Title of Invention: PROCESS FOR PREPARING FLUORINE-CONTAINING PROPENES CONTAINING 2, 3, 3, 3-TETRAFLUOROPROPENE AND 1,3,3,3- TETRAFLUOROPROPENE

Technical field

The present invention relates to a process for preparing fluorine-containing propenes containing 2,3,3,3- tetrafluoropropene and 1, 3, 3, 3-tetrafluoropropene .

Background art

2, 3, 3, 3-Tetrafluoropropene represented by the formula CF ₃ CF=CH ₂ (HFC-1234yf) and 1, 3, 3, 3-tetrafluoropropene represented by the formula CF ₃ CH=CHF (HFC-1234 ze) are compounds that are useful as refrigerants; these compounds have been receiving attention as constituents of refrigerants or mixed refrigerants that can be used as an alternative to chlorofluorocarbons .

A method for producing one of these compounds, HFC- 1234yf, is, for example, disclosed in Non-Patent Literature (NPL) 1 listed below; it is a single step method carried out by reacting a compound represented by CF ₃ CF ₂ CH ₂ X (X is Cl or I) with zinc in ethanol. However, this method is not suitable for industrial-scale production, because zinc is expensive and a large amount of waste is generated. Methods for producing HFC-1234yf are also reported in other publications. Patent Literature (PTL) 1 discloses a method comprising reacting chloromethyl tetrafluoropropanate with an amine; Patent Literature (PTL) 2 discloses a method comprising thermal decomposition of 1-trifluoromethyl-l, 2, 2- trifluorocyclobutane; Patent Literature (PTL) 3 discloses a method comprising reacting chlorotrifluoroethylene (CClF=CF ₂ ) and methyl fluoride (CH ₃ F) in the presence of a Lewis acid such as SbF ₅ ; and Patent Literature 4 (PTL) discloses a method comprising thermal decomposition of tetrafluoroethylene (CF ₂ =CF ₂ ) and chloromethane (CH ₃ Cl) . Non-Patent Literatures (NPL) 2 and 3 listed below also disclose HFC-1234yf production methods.

These methods, however, are not considered to be effective for industrial purposes, because the starting materials are difficult to produce and cannot be easily obtained, the reaction conditions are severe, the reaction reagents are expensive, the yield is low, etc.

Known methods for producing HFC-1234 ze include a method comprising dehydrohalogenation of CF ₃ CH ₂ CHFX (wherein X is F, Cl, Br, or I) (see Patent Literatures (PTL) 5 to 9); a method comprising dehydrofluorination of CF ₃ CHFCH ₂ F (HFC-245eb) (see Patent Literatures (PTL) 10 and 11) ; a method comprising fluorination of CF ₃ CH=CHCl (HCFC-1233zd) (Patent Literature (PTL) 12) ; and a method comprising dehydrohalogenation of CF ₃ CHXCH ₂ F (wherein X is Cl, Br, or I) (see Patent Literature (PTL) 13). However, these methods need to be improved for industrial usage because the starting materials are difficult to produce and are not easily obtained, the yield is low, multiple steps are required, etc.

For example, Patent Literature (PTL) 5 discloses a method for producing HFC-1234ze comprising dehydrohalogenation of CF ₃ CH ₂ CHFX (wherein X is F, Cl, Br, or I) . As a method for producing CF ₃ CH ₂ CHFX, Patent Literature (PTL) 5 discloses a method comprising reacting CY ₃ CH ₂ CHY ₂ (wherein Y is F, Cl, Br, or I) with HF (hydrogen fluoride) in the presence of a catalyst such as Cr ₂ O ₃ . However, this method requires two steps, i.e., a reaction with HF (hydrogen fluoride) and dehydrohalogenation, to produce 1,3,3,3- tetrafluoropropene; therefore, the reaction process is complicated. As another method for producing CF ₃ CH ₂ CHFX, which is an intermediate of the reaction, a method comprising reacting CF ₃ X (wherein X is Cl, Br, or I) with vinyl fluoride is also disclosed. However, this method is not considered to be effective for industrial purposes, because CF ₃ X, which is an expensive compound, is used.

