Process for the production of monofluoroethane

Abstract

Provided is a monofluoroethane production method capable of producing monofluoroethane from ethylene and hydrogen fluoride at a high conversion rate even under mild reaction conditions. The monofluoroethane production method includes reacting ethylene gas and hydrogen fluoride gas in the presence of a catalyst to obtain monofluoroethane. The catalyst contains a chromium compound that is at least one of chromium fluoride and chromium oxyfluoride.

Description

Technical Field

[0001] This disclosure relates to a method for manufacturing monofluoroethane. Background Technology

[0002] Monofluoroethane (C2H5F) is sometimes used as a raw material for synthesizing fluorocarbons used as etching gases in semiconductor manufacturing. Patent Document 1 discloses a technique for producing monofluoroethane by reacting ethylene with hydrogen fluoride in the presence of a catalyst.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Description of Chinese Patent Application Publication No. 110615728 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] The technology disclosed in Patent Document 1 requires harsh reaction conditions such as high temperature and high pressure in the reaction of ethylene with hydrogen fluoride. In addition, the technology disclosed in Patent Document 1 also has the following problem: the proportion of ethylene used as a raw material that is converted into other compounds (referred to as "conversion rate" in this specification) is not sufficiently high.

[0008] The objective of this disclosure is to provide a method for producing monofluoroethane, which can produce monofluoroethane from ethylene and hydrogen fluoride with high conversion even under mild reaction conditions.

[0009] Methods for solving problems

[0010] To address the aforementioned issues, one approach of this disclosure is shown below [1] to [9].

[0011] [1] A method for producing monofluoroethane, comprising reacting ethylene gas with hydrogen fluoride gas in the presence of a catalyst to obtain monofluoroethane, wherein the catalyst contains a chromium compound as at least one of chromium fluoride and chromium oxyfluoride.

[0012] [2] According to the method for manufacturing monofluoroethane described in [1], wherein the chromium compound has the composition formula CrO. m F n The formula in which m and n satisfy the formula 2m+n=3 and the formula 2.83≤n≤3.

[0013] [3] The method for manufacturing monofluoroethane according to [1] or [2], wherein the catalyst is a support on which the chromium compound is loaded.

[0014] [4] According to the method for manufacturing monofluoroethane described in [3], the carrier is an aluminum compound, which is at least one of aluminum fluoride and aluminum oxyfluoride.

[0015] [5] According to the method for manufacturing monofluoroethane described in [4], wherein the aluminum compound has the compositional formula AlO p F q The p and q in the composition satisfy the formula 2p+q=3 and the formula 2.83≤q≤3.

[0016] [6] The method for producing monofluoroethane according to [4] or [5], wherein the molar ratio of chromium to aluminum in the catalyst is 0.008 or more and 0.30 or less.

[0017] [7] The method for manufacturing monofluoroethane according to any one of [4] to [6], wherein the catalyst is obtained by fluorination treatment of aluminum oxide supported on chromium oxide at a temperature of 250°C or higher and 450°C or lower to react hydrogen fluoride.

[0018] [8] According to the method for manufacturing monofluoroethane described in [7], the catalyst is obtained by performing the fluorination treatment until the amount of water produced by the fluorination treatment is less than 100 mg / hr per 1 L of the catalyst.

[0019] [9] The method for producing monofluoroethane according to any one of [3] to [8], wherein the catalyst has a BET specific surface area of ​​5 m². 2 / g or more and 100m 2 / g or less.

[0020] Invention Effects

[0021] According to this disclosure, monofluoroethane can be produced from ethylene and hydrogen fluoride with high conversion even under mild reaction conditions. Detailed Implementation

[0022] The following describes one embodiment of this disclosure. It should be noted that this embodiment illustrates one example of this disclosure, and this disclosure is not limited to this embodiment. Furthermore, various modifications or improvements can be made to this embodiment, and such modifications or improvements can also be included in this disclosure.

[0023] The method for producing monofluoroethane according to this embodiment involves reacting ethylene (CH2=CH2) gas with hydrogen fluoride (HF) gas in the presence of a catalyst to obtain monofluoroethane, wherein the catalyst contains a chromium compound as at least one of chromium fluoride and chromium oxyfluoride.

[0024] With such a configuration, monofluoroethane can be produced from ethylene and hydrogen fluoride with high conversion even under mild reaction conditions.

[0025] The method for manufacturing monofluoroethane according to this embodiment will be described in detail below.

[0026] 〔catalyst〕

[0027] The valence state of the chromium in the chromium compound contained in the catalyst (hereinafter sometimes simply referred to as "catalyst") used in the method for producing monofluoroethane according to this embodiment is not particularly limited, but can be trivalent.

[0028] Hexavalent chromium is more reactive than trivalent chromium. For example, hexavalent chromium oxide (CrO3) readily reacts with hydrogen fluoride to produce chromyl fluoride (CrO2F2) and water. This chromyl fluoride has a boiling point of approximately 30°C at 1 atmosphere.

[0029] If the reaction gas generated during the production of monofluoroethane contains chromyl fluoride in addition to monofluoroethane, then equipment is needed to remove the chromyl fluoride from the reaction gas and render it harmless. Therefore, the chromium valence state of the chromium compound contained in the catalyst is preferably trivalent.

[0030] The compositional formula of chromium compounds can be CrO. m F n Preferably, the formulas for m and n satisfy the conditions 2m + n = 3 and 2.83 ≤ n ≤ 3. That is, the chromium compound is preferably chromium fluoride or chromium oxyfluoride with a high fluorination rate. If a catalyst containing chromium fluoride or chromium oxyfluoride with a high fluorination rate is used, monofluoroethane can be produced from ethylene and hydrogen fluoride with higher conversion and selectivity. Therefore, monofluoroethane can be produced from ethylene and hydrogen fluoride in high yield.

