Method for producing monofluoroethane

Abstract

Provided is a method for producing monofluoroethane, which enables production of monofluoroethane from ethylene and hydrogen fluoride at a high conversion rate even under mild reaction conditions. This method for producing monofluoroethane comprises reacting ethylene gas with hydrogen fluoride gas in the presence of a catalyst to obtain monofluoroethane. The catalyst contains a chromium compound, which is at least one selected from chromium fluoride and chromium oxyfluoride.

Description

Method for producing monofluoroethane

[0001] The present disclosure relates to a process for producing monofluoroethane.

[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 technology for producing monofluoroethane by reacting ethylene with hydrogen fluoride in the presence of a catalyst.

[0003] Chinese Patent Application Publication No. 110615728

[0004] The technology disclosed in Patent Document 1 required severe reaction conditions of high temperature and high pressure for the reaction of ethylene with hydrogen fluoride. Furthermore, the technology disclosed in Patent Document 1 also had the problem that the proportion of ethylene used as a raw material that is converted to other compounds (referred to as "conversion rate" in this specification) was not sufficiently high. An object of the present disclosure is to provide a method for producing monofluoroethane that can produce monofluoroethane from ethylene and hydrogen fluoride with a high conversion rate even under mild reaction conditions.

[0005] In order to solve the above problems, one aspect of the present disclosure is as follows [1] to [9]: [1] A method for producing monofluoroethane, comprising reacting ethylene gas with hydrogen fluoride gas in the presence of a catalyst to obtain monofluoroethane, the catalyst containing a chromium compound which is at least one of chromium fluoride and chromium oxyfluoride.

[0006] [2] The composition formula of the chromium compound is CrO m F n wherein m and n in the composition formula satisfy the formula 2m + n = 3 and the formula 2.83 ≦ n ≦ 3. [3] The method for producing monofluoroethane according to [1] or [2], wherein the catalyst is a carrier supporting the chromium compound.

[0007] [4] The method for producing monofluoroethane according to [3], wherein the material of the support is an aluminum compound selected from the group consisting of aluminum fluoride and aluminum oxyfluoride. [5] The aluminum compound has a composition formula of AlO p F q wherein p and q in the composition formula satisfy the formula 2p+q=3 and the formula 2.83≦q≦3.

[0008] [6] The method for producing monofluoroethane according to [4] or [5], wherein the ratio of the molar amount of chromium to the molar amount of aluminum in the catalyst is 0.008 or more and 0.30 or less. [7] The method for producing monofluoroethane according to any one of [4] to [6], wherein the catalyst is obtained by subjecting aluminum oxide supporting chromium oxide to a fluorination treatment in which hydrogen fluoride is reacted with aluminum oxide at a temperature of 250°C or more and 450°C or less.

[0009] [8] The method for producing monofluoroethane according to [7], wherein the catalyst is obtained by performing the fluorination treatment until the amount of water generated by the fluorination treatment is 100 mg / hr or less per 1 L of the volume of the catalyst. [9] The method for producing monofluoroethane according to [7], wherein the BET specific surface area of ​​the catalyst is 5 m 2 / g or more 100m 2 / g or less [3] to [8]. The method for producing monofluoroethane according to any one of [3] to [8].

[0010] According to the present disclosure, monofluoroethane can be produced from ethylene and hydrogen fluoride with a high conversion rate even under mild reaction conditions.

[0011] An embodiment of the present disclosure will be described below. Note that this embodiment shows an example of the present disclosure, and the present disclosure is not limited to this embodiment. Furthermore, various modifications or improvements can be made to this embodiment, and such modifications or improvements may also be included in the present disclosure.

[0012] The method for producing monofluoroethane according to this embodiment comprises reacting ethylene (CH═CH) gas with hydrogen fluoride (HF) gas in the presence of a catalyst to obtain monofluoroethane, the catalyst containing a chromium compound selected from the group consisting of chromium fluoride and chromium oxyfluoride. With this configuration, monofluoroethane can be produced from ethylene and hydrogen fluoride with a high conversion rate even under mild reaction conditions.

[0013] The method for producing monofluoroethane according to this embodiment will be described in detail below. [Catalyst] The valence of 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 may be trivalent.

[0014] Hexavalent chromium is more reactive than trivalent chromium. For example, hexavalent chromium oxide (CrO3) reacts easily with hydrogen fluoride, and the reaction between hexavalent chromium oxide and hydrogen fluoride produces chromyl fluoride (CrO2F2) and water. This chromyl fluoride has a boiling point of approximately 30°C at 1 atmosphere.

[0015] If the reaction gas produced during the production of monofluoroethane contains chromyl fluoride together with monofluoroethane, equipment is required to remove chromium fluoride from the reaction gas and render it harmless. Therefore, the valence of chromium in the chromium compound contained in the catalyst is preferably trivalent.

[0016] The formula of chromium compounds is CrO m F n The compound may be, and it is preferable that m and n in the composition formula satisfy the formula 2m + n = 3 and the formula 2.83 ≦ n ≦ 3. That is, the chromium compound is preferably chromium fluoride (CrF3) or a chromium oxyfluoride having a high fluorination rate. By using a catalyst containing chromium fluoride or a chromium oxyfluoride having a high fluorination rate, monofluoroethane can be produced from ethylene and hydrogen fluoride with a higher conversion rate and higher selectivity. Therefore, monofluoroethane can be produced from ethylene and hydrogen fluoride with a high yield.

[0017] The catalyst in the method for producing monofluoroethane according to this embodiment may be a carrier supporting a chromium compound. That is, a carrier supporting a chromium compound, which is at least one of chromium fluoride and chromium oxyfluoride, may be used as a catalyst in the reaction for producing monofluoroethane. The material of the carrier is not particularly limited, but examples include porous metals, activated carbon, and porous ceramics (e.g., metal oxides).