Citation List Patent Literature

PTL 1: JP No. 63-211245 A

PTL 2: U.S. Patent No. 3996299

PTL 3: US 2006/258891 Al PTL 4: U.S. Patent No. 2931840

PTL 5: US 2005/0245773 Al

PTL 6: US 2008/051611 Al

PTL 7: EP 2000/974571 A2

PTL 8: JP 11-140002 A PTL 9: US 2007/0129579 Al

PTL 10: WO 2008/002499 A2

PTL 11: WO 2008/002500 Al

PTL 12: JP 2007-320896 A

PTL 13: WO 2005/108334 Al Non Patent Literature

NPL 1: J. Chem. Soc, 1957, 2193-2197

NPL 2: J. Chem. Soc, 1970, 3, 414-421

NPL 3: J. Fluorine Chem., 1997, 82, 171-174

Summary of Invention Technical Problem

The present invention has been accomplished in view of the foregoing problems found in the prior art. A primary object of the present invention is to provide an industrially applicable, simple and effective process for preparing fluorine-containing propenes containing 2, 3, 3, 3-tetrafluoropropene and 1,3,3,3- tetrafluoropropene . Solution to Problem

The present inventors conducted extensive research to achieve the above object, and found the following. Fluorine- containing propenes containing 2, 3, 3, 3-tetrafluoropropene (HFC- 1234yf) and 1, 3, 3, 3-tetrafluoropropene (HFC-1234ze) can be prepared in a single step reaction by reacting 1,1,1,3- tetrachloro-3-fluoropropane (HCFC-241fb) with anhydrous hydrogen fluoride in a gas phase in the presence of a catalyst. This reaction process can be used as an industrially advantageous method for producing these compounds. The present invention has been accomplished based on these findings.

More specifically, the present invention provides the following processes for preparing fluorine-containing propenes containing 2,3,3, 3-tetrafluoropropene and 1,3,3,3- tetrafluoropropene .

1. A process for preparing fluorine-containing propenes containing 2,3,3, 3-tetrafluoropropene and 1,3,3,3- tetrafluoropropene, comprising reacting 1, 1, 1, 3-tetrachloro-3- fluoropropane represented by the formula CCl ₃ CH ₂ CHClF and anhydrous hydrogen fluoride in a gas phase in the presence of a catalyst.

2. The process according to item 1 wherein the catalyst is a chromium oxide or a fluorinated chromium oxide obtained by fluorination of the chromium oxide.

3. The process according to item 2 wherein the chromium oxide is a compound represented by the formula CrO _1n wherein m is in the range of 1.5 < m < 3. 4. The process according to item 2 wherein the chromium oxide is a compound represented by the formula CrO _n , wherein m is in the range of 1.8 ≤ m < 2.5.

5. The process according to any one of items 2 to 4 wherein the chromium oxide further contains at least one metal element selected from the group consisting of indium, gallium, cobalt, nickel, zinc, and aluminum.

6. The process according to item 5 wherein the chromium oxide containing at least one metal element selected from the group consisting of indium, gallium, cobalt, nickel, zinc, and aluminum is a compound obtained by a method comprising a step of forming a precipitate from an aqueous solution containing chromium ions and metal ions.

7. The process according to any one of items 1 to 6 wherein the anhydrous hydrogen fluoride is reacted with 1, 1, 1, 3-tetrachloro- 3-fluoropropane in an amount of at least 3 moles per mole of 1,1,1, 3-tetrachloro-3-fluoropropane .

8. The process according to any one of items 1 to 7 wherein the

1, 1, 1, 3-tetrachloro-3-fluoropropane is a reaction product of carbon tetrachloride and vinyl fluoride.

The production process of the present invention is described below more specifically.

Starting compounds

In the present invention, 1, 1, 1, 3-tetrachloro-3- fluoropropane (HCFC-241fb) represented by the formula CCl ₃ CH ₂ CHClF and anhydrous hydrogen fluoride (HF) are used as starting materials.

1, 1, 1, 3-tetrachloro-3-fluoropropane, which is one of the starting materials, is a known substance, and can be easily obtained, for example, by reacting carbon tetrachloride with vinyl fluoride. Carbon tetrachloride and vinyl fluoride, which are used as starting materials in this production process, are relatively inexpensive substances, and the production process is simple. Accordingly, 1, 1, 1, 3-tetrachloro-3-fluoropropane, which is used as a starting material in the process of the present invention, is a substance that is available at low cost.