[0031] The catalyst in the method for producing monofluoroethane according to this embodiment can be a support loaded with a chromium compound. That is, a support loaded with a chromium compound, which is at least one of chromium fluoride and chromium oxyfluoride, can be used as a catalyst for the reaction to produce monofluoroethane. The material of the support is not particularly limited, and examples include porous metals, activated carbon, and porous ceramics (e.g., metal oxides).

[0032] The carrier material can be alumina (Al2O3). Other examples besides alumina include silicon dioxide (SiO2), zirconium oxide (ZrO2), titanium dioxide (TiO2), zeolite, silica-alumina, magnesium oxide (MgO), calcium oxide (CaO), iron oxide (Fe2O3), nickel oxide (NiO), cobalt oxide (Co3O4), copper oxide (CuO), manganese oxide (MnO2), cerium oxide (CeO2), lanthanum oxide (La2O3), yttrium oxide (Y2O3), scandium oxide (Sc2O3), tungsten oxide (WO3), vanadium oxide (V2O5), molybdenum oxide (MoO3), ruthenium oxide (RuO2), iridium oxide (IrO2), rhodium oxide (Rh2O3), zinc oxide (ZnO), tin oxide (SnO2), indium oxide (In2O3), and gallium oxide (Ga2O3). Considering ease of use and stability of the reactants and products, activated alumina and activated carbon are preferred, with activated alumina being more preferred.

[0033] Furthermore, the carrier material can be an aluminum compound, which is at least one of aluminum fluoride and aluminum fluoride oxyfluoride. And the compositional formula of the aluminum compound can be AlO. p F q Preferably, the p and q in the composition satisfy the formula 2p+q=3 and the formula 2.83≤q≤3. If the support material is the aforementioned aluminum compound, monofluoroethane can be produced from ethylene and hydrogen fluoride with higher conversion and higher selectivity.

[0034] The method for producing the monofluoroethane described in this embodiment is not particularly limited. The support (catalyst) loaded with a chromium compound can be manufactured, for example, as follows.

[0035] First, aqueous solutions of chromium salts such as chromium chloride (CrCl3), chromium nitrate (Cr(NO3)3), and chromium hydroxide (Cr(OH)3) are impregnated in a support such as activated alumina. After drying in air, the solutions are calcined in an oxygen (O2) stream to convert the chromium salts into chromium oxide. Further reduction with hydrogen (H2) reduces the high-valent chromium to trivalent chromium. This yields a support loaded with trivalent chromium oxide.

[0036] Next, the chromium oxide-supported support is subjected to a fluorination treatment that reacts with hydrogen fluoride, thereby fluorinating the chromium oxide to form a chromium compound, which is at least one of chromium fluoride and chromium fluoride oxide. Thus, a support (catalyst) supported on the above-mentioned chromium compound is obtained (hereinafter, sometimes referred to as "supported catalyst").

[0037] Catalysts that are not supported catalysts can be obtained, for example, by the following method. First, chromium hydroxide powder is obtained by neutralizing an aqueous solution of chromium nitrate with ammonia (NH3). This chromium hydroxide powder is then filtered, washed, dried, pulverized, and pressed into tablets. The tablets are then calcined in an oxygen stream to produce chromium oxide, which is further reduced by hydrogen to reduce the high-valent chromium to trivalent chromium. This yields a tablet of trivalent chromium oxide powder.

[0038] Next, the chromium oxide powder tablet is subjected to a fluorination treatment that reacts with hydrogen fluoride to fluorinate the chromium oxide, making it a chromium compound that is at least one of chromium fluoride and chromium fluoride oxide. Thus, a tablet of the above-mentioned chromium compound powder is obtained (hereinafter, sometimes referred to as "tablet catalyst").

[0039] Supported catalysts are preferred as the form of catalyst. This is because supported catalysts are easier to fluorinate based on hydrogen fluoride. Therefore, supported catalysts more readily yield CrO with the aforementioned composition. m F n Catalysts with high fluorination rates where m and n satisfy the above two formulas. Tableted catalysts, due to their high chromium oxide content, may require a longer fluorination treatment time.

[0040] There are no particular restrictions on the alumina used as a carrier, but a large specific surface area is preferred; a BET specific surface area of ​​50 m² is acceptable. 2 / g or more and 400m 2 / g or less. Specific examples of activated alumina that can be used as a carrier include: Manufactured by Co., Ltd. NST-3. In the micropore distribution of this activated alumina, the proportion of micropores with a diameter in the range of 4 nm to 50 nm is more than 70% and less than 90% of the total number of micropores, and therefore it is preferred.

[0041] There are no particular restrictions on the type of liquid containing chromium salts (impregnation solution) used to impregnate a carrier such as activated alumina, as long as it is converted into chromium oxide through calcination. Aqueous solutions of chromium chloride, chromium nitrate, chromium hydroxide, and chromic acid are acceptable. Liquids with high chromium salt solubility are preferred; therefore, aqueous solutions of chromium chloride and chromium nitrate are more preferred, and aqueous solutions of chromium chloride are even more preferred. While chromium nitrate produces NOx during calcination and chromium chloride produces hydrogen chloride, removing (neutralizing) hydrogen chloride as part of the exhaust gas treatment is simpler. Therefore, aqueous solutions of chromium chloride are preferred over aqueous solutions of chromium nitrate.

[0042] The concentration of the chromium chloride aqueous solution is not particularly limited and can be 1.5% by mass or more and 40% by mass or 10% by mass or more and 35% by mass or less. If the concentration of the chromium chloride aqueous solution is within the above range, the viscosity of the chromium chloride aqueous solution is appropriate, thus the impregnation rate of the chromium chloride aqueous solution onto the support such as activated alumina is faster, and the dispersion onto the support is also easier to become uniform. In addition, the loading of chromium compounds on the support is also easier to achieve, thus eliminating the need for multiple impregnation operations.