[0018] The support material may be aluminum oxide (Al2O3). Examples of oxides other than aluminum oxide include silica (SiO), zirconia (ZrO), titania (TiO), zeolite, silica alumina, magnesium oxide (MgO), calcium oxide (CaO), iron oxide (FeO), nickel oxide (NiO), cobalt oxide (CoO), copper oxide (CuO), manganese oxide (MnO), cerium oxide (CeO), lanthanum oxide (LaO), yttrium oxide (YO), scandium oxide (ScO), tungsten oxide (WO), vanadium oxide (VO), molybdenum oxide (MoO), ruthenium oxide (RuO), iridium oxide (IrO), rhodium oxide (RhO), zinc oxide (ZnO), tin oxide (SnO), indium oxide (InO), and gallium oxide (GaO). Considering availability and stability against the reaction raw materials and products, activated alumina and activated carbon are preferred, with activated alumina being more preferred.

[0019] Furthermore, the material of the support may be an aluminum compound which is at least one of aluminum fluoride and aluminum oxyfluoride. The aluminum compound has a composition formula of AlO p F q In the composition formula, p and q preferably satisfy the formula 2p + q = 3 and the formula 2.83 ≦ q ≦ 3. When the support material is the above aluminum compound, monofluoroethane can be produced from ethylene and hydrogen fluoride with a higher conversion and a higher selectivity.

[0020] The method for producing the catalyst used in the monofluoroethane production method according to this embodiment is not particularly limited. A support (catalyst) carrying a chromium compound can be produced, for example, as follows. First, a support such as activated alumina is impregnated with an aqueous chromium salt solution, such as an aqueous chromium chloride (CrCl) solution, an aqueous chromium nitrate (Cr(NO)) solution, or an aqueous chromium hydroxide (Cr(OH)) solution. The impregnated support is dried in air and then calcined in an oxygen gas (O) stream to convert the chromium salt into chromium oxide. Further reduction with hydrogen gas (H) reduces the higher-order chromium to trivalent chromium. This yields a support carrying trivalent chromium oxide.

[0021] Next, the support carrying chromium oxide is subjected to a fluorination treatment in which hydrogen fluoride is reacted with the support to fluorinate the chromium oxide, thereby forming a chromium compound, which is at least one of chromium fluoride and chromium oxyfluoride, thereby obtaining a support (catalyst) carrying the chromium compound (hereinafter, sometimes referred to as a "supported catalyst").

[0022] A catalyst that is not a supported catalyst can be obtained, for example, by the following method. First, a chromium hydroxide powder is obtained by adding ammonia water (NH3) to an aqueous chromium nitrate solution to neutralize it. This chromium hydroxide powder is filtered, washed, dried, pulverized, and tableted, and then calcined in an oxygen gas stream to form chromium oxide. The higher chromium is further reduced to trivalent chromium by reduction with hydrogen gas. This results in a tableted product of trivalent chromium oxide powder.

[0023] Next, the tablet-molded product of the chromium oxide powder is subjected to a fluorination treatment in which hydrogen fluoride is reacted with the tablet-molded product of the chromium oxide to fluorinate the chromium oxide into a chromium compound which is at least one of chromium fluoride and chromium oxyfluoride, thereby obtaining a tablet-molded product of the chromium compound powder (hereinafter, sometimes referred to as a "tablet-type catalyst").

[0024] The catalyst is preferably in the form of a supported catalyst, because the fluorination treatment with hydrogen fluoride is more likely to proceed with the supported catalyst. Therefore, the supported catalyst is more likely to be used in the form of a catalyst having the above composition formula CrO mF n A catalyst with a high fluorination rate is easily obtained when m and n satisfy the above two formulas. Tablet-type catalysts have a high chromium oxide content, so there is a risk that the time required for the fluorination treatment will be long.

[0025] There is no particular limitation on the alumina used as the support, but it is preferable that the specific surface area is large, and the BET specific surface area is 50 m 2 / g or more 400m 2 / g or less. A specific example of activated alumina that can be used as a carrier is Grade NST-3 manufactured by Nikki-Universal Co., Ltd. The pore distribution of this activated alumina is preferable because the proportion of pores having a pore diameter in the range of 4 nm to 50 nm is 70% to 90% of the total number of pores.

[0026] The chromium salt solution (impregnation solution) to be impregnated into a carrier such as activated alumina is not particularly limited as long as it is converted to chromium oxide by calcination, and examples thereof include an aqueous chromium chloride solution, an aqueous chromium nitrate solution, an aqueous chromium hydroxide solution, and an aqueous chromic acid solution. A solution with a high solubility of the chromium salt is preferred, and therefore an aqueous chromium chloride solution and an aqueous chromium nitrate solution are more preferred, with an aqueous chromium chloride solution being even more preferred. While chromium nitrate generates NOx during calcination and chromium chloride generates hydrogen chloride during calcination, an aqueous chromium chloride solution is preferred over an aqueous chromium nitrate solution because it is easier to detoxify (neutralize) the hydrogen chloride in exhaust gas treatment.

[0027] The concentration of the aqueous chromium chloride solution is not particularly limited, but may be 1.5% by mass or more and 40% by mass or less, or 10% by mass or more and 35% by mass or less. When the concentration of the aqueous chromium chloride solution is within the above-mentioned range, the viscosity of the aqueous chromium chloride solution is suitable, which increases the impregnation rate of the aqueous chromium chloride solution into a support such as activated alumina and facilitates uniform dispersion on the support. In addition, the amount of chromium compound supported on the support is likely to be sufficient, eliminating the need for multiple impregnation operations.

