Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C17/00—Preparation of halogenated hydrocarbons
  • C07C17/23—Preparation of halogenated hydrocarbons by dehalogenation
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C17/00—Preparation of halogenated hydrocarbons
  • C07C17/25—Preparation of halogenated hydrocarbons by splitting-off hydrogen halides from halogenated hydrocarbons
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C21/00—Acyclic unsaturated compounds containing halogen atoms
  • C07C21/02—Acyclic unsaturated compounds containing halogen atoms containing carbon-to-carbon double bonds
  • C07C21/18—Acyclic unsaturated compounds containing halogen atoms containing carbon-to-carbon double bonds containing fluorine
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07B—GENERAL METHODS OF ORGANIC CHEMISTRY; APPARATUS THEREFOR
  • C07B61/00—Other general methods

Definitions

• This disclosure relates to a method for producing fluoroolefins.
• Non-Patent Document 1 describes a method for obtaining trifluoroethylene by using ⁇ -alumina, ⁇ -alumina, ⁇ -alumina or the like in the dehydrofluorination reaction of 1,1,1,2-tetrafluoroethane.
• the objective is to provide a method for producing fluoroolefins with a higher conversion rate than conventional methods.
• the present disclosure includes the following aspects. ⁇ 1>
• the method includes a step of contacting a fluorocarbon represented by the following formula (1) with an alumina-containing catalyst to produce a fluoroolefin represented by the following formula (2):
• the alumina-containing catalyst satisfies at least one of the following (I) and (II): CX 1 X 2 F-CX 3 X 4 H...(1)
• CX1X2 CX3X4 ...
• X 1 , X 2 , X 3 and X 4 each independently represent a hydrogen atom or a fluorine atom, provided that at least one of X 1 , X 2 , X 3 and X 4 is a fluorine atom.
• the total content of alkali metal elements and alkaline earth metal elements is 100 ppm by mass or less.
• the Si content is 1000 ppm by mass or less.
• ⁇ 3> The method for producing a fluoroolefin according to ⁇ 1> or ⁇ 2>, wherein the fluorocarbon is at least one selected from the group consisting of 1,1,1-trifluoroethane, 1,1,2-trifluoroethane, 1,1,2,2-tetrafluoroethane, and 1,1,1,2-tetrafluoroethane.
• the fluorocarbon is at least one selected from the group consisting of 1,1,1-trifluoroethane, 1,1,2-trifluoroethane, 1,1,2,2-tetrafluoroethane, and 1,1,1,2-tetrafluoroethane.
• ⁇ 5> The method for producing a fluoroolefin according to any one of ⁇ 1> to ⁇ 4>, wherein the fluorocarbon is 1,1,1,2-tetrafluoroethane and the fluoroolefin is trifluoroethylene.
• ⁇ 6> The method for producing a fluoroolefin according to any one of ⁇ 1> to ⁇ 5>, wherein the fluorocarbon is contacted with the alumina-containing catalyst at a temperature of 300 to 800° C.
• ⁇ 7> The fluorocarbon is contacted with the alumina-containing catalyst in the presence of an inert gas
• the fluorocarbon is contacted with the alumina-containing catalyst in the presence of water in a gas phase,
• the present disclosure provides a method for producing fluoroolefins with a higher conversion rate than conventional methods.
• a numerical range indicated using “to” means a range that includes the numerical values before and after “to” as the minimum and maximum values, respectively.
• the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in the present disclosure.
• the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples.
• combinations of two or more preferred aspects are more preferred aspects.
• the amount of each component means the total amount of the multiple substances, unless otherwise specified.
• X 1 , X 2 , X 3 and X 4 each independently represent a hydrogen atom or a fluorine atom, provided that at least one of X 1 , X 2 , X 3 and X 4 is a fluorine atom.
• the total content of alkali metal elements and alkaline earth metal elements is 100 ppm by mass or less.
• the Si content is 1000 ppm by mass or less.
• Non-Patent Document 1 when alumina was used as a catalyst, the conversion rate was sometimes low. This may be due to the difference in crystal structure between ⁇ -alumina, ⁇ -alumina, etc., but may also be due to other reasons. Therefore, the present inventors conducted compositional analysis of various alumina-containing catalysts and found that the contents of alkali metals and alkaline earth metals, and the content of Si in the alumina-containing catalyst affect the conversion rate. Further investigations led to experimentally finding that the use of an alumina-containing catalyst that satisfies at least one of the above (I) and (II) results in a high conversion rate.