[0043] There is no particular limitation on the temperature of the impregnation solution when impregnating the carrier; it can be above 5°C and below 45°C, or above 20°C and below 35°C. If the temperature of the impregnation solution is within the above range, the viscosity of the impregnation solution is appropriate, thus making impregnation easier and more uniform. In addition, changes in the concentration of the impregnation solution due to water evaporation are less likely to occur.

[0044] There are no particular limitations on the impregnation method used to impregnate the carrier with the impregnating solution. For example, it could be a method of impregnating activated alumina in a chromium chloride aqueous solution for a certain period of time, or it could be a method of measuring the water absorption capacity of activated alumina and then allowing the activated alumina to absorb the entire volume of a chromium chloride aqueous solution similar to its water absorption capacity. When using the impregnation method, since bubbles can be observed in the chromium chloride aqueous solution if activated alumina is impregnated, the impregnation time can be determined simply by using the time when the bubbles no longer generate as a standard.

[0045] There is no particular limitation on the number of times the impregnation operation (the operation of impregnating activated alumina with an aqueous chromium chloride solution) is performed, but it is preferred to perform it once. The amount of chromium compound loaded on the support can be adjusted by adjusting the concentration of the aqueous chromium chloride solution.

[0046] The amount of chromium oxide (Cr2O3) supported on activated alumina is not particularly limited, but the molar ratio of chromium to aluminum in the support can be 0.008 or more and 0.30 or less, 0.034 or more and 0.22 or less, or 0.074 or more and 0.168 or less. Furthermore, the lower limit of the molar ratio of chromium to aluminum in the support can be 0.008 or more, 0.034 or more, or 0.074 or more, while the upper limit can be 0.30 or less, 0.22 or less, or 0.168 or less.

[0047] Furthermore, in the fluorinated catalyst, there is no particular limitation on the amount of chromium compound supported on the fluorinated activated alumina, which is at least one of chromium fluoride and chromium oxyfluoride. Similarly, the molar ratio of chromium to aluminum in the catalyst can be 0.008 or more and 0.30 or less, 0.034 or more and 0.22 or less, or 0.074 or more and 0.168 or less. Moreover, the lower limit of the molar ratio of chromium to aluminum in the catalyst can be 0.008 or more, 0.034 or more, or 0.074 or more, and the upper limit can be 0.30 or less, 0.22 or less, or 0.168 or less.

[0048] If expressed as the ratio of the mass of the supported chromium oxide to the mass of the support, it can be 1% to 31% by mass, 5% to 25% by mass, or 10% to 20% by mass. If the ratio of the supported chromium oxide to the mass of the support is within the above range, the catalyst can be supported by a single impregnation operation, and the catalyst activity is also easily increased.

[0049] After immersing the carrier in the impregnation solution, remove the carrier from the solution and allow it to stand in the air for a period of time (e.g., about 30 minutes). Then, dry it at, for example, 110°C for about 3 hours. Place the dried carrier in a stainless steel or heat-resistant glass container, and heat it while allowing air circulation to increase the temperature. An exothermic reaction occurs at a temperature around 200°C, so maintain the temperature at 200°C until the exothermic reaction ceases. Afterward, raise the temperature to, for example, 400°C and process for about 3 hours.

[0050] Next, the air supply is stopped and nitrogen (N2) is supplied instead, while hydrogen is supplied at a concentration of 2% by volume to reduce hexavalent chromium. Since the supply of hydrogen is exothermic when it is initiated, hydrogen is supplied until the exothermic reaction disappears; once the exothermic reaction has disappeared, the hydrogen supply is stopped, and the support is cooled. Through these operations, a substance in which chromium oxide is supported on a support such as activated alumina is obtained.

[0051] The following is an example of a method for fluorinating chromium oxide obtained as described above. Chromium oxide (or a carrier loaded with chromium oxide) is packed into a reactor. The shape of the reactor is not particularly limited; for example, a tubular reactor can be used. The following is an example of fluorination using a reaction tube as a tubular reactor.

[0052] The reaction tube for fluorination is preferably made of a metal that is corrosion-resistant to the mixture of water produced during the fluorination process and the hydrogen fluoride gas supplied to the reaction tube. Examples of such metals include... (Registered Trademark) (Registered trademark), nickel (Ni), etc.

[0053] Heating of the reaction tube is preferably achieved by circulating the heated medium within the outer jacket of the reaction tube, or by warming the stirred medium within the outer jacket using an electric heater from outside the jacket. This is because the fluorination reaction of chromium oxide generates a large amount of exothermic heat.

[0054] The inner diameter of the reaction tube is not particularly limited, but can be 1 inch or more and 2.5 inches or less. If it is 1 inch or more and 2.5 inches or less, the interior can be filled with a sufficient amount of chromium oxide (or a chromium oxide-supported carrier). Furthermore, if it is 1 inch or more and 2.5 inches or less, the heat removal efficiency is good, preventing the internal temperature from becoming too high, thus allowing a sufficient amount of hydrogen fluoride to be supplied to the reaction tube for fluorination treatment in a short time. The height of the chromium oxide (or chromium oxide-supported carrier) layer filling the reaction tube is not particularly limited, but can be 5 cm or more and 3 m or less.

[0055] During fluorination, nitrogen gas is first passed through a reaction tube filled with chromium oxide (or a chromium oxide-supported carrier) while the temperature of the reaction tube is increased. There is no particular limitation on the fluorination temperature, but it is preferable to perform the fluorination at a temperature higher than the temperature at which ethylene reacts with hydrogen fluoride.

[0056] If the catalyst activity decreases during the production of monofluoroethane, the reaction temperature of ethylene with hydrogen fluoride may sometimes rise. Therefore, it is preferable to control the temperature inside the chromium oxide (or chromium oxide-supported support) filling layer during fluorination treatment to a temperature of 250°C or higher and 450°C or lower, more preferably to a temperature of 300°C or higher and 400°C or lower, and even more preferably to a temperature of 330°C or higher and 380°C or lower.