[0028] The temperature of the impregnation liquid when impregnating the carrier is not particularly limited, but may be 5° C. or higher and 45° C. or lower, or 20° C. or higher and 35° C. or lower. If the temperature of the impregnation liquid when impregnating the carrier is within the above range, the viscosity of the impregnation liquid is suitable, making it easy to impregnate the carrier uniformly. In addition, the concentration of the impregnation liquid is less likely to change due to evaporation of water.

[0029] The impregnation method for impregnating the carrier with the impregnation solution is not particularly limited, but may include, for example, immersing activated alumina in an aqueous chromium chloride solution for a certain period of time, or measuring the amount of water absorbed by activated alumina and allowing the activated alumina to absorb an entire amount of chromium chloride solution close to that amount. In the case of the immersion method, bubbles can be observed in the chromium chloride solution when activated alumina is immersed, and the immersion time can be determined based on the time until the generation of these bubbles disappears. The number of times the impregnation operation (operation of immersing activated alumina in an aqueous chromium chloride solution) for impregnating the carrier with the impregnation solution is not particularly limited, but it is preferably performed in one go. The amount of chromium compound supported on the carrier can be adjusted by adjusting the concentration of the aqueous chromium chloride solution.

[0030] The amount of chromium oxide (Cr2O3) supported on activated alumina is not particularly limited, but the ratio of the molar amount of chromium to the molar amount of aluminum in the support may be 0.008 to 0.30, 0.034 to 0.22, or 0.074 to 0.168. The lower limit of the ratio of the molar amount of chromium to the molar amount of aluminum in the support may be 0.008 or more, 0.034 or more, or 0.074 or more, and the upper limit may be 0.30 or less, 0.22 or less, or 0.168 or less.

[0031] Furthermore, in the catalyst after fluorination treatment, the amount of chromium compound, which is at least one of chromium fluoride and chromium oxyfluoride, supported on the fluorination-treated activated alumina is not particularly limited. As in the above case, the ratio of the molar amount of chromium to the molar amount of aluminum in the catalyst may 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. The lower limit of the ratio of the molar amount of chromium to the molar amount of aluminum in the catalyst may be 0.008 or more, 0.034 or more, or 0.074 or more, and the upper limit may be 0.30 or less, 0.22 or less, or 0.168 or less.

[0032] The ratio of the mass of the supported chromium oxide to the mass of the support may be 1% by mass or more and 31% by mass or less, 5% by mass or more and 25% by mass or less, or 10% by mass or more and 20% by mass or less. When the ratio of the mass 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 catalytic activity is likely to be high.

[0033] After the carrier is impregnated with the impregnation solution, it is removed from the impregnation solution and allowed to stand in air for a while (for example, about 30 minutes). Then, it is dried, for example, at 110°C for about 3 hours. The dried carrier is placed in a stainless steel container or a heat-resistant glass container, and heated while circulating air to raise the temperature. Since an exothermic reaction occurs at a temperature of around 200°C, the temperature is maintained at 200°C until the heat generation ceases, and then the temperature is raised to, for example, 400°C and treated for about 3 hours.

[0034] Thereafter, the supply of air is stopped, nitrogen gas (N2) is supplied, and hydrogen gas is supplied to a concentration of 2% by volume, thereby reducing the hexavalent chromium. When the supply of hydrogen gas begins, heat is generated, so hydrogen gas is supplied until this heat generation ceases, and when the heat generation ceases, the supply of hydrogen gas is stopped and the support is cooled. By the above operation, chromium oxide supported on a support such as activated alumina is obtained.

[0035] An example of a method for subjecting the chromium oxide obtained as described above to a fluorination treatment will be described below. Chromium oxide (or a support carrying chromium oxide) is packed into a reactor. The shape of the reactor is not particularly limited, and a tubular reactor, for example, can be used. An example of a fluorination treatment using a reaction tube, which is a tubular reactor, will be described below.

[0036] The reaction tube in which the fluorination treatment is carried out is preferably made of a metal that is corrosion-resistant to a mixed gas of water generated during the fluorination treatment and hydrogen fluoride supplied to the reaction tube, such as Inconel (registered trademark), Hastelloy (registered trademark), and nickel (Ni).

[0037] The reaction tube is preferably heated by circulating a heated heat medium in an external jacket provided on the reaction tube, or by heating the heat medium being stirred in the external jacket by heating it from the outside with an electric heater, because the fluorination reaction of chromium oxide generates a large amount of heat.

[0038] The inner diameter of the reaction tube is not particularly limited, but may be 1 inch or more and 2.5 inches or less. If the inner diameter is 1 inch or more and 2.5 inches or less, a sufficient amount of chromium oxide (or a support supporting chromium oxide) can be packed inside. Furthermore, if the inner diameter is 1 inch or more and 2.5 inches or less, heat removal efficiency is good and the internal temperature can be prevented from becoming too high, so that a sufficient amount of hydrogen fluoride can be supplied to the reaction tube and the fluorination treatment can be performed in a short time. The height of the packed bed of chromium oxide (or a support supporting chromium oxide) packed inside the reaction tube is not particularly limited, but may be 5 cm or more and 3 m or less.

[0039] When the fluorination treatment is carried out, first, the temperature of a reaction tube filled with chromium oxide (or a carrier carrying chromium oxide) is increased while nitrogen gas is passed through the reaction tube. The temperature at which the fluorination treatment is carried out is not particularly limited, but it is preferable to carry out the fluorination treatment at a temperature higher than the temperature at which the reaction of ethylene with hydrogen fluoride is carried out.