The reaction of carbon tetrachloride and vinyl fluoride to obtain 1, 1, 1, 3-tetrachloro-3-fluoropropane can be carried out in the presence of at least one component selected from the group consisting of metals and metal halides, optionally using a nonpolar solvent that is inert to the reaction, such as methylene chloride or carbon bisulfide. Examples of metals that can be used for the reaction include copper, iron, manganese, and the like.

Examples of metal halides include aluminium chloride, cuprous chloride, cupric chloride, ferric chloride, manganese chloride, and the like. Such metals and metal halides can be used singly or in a combination of two or more.

Further, if necessary, a pentavalent phosphorus compound, such as trimethyl phosphate, trimethylphosphine, triethyl phosphate, triethylphosphine, or tributyl phosphate, can be used as a reaction accelerator in the reaction of carbon . tetrachloride and vinyl fluoride.

In the reaction, the amount of vinyl fluoride is typically about 0.1 to about 10 moles per mole of carbon tetrachloride.

The amount of at least one component selected from the group consisting of metals and metal halides is typically about 0.001 to about 2 moles per mole of carbon tetrachloride.

The amount of pentavalent phosphorus compound used as a reaction accelerator is typically about 0.1 to about 10 moles per mole of the total amount of metal and metal halide.

The reaction temperature during the reaction of carbon tetrachloride with vinyl fluoride is typically about room temperature to 150 ⁰ C, and preferably about 8O ⁰ C to about 12O ⁰ C. The reaction pressure may be atmospheric pressure, an increased pressure, or a reduced pressure. The reaction is typically carried out in a hermetically sealed container under increased pressure. Production process of the invention According to the process of the present invention,

1, 1, 1, 3-tetrachloro-3-fluoropropane represented by the formula CCl ₃ CH ₂ CHClF and anhydrous hydrogen fluoride are reacted in a gas phase in the presence of a catalyst to produce fluorine- containing propenes containing 2, 3, 3, 3-tetrafluoropropene represented by the formula CF ₃ CF=CH ₂ and 1,3,3,3- tetrafluoropropene represented by the formula CF ₃ CH=CHF.

As described above, Patent Literature (PTL) 5 discloses a method for producing HFC-1234ze by dehydrohalogenation of CF ₃ CH ₂ CHFX (wherein X is F, Cl, Br, or I) . This method is not considered to be effective for industrial purposes, because the reaction process is complicated and the starting materials are expensive. Furthermore, the only useful substance among the obtained products is HFC-1234ze.

Comparatively, the process of the present invention uses inexpensive starting materials, and can produce fluorine- containing propenes containing two types of useful compounds, i.e., 2, 3, 3, 3-tetrafluoropropene and 1, 3, 3, 3-tetrafluoropropene in a substantially single step reaction. Therefore, the process of the present invention is highly useful for industrial purposes. Catalyst

The catalyst used in the present invention is not particularly limited, and any catalyst that is effective in the fluorination reaction with hydrogen fluoride can be used. Examples of catalysts include metal oxides, metal halides, transition metals, etc.

In the present invention, particularly when a chromium oxide or a fluorinated chromium oxide obtained by fluorination of the chromium oxide is used as a catalyst, the reaction can efficiently proceed. The chromium oxide is a compound represented by the composition formula CrO _1n , wherein m is preferably in the range of 1.5 < m < 3, more preferably 1.8 ≤ m ≤ 2.5, and particularly preferably 2.0 ≤ m < 2.3. In the above formula, if m is excessively small, the catalytic activity and selectivity of HFC-1234yf and HFC-1234ze tend to decrease, whereas if m is excessively large, the deterioration of the catalyst tends to progress, neither of which is desirable. One example of a method for preparing the above chromium oxide is as follows.