[0057] Furthermore, the lower limit of the temperature inside the chromium oxide (or chromium oxide-supported carrier) filling layer during fluorination treatment can be above 250°C, above 300°C, or above 330°C, and the upper limit can be below 450°C, below 400°C, or below 380°C.

[0058] After the temperature of the reaction tube is raised, hydrogen fluoride diluted with nitrogen is supplied to the reaction tube. While controlling the concentration of hydrogen fluoride gas in the gas supplied to the reaction tube to be below 15% by volume, the exothermic reaction between hydrogen fluoride and chromium oxide is detected by measuring the temperature inside the chromium oxide (or chromium oxide-supported carrier) packing layer inside the reaction tube. Then, the supply of hydrogen fluoride is adjusted so that the exothermic peak temperature is preferably below 400°C.

[0059] When the reaction tube has an inner diameter of 2 inches, if nitrogen gas is used to dilute the hydrogen fluoride to 10% by volume, the exothermic peak temperature can be kept below 400°C even when supplied at a flow rate of approximately 300 mL / min (unless otherwise specified, gas supply rates are based on standard conditions). Maintaining the exothermic peak temperature below 450°C is important to prevent a decrease in the catalyst's specific surface area. Furthermore, the temperature of the chromium oxide (or chromium oxide-supported carrier) packing layer can be kept below 250°C during fluorination, but the fluorination time will be longer. Fluorination of chromium oxide may also occur in the reaction of ethylene with hydrogen fluoride.

[0060] The exothermic peak of the chromium oxide (or chromium oxide-supported carrier) packing layer moves from the inlet side to the outlet side of the reaction tube. Eventually, there is no longer a temperature difference between the temperature of the heat medium in the reaction tube and the internal temperature of the reaction tube, and the exothermic reaction ends. Therefore, the dilution of hydrogen fluoride gas with nitrogen is reduced, and the concentration of hydrogen fluoride gas supplied to the reaction tube is increased.

[0061] Stop supplying nitrogen to the reaction tube and continue fluorination treatment by supplying only hydrogen fluoride gas. The termination of fluorination treatment is determined by the amount of water produced at the reaction tube outlet. This is done by measuring the amount of water contained in the hydrogen fluoride gas exiting the reaction tube outlet, dividing the amount of water produced per unit time (in mg) by the volume of catalyst obtained through fluorination treatment (in L), to calculate the amount of water produced per 1 L of the obtained catalyst. Fluorination treatment is terminated when the amount of water produced per 1 L of the obtained catalyst is below 100 mg / hr.

[0062] The following describes an example of a method for determining the water content in the hydrogen fluoride gas discharged from the reaction tube outlet. The gas discharged from the reaction tube outlet is passed into a collection container immersed in a refrigerant. An example of a refrigerant is isopropanol with dry ice. The hydrogen fluoride gas and water are liquefied together and thus collected in the collection container. After determining the mass of the collected material in the collection container, the collection container containing the collected material is placed in a hot water bath at 60°C to evaporate only the hydrogen fluoride in the collected material. A known amount of ethanol is used to extract the trace amount of aqueous hydrogen fluoride remaining in the collection container. The water content of the ethanol used for extraction is determined beforehand. The water content of the ethanol from which the aqueous hydrogen fluoride solution was extracted is determined using a Karl Fischer titration apparatus. From this, the water content in the hydrogen fluoride gas discharged from the reaction tube outlet can be determined.

[0063] If the fluorination process is deemed complete based on the amount of water contained in the hydrogen fluoride gas discharged from the reaction tube outlet, then the supply of hydrogen fluoride gas to the reaction tube is stopped. Then, the reaction tube is cooled while nitrogen is flowing through it.

[0064] That is, in the method for manufacturing monofluoroethane according to this embodiment, the catalyst can also be obtained by performing a fluorination treatment on alumina supported on chromium oxide at a temperature of 250°C or higher and 450°C or lower to react hydrogen fluoride.

[0065] Furthermore, in the method for producing monofluoroethane according to this embodiment, the catalyst may be obtained by fluorination treatment until the amount of water produced by the fluorination treatment is less than 100 mg / hr per 1L of the obtained catalyst. It should be noted that the amount of water produced by the fluorination treatment can be more than 5 mg / hr and less than 100 mg / hr per 1L of the obtained catalyst.

[0066] By fluorination, chromium oxide is fluorinated to obtain a catalyst, and the proportion of fluorinated material can be determined. The method is not particularly limited; for example, one could measure the amount of hydrogen fluoride supplied to the inlet of the reaction tube and the amount of hydrogen fluoride discharged from the outlet of the reaction tube, determine the amount of hydrogen fluoride consumed based on the difference, and then calculate the proportion of fluorinated material.

[0067] The proportion of chromium oxide that is fluorinated (the fluorination rate of the catalyst) can be determined by dividing the amount of hydrogen fluoride consumed during the fluorination process by the amount of hydrogen fluoride required to fluorinate all chromium oxide into chromium fluoride.

[0068] Alternatively, the fluorination rate of the catalyst can be determined, for example, by the mass difference before and after fluorination treatment. Since the mass of all chromium oxide before fluorination treatment can be calculated, the fluorination rate of the catalyst can be obtained by dividing that value by the mass of the chromium compound after fluorination treatment.

[0069] Furthermore, for example, the fluorination rate of the catalyst can be determined by dissolving the fluorinated catalyst in an acid such as aqua regia and performing elemental analysis.

[0070] The simplest method for determining the fluorination rate of a catalyst is to measure its mass before and after fluorination treatment. Using the fluorination rate obtained by this method as an indicator of catalyst activity is perfectly acceptable.

[0071] The compositional formula of chromium compounds is CrO. m F n The preferred value of n is 2.83 or higher and 3 or lower, which is expressed as 94.3% or higher and 100% or lower in terms of fluorination rate.