[0040] If the activity of the catalyst decreases during the production of monofluoroethane, the reaction temperature between ethylene and hydrogen fluoride may increase. Therefore, the temperature inside the packed bed of chromium oxide (or a carrier carrying chromium oxide) during the fluorination treatment is preferably controlled to be 250°C or higher and 450°C or lower, more preferably 300°C or higher and 400°C or lower, and even more preferably 330°C or higher and 380°C or lower.

[0041] The lower limit of the temperature inside the packed bed of chromium oxide (or a carrier carrying chromium oxide) during the fluorination treatment may be 250°C or higher, 300°C or higher, or 330°C or higher, and the upper limit may be 450°C or lower, 400°C or lower, or 380°C or lower.

[0042] After the temperature of the reaction tube is increased, hydrogen fluoride diluted with nitrogen gas is supplied to the reaction tube. While controlling the concentration of hydrogen fluoride gas in the gas supplied to the reaction tube to 15% by volume or less, the temperature inside the packed layer of chromium oxide (or a carrier supporting chromium oxide) inside the reaction tube is measured to detect the heat generated by the reaction between hydrogen fluoride and chromium oxide. The amount of hydrogen fluoride supplied is then adjusted so that the exothermic peak temperature is preferably 400°C or less.

[0043] When the inner diameter of the reaction tube is 2 inches, the exothermic peak temperature can be kept at 400°C or less even if hydrogen fluoride gas diluted to 10% by volume with nitrogen gas is supplied at a flow rate of about 300 mL / min (hereinafter, unless otherwise specified, the gas supply rate is expressed on a standard condition basis). Keeping the exothermic peak temperature at 450°C or less is important in preventing a decrease in the specific surface area of ​​the catalyst. There is no problem if the temperature of the packed bed of chromium oxide (or a carrier carrying chromium oxide) during the fluorination treatment is 250°C or less, but the time required for the fluorination treatment will be longer, and the fluorination treatment of chromium oxide may proceed even during the reaction of ethylene with hydrogen fluoride.

[0044] The exothermic peak of the packed bed of chromium oxide (or a carrier carrying chromium oxide) moves from the inlet side to the outlet side of the reaction tube, and eventually there is no difference between the temperature of the heat medium heating the reaction tube and the temperature inside the reaction tube, and heat generation ends. Therefore, the dilution of hydrogen fluoride gas with nitrogen gas is reduced, and the concentration of hydrogen fluoride gas in the gas supplied to the reaction tube is increased.

[0045] The supply of nitrogen gas to the reaction tube is stopped, and only hydrogen fluoride gas is supplied to continue the fluorination treatment. The end of the fluorination treatment is determined by the amount of water generated at the outlet of the reaction tube. The amount of water contained in the hydrogen fluoride gas coming out of the outlet of the reaction tube is measured, and the amount of water generated per unit time (unit: mg) is divided by the volume of the catalyst obtained by the fluorination treatment (unit: L), thereby determining the amount of water generated per 1 L of the resulting catalyst volume. When the amount of water generated per 1 L of the resulting catalyst volume becomes 100 mg / hr or less, the fluorination treatment is terminated.

[0046] An example of a method for measuring the amount of water contained in hydrogen fluoride gas emerging from the outlet of the reaction tube is described below. The gas emerging from the outlet of the reaction tube is passed through a collection vessel immersed in a cryogen. An example of a cryogen is isopropyl alcohol with dry ice added. This liquefies both the hydrogen fluoride gas and water, which are then collected in the collection vessel. After measuring the mass of the material collected in the collection vessel, the collection vessel containing the material is placed in a water bath at 60°C to evaporate only the hydrogen fluoride in the material. The trace amount of aqueous hydrogen fluoride solution remaining in the collection vessel is extracted with a known amount of ethanol. The amount of water contained in the ethanol used for extraction is measured in advance. The amount of water contained in the ethanol used to extract the aqueous hydrogen fluoride solution is measured using a Karl Fischer titrator. This allows the amount of water contained in the hydrogen fluoride gas emerging from the outlet of the reaction tube to be determined.

[0047] When the completion of the fluorination treatment can be determined based on the amount of water contained in the hydrogen fluoride gas coming out of the outlet of the reaction tube, the supply of hydrogen fluoride gas to the reaction tube is stopped. Then, the reaction tube is cooled while nitrogen gas is circulated. That is, in the method for producing monofluoroethane according to this embodiment, the catalyst may be obtained by subjecting aluminum oxide supporting chromium oxide to a fluorination treatment in which hydrogen fluoride is reacted with aluminum oxide at a temperature of 250°C or higher and 450°C or lower.

[0048] Furthermore, in the method for producing monofluoroethane according to this embodiment, the catalyst may be one obtained by carrying out a fluorination treatment until the amount of water generated by the fluorination treatment is 100 mg / hr or less per 1 L of the volume of the obtained catalyst. The amount of water generated by the fluorination treatment may be 5 mg / hr or more and 100 mg / hr or less per 1 L of the volume of the obtained catalyst.

[0049] The fluorination treatment fluorinates chromium oxide to obtain a catalyst, and the fluorination rate can be measured. The method is not particularly limited, but for example, 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 are measured, and the amount of consumed hydrogen fluoride is calculated based on the difference between the amounts, and then converted into the fluorination rate. The amount of hydrogen fluoride consumed in the fluorination treatment is divided by the amount of hydrogen fluoride required to fluorinate all of the chromium oxide to chromium fluoride, thereby determining the fluorination rate of the chromium oxide (the fluorination rate of the catalyst).

[0050] The fluorination rate of the catalyst can also be determined from the difference in mass between before and after the fluorination treatment. The mass of the chromium oxide before the fluorination treatment when it is completely fluorinated can be calculated, and the fluorination rate of the catalyst can be determined by dividing the mass of the chromium compound after the fluorination treatment by this value.