• a fluorocarbon represented by formula (1) In the method for producing a fluoroolefin according to the present disclosure, a fluorocarbon represented by the following formula (1) is used as a raw material.
• X 1 , X 2 , X 3 and X 4 each independently represent a hydrogen atom or a fluorine atom, provided that at least one of X 1 , X 2 , X 3 and X 4 is a fluorine atom.
• Examples of the fluorocarbon represented by formula (1) include the following compounds.
• CHF2CH3 1,1-difluoroethane (HFC - 152a)
• CF3CH3 1,1,1-trifluoroethane (HFC - 143a)
• CHF2CH2F 1,1,2- trifluoroethane (HFC-143)
• CF3CH2F 1,1,1,2- tetrafluoroethane (HFC-134a)
• CHF2CHF2 1,1,2,2-tetrafluoroethane (HFC - 134)
• CF3CHF2 1,1,1,2,2-pentafluoroethane (HFC - 125)
• the fluorocarbon represented by formula (1) is preferably at least one selected from the group consisting of HFC-143a, HFC-143, HFC-134a, and HFC-134, from the viewpoint of minimizing side reactions and suppressing the production of by-products.
• the fluorocarbon represented by formula (1) is preferably HFC-134a, since one type of fluoroolefin can be obtained with high selectivity.
• a fluoroolefin represented by formula (2) In the method for producing a fluoroolefin according to the present disclosure, a fluoroolefin represented by the following formula (2) is obtained as a reaction product.
• CX1X2 CX3X4 ... ( 2 )
• X 1 , X 2 , X 3 and X 4 each independently represent a hydrogen atom or a fluorine atom, provided that at least one of X 1 , X 2 , X 3 and X 4 is a fluorine atom.
• fluoroolefin represented by formula (2) examples include the following compounds.
• CHF CH 2 : Fluoroethylene CF 2 ⁇ CH 2 : 1,1-difluoroethylene (HFO-1132a)
• CHF CHF: 1,2-difluoroethylene (HFO-1132(E), HFO-1132(Z))
• CHF CF2 : Trifluoroethylene (HFO-1123)
• CF2 CF2 : tetrafluoroethylene
• the fluoroolefin represented by formula (2) is preferably at least one selected from the group consisting of HFO-1132, HFO-1132a, and HFO-1123.
• the fluorocarbon is HFC-134a and the fluoroolefin is HFO-1123.
• olefins other than the fluoroolefin represented by formula (2) may be produced, and the olefins other than the fluoroolefin represented by formula (2) may include ethylene.
• a fluorocarbon represented by formula (1) is contacted with an alumina-containing catalyst.
• the alumina-containing catalyst that is contacted with the fluorocarbon satisfies at least one of the following (I) and (II).
• the total content of alkali metal elements and alkaline earth metal elements is 100 ppm by mass or less.
• the Si content is 1000 ppm by mass or less.
• 100 ppm by mass or less includes both cases where the target element is contained at 100 ppm by mass or less, and cases where the target element is not contained (i.e., 0 ppm by mass). The same applies when only the upper limit value is specified for the content of other elements.
• an alumina-containing catalyst refers to one that contains aluminum element (Al) and oxygen element (O) when subjected to elemental analysis by X-ray fluorescence analysis (XRF).
• the alumina-containing catalyst preferably contains 1.0 mass% or more of Al, may contain 5.0 mass% or more, or may contain 10 mass% or more.
• the content of each element in the catalyst is the value obtained by elemental analysis using XRF.
• XRF uses an X-ray fluorescence analyzer (for example, a scanning X-ray fluorescence analyzer, ZSX Primus II, manufactured by Rigaku Corporation) to carry out qualitative and quantitative analysis measurements. All elements present in the measurement area are measured, and the atomic weights of these elements and the atomic weight of specific metal elements are calculated. The atomic weights of all elements present in the measurement area and the atomic weight of the target element are then converted into mass. From these results, the percentage of the mass of each element relative to the mass of all elements present in the measurement area is calculated.
• X-ray fluorescence analyzer for example, a scanning X-ray fluorescence analyzer, ZSX Primus II, manufactured by Rigaku Corporation
• the elemental analysis of the alumina-containing catalyst may be performed before or after the treatment.