[0072] In supported catalysts, if the support material before fluorination is alumina, then during fluorination, the support is also fluorinated along with chromium oxide. Compared to chromium oxide, the fluorination reaction of alumina by hydrogen fluoride has a lower reaction start temperature. The fluorination rate of the support after fluorination, i.e., the composition of the aluminum compound AlO, is determined by the fluorination process. p F qThe q in this context can be greater than 2.83 and less than 3. Therefore, as long as the alumina support has undergone fluorination treatment, even the support alone can function as a catalyst for the synthesis of monofluoroethane from ethylene and hydrogen fluoride. However, the catalytic activity decreases when the chromium compound is not supported on the support.

[0073] The BET specific surface area of ​​the catalyst (supported catalyst) after fluorination treatment can be 5 m². 2 / g or more and 100m 2 / g or less. If the BET specific surface area is within the above range, the catalyst activity is high. When using Activated alumina manufactured by the company ( When NST-3 is used as a support, the BET specific surface area of ​​the fluorinated catalyst is shown to be 20 m². 2 / g or more and 70m 2 / g or less. For commonly available alumina, the maximum BET specific surface area after fluorination is 100m². 2 Approximately / g.

[0074] [Method for manufacturing monofluoroethane]

[0075] The following describes an example of the method for manufacturing monofluoroethane according to this embodiment. A catalyst manufactured by fluorination is filled into a reaction tube. This reaction tube can be the same as the one used in the fluorination process, or a different reaction tube can be used. Since almost no water is produced from the catalyst after fluorination, a reaction tube made of stainless steel or the like, which is resistant to hydrogen fluoride, can be used.

[0076] There is no particular limitation on the inner diameter of the reaction tube used to manufacture monofluoroethane, but it can be more than 1 inch and less than 5 inches.

[0077] There are no particular limitations on the method of supplying ethylene and hydrogen fluoride as raw materials to the reaction tube. However, since ethylene is a gas at room temperature (boiling point of -103.7°C at 1 atmosphere), it is sufficient to supply gaseous ethylene to the reaction tube. Furthermore, since hydrogen fluoride is a liquefied gas (boiling point of 19.5°C at 1 atmosphere), it is sufficient to supply gaseous hydrogen fluoride gas to the reaction tube by heating the hydrogen fluoride storage container.

[0078] If the molar ratio is obtained by dividing the supply of hydrogen fluoride (the number of moles supplied per unit time) by the supply of ethylene (the number of moles supplied per unit time), then the molar ratio of hydrogen fluoride to ethylene can be greater than 0.5 and less than 20, greater than 0.7 and less than 10, or greater than 1.0 and less than 5.0.

[0079] If the molar ratio of hydrogen fluoride to ethylene is within the above-mentioned range, unreacted ethylene and hydrogen fluoride are less likely to be generated. If unreacted hydrogen fluoride is generated, it is necessary to recover the hydrogen fluoride from the reaction gas and resupply it to the reaction tube. The molar ratio of hydrogen fluoride to ethylene is preferably as close as possible to the stoichiometric value of 1.0, and preferably the condition that minimizes the generation of unreacted ethylene and unreacted hydrogen fluoride.

[0080] The reaction temperature of hydrogen fluoride with ethylene can be above 30°C and below 300°C, above 40°C and below 250°C, above 40°C and below 200°C, above 50°C and below 150°C, or above 50°C and below 100°C.

[0081] The reaction pressure between hydrogen fluoride and ethylene is not particularly limited; it can be either depressurized or pressurized, but it is preferably above atmospheric pressure and below 1.0 MPa (absolute pressure), more preferably above atmospheric pressure and below 0.5 MPa (absolute pressure), even more preferably above atmospheric pressure and below 0.2 MPa (absolute pressure), and particularly preferably atmospheric pressure.

[0082] The space velocity (hereinafter sometimes referred to as "SV") in the reaction of hydrogen fluoride with ethylene is not particularly limited and can be above 100 / hr and below 2000 / hr, or above 200 / hr and below 1000 / hr. If the space velocity is above 100 / hr, the amount of monofluoroethane produced per unit time increases, so there is no need to increase the size of the reaction tube. If the space velocity is below 2000 / hr, there is no need to reduce the diameter of the reaction tube to improve heat removal efficiency.

[0083] As explained above, according to the method for producing monofluoroethane disclosed herein, monofluoroethane can be produced from ethylene and hydrogen fluoride with high conversion even under mild reaction conditions. That is, according to the method for producing monofluoroethane disclosed herein, the reaction between ethylene and hydrogen fluoride does not require harsh reaction conditions such as high temperature and high pressure; even under the aforementioned low temperature and low pressure reaction conditions, monofluoroethane can be produced from ethylene and hydrogen fluoride with high conversion.

[0084] Example

[0085] The following examples and comparative examples further illustrate this disclosure in detail. It should be noted that, unless otherwise specified, the pressure used in the various processes and operations described below is atmospheric pressure.

[0086] [Example 1]

[0087] (1) Modulation of metal oxides

[0088] use Activated alumina manufactured by the company ( NST-3 was used as the carrier. The activated alumina was in the form of particles with an outer diameter of 3 mm. 100 mL (39.5 g) of the carrier was placed in a basket formed of a stainless steel mesh, and the basket was immersed in 200 mL of impregnation solution at room temperature. The impregnation solution was a 35% by mass aqueous solution of chromium chloride (CrCl3) manufactured by Nippon Chemical Industries, Ltd. Therefore, chromium chloride was loaded onto the carrier through the above impregnation.

[0089] After soaking for 10 minutes, remove the basket from the impregnation solution and allow it to air dry for 30 minutes. Then, transfer the carrier to an evaporating dish and place the evaporating dish in an air-atmosphere dryer to dry at 110°C for 3 hours.