[0051] Furthermore, the fluorination rate of the catalyst can also be determined by, for example, dissolving the catalyst after the fluorination treatment in an acid such as aqua regia and performing elemental analysis. The simplest method for determining the fluorination rate of the catalyst is to measure the mass before and after the fluorination treatment, and there is no problem in using the fluorination rate determined by this method as an index of catalytic activity. The composition formula of the chromium compound is CrO m F n In the formula, n is preferably 2.83 or more and 3 or less, and expressed as a fluorination rate of 94.3% or more and 100% or less.

[0052] In a supported catalyst, if the material of the support before the fluorination treatment is aluminum oxide, the support is fluorinated together with the chromium oxide by the fluorination treatment. The reaction initiation temperature of the fluorination reaction with hydrogen fluoride is lower for aluminum oxide than for chromium oxide. However, the fluorination rate of the support after the fluorination treatment, i.e., the composition formula of the aluminum compound, AlO p F q In the formula, q may be 2.83 or more and 3 or less. Therefore, if the support is made of fluorinated aluminum oxide, even if it is only the support, it functions as a catalyst for the reaction of synthesizing monofluoroethane from ethylene and hydrogen fluoride. However, if a chromium compound is not supported on the support, the catalytic activity will be low.

[0053] The BET specific surface area of ​​the catalyst (supported catalyst) after the fluorination treatment was 5 m 2 / g or more 100m 2 / g or less. If the BET specific surface area is within the above range, the activity of the catalyst is high. When activated alumina (grade NST-3) manufactured by Nikki-Universal Co., Ltd. is used as the carrier, the BET specific surface area of ​​the catalyst after fluorination treatment is 20 m 2 / g or more 70m 2 For commonly available aluminum oxide, the BET specific surface area after fluorination treatment is at most 100 m 2 / g.

[0054] [Monofluoroethane Production Method] An example of the monofluoroethane production method according to this embodiment is described below. A catalyst produced by a fluorination treatment is packed into a reaction tube. This reaction tube may be the same as that used in the fluorination treatment, or a reaction tube different from that used in the fluorination treatment may be used. Since almost no water is generated from the catalyst after the fluorination treatment, a reaction tube made of stainless steel or the like that is corrosion-resistant to hydrogen fluoride can be used. The inner diameter of the reaction tube used for monofluoroethane production is not particularly limited, but may be 1 inch or more and 5 inches or less.

[0055] The method for supplying the raw materials ethylene and hydrogen fluoride to the reaction tube is not particularly limited, but since ethylene is a gas at room temperature (its boiling point at 1 atmosphere is -103.7°C), gaseous ethylene may be supplied to the reaction tube. Also, since hydrogen fluoride is a liquefied gas (its boiling point at 1 atmosphere is 19.5°C), the hydrogen fluoride storage vessel may be heated and gaseous hydrogen fluoride gas may be supplied to the reaction tube.

[0056] When the molar ratio is the value obtained by dividing the supply amount of hydrogen fluoride (the number of moles supplied per unit time) by the supply amount of ethylene (the number of moles supplied per unit time), the molar ratio of hydrogen fluoride to ethylene may be 0.5 or more and 20 or less, 0.7 or more and 10 or less, or 1.0 or more and 5.0 or less.

[0057] If the molar ratio of hydrogen fluoride to ethylene is within the above range, unreacted ethylene and hydrogen fluoride are unlikely to be produced. If unreacted hydrogen fluoride is produced, equipment is required to recover 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 to the stoichiometric value of 1.0 as possible, and conditions that minimize the amount of unreacted ethylene and unreacted hydrogen fluoride produced are preferred.

[0058] The reaction temperature of hydrogen fluoride and ethylene may be 30° C. or higher and 300° C. or lower, 40° C. or higher and 250° C. or lower, 40° C. or higher and 200° C. or lower, 50° C. or higher and 150° C. or lower, or 50° C. or higher and 100° C. The reaction pressure of hydrogen fluoride and ethylene is not particularly limited and may be reduced or increased pressure, but is preferably atmospheric pressure or higher and 1.0 MPa (absolute pressure) or lower, more preferably atmospheric pressure or higher and 0.5 MPa (absolute pressure) or lower, even more preferably atmospheric pressure or higher and 0.2 MPa (absolute pressure) or lower, and particularly preferably atmospheric pressure.

[0059] The space velocity (hereinafter sometimes referred to as "SV") in the reaction of hydrogen fluoride and ethylene is not particularly limited, and may be 100 / hr or more and 2000 / hr or less, or 200 / hr or more and 1000 / hr or less. If the space velocity is 100 / hr or more, the amount of monofluoroethane generated per unit time increases, so there is no need to increase the size of the reaction tube. If the space velocity is 2000 / hr or less, there is no need to increase the heat removal efficiency by reducing the diameter of the reaction tube in order to remove the reaction heat from the reaction tube.

[0060] As explained above, according to the method for producing monofluoroethane of the present disclosure, monofluoroethane can be produced at a high conversion rate from ethylene and hydrogen fluoride even under mild reaction conditions. That is, according to the method for producing monofluoroethane of the present disclosure, severe reaction conditions such as high temperature and high pressure are not required for the reaction of ethylene and hydrogen fluoride, and monofluoroethane can be produced at a high conversion rate from ethylene and hydrogen fluoride even under the reaction conditions of low temperature and low pressure as described above.

[0061] The present disclosure will be explained in more detail below with reference to examples and comparative examples. Note that the pressure in the various treatments and operations described below is atmospheric pressure unless otherwise specified. [Example 1] (1) Preparation of Metal Oxide: Activated alumina (Grade NST-3) manufactured by Nikki-Universal Co., Ltd. was used as a support. This activated alumina was in the form of particles with an outer diameter of 3 mm. 100 mL (39.5 g) of the support was placed in a basket made of 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 Industry Co., Ltd. Thus, chromium chloride was supported on the support by the above immersion.