• the alumina contained in the alumina-containing catalyst may be of one type alone or two or more types in combination.
• Alumina is a dehydrated product of aluminum hydroxide, and its properties differ depending on the degree of dehydration and the degree of crystallinity.
• Examples of alumina contained in the alumina-containing catalyst include ⁇ -alumina, ⁇ -alumina, ⁇ -alumina, ⁇ -alumina, boehmite, and gibbsite, and it is more preferable to contain ⁇ -alumina.
• ⁇ -alumina is a high-temperature stable phase with a high degree of crystallinity, and although it has a small specific surface area, it is considered to be thermally stable and has a high thermal conductivity.
• ⁇ -alumina has a high barrier for conversion from Al-O to Al-F in the presence of hydrogen fluoride. Therefore, by using a catalyst containing ⁇ -alumina, it is possible to suppress the generation of AlF3 , and it is possible to more effectively suppress the deactivation of the catalyst and the decrease in selectivity.
• the reason why the selectivity is improved in ⁇ -alumina compared to ⁇ -alumina is not clear, but it is thought that this is due to the fact that the crystal structure of ⁇ -alumina changes significantly in a high-temperature environment, which changes the bond distance between alkali metal elements, alkaline earth metal elements, and Si and Al in the alumina-containing catalyst.
• ⁇ -alumina has a higher catalyst durability than ⁇ -alumina, when a large amount of raw material is supplied to the catalyst, a decrease in conversion rate during long-term production is effectively suppressed. Therefore, by using a catalyst containing ⁇ -alumina, it is possible to increase the amount of raw material supplied to the catalyst, which is advantageous in industrial production.
• ⁇ -alumina in an alumina-containing catalyst can be confirmed by the diffraction pattern obtained by X-ray diffraction, in other words, XRD (X-Ray Diffractometer).
• XRD X-Ray Diffractometer
• the alumina-containing catalyst may also contain aluminum oxide fluoride, aluminum fluoride, etc., in which alumina is fluorinated.
• the alumina-containing catalyst may contain compounds other than alumina.
• compounds other than alumina include oxides other than alumina, such as chromium oxide, copper oxide, iron oxide, nickel oxide, magnesium oxide, zinc oxide, and zirconium oxide.
• ⁇ -alumina is the main component in the alumina-containing catalyst.
• the content of the ⁇ -alumina crystal structure may be 65% by mass or more, 70% by mass or more, 75% by mass or more, 80% by mass or more, 85% by mass or more, or 100% by mass.
• the content of the ⁇ -alumina crystal structure in the alumina-containing catalyst can be confirmed by performing Rietveld analysis from the XRD crystal structure. Specifically, the peaks obtained by XRD measurement of the catalyst are compared with known peak models derived from each alumina structure, and the mass proportion of each crystal structure is calculated by performing Rietveld analysis.
• the total content of alkali metal elements and alkaline earth metal elements in the alumina-containing catalyst is 100 ppm by mass or less, preferably 80 ppm by mass or less, more preferably 50 ppm by mass or less, and may be 0 ppm by mass (i.e., not contained).
• the Si content in the alumina-containing catalyst is 1000 ppm by mass or less
• the total content of alkali metal elements and alkaline earth metal elements in the alumina-containing catalyst may exceed 100 ppm by mass, but is preferably 100 ppm by mass or less.
• the content of alkali metal elements in the alumina-containing catalyst is 100 ppm by mass or less, preferably 40 ppm by mass or less, more preferably 25 ppm by mass or less, and may be 0 ppm by mass (i.e., not contained).
• the content of Si in the alumina-containing catalyst is 1000 ppm by mass or less
• the content of alkali metal elements in the alumina-containing catalyst may be more than 100 ppm by mass, but is preferably 100 ppm by mass or less.
• Na and K are elements that are likely to be contained in alumina-containing catalysts.
• the total content of Na and K in the alumina-containing catalyst is 100 ppm by mass or less, preferably 40 ppm by mass or less, more preferably 25 ppm by mass or less, and may be 0 ppm by mass (i.e., not contained).
• the content of alkaline earth metal elements in the alumina-containing catalyst is 100 ppm by mass or less, preferably 40 ppm by mass or less, more preferably 25 ppm by mass or less, and may be 0 ppm by mass (i.e., not contained).
• the content of Si in the alumina-containing catalyst is 1000 ppm by mass or less
• the content of alkaline earth metal elements in the alumina-containing catalyst may be more than 100 ppm by mass, but is preferably 100 ppm by mass or less.