[0090] The dried carrier was filled into a nickel reaction tube with an inner diameter of 1 inch, and air was circulated at SV 500 / hr while firing at 200°C until no more exothermic reactions occurred. The temperature was then raised to 400°C and fired for another 3 hours. This firing process oxidized chromium chloride to produce chromium oxide (Cr2O3).

[0091] Next, while maintaining a temperature of 400°C, the circulating gas was changed from air to a mixture of nitrogen and hydrogen, and a reduction treatment was performed for 1 hour. The SV of the nitrogen and hydrogen mixture was 200 / hr, and the hydrogen concentration in the mixture was 2% by volume.

[0092] After stopping the hydrogen supply and cooling the reaction tube, the support was removed from the reaction tube. This yielded a support loaded with chromium oxide. The mass of the support was measured to be 50.0 g, an increase of 10.5 g compared to the support before impregnation with the impregnation solution.

[0093] The chromium oxide-supported support was dissolved in aqua regia, and the elemental ratios of the various metals were determined. The chromium / aluminum ratio was found to be 0.178. Therefore, the chromium oxide-supported support contains 21.0% by mass of chromium oxide (Cr₂O₃) and 79.0% by mass of aluminum oxide (Al₂O₃).

[0094] The oxygen content of the chromium oxide-supported support was also determined. Specifically, the oxygen content was measured by determining the amount of carbon dioxide produced when carbon powder was mixed into the chromium oxide-supported support and sintered under an inactive atmosphere. The results showed that the chromium and aluminum in the chromium oxide-supported support were both in the trivalent state.

[0095] (2) Fluorination treatment of metal oxides

[0096] 100 mL of the chromium oxide-loaded carrier, prepared as described above, is filled into a nickel reaction tube with an inner diameter of 1 inch. A jacket containing a molten salt bath is installed around the outer periphery of the reaction tube, and the reaction tube is heated by heating the jacket with an electric heater. Since a thermocouple is installed inside the reaction tube, the temperature of the carrier inside the reaction tube is measured using the thermocouple.

[0097] While supplying nitrogen gas at a flow rate of 450 mL / min through the inlet of the reaction tube, the temperature of the reaction tube was raised to 340 °C. Once the internal temperature of the reaction tube stabilized at 340 °C, hydrogen fluoride gas was supplied through the inlet at a flow rate of 50 mL / min to perform fluorination treatment of the metal oxides (i.e., chromium oxide and aluminum oxide). The peak temperature of the support inside the reaction tube was 360 °C, and the ΔT was 20 °C.

[0098] After the exothermic peak of the support inside the reaction tube disappeared, the nitrogen supply was stopped, and only hydrogen fluoride gas was supplied at a flow rate of 200 mL / min to continue the fluorination treatment of the metal oxide for 5 hours. Thus, chromium oxide and aluminum oxide were fluorinated to almost the same degree. As a result, a support (catalyst) loaded with a chromium compound as at least one of chromium fluoride and chromium fluoride oxide was obtained.

[0099] An absorption bottle containing an aqueous potassium hydroxide solution was connected to the outlet of the reaction tube. Hydrogen fluoride gas exiting the reaction tube outlet was then fed to the absorption bottle, allowing the potassium hydroxide solution to absorb the gas. As a result, the potassium hydroxide solution did not change color during the fluorination treatment.

[0100] A 50 mL container was immersed in an isopropanol / dry ice bath. (Registered Trademark) A trapping container is connected to the outlet of a reaction tube, and hydrogen fluoride gas discharged from the reaction tube outlet is sent to the trapping container. The hydrogen fluoride gas discharged from the reaction tube outlet is continuously sent to the trapping container for 1 hour, and the condensed and liquefied hydrogen fluoride gas is captured in the trapping container. As a result, the mass of the trapping container increases (i.e., the mass of the captured material) by 10.4 g.

[0101] The collection container was immersed in a hot water bath at 60°C for 30 minutes to vaporize the hydrogen fluoride in the collected material. Ethanol with a known water content was then added to the residue and mixed. The ethanol mixture was analyzed using a Karl Fischer titration apparatus to determine the water content. The results showed that the water concentration in the 10.4 g of hydrogen fluoride collected was 615 ppm by mass.

[0102] Based on this result, the amount of water produced by fluorination of the metal oxide for 1 hour was calculated. Specifically, the product of the mass of the collected material (mg / h) and the concentration of water in the collected hydrogen fluoride (mass ppm) was calculated, and this product was divided by the volume (L) of the support (catalyst) loaded with the chromium compound. The result is a value per 1L of the support (catalyst) loaded with the chromium compound.

[0103] Therefore, the amount of water produced by the fluorination of the metal oxide is 64 mg / hr per 1 L of the support (catalyst) loaded with chromium compounds. Since the reaction temperature during the production of monofluoroethane is below 340°C, the amount of water produced by the fluorination of the catalyst and support during the production of monofluoroethane is less than this value.

[0104] Stop supplying hydrogen fluoride gas to the reaction tube and cool it to room temperature while simultaneously introducing nitrogen gas. Remove the carrier from the reaction tube for mass and specific surface area determination.

[0105] The mass of the support removed from the reaction tube is 78.9 g. Since the mass of the support loaded with chromium oxide is 50.0 g, the mass of the support loaded with chromium oxide when all the metals are completely fluorinated is calculated by the following formula, which is 80.13 g.

[0106] The mass (g) of all metals when completely fluorinated = (mass of the chromium oxide-supported support) (g) × {(molar ratio of chromium oxide in the chromium oxide-supported support) × 2 × (molecular weight of chromium fluoride) / (molecular weight of chromium oxide) + (molar ratio of aluminum oxide in the chromium oxide-supported support) × 2 × (molecular weight of aluminum fluoride) / (molecular weight of aluminum oxide)}

[0107] Furthermore, the fluorination rate of the metal on the support (fluorination rate of the catalyst) is calculated using the following formula, and its value is 95.9%. Therefore, the composition formula CrO m F n The value of n and the composition formula AlO p F q The q value in all cases is 2.88.