[0062] After immersion for 10 minutes, the basket was removed from the impregnation solution and allowed to drain in air for 30 minutes. The carrier was then transferred to an evaporating dish, which was then placed in a dryer in an air atmosphere and dried at 110°C for 3 hours. The dried carrier was packed into a nickel reaction tube with an inner diameter of 1 inch and calcined at 200°C while circulating air at SV500 / hr until heat generation ceased. The temperature was then raised to 400°C and calcined for an additional 3 hours. This calcination oxidized the chromium chloride to chromium oxide (CrO).

[0063] Next, while maintaining the temperature at 400°C, the gas flow was changed from air to a mixed gas of nitrogen gas and hydrogen gas, and reduction treatment was performed for 1 hour. The SV of the mixed gas of nitrogen gas and hydrogen gas was 200 / hr, and the concentration of hydrogen gas in the mixed gas was 2% by volume. The supply of hydrogen gas was stopped, the reaction tube was cooled, and the support was then removed from the reaction tube. This yielded a support supporting chromium oxide. The mass of the support was measured to be 50.0 g, which was an increase of 10.5 g compared to the support before immersion in the impregnation solution.

[0064] The chromium oxide-loaded support was dissolved in aqua regia to determine the elemental ratio of each metal, and the chromium / aluminum elemental ratio was found to be 0.178. Therefore, the chromium oxide-loaded support contains 21.0 mass % chromium oxide (CrO) and 79.0 mass % aluminum oxide (AlO).

[0065] The amount of oxygen contained in the support carrying chromium oxide was also measured. That is, the support carrying chromium oxide was powdered, and carbon powder was mixed with the powder, followed by calcination under an inert atmosphere, and the amount of carbon dioxide generated was measured to measure the amount of oxygen. As a result, it was found that the valences of chromium and aluminum contained in the support carrying chromium oxide were both trivalent.

[0066] (2) Fluorination Treatment of Metal Oxide 100 mL of the support carrying chromium oxide prepared as described above was packed into a nickel reaction tube with an inner diameter of 1 inch. A jacket containing a niter bath was installed around the outer periphery of the reaction tube, and the reaction tube was heated by heating the jacket with an electric heater. A thermocouple was installed inside the reaction tube, and the temperature of the support inside the reaction tube was measured with the thermocouple.

[0067] The temperature of the reaction tube was raised to 340°C while supplying nitrogen gas from the inlet of the reaction tube at a flow rate of 450 mL / min. Once the internal temperature of the reaction tube stabilized at 340°C, hydrogen fluoride gas was supplied from the inlet of the reaction tube at a flow rate of 50 mL / min to carry out a 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 ΔT was 20°C.

[0068] After the exothermic peak of the support inside the reaction tube disappeared, the supply of nitrogen gas was stopped, and only hydrogen fluoride gas was supplied at a flow rate of 200 mL / min, and the fluorination treatment of the metal oxide was continued for 5 hours. As a result, the chromium oxide and aluminum oxide were fluorinated to approximately the same extent. As a result, a support (catalyst) on which a chromium compound, which was at least one of chromium fluoride and chromium oxyfluoride, was supported was obtained.

[0069] An absorption bottle containing an aqueous potassium hydroxide solution was connected to the outlet of the reaction tube, and the hydrogen fluoride gas discharged from the outlet of the reaction tube was sent to the absorption bottle, where it was absorbed into the aqueous potassium hydroxide solution. As a result, the aqueous potassium hydroxide solution did not discolor during the fluorination treatment.

[0070] A 50 mL Teflon (registered trademark) collection vessel immersed in an isopropyl alcohol / dry ice bath was connected to the outlet of the reaction tube, and hydrogen fluoride gas discharged from the outlet of the reaction tube was sent to the collection vessel. The hydrogen fluoride gas discharged from the outlet of the reaction tube was continuously sent to the collection vessel for 1 hour, and the condensed hydrogen fluoride gas was collected in the collection vessel. As a result, the mass increase of the collection vessel (i.e., the mass of the collected material) was 10.4 g.

[0071] The collection vessel was immersed in a 60°C water bath for 30 minutes to vaporize the hydrogen fluoride in the collected material, and ethanol with a known water content was added to the residue and mixed. This ethanol mixture was analyzed using a Karl Fischer titrator to measure the amount of water contained in the ethanol mixture. As a result, the water concentration in 10.4 g of collected hydrogen fluoride was 615 ppm by mass.

[0072] From these results, the amount of water generated by carrying out the fluorination treatment of the metal oxide for one hour was calculated. That is, the product of the mass (mg / h) of the collected material and the water concentration (ppm by mass) in the collected hydrogen fluoride was calculated, and this product was divided by the volume (L) of the support (catalyst) on which the chromium compound was supported, thereby calculating the amount of water generated by carrying out the fluorination treatment of the metal oxide for one hour. This result is a numerical value per 1 L of the volume of the support (catalyst) on which the chromium compound was supported.

[0073] Therefore, the amount of water generated by the fluorination treatment of the metal oxide is 64 mg / hr per L of the volume of the carrier (catalyst) on which the chromium compound is supported. Because the reaction temperature during monofluoroethane production is lower than 340°C, the amount of water generated by the fluorination of the catalyst and carrier during monofluoroethane production is smaller than this value.