First, an aqueous solution of a chromium salt (e.g., chromium nitrate, chromium chloride, chromium alum, chromium sulfate, etc.) is mixed with aqueous ammonia to produce a precipitate of chromium hydroxide. For example, 10% aqueous ammonia is added dropwise to a 5.7% aqueous solution of chromium nitrate in an amount of about 1 to about 1.2 equivalents per equivalent of chromium nitrate to precipitate chromium hydroxide. The properties of chromium hydroxide can be controlled by varying the reaction rate during precipitation. A higher reaction rate is preferable, because catalytic activity can be enhanced by increasing the reaction rate. The reaction rate varies depending on the temperature of the reaction solution, method of mixing aqueous ammonia (mixing speed) , stirring conditions, etc. Therefore, the reaction rate can be suitably adjusted by- controlling these conditions.

The precipitate is filtered, washed, and then dried. The drying may be performed, for example, in air at about 70 ⁰ C to about 200 ⁰ C, and particularly at about 120 ⁰ C, for about 1 to about 100 hours, and particularly for about 12 hours. The product obtained at this stage is referred to as being in the form of chromium hydroxide. This product is subsequently disintegrated into a powder. The rate of precipitation is adjusted so that the density of the disintegrated powder (for example, a particle size of 1,000 um or less, and 95% of the powder having a size between 46 to 1,000 um) falls within a range of about 0.6 to about 1.1 g/ml, and preferably about 0.6 to about 1.0 g/ml. A powder density of less than 0.6 g/ml is not preferable, because the pellet strength is weakened. Conversely, a powder density of more than 1.1 g/ml is not preferable, because the catalytic activity- is lowered, and the pellets break easily. The specific surface area of the powder determined at 200°C with 80 minutes of degassing is preferably about 100 m ² /g or more, and more preferably about 120 m ² /g or more. The upper limit of the specific surface area is, for example, about 220 m ² /g. In the present specification, the specific surface area is measured by the BET method.

If necessary, not more than approximately 3 wt.% of graphite may be mixed into the thus-obtained chromium hydroxide powder. The resulting mixture is formed into pellets using a tableting machine. The size of the pellets may be about 3.0 mm in diameter and about 3.0 mm in height. The pellets preferably have a compressive strength (pellet strength) of about 210 ± 40 kg/cm ² . If the compressive strength is excessively high, the gas contact efficiency decreases and thus lowers the catalytic activity, and the pellets break easily. Conversely, if the compressive strength is excessively low, the resulting pellets are liable to be powdered and thereby become difficult to handle. The resulting pellets are calcined in an inert atmosphere, for example, in a nitrogen gas stream, to produce an amorphous chromium oxide. The calcination temperature is preferably not lower than 360 ⁰ C. However, because chromium oxide is crystallized at exceedingly high temperatures, setting the calcination temperature at the highest possible temperature within the range that the crystallization of chromium oxide can be avoided is desirable. For example, the pellets may be calcined at a temperature of about 380 ⁰ C to about 460 ⁰ C, and particularly about 400 ⁰ C, for about 1 to about 5 hours, and particularly for about 2 hours.

The calcined chromium oxide may have a specific surface area of about 170 m ² /g or more, preferably about 180 m ² /g or more, and more preferably about 200 m ² /g or more. The upper limit of the specific surface area is generally about 240 m ² /g, and preferably about 220 m ² /g. If the specific surface area is more than 240 m ² /g, the catalytic activity is high but the deterioration rate increases. If the specific surface area is less than 170 m ² /g, the catalytic activity becomes undesirably low. Fluorinated chromium oxide can be prepared by the method disclosed in Japanese Unexamined Patent Publication No. 1993-146680. For example, fluorinated chromium oxide can be prepared by subjecting the chromium oxide obtained by the above- described method to fluorination (HF treatment) with hydrogen fluoride. The fluorination temperature may be suitably selected within a range in which the water generated does not condense (for example, about 150 ⁰ C at 0.1 MPa); the upper limit is the temperature at which the catalyst does not crystallize due to the reaction heat. The pressure during fluorination is not particularly limited, but the fluorination may preferably be conducted at the same pressure as the pressure at which the catalyst will be used in a catalytic reaction. The fluorination temperature is, for example, in the range of about 100 ⁰ C to about 46O ⁰ C.