• Mg and Ca are elements that are likely to be contained in alumina-containing catalysts.
• the total content of Mg and Ca in the alumina-containing catalyst is 100 ppm by mass or less, preferably 40 ppm by mass or less, more preferably 25 ppm by mass or less, and may be 0 ppm by mass (i.e., not contained).
• the Si content in the alumina-containing catalyst is 1000 ppm by mass or less, preferably 800 ppm by mass or less, more preferably 600 ppm by mass or less, and may be 0 ppm by mass (i.e., not contained).
• the Si content in the alumina-containing catalyst may be more than 1000 ppm by mass, but is preferably 1000 ppm by mass or less.
• the alumina-containing catalyst may contain other elements such as C, Fe, Zn, Ga, etc., in addition to Al and O.
• the content of other elements in the alumina-containing catalyst may be within a range that does not impair the effects of the present disclosure.
• the Fe content may be 0.02 mass% or less, or may not contain Fe.
• the Fe content in the alumina-containing catalyst may be more than 0.02 mass%.
• the alumina-containing catalyst may further contain other elements other than those mentioned above.
• the other elements include Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, La, and Ce.
• the origin of these elements is not limited, and they may be derived from the raw materials or the production equipment.
• the content of other elements in the alumina-containing catalyst may be within a range that does not impair the effects of the present disclosure.
• Alumina may function not only as a catalyst, but also as a support while functioning as a catalyst. Alumina may also be supported on a support other than alumina.
• Examples of carriers other than alumina include carbon, zirconia, silica, and titania.
• the form of the alumina-containing catalyst is not particularly limited, and it may be in the form of a powder, pellets, or spheres.
• ⁇ -alumina is preferably in the form of a molded body such as a sphere or pellet from the viewpoint of handling when used for about 10 hours.
• a molded body is different from a powder and can be obtained, for example, by putting a powder into a mold and compressing it.
• the form of the alumina-containing catalyst is not particularly limited, and may be in the form of a powder, pellets, or spheres. From the viewpoints of packing properties when packed into a reactor, flowability of the reaction gas, and ease of handling when used for about 10 hours, the ⁇ -alumina is preferably in the form of a molded body such as a sphere or pellet. A molded body is different from a powder and can be obtained, for example, by putting a powder into a mold and compressing it.
• the raw material gas may contain a fluorocarbon represented by formula (1), and may contain components other than the fluorocarbon represented by formula (1).
• the raw material gas may consist of only the fluorocarbon represented by formula (1), or may contain isomers, disproportionation products, impurities, etc. obtained during the production of the fluorocarbon represented by formula (1).
• the raw material gas preferably contains an inert gas such as nitrogen, argon, helium, carbon dioxide, and octafluorocyclobutane in addition to the fluorocarbon represented by formula (1).
• the inert gas can dilute the target product and the by-product hydrogen fluoride.
• the content of the fluorocarbon represented by formula (1) is preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 75 mol% or more, and particularly preferably 80 mol% or more, based on the total amount of the raw material gas.
• the method for producing fluoroolefins disclosed herein may be carried out in either the gas phase or the liquid phase. Since the fluorocarbon represented by formula (1) is a gas at room temperature, it is preferable to contact the fluorocarbon with the alumina-containing catalyst in the gas phase.
• the reactor in which the fluorocarbon is brought into contact with the alumina-containing catalyst may be one that can withstand the temperature and pressure described below, and there are no particular limitations on its shape or structure.
• An example of the reactor is a cylindrical vertical reactor. Examples of materials for the reactor include glass, stainless steel, iron, nickel, and alloys mainly composed of iron or nickel.
• the reactor may be equipped with a heating means such as an electric heater for heating the inside of the reactor.
• the alumina-containing catalyst may be housed in any of the following formats: fixed bed, fluidized bed, or moving bed. If it is a fixed bed type, it may be either a horizontal fixed bed type or a vertical fixed bed type.
• the reaction system may be either a flow system or a batch system.
• a method in which an alumina-containing catalyst is filled in the same way as in a fixed bed reactor, moved by gravity, and extracted from the bottom of the reactor for regeneration is called a moving bed.
• the catalyst layer is operated so that it exhibits fluid-like properties due to the reaction fluid, so the catalyst particles are suspended in the reaction fluid and move inside the reactor.