[0074] The supply of hydrogen fluoride gas to the reaction tube was stopped, and the reaction tube was cooled to room temperature while nitrogen gas was circulated through the reaction tube. The support was removed from the reaction tube, and its mass and specific surface area were measured. The mass of the support removed from the reaction tube was 78.9 g. Since the mass of the support supporting chromium oxide was 50.0 g, the mass of the support supporting chromium oxide when all metals contained therein were completely fluorinated was calculated using the following formula, which was 80.13 g.

[0075] Mass (g) when all metals are completely fluorinated = (mass (g) of support supporting chromium oxide) × {(molar ratio of chromium oxide in support supporting chromium oxide) × 2 × (molecular weight of chromium fluoride) / (molecular weight of chromium oxide) + (molar ratio of aluminum oxide in support supporting chromium oxide) × 2 × (molecular weight of aluminum fluoride) / (molecular weight of aluminum oxide)}

[0076] The fluorination rate of the metals contained in the carrier (fluorination rate of the catalyst) was calculated using the following formula, and the value was 95.9%. m F n The value of n and the composition formula AlO p F q The value of q in each of the above cases is 2.88. Fluorination rate of metals on the support (%) = {(mass of support after fluorination treatment) - (mass of support supporting chromium oxide)} / {(mass when all metals on the support supporting chromium oxide are completely fluorinated) - (mass of support supporting chromium oxide)} × 100

[0077] The specific surface area of ​​the obtained catalyst was measured by the BET method. 2 The measurement conditions were as follows: Measurement equipment: Belsorp max manufactured by Nikkiso Co., Ltd. Adsorbate: Nitrogen gas Measurement temperature: 77K Sample pretreatment: Heat-dried under vacuum at 300°C for 6 hours. Sample amount: 0.10 to 0.11 g

[0078] (3) Production of monofluoroethane (hydrogen fluoride addition reaction of ethylene) 100 mL of the obtained catalyst was again packed into the nickel reaction tube used in the fluorination treatment. The support was heated to 300°C while flowing nitrogen gas through the reaction tube under atmospheric pressure. The supply of nitrogen gas to the reaction tube was stopped, and a mixed gas of ethylene gas and hydrogen fluoride gas was flowed through the reaction tube to carry out the reaction at atmospheric pressure. The molar ratio of hydrogen fluoride to ethylene (HF / C2H4) was 3.0, and the space velocity of the mixed gas of ethylene gas and hydrogen fluoride gas was SV = 240 / hr.

[0079] The reaction gas discharged from the outlet of the reaction tube was passed through a gas chromatograph mass spectrometer, and the reaction gas was analyzed to identify and quantify the compounds contained in the reaction gas. The gas chromatograph mass spectrometer used was a gas chromatograph GC-2014s manufactured by Shimadzu Corporation. The column used in the gas chromatograph mass spectrometer was a CarboPak B 60 / 80 SP-1000, and the detector was a flame ionization detector (FID).

[0080] The analytical conditions for gas chromatography were as follows: the column temperature was raised to 150°C and maintained for 5 minutes, then raised at a rate of 10°C / min for 5 minutes to 200°C, and maintained at that temperature for 20 minutes. The injection temperature was 200°C, and the carrier gas was helium (He).

[0081] The ethylene, hydrogen fluoride, and monofluoroethane contained in the reaction gas were quantitatively determined by gas chromatography. Based on the results, the ethylene conversion and the monofluoroethane selectivity were calculated. The ethylene conversion is a value obtained by subtracting the molar amount of unreacted ethylene discharged from the reaction tube from the molar amount of ethylene supplied to the reaction tube, and dividing the result by the molar amount of ethylene supplied to the reaction tube.

[0082] The selectivity of monofluoroethane is a numerical 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 among the products produced by the reaction of ethylene with hydrogen fluoride. In Example 1, the conversion of ethylene was 20%, and the selectivity of monofluoroethane was 40%. The results are shown in Table 1.

[0083]

[0084] Example 2 (1) Preparation of Metal Oxide A support supporting chromium oxide was prepared in the same manner as in Example 1. (2) Fluorination Treatment of Metal Oxide The support supporting chromium oxide was fluorinated in the same manner as in Example 1 to fluorinate the metal oxide (i.e., chromium oxide and aluminum oxide), thereby obtaining a support (catalyst) supporting a chromium compound, which is at least one of chromium fluoride and chromium oxyfluoride.

[0085] (3) Production of Monofluoroethane (Addition Reaction of Ethylene with Hydrogen Fluoride) Monofluoroethane was produced in the same manner as in Example 1 except that the reaction temperature was 150°C, and the conversion of ethylene and the selectivity of monofluoroethane were calculated. In Example 2, the conversion of ethylene was 41%, and the selectivity of monofluoroethane was 99%. The results are shown in Table 1.

[0086] Example 3 (1) Preparation of Metal Oxide A carrier supporting chromium oxide was prepared in the same manner as in Example 1. (2) Fluorination Treatment of Metal Oxide The carrier supporting chromium oxide was fluorinated in the same manner as in Example 1 to fluorinate the metal oxide (i.e., chromium oxide and aluminum oxide), thereby obtaining a carrier (catalyst) supporting a chromium compound, which is at least one of chromium fluoride and chromium oxyfluoride.

[0087] (3) Production of Monofluoroethane (Addition Reaction of Ethylene with Hydrogen Fluoride) Monofluoroethane was produced in the same manner as in Example 1 except that the reaction temperature was 80°C, and the conversion of ethylene and the selectivity of monofluoroethane were calculated. In Example 3, the conversion of ethylene was 44%, and the selectivity of monofluoroethane was 99%. The results are shown in Table 1.