The surface area of the catalyst decreases as a result of fluorination. Generally, a greater specific surface area results in higher catalytic activity. The specific surface area of the catalyst after fluorination is preferably about 25 to about 130 m ² /g, and more preferably about 40 to about 100 m ² /g, but it is not limited to the above range. The fluorination reaction of chromium oxide may be conducted by supplying hydrogen fluoride to a reactor containing chromium oxide, prior to carrying out the process of the invention described later. After chromium oxide is fluorinated by this method, the reaction for producing 2,3,3,3- tetrafluoropropene and 1, 3, 3, 3-tetrafluoropropene can be conducted by supplying 1, 1, 1, 3-tetrachloro-3-fluoropropane, which is a starting material, to the reactor.

Although the degree of fluorination is not particularly- limited, a fluorinated chromium oxide having a fluorine content of about 10 to about 30 wt.% can be preferably used.

Further, the chromium-based catalyst (hereinafter, sometimes referred to as a "metal component-containing chromium catalyst") disclosed in Japanese Unexamined Patent Publication No. 11-171806 is usable as a chromium oxide catalyst or a fluorinated chromium oxide catalyst in the present invention. This chromium- based catalyst is amorphous and mainly comprises a chromium compound containing at least one metal element selected from the group consisting of indium, gallium, cobalt, nickel, zinc, and aluminum, wherein the average valence of the chromium in the chromium compound is +3.5 or more and +5.0 or less.

The method for producing the metal component-containing chromium catalyst is not particularly limited. For example, after a chromium oxide catalyst is obtained by the above method, the catalyst may be impregnated with an aqueous solution containing at least one metal element described above and then calcined to produce a metal component-containing chromium catalyst. To produce the metal component-containing chromium catalyst, the following process is particularly preferable. During the process of producing the above-mentioned chromium oxide catalyst, a compound containing a metal element described above is added to an aqueous solution of a chromium salt to prepare an aqueous solution containing chromium ions and metal ions . Subsequently, ammonia water is added to this solution to form a precipitate containing chromium hydroxide and the metal component, and the precipitate is dried and calcined according to the methods described above. When using a metal component-containing chromium catalyst obtained by this method, the target 2,3,3,3- tetrafluoropropene and 1, 3, 3, 3-tetrafluoropropene can be obtained with high selectivity, and the selectivity of 1,3,3,3- tetrafluoropropene can be particularly increased.

The compound containing at least one metal element selected from the group consisting of indium, gallium, cobalt, nickel, zinc, and aluminum can be selected from compounds that are soluble in an aqueous solution containing a chromium salt. For example, halides, nitrates, sulfates, and like water-soluble compounds can be used. The amount of metal element is preferably about 0.1 to about 50 wt.%, and more preferably about 1.0 to about 30 wt.%, based on the total amount of the final metal component-containing chromium catalyst. The metal component-containing chromium catalyst thus obtained may be fluorinated in the same manner as described above.

Each of the aforementioned catalysts can be supported on a carrier such as alumina, activated carbon, or the like. Reaction process According to the process of the present invention, the reaction may typically be performed by supplying 1,1,1,3- tetrachloro-3-fluoropropane and anhydrous hydrogen fluoride as starting materials in a gas phase to a reactor containing a catalyst as mentioned above, whereby a reaction product containing 2, 3, 3, 3-tetrafluoropropene (HFC-1234yf) and 1,3,3,3- tetrafluoropropene (£-HFC-1234ze + Z-HFC-1234ze) can be obtained in a single step reaction.

The ratio of 1, 1, 1, 3-tetrachloro-3-fluoropropane to anhydrous hydrogen fluoride, which are used as starting materials in the invention, is not particularly limited. For example, the amount of hydrogen fluoride may be at least 3 moles, and preferably at least 5 moles, per mole of 1, 1, 1, 3-tetrachloro-3- fluoropropane . The upper limit of the amount of hydrogen fluoride is preferably about 20 moles, and more preferably about 15 moles per mole of 1, 1, 1, 3-tetrachloro-3-fluoropropane.

When anhydrous hydrogen fluoride is used in an amount within the above-mentioned range, a high HCFC-241fb conversion and good catalytic activity can be satisfactorily maintained. An excessively small amount of hydrogen fluoride is undesirable because the selectivity of 2, 3, 3, 3-tetrafluoropropene (HFC-

1234yf) and 1, 3, 3, 3-tetrafluoropropene (£-HFC-1234ze + Z-HFC- 1234ze) is lowered. Conversely, supplying an excessively large amount of hydrogen fluoride is uneconomical because no particular improvement in effects is observed. The starting materials may be supplied to the reactor as is, or may be diluted with an inert gas such as nitrogen, helium, or argon and then supplied to the reactor.