• Fixed bed reactors are preferred because there are a wide range of options for the shape of the alumina-containing catalyst and wear of the alumina-containing catalyst can be suppressed.
• Fixed bed reactors include tubular reactors and tank reactors, and tubular reactors are preferred because of the ease of controlling the reaction temperature.
• a multi-tube heat exchange reaction in which a large number of reaction tubes with small diameters are arranged in parallel and a heat medium is circulated on the outside can be used.
• multiple catalyst layers are installed. There is at least one catalyst layer, but there may be two or more.
• the fluoroolefin production method of the present disclosure is preferably carried out in a flow-through manner using a fixed-bed reactor (particularly a vertical fixed-bed type reactor).
• the amount of fluorocarbon supplied to the alumina-containing catalyst is preferably 0.1 g/hr/g or more, more preferably 0.2 g/hr/g or more, and even more preferably 0.3 g/hr/g or more. Also, from the viewpoint of maintaining a constant or higher conversion rate, the raw material supply amount is preferably 5.0 g/hr/g or less, more preferably 4.5 g/hr/g or less, and even more preferably 4.0 g/hr/g or less.
• the raw material supply amount is the amount of fluorocarbon (raw material) supplied per 1 g of alumina-containing catalyst per unit time (g/hr), and it is preferable that the amount of fluorocarbon that comes into contact with the catalyst by being supplied thereto is within the above-mentioned range.
• the fluorocarbon and the alumina-containing catalyst are preferably contacted at a temperature of 300 to 800°C, more preferably at a temperature of 400 to 700°C, and even more preferably at a temperature of 400 to 600°C. If the contact temperature is 300°C or higher, the conversion rate of the fluoroolefin is improved. On the other hand, if the contact temperature is 800°C or lower, decomposition of the fluoroolefin can be suppressed.
• the contact temperature is 300°C or higher, the reaction will proceed properly. On the other hand, if the contact temperature is 800°C or lower, the selectivity will decrease due to the cleavage of the carbon-carbon bonds in the raw material, and the disproportionation reaction of the product (unsaturated compound) will be suppressed.
• the dehydrofluorination reaction is generally an endothermic reaction
• the decrease in the conversion rate can be suppressed by appropriately maintaining the reaction temperature.
• the reaction temperature in the catalyst layer increases, the conversion rate of the raw material increases. Therefore, it is preferable to maintain the reaction temperature in the catalyst layer at a desired temperature so that a high conversion rate can be maintained.
• a method of heating the catalyst layer from the outside with a heat medium or the like can be mentioned. Catalysts usually deteriorate over time as the reaction progresses.
• the decrease in the conversion rate can be suppressed by heating the catalyst layer with a heat medium or the like and appropriately maintaining or increasing the reaction temperature.
• the reaction zone begins at the introduction point for the raw material gas.
• the catalyst at the introduction point for the raw material gas deteriorates over time as the reaction progresses, the reaction zone moves downstream in the direction of gas flow. Since the low-temperature product gas generated in the reaction zone flows into the vicinity of the downstream side of the reaction zone, the vicinity of the downstream side is usually the coldest in the catalyst layer.
• the temperature of this region of the catalyst layer that is at the coldest temperature is referred to as the "minimum temperature of the catalyst layer.”
• the temperature from the vicinity of the downstream side further downstream usually increases from the minimum temperature of the catalyst layer as it moves away from the reaction zone.
• the raw material gas containing fluorocarbons may be supplied to the reactor at room temperature. However, it is preferable to properly heat (preheat) the raw material gas before supplying it to the reactor. When preheating is performed, it is preferable to heat the raw material gas to a temperature of 80 to 600°C before supplying it to the reactor. Preheating to 80°C or higher makes it difficult for the internal temperature of the reactor to decrease, making it easier to achieve the set conversion rate. Preheating to 600°C or lower also makes it difficult for the internal temperature of the reactor to increase, suppressing undesirable reactions and improving the selectivity.
• the dehydrofluorination reaction in the present disclosure is a reaction in which the number of molecules increases, so increasing the pressure makes the forward reaction unfavorable.
• the pressure when the fluorocarbon is contacted with the alumina-containing catalyst is not particularly limited, but from the viewpoint of improving the conversion rate, it is preferably from ⁇ 0.05 to 2 MPa, more preferably from ⁇ 0.01 to 1 MPa, and even more preferably from normal pressure to 0.5 MPa. In this disclosure, pressure means gauge pressure.
