dichloro-2,2,2-trifluoroethane (HCFC-123), 1,2-dichloro-1,2,2-trifluoroethane (HCFC-123a), and 1, 1-dichloro-
It means the sum of isomers of 1,2,2-trifluoroethane (HCFC-123b). HCFC-124m is 1-chloro-1,2,2,2-tetrafluoroethane (HCFC-124) and 1-chloro-1,1,2,2-
It refers to the sum of the isomers of tetrafluoroethane (HCFC-124a). (Similarly described in each table below)

[0034]

[Table 2]

From Table 2, it was found that the reaction activity was hardly reduced even after 150 days and the initial activity could be maintained. It was also found that the production of R-125 can be suppressed to 3% or less.

Example 2 Using the catalyst prepared in Preparation Example 1, the reaction temperature was 330 ° C.,
Gasified TCE, oxygen and hydrogen fluoride, respectively
The reaction was carried out under the same conditions as in Example 1 except that 80 ml / min, 2 ml / min and 320 ml / min were supplied. The reaction results are summarized in Table 3.

[0037]

[Table 3]

From Table 3, it can be seen that the production amounts of R-124m and R-125 can be suppressed to 3% and 1%, respectively.

Example 3 Using the catalyst prepared in Preparation Example 1, the reaction temperature was 390 ° C.,
Gasified TCE, oxygen and hydrogen fluoride, respectively
The reaction was carried out under the same conditions as in Example 1 except that 40 ml / min, 2 ml / min and 320 ml / min were supplied. The reaction results are summarized in Table 4.

[0040]

[Table 4]

From Table 4, R-124m and R-125 are 43
%, 27% can be generated. Combining with the results of Examples 1 and 2 in Table 2 and Table 3, HCFC-1 can be obtained by keeping the conversion rate of TCE high by selecting the reaction conditions.
It will be appreciated that the selectivity of the product can be varied widely, such as by suppressing the selectivity of 25 and / or HCFC-124.

Example 4 The reaction was carried out under the same conditions as in Example 1 except that the catalyst prepared in Preparation Example 2 was used. Table 5 shows the reaction results 3 days after the reaction was started and the reaction results after the reaction was continued for 150 days under the same conditions.

[0043]

[Table 5]

Example 5 The reaction was carried out under the same conditions as in Example 1 except that the catalyst prepared in Preparation Example 3 was used. The reaction results are summarized in Table 6.

[0045]

[Table 6]

Example 6 Using the catalyst prepared in Preparation Example 4, the reaction temperature was 360 ° C.
The reaction was carried out under the same conditions as in Example 1 except that Table 7 shows the reaction results 3 days after the start of the reaction.

[0047]

[Table 7]

Example 7 Using the catalyst prepared in Preparation Example 5, the reaction temperature was 360 ° C.
The reaction was carried out under the same conditions as in Example 1 except that Reaction under the same conditions as well as the reaction results 3 days after the start of reaction
Table 8 summarizes the reaction results after the continuous 150 days.

[0049]

[Table 8]

Example 8 Using the catalyst prepared in Preparation Example 6, the reaction temperature was 360 ° C.
The reaction was carried out under the same conditions as in Example 1 except that The reaction results are summarized in Table 9.

[0051]

[Table 9]

Comparative Examples 1 to 3 Using the catalyst prepared in Comparative Preparation Example 1, the reaction temperature was adjusted to 3
30 ° C. (Comparative Example 1), 60 ° C. (Comparative Example 2) and 390 ° C. (Comparative Example 3), except that the gasified TCE, oxygen and hydrogen fluoride are reacted under the reaction conditions shown in Table 9. Example 1
The reaction was carried out under the same conditions as above. The reaction results are summarized in Table 10.

[0053]

[Table 10]

Compared with the reaction conditions of Examples 1 to 3, in Comparative Examples 1 to 3, the amount of R-110S produced was large, and R-124m and R-125 were produced from the low reaction temperature side. It turns out that it is difficult to control the production amount.

Comparative Example 4 Using the catalyst prepared in Comparative Preparation Example 2, a reaction was carried out under the same conditions as in Example 1. The reaction results are summarized in Table 11
Shown in.

[0056]

[Table 11]

Also in this comparative example, a large amount of R-110S was produced, and it was found that it is difficult to suppress the amount of R-124m and R-125 produced even with a supported catalyst. It was also found that the catalyst deteriorated significantly after the reaction for 150 days.

Comparative Example 5 Using the catalyst prepared in Comparative Preparation Example 3, a reaction was carried out under the same conditions as in Example 1. The reaction results are summarized in Table 12
Shown in.

[0059]

[Table 12]

From the results of this comparative example, it was found that when only Co was supported, the initial characteristics were comparable to those of the Co.Ce binary catalyst, but after 150 days of reaction, the catalyst deteriorated significantly. It was

Comparative Example 6 Using the catalyst prepared in Comparative Preparation Example 4, a reaction was carried out under the same conditions as in Example 1. The reaction results are summarized in Table 13
Shown in.

[0062]

[Table 13]

It was found that the reaction rate of TCE was low and the amount of R-110S produced was relatively large when alumina in which part of oxygen was not replaced with halogen was used.

[0064]

INDUSTRIAL APPLICABILITY According to the present invention, in the fluorination of TCE as shown in the examples, alumina in which a part of oxygen is substituted with halogen is provided with at least one element selected from Mn and an iron group element as a main component. , At least one selected from alkaline earth elements and lanthanoid elements as subcomponents
By using a catalyst that supports different kinds of elements, it is possible to improve the conversion rate of TCE in a single flow compared with conventionally known catalysts, and also to prolong the life of the catalyst. 2-dichloro-1,1,1-trifluoroethane (R-123
), 2-chloro-1,1,1,2-tetrafluoroethane (R-124
), And pentafluoroethane (R-125) and other products can be produced according to the target quantitative ratio.

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Claims (7)

[Claims] 1. Alumina in which a part of oxygen is replaced by halogen, at least one element selected from Mn and an iron group element as a main component, and at least an alkaline earth element and a lanthanoid-based element as an accessory component. A method for fluorinating tetrachloroethylene, which comprises reacting tetrachloroethylene and hydrogen fluoride in a gas phase in the presence of a fluorination catalyst supporting one kind of element. 2. The method for fluorinating tetrachloroethylene according to claim 1, wherein 0.01 to 90 mol% of oxygen contained in alumina is replaced with halogen, and then the main component element and the subcomponent element are supported. 3. The method for fluorinating tetrachloroethylene according to claim 1, wherein the weight ratio of the main component to the subcomponent among the supported metal components is 50:50 to 99.9: 0.1. 4. The total amount of supported metal is based on alumina.
The method for fluorinating tetrachloroethylene according to claim 1, wherein the content is 0.01 to 20 wt%. 5. A pore volume of 0.6 ml / g or more and a surface area of 150 m ²
The method for fluorinating tetrachloroethylene according to claim 1, wherein a part of oxygen in alumina having a pore size of / g or more and a pore size of 100 to 1000Å accounts for 50% or more is replaced with halogen. 6. The reaction is carried out in a gas phase under atmospheric pressure or under pressure at a pressure of 150.
The method for fluorinating tetrachloroethylene according to claim 1, which is carried out in a temperature range of from ℃ to 550 ℃. 7. The method for fluorinating tetrachloroethylene according to claim 1, wherein oxygen is added to the reaction system as a catalyst activity maintaining aid during the fluorination reaction.