In order to maintain the catalytic activity for an extended period of time, the starting materials may be supplied to the reactor together with oxygen. In this case, the amount of oxygen is preferably about 0.1 mol% to about 5 mol%, based on the total number of moles of 1, 1, 1, 3-tetrachloro-3-fluoropropane and anhydrous hydrogen fluoride.

The type of the reactor used in the process of the invention is not particularly limited. Examples of usable reactors include an adiabatic reactor containing a catalyst, a multitubular reactor cooled using a heat transfer medium, etc. Reactors made of a material resistant to the corrosive action of hydrogen fluoride, such as Hastelloy, Inconel, Monel, or the like, are preferably used.

In the process of the invention, the reaction temperature, i.e., the temperature in the reactor is preferably about 170 ⁰ C to about 450 ⁰ C, and more preferably about 210°C to about 400 ⁰ C. If the reaction temperature is higher than this range, the catalytic activity decreases. Conversely, if the reaction temperature is lower than this range, the starting material conversion and the selectivity of 1,3,3,3- tetrafluoropropene become undesirably low.

The pressure during the reaction is not particularly limited, and the reaction may be conducted under normal pressure or increased pressure. More specifically, the reaction of the invention can be performed at atmospheric pressure (0.1 MPa), but may be performed at an increased pressure of up to about 1.0 MPa. The reaction time is not particularly limited. However, the contact time, which is determined by W/F _o , may typically be adjusted to a range of about 2 to about 30 g-sec/cc, and preferably about 4 to about 15 g-sec/cc. W/F _o is a ratio of a catalyst weight W (g) to a total flow rate F ₀ (flow rate at 0 ⁰ C, 0.1 MPa: cc/sec) of starting material gases that are introduced to a reaction system. The total flow rate F ₀ refers to the flow rate of 1, 1, 1, 2-tetrachloro-3-fluoropropane and hydrogen fluoride that are supplied as starting materials, or the flow rate of these starting materials plus the flow rate of an inert gas and/or an oxygen gas, when such gases are also supplied. A reaction product containing 2,3,3,3- tetrafluoropropene (HFC-1234yf) and 1, 3, 3, 3-tetrafluoropropene (£-HFC-1234ze + Z-HFC-1234ze) can be obtained from the reactor outlet. 1, 3, 3, 3-tetrafluoropropene is obtained as a mixture of E- and Z-isomers. When the reaction is performed under the above- mentioned conditions, the selectivity of 2,3,3,3- tetrafluoropropene (HFC-1234yf) is about 2 to about 5%, and the selectivity of 1, 3, 3, 3-tetrafluoropropene (£-HFC-1234ze + Z-HFC- 1234ze) can be increased to 25% or more by appropriately selecting the catalyst and reaction conditions.

The reaction product may be used as is or can be separated and purified by distillation etc. to separately recover 2, 3, 3, 3-tetrafluoropropene and 1, 3, 3, 3-tetrafluoropropene. Other fluorine-containing olefins may be converted into other compounds in a subsequent reaction step. Furthermore, unreacted CCl ₃ CH ₂ CHClF (HCFC-241fb), when present, may be returned to the reactor after isolation and purification, and can be used as a starting material again. Therefore, high productivity can be maintained even if the conversion of the starting material is low because the unreacted starting material can be recycled.

Advantageous Effects of Invention

According to the process of the present invention, the target fluorine-containing propenes containing 2,3,3,3- tetrafluoropropene (HFC-1234yf) and 1, 3, 3, 3-tetrafluoropropene (£-HFC-1234ze + Z-HFC-1234ze) can be obtained in a single step reaction by using readily available 1, 1, 1, 3-tetrachloro-3- fluoropropane and hydrogen fluoride as starting materials.