• the contact time (seconds) between the fluorocarbon and the alumina-containing catalyst is preferably 0.5 to 100.0 seconds, more preferably 1.0 to 50.0 seconds, and even more preferably 2.0 to 20.0 seconds.
• the contact time (g ⁇ sec/mL) between the fluorocarbon and the alumina-containing catalyst is preferably 1 to 200 g ⁇ sec/mL, more preferably 5 to 175 g ⁇ sec/mL, even more preferably 7 to 150 g ⁇ sec/mL, and particularly preferably 10 to 125 g ⁇ sec/mL. If the contact time (g ⁇ sec/mL) is 1 g ⁇ sec/mL or more, the conversion rate is improved. If the contact time (g ⁇ sec/mL) is 200 g ⁇ sec/mL or less, equipment costs can be reduced.
• the inert gas is preferably at least one selected from the group consisting of nitrogen, helium, argon, octafluorocyclobutane, and carbon dioxide. Of these, the inert gas is preferably nitrogen.
• the molar ratio of fluorocarbon to inert gas in the gas phase is preferably 0.1 to 30, more preferably 0.5 to 25.
• the fluorocarbon is contacted with the alumina-containing catalyst in the gas phase in the presence of water, and the concentration of water is less than 500 ppm by mass based on the total amount of the raw material gas containing the fluorocarbon.
• water is adsorbed on the Lewis acid sites on the surface of the alumina-containing catalyst.
• the above water concentration is preferably 300 mass ppm or less, more preferably 100 mass ppm or less, even more preferably 50 mass ppm or less, and particularly preferably 10 mass ppm or less, from the viewpoint of further improving the conversion rate and obtaining the target compound with a higher selectivity.
• the alumina-containing catalyst becomes alkaline, which changes the structure of the acid sites that exhibit the activity of dehydrofluorination, and it is preferable to suppress a decrease in the catalytic activity.
• a common method for measuring water concentration is to use a commercially available Karl Fischer water content meter.
• the above water concentration is the water content contained in the raw material gas when the fluorocarbon is brought into contact with the alumina-containing catalyst.
• the water concentration may be replaced with the water content contained in the raw material gas before it is flowed into the reactor.
• a step of drying the alumina-containing catalyst water contained in the alumina-containing catalyst is removed, increasing the reactivity of the alumina-containing catalyst with respect to the fluorocarbon and improving the conversion rate.
• the method for drying the alumina-containing catalyst is not particularly limited, and the alumina-containing catalyst may be dried before being loaded into the reactor, or may be dried after being loaded into the reactor.
• the alumina-containing catalyst is loaded into the reactor and then dried, this is preferable because the reactor can be preheated while drying the alumina-containing catalyst.
• it is preferable to dry the alumina-containing catalyst by loading the reactor with the alumina-containing catalyst and heating the reactor while passing an inert gas through it.
• hydrogen fluoride is produced as a by-product.
• Hydrogen fluoride has the function of fluorinating the oxide contained in the alumina-containing catalyst to strengthen the acidity. Therefore, it is preferable to reduce the concentration of hydrogen fluoride.
• concentration of hydrogen fluoride By reducing the concentration of hydrogen fluoride, the selectivity is maintained, the deactivation of the alumina-containing catalyst is suppressed, and the decrease in reaction activity due to the decrease in the specific surface area of the alumina-containing catalyst is suppressed.
• One method for reducing the concentration of hydrogen fluoride is to dilute it with an inert gas.
• the hydrogen fluoride concentration during the reaction is preferably 15 mol% or less. From the viewpoint of extending the catalyst life, the hydrogen fluoride concentration is more preferably 13 mol% or less, even more preferably 10 mol% or less, particularly preferably 8 mol% or less, and most preferably 7 mol% or less.
• the hydrogen fluoride concentration is preferably 0.5 mol% or more, more preferably 0.8 mol% or more, even more preferably 1.0 mol% or more, particularly preferably 1.3 mol% or more, and most preferably 1.5 mol% or more.
• the fluoroolefin production method of the present disclosure is preferably carried out in the presence of an oxidizing agent.
• the oxidizing agent is preferably oxygen, chlorine, bromine or iodine, since it has a high conversion rate and can obtain the target compound with high selectivity. Among them, oxygen is more preferable as the oxidizing agent.