[0088] Example 4 (1) Preparation of Metal Oxide A carrier supporting chromium oxide was prepared in the same manner as in Example 1. (2) Fluorination Treatment of Metal Oxide The carrier supporting chromium oxide was fluorinated in the same manner as in Example 1 to fluorinate the metal oxide (i.e., chromium oxide and aluminum oxide), thereby obtaining a carrier (catalyst) supporting a chromium compound, which is at least one of chromium fluoride and chromium oxyfluoride.

[0089] (3) Production of Monofluoroethane (Addition Reaction of Ethylene with Hydrogen Fluoride) Monofluoroethane was produced in the same manner as in Example 1 except that the reaction temperature was 50°C, and the conversion of ethylene and the selectivity of monofluoroethane were calculated. In Example 4, the conversion of ethylene was 50%, and the selectivity of monofluoroethane was 96%. The results are shown in Table 1.

[0090] Comparative Example 1 100 mL of nickel wire mesh pieces were packed into the same reaction tube as used in the production of monofluoroethane in Example 1. The wire mesh pieces were prepared by cutting a 40-mesh wire mesh with a wire diameter of 0.18 mm and a mesh opening of 0.455 mm into a square shape with a side length of 1 cm. The wire mesh pieces were packed into the reaction tube so as to minimize gaps between the wire mesh pieces.

[0091] Monofluoroethane was produced using the reaction tube obtained as 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 wire mesh. The ethylene conversion and monofluoroethane selectivity were calculated in the same manner as in Example 1. In Comparative Example 1, the ethylene conversion was 0% and the monofluoroethane selectivity was 0%. The results are shown in Table 1.

[0092] [Comparative Example 2] Monofluoroethane was produced in the same manner as in Comparative Example 1, except that an empty reaction tube was used instead of filling the reaction tube with small pieces of nickel wire mesh, and the ethylene conversion and monofluoroethane selectivity were calculated. In Comparative Example 2, the ethylene conversion was 0%, and the monofluoroethane selectivity was 0%. The results are shown in Table 1.

[0093] Comparative Example 3 (1) Preparation of Metal Oxide In Comparative Example 3, the step of supporting chromium oxide on a carrier was not carried out, and the activated alumina manufactured by Nikki-Universal Co., Ltd., which was used as the carrier in Example 1, was subjected to the following fluorination treatment.

[0094] (2) Fluorination treatment was carried out in the same manner as in Example 1, except that a support not supporting chromium oxide was used instead of the support supporting fluorination-treated chromium oxide, and the temperature was changed to 300°C, and the fluorination-treated support was analyzed. The peak temperature of the support inside the reaction tube was 315°C, and ΔT was 15°C. The mass increase of the collection vessel (i.e., the mass of the collected material) was 10.4 g. The water concentration in the collected 10.4 g of hydrogen fluoride was 210 ppm by mass.

[0095] From these results, the amount of water generated by carrying out the fluorination treatment of metal oxide (i.e., aluminum oxide) for 1 hour was calculated to be 22 mg / hr per L of carrier volume in the same manner as in Example 1. Since the reaction temperature during monofluoroethane production is lower than 300°C, the amount of water generated by the fluorination of the carrier during monofluoroethane production is smaller than this numerical value.

[0096] The mass of the carrier taken out of the reaction tube after the fluorination treatment was 62.8 g. Since the mass of the carrier before the fluorination treatment was 39.5 g, the mass when all the metals contained in the carrier were completely fluorinated was 63.9 g. Therefore, the fluorination rate of the metals contained in the carrier was 98.3%. p F q The value of q in this case is 2.93. Furthermore, the specific surface area of ​​the carrier was measured by the BET method in the same manner as in Example 1, and was found to be 67.1 m 2 / g.

[0097] (3) Production of Monofluoroethane Monofluoroethane was produced using the fluorination-treated support obtained as described above. The method for producing monofluoroethane was the same as in Example 4, except that no chromium compound was supported on the support. The ethylene conversion and monofluoroethane selectivity were calculated in the same manner as in Example 1. In Comparative Example 3, the ethylene conversion was 16%, and the monofluoroethane selectivity was 50%. The results are shown in Table 1.

[0098] As can be seen from the results shown in Table 1, in Examples 1 to 4, the catalyst contained a chromium compound, and therefore the ethylene conversion was higher than in Comparative Examples 1 to 3. Furthermore, as can be seen from the results shown in Table 1, in Examples 1 to 4 the selectivity for monofluoroethane was higher than in Comparative Examples 1 to 3. Thus, in Examples 1 to 4, both the ethylene conversion and the selectivity for monofluoroethane were high, and therefore, monofluoroethane could be produced in high yield 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, the catalyst containing a chromium compound selected from the group consisting of chromium fluoride and chromium oxyfluoride.

2. The composition formula of the chromium compound is CrO m F n 2. The method for producing monofluoroethane according to claim 1, wherein m and n in the composition formula 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 carrier supporting the chromium compound.

4. The method for producing monofluoroethane according to claim 3, wherein the material of the carrier is an aluminum compound selected from the group consisting of aluminum fluoride and aluminum oxyfluoride.

5. The aluminum compound has a composition formula of AlO p F q 5. The method for producing monofluoroethane according to claim 4, wherein p and q in the composition formula 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 ratio of the molar amount of chromium to the molar amount of aluminum in the catalyst is 0.008 or more and 0.30 or less.

7. The method for producing monofluoroethane according to claim 4, wherein the catalyst is obtained by subjecting aluminum oxide supporting chromium oxide to a fluorination treatment in which hydrogen fluoride is reacted with the aluminum oxide at a temperature of 250°C or higher and 450°C or lower.

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

9. The BET specific surface area of ​​the catalyst is 5 m 2 / g or more 100m 2 The method for producing monofluoroethane according to claim 3, wherein the fluorine content is 1 / g or less.

Images