Description of Embodiments

The present invention is described in more detail below, with reference to production examples of 1, 1, 1, 3-tetrachloro-3- fluoropropane (HCFC-241fb) , which is used as a starting material, and examples of the invention. Production Example 1

Synthesis of 1, 1, 1, 3-tetrachloro-3-fluoropropane (HCFC- 241fb)

A 1000-ml autoclave equipped with a thermometer, a vacuum line, a nitrogen purge line, a feeding line, a gauge, and a pressure release valve was filled with 4.5 g (79.2 mmol) of soft iron powder, 20 g (79.2 mmol) of triethyl phosphate, 100 mg of ferric chloride, and 420 g (2.73 mol) of carbon tetrachloride. The autoclave was purged five times with nitrogen, and once with vinyl fluoride. The autoclave was subsequently evacuated, and vinyl fluoride was introduced thereinto with stirring until a gauge pressure of 0.4 MPa was reached. When the autoclave was heated to 120 ⁰ C, a reaction began. The internal temperature increased to 127°C, and the internal pressure decreased from 0.9 MPa to 0.4 MPa. While the pressure of vinyl fluoride was maintained at 0.8 MPa, stirring was continued at an internal temperature of 120°C for 8 hours. Then, 10 g (39.6 mmol) of triethyl phosphate was injected into the autoclave, and the reaction was further allowed to proceed at 120 ⁰ C for 10 hours.

After completion of the reaction, the crude product was analyzed by gas chromatography. The results of the analysis confirmed that carbon tetrachloride was completely consumed. The crude product was washed twice with a threefold amount of water, and the organic layer was dried over magnesium sulfate to obtain HCFC-241fb with a purity of 88.9%, as determined by gas chromatography. Ethylene and vinyl fluoride oligomer were obtained as by-products. The obtained crude product was distilled under reduced pressure (10 mmHg) , and a fraction at 63°C to 65°C was collected to obtain 467 g (2.35 mol, yield: 86%) of HCFC- 241fb with a purity of 98% or more. Example 1

A tubular Hastelloy reactor with an inner diameter of 20 mm and a length of 1 m was charged with 42.7 g of a catalyst (fluorine content: about 16.4 wt.%) obtained by fluorinating a chromium oxide represented by the composition formula CrO _2-O - The reactor was maintained at atmospheric pressure (0.1

MPa) and 250 ⁰ C, and a supply of anhydrous hydrogen fluoride (HF) gas at 300 cc/min (flow rate at 0 ⁰ C and 0.1 MPa) and nitrogen (N ₂ ) at 100 cc/min (flow rate at 0 ⁰ C and 0.1 Mpa) to the reactor was maintained for 2 hours. After the supply of nitrogen (N ₂ ) gas was stopped, 1, 1, 1, 3-tetrachloro-3-fluoropropane (HCFC-241fb, purity: 98.9%) was supplied at a rate of 20 cc/min (flow rate at 0 ⁰ C and 0.1 MPa), and the temperature of the reactor was changed to 281°C. The molar ratio of HF (hydrogen fluoride) to 1, 1, 1, 3-tetrachloro- 3-fluoropropane was 15, and the contact time (W/F0) was 8.0 g-sec/cc. Two hours after the reaction temperature reached the target temperature, the outlet gas from the reactor was analyzed using gas chromatography. Table 1 shows the results. The structures of the resulting products are as follows: CF ₃ CF=CH ₂ (HFC-1234yf) CF ₃ CH=CHF (E-HFC-1234ze + Z-HFC-1234ze) CF ₃ CF ₂ CH ₃ (HFC-245cb) CF ₃ CH ₂ CHF ₂ (HFC-245fa) CF ₃ CCl=CH ₂ (HCFC-1233xf)

CF ₃ CH=CHCl (£-HCFC-1233zd + Z-HCFC-1233zd) CF ₃ CH=CH ₂ (HFC-1243zf) CF ₃ CH ₂ CHCl ₂ (HCFC-243fa) Example 2

An experiment was conducted under the same conditions as in Example 1 except that 42.7 g of a catalyst (fluorine content: about 17.8 wt.%) obtained by fluorinating a chromium oxide represented by the composition formula CrO _2-2 was used. The molar ratio of HF to 1, 1, 1, 3-tetrachloro-3-fluoropropane was 15, and the contact time (W/F0) was 8.0 g-sec/cc. Table 1 shows the results of the analysis. Example 3