[0108] Fluorination rate (%) of the metal on the carrier = {(mass of the carrier after fluorination treatment) - (mass of the carrier loaded with chromium oxide)} / {(mass of the carrier loaded with chromium oxide when all metals are completely fluorinated) - (mass of the carrier loaded with chromium oxide)} × 100

[0109] Furthermore, the specific surface area of ​​the obtained catalyst was determined by the BET method. The result showed a specific surface area of ​​55.9 m². 2 / g. The determination conditions are as follows.

[0110] Measuring instrument: Belserp Max manufactured by Nikkiso Corporation

[0111] Adsorbate: Nitrogen

[0112] Measurement temperature: 77K

[0113] Sample pretreatment: Heat and dry at 300℃ under vacuum for 6 hours.

[0114] Sample size: 0.10–0.11 g

[0115] (3) Production of monofluoroethane (hydrofluorination addition reaction of ethylene)

[0116] 100 mL of the obtained catalyst was refilled into the nickel reaction tube used for the fluorination treatment. While nitrogen gas was flowing into the reaction tube at atmospheric pressure, the support was heated to 300 °C. The nitrogen supply to the reaction tube was then stopped, allowing a mixture of ethylene and hydrogen fluoride gases to flow through the tube, and the reaction was carried out at atmospheric pressure. It should be noted that the molar ratio of hydrogen fluoride to ethylene (HF / C₂H₄) was 3.0, and the space velocity of the ethylene and hydrogen fluoride mixture was SV = 240 / hr.

[0117] The reaction gas exiting the reaction tube is fed into a gas chromatography-mass spectrometry (GC-MS) instrument for analysis to identify and quantify the compounds contained within it. The GC-MS instrument used is a Shimadzu GC-2014s manufactured by Shimadzu Corporation. Furthermore, the chromatographic column used in the GC-MS is a CarboPak B 60 / 80 SP-1000, and the detector is a flame ionization detector (FID).

[0118] It should be noted that the analytical conditions for gas chromatography are as follows. Regarding column temperature, the temperature is raised to 150°C and held for 5 minutes, then increased at a rate of 10°C / min for 5 minutes to reach 200°C, and maintained at this temperature for 20 minutes. Furthermore, the injection port temperature is 200°C, and the carrier gas is helium (He).

[0119] The ethylene, hydrogen fluoride, and monofluoroethane contained in the reaction gas were quantified by gas chromatography. The conversion rate of ethylene and the selectivity of monofluoroethane were then calculated based on the results.

[0120] The conversion rate of ethylene is the value obtained by subtracting the amount of unreacted ethylene discharged from the reaction tube from the amount of ethylene supplied to the reaction tube, and then dividing the result by the amount of ethylene supplied to the reaction tube.

[0121] The selectivity of monofluoroethane is the value obtained by dividing the molar amount of monofluoroethane discharged from the reaction tube by the molar amount of all carbon compounds other than ethylene discharged from the reaction tube. In other words, the selectivity of monofluoroethane is the ratio of the molar amount of monofluoroethane to the molar amount of all carbon compounds other than ethylene in the products generated from the reaction of ethylene with hydrogen fluoride.

[0122] In Example 1, the conversion rate of ethylene was 20%, and the selectivity for monofluoroethane was 40%. The results are shown in Table 1.

[0123] [Table 1]

[0124] [Example 2]

[0125] (1) Modulation of metal oxides

[0126] The chromium oxide-loaded support was prepared in the same manner as in Example 1.

[0127] (2) Fluorination treatment of metal oxides

[0128] Similar to Example 1, the chromium oxide-supported support was fluorinated, and the metal oxides (i.e., chromium oxide and aluminum oxide) were fluorinated to obtain a support (catalyst) loaded with a chromium compound as at least one of chromium fluoride and chromium fluoride oxide.

[0129] (3) Production of monofluoroethane (hydrofluorination addition reaction of ethylene)

[0130] Except for the reaction temperature of 150°C, monofluoroethane was produced in the same manner as in Example 1, and the conversion rate of ethylene and the selectivity of monofluoroethane were calculated. In Example 2, the conversion rate of ethylene was 41%, and the selectivity of monofluoroethane was 99%. The results are shown in Table 1.

[0131] [Example 3]

[0132] (1) Modulation of metal oxides

[0133] The chromium oxide-loaded support was prepared in the same manner as in Example 1.

[0134] (2) Fluorination treatment of metal oxides

[0135] Similar to Example 1, the chromium oxide-supported support was fluorinated, and the metal oxides (i.e., chromium oxide and aluminum oxide) were fluorinated to obtain a support (catalyst) loaded with a chromium compound as at least one of chromium fluoride and chromium fluoride oxide.

[0136] (3) Production of monofluoroethane (hydrofluorination addition reaction of ethylene)

[0137] Except for the reaction temperature of 80°C, monofluoroethane was produced in the same manner as in Example 1, and the conversion rate of ethylene and the selectivity of monofluoroethane were calculated. In Example 3, the conversion rate of ethylene was 44%, and the selectivity of monofluoroethane was 99%. The results are shown in Table 1.

[0138] [Example 4]

[0139] (1) Modulation of metal oxides

[0140] The chromium oxide-loaded support was prepared in the same manner as in Example 1.

[0141] (2) Fluorination treatment of metal oxides

[0142] Similar to Example 1, the chromium oxide-supported support was fluorinated, and the metal oxides (i.e., chromium oxide and aluminum oxide) were fluorinated to obtain a support (catalyst) loaded with a chromium compound as at least one of chromium fluoride and chromium fluoride oxide.

[0143] (3) Production of monofluoroethane (hydrofluorination addition reaction of ethylene)

[0144] Except for the reaction temperature of 50°C, monofluoroethane was produced in the same manner as in Example 1, and the conversion rate of ethylene and the selectivity of monofluoroethane were calculated. In Example 4, the conversion rate of ethylene was 50%, and the selectivity of monofluoroethane was 96%. The results are shown in Table 1.