An experiment was conducted under the same conditions as in Example 1 except that 36.7 g of a catalyst obtained by fluorinating a chromium oxide represented by the composition formula CrOi. ₉ was used, the flow rate of anhydrous hydrogen fluoride was changed to 200 cc/min (0°C, 0.1 MPa), and the reaction temperature was changed to 300 ⁰ C. The molar ratio of HF to 1, 1, 1, 3-tetrachloro-3-fluoropropane was 10, and the contact time (W/Fo) was 10.0 g-sec/cc. Table 1 shows the results of the analysis. Example 4

An experiment was conducted under the same conditions as in Example 1 except that the amount of the catalyst was changed to 35.0 g, the flow rate of the anhydrous hydrogen fluoride (HF) gas was changed to 400 cc/min (flow rate at O ⁰ C and 0.1 MPa), and the reaction temperature was changed to 380 ⁰ C. The molar ratio of HF to 1, 1, 1, 3-tetrachloro-3-fluoropropane was 20, and the contact time (W/F _o ) was 5.0 g-sec/cc. Table 1 shows the results of the analysis.

Example 5 An experiment was conducted under the same conditions as in Example 1 except that 42.7 g of a catalyst (fluorine content: about 13.9 wt.%) obtained by fluorinating a chromium oxide represented by the composition formula CrOi _-6 was used. The molar ratio of HF to 1, 1, 1, 3-tetrachloro-3-fluoropropane was 15, and the contact time (W/F _o ) was 8.0 g-sec/cc. Table 1 shows the results of the analysis. Example 6

(1) Catalyst preparation step

221.4 g (0.549 mol) of chromium nitrate enneahydrate and 41.4 g (0.137 mol) of nickel nitrate hexahydrate were dissolved in pure water to make a mixed solution weighing 2,710 g. While the mixed solution was maintained at 50°C, 402 g of 10 wt.% aqueous ammonia was added dropwise to produce a chromium hydroxide precipitate containing nickel . After the precipitate was separated by filtration and washed with pure water, a portion of the resulting product was dried in air at 120°C for 12 hours. The resulting solid chromium hydroxide was pulverized to a particle size of 0.2 mm or less to produce 63.4 g of a chromium hydroxide powder. Subsequently, 2.5 wt.% of graphite was added to this powder, and the resulting powder was compression-molded into cylindrical pellets having a diameter of 3 mm and a height of 3 mm. The pellets were calcined at 400 ⁰ C for 2 hours in a nitrogen gas stream to yield 46.0 g of a nickel-containing chromium oxide. The valence number of Cr of the nickel-containing chromium oxide determined from magnetic susceptibility measurements was CrO _2-O - Further, the results of X-ray diffraction analysis (XRD) confirmed that this catalyst is amorphous. The specific surface area of the catalyst was 187.1 m ² /g. The weight ratio of the metals contained in the obtained catalyst was calculated from SEM (scanning electron microscopic) analysis results. The ratio of Ni to Cr was 20.2 to 79.8.

(2) Reaction step A tubular Hastelloy reactor with an inner diameter of 20 mm and a length of 1 m was charged with 36.7 g of a catalyst (fluorine content: about 15.1 wt.%) obtained by fluorinating the catalyst prepared in Step (1) .

The reactor was maintained at atmospheric pressure (0.1 MPa) and 250 ⁰ C, and a supply of anhydrous hydrogen fluoride (HF) gas at 200 cc/min (flow rate at 0 ⁰ C and 0.1 MPa) and nitrogen (N ₂ ) at 100 cc/min (flow rate at 0°C and 0.1 MPa) to the reactor was maintained for 2 hours. After the supply of nitrogen (N ₂ ) gas was stopped, 1, 1, 1, 3-tetrachloro-3-fluoropropane (HCFC-241fb, purity: 98.9%) was supplied at a rate of 20 cc/min (flow rate at 0 ⁰ C and 0.1 MPa), and the temperature of the reactor was changed to 300°C. The molar ratio of HF to 1, 1, 1, 3-tetrachloro-3-fluoropropane was

10, and the contact time (W/F _o ) was 10.0 g- sec/cc. Three hours after the reaction temperature reached the target temperature, the outlet gas from the reactor was analyzed using gas chromatography. Table 1 shows the results.

Table 1