[0145] [Comparative Example 1]

[0146] In the same reaction tube used in Example 1 for manufacturing monofluoroethane, 100 mL of small pieces of nickel metal mesh were filled. These small pieces of metal mesh were made by cutting 40-mesh metal mesh with a wire diameter of 0.18 mm and an aperture of 0.455 mm into squares with sides of 1 cm. The small pieces of metal mesh were filled into the reaction tube in a manner that minimized gaps between them.

[0147] Monofluoroethane was produced using a reaction tube obtained through the operation described above. The method for producing monofluoroethane was the same as in Example 1, except that the reaction tube was filled with small pieces of metal mesh. Then, the conversion rate of ethylene and the selectivity of monofluoroethane were calculated in the same manner as in Example 1. In Comparative Example 1, the conversion rate of ethylene was 0%, and the selectivity of monofluoroethane was 0%. The results are shown in Table 1.

[0148] [Comparative Example 2]

[0149] Except for the fact that the reaction tube was not filled with a small piece of nickel mesh and an empty reaction tube was used, monofluoroethane was prepared in the same manner as in Comparative Example 1, and the conversion rate of ethylene and the selectivity of monofluoroethane were calculated. In Comparative Example 2, the conversion rate of ethylene was 0%, and the selectivity of monofluoroethane was 0%. The results are shown in Table 1.

[0150] [Comparative Example 3]

[0151] (1) Modulation of metal oxides

[0152] In Comparative Example 3, the process of loading chromium oxide onto a support was not performed, and the support used in Example 1 was not performed. The activated alumina manufactured by the company has undergone the following fluorination treatment.

[0153] (2) Fluorination treatment

[0154] Except for using a support without chromium oxide instead of a support loaded with chromium oxide, and setting the temperature to 300°C, the fluorination treatment was performed in the same manner as in Example 1, and the fluorinated support was analyzed.

[0155] The peak temperature of the carrier inside the reaction tube was 315°C, and the ΔT was 15°C. Furthermore, the mass increase of the trapping container (i.e., the mass of the trapped material) was 10.4 g. Consequently, the water concentration in the 10.4 g of hydrogen fluoride trapped was 210 ppm by mass.

[0156] Based on this result, the amount of water produced by fluorination of the metal oxide (i.e., alumina) for 1 hour was calculated in the same manner as in Example 1, resulting in 22 mg / hr per 1 L of carrier volume. Since the reaction temperature during the production of monofluoroethane is below 300°C, the amount of water produced by the fluorination of the carrier during the production of monofluoroethane is less than this value.

[0157] The mass of the support removed from the reaction tube after fluorination was 62.8 g. Since the mass of the support before fluorination was 39.5 g, the mass of the support after all metals were completely fluorinated was 63.9 g. Therefore, the fluorination rate of the metals in the support was 98.3%. Furthermore, the composition is AlO₂. p F q The value of q was 2.93. Furthermore, the specific surface area of ​​the carrier was determined by the BET method, similar to Example 1, and the result was 67.1 m². 2 / g.

[0158] (3) Manufacturing of monofluoroethane

[0159] Monofluoroethane was produced using a fluorinated support obtained as described above. The method for producing monofluoroethane was the same as in Example 4, except that no chromium compound was loaded on the support. Then, the conversion of ethylene and the selectivity of monofluoroethane were calculated in the same manner as in Example 1. In Comparative Example 3, the conversion of ethylene was 16%, and the selectivity of monofluoroethane was 50%. The results are shown in Table 1.

[0160] As shown in Table 1, the ethylene conversion rates in Examples 1-4 were higher than those in Comparative Examples 1-3 due to the presence of chromium compounds in the catalyst. Furthermore, as shown in Table 1, the selectivity for monofluoroethane was higher in Examples 1-4 compared to Comparative Examples 1-3. Therefore, both the ethylene conversion rate and the selectivity for monofluoroethane were high in Examples 1-4, enabling the production of monofluoroethane in high yields even under mild reaction conditions.

Claims

1. A method for producing monofluoroethane, comprising reacting ethylene gas with hydrogen fluoride gas in the presence of a catalyst to obtain monofluoroethane, wherein, The catalyst contains a chromium compound as at least one of chromium fluoride and chromium oxyfluoride.

2. The method for producing monofluoroethane according to claim 1, wherein, The composition of the chromium compound is CrO m F n The formula in which m and n satisfy the formula 2m+n=3 and the formula 2.83≤n≤3.

3. The method for producing monofluoroethane according to claim 1 or 2, wherein, The catalyst is a support on which the chromium compound is loaded.

4. The method for producing monofluoroethane according to claim 3, wherein, The carrier is made of an aluminum compound, which is at least one of aluminum fluoride and aluminum fluoride oxyfluoride.

5. The method for producing monofluoroethane according to claim 4, wherein, The aluminum compound has the following composition: AlO p F q The p and q in the composition satisfy the formula 2p+q=3 and the formula 2.83≤q≤3.

6. The method for producing monofluoroethane according to claim 4, wherein, The molar ratio of chromium to aluminum in the catalyst is greater than 0.008 and less than 0.

30.

7. The method for producing monofluoroethane according to claim 4, wherein, The catalyst is obtained by fluorination of chromium oxide-supported alumina at a temperature above 250°C and below 450°C to react with hydrogen fluoride.

8. The method for producing monofluoroethane according to claim 7, wherein, The catalyst is obtained by performing the fluorination treatment until the amount of water produced by the fluorination treatment is less than 100 mg / hr per 1 L of the catalyst.

9. The method for producing monofluoroethane according to claim 3, wherein, The catalyst has a BET specific surface area of ​​5 m². 2 / g or more and 100m 2 / g or less.

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