• the concentration of the oxidizing agent is preferably 0.01 to 21 mol% relative to the raw material gas.
• the concentration of the oxidizing agent is more preferably 1 to 20 mol% relative to the raw material compound, even more preferably 5 to 18 mol%, and particularly preferably 7.5 to 16 mol%, since it can further improve the conversion rate and obtain the target compound with higher selectivity.
• the conversion rate means the ratio (mol %) of the total molar amount of compounds other than the raw material compounds contained in the effluent gas from the reactor outlet to the molar amount of the raw material compounds supplied to the reactor. In general, a higher conversion rate is preferable from the viewpoint of productivity. However, in the dehydrofluorination reaction in the present disclosure, it is preferable to appropriately control the conversion rate. When the conversion rate is controlled, the concentration of hydrogen fluoride produced in the gas phase is reduced, and it is considered that deactivation of the alumina-containing catalyst by hydrogen fluoride is suppressed.
• the use of an inert gas increases the energy load of the purification process after the reaction, so that the use of an excessive inert gas is not preferable. From the viewpoint of extending the catalyst life, it is preferable to suppress the hydrogen fluoride concentration during the reaction to 15 mol% or less.
• the conversion rate does not become too high and deactivation of the alumina-containing catalyst is suppressed.
• the conversion rate 10 hours after contacting the fluorocarbon with the catalyst is preferably 5.0 to 15.0%, more preferably 7.0 to 13.0%, and even more preferably 5.0 to 12.5%.
• the selectivity means the ratio (mol %) of the molar amount of the target product contained in the reactor outlet gas to the total molar amount of compounds other than the raw material compounds contained in the reactor outlet gas.
• a selectivity of 100% is preferred since it eliminates the need for post-reaction purification steps, but side reactions may occur in the reaction temperature range required to achieve the desired conversion.
• a high selectivity is preferred because it reduces the amount of waste, reduces the energy load of post-reaction purification steps, and extends the catalyst life.
• the selectivity 10 hours after contacting the fluorocarbon with the alumina-containing catalyst is preferably 90% or more, more preferably 93% or more, and even more preferably 95% or more.
• HFO-1123 is obtained with high selectivity by using HFC-134a as the fluorocarbon.
• Other compounds contained in the reactor outlet gas other than the raw material compounds and the target product include, for example, hydrogen fluoride, carbon monoxide, carbon dioxide, water, etc.
• HFC-134a is used as the raw material compound fluorocarbon
• other compounds further include HFC-134, 1,1-difluoroethylene (VdF), E/Z-1,2-difluoroethylene (HFO-1132(E)/(Z)), etc.
• Examples 1 to 9 are working examples, and Examples 10 to 13 are comparative examples.
• Example 1 1 mL of ⁇ -alumina (product name "N612N", manufactured by JGC Catalysts and Chemicals) was weighed out and used as a catalyst.
• a stainless steel (SUS304) reaction tube having an inner diameter of 10 mm and a length of 30 cm was filled with the catalyst and placed in a tubular electric furnace. The catalyst-filled portion was heated to 475° C. in the tubular furnace while flowing nitrogen, to dehydrate the catalyst. Thereafter, a 0.1/1 (mol/mol) mixed gas of nitrogen/HFC-134a was passed through for a contact time of 4.7 seconds, to carry out a dehydrofluorination reaction to produce HFO-1123. The water concentration in the 0.1/1 (mole/mole) mixed gas of nitrogen/HFC-134a was measured with a Karl Fischer water content analyzer and found to be 5 ppm.
• Example 2 to 13 In Examples 2 to 13, the HF deprotection reaction was carried out in the same manner as in Example 1, except that the catalyst was changed and the various conditions were changed to the values shown in Table 2. The catalysts used in Examples 2 to 13 will be described below.
• Example 2 ⁇ -alumina (product name "N612N", manufactured by JGC Catalysts and Chemicals) was pulverized in a mortar to obtain a powder. The obtained powder was calcined at 1300°C for 6 hours in an air atmosphere, and then analyzed by X-ray diffraction, which revealed that ⁇ -alumina was the main component. This powder was used as a catalyst.
• Example 3 ⁇ -alumina (product name "SA52124", manufactured by Saint-Gobain) was used as a catalyst.
• Example 4 ⁇ -alumina (product name "SA52238", manufactured by Saint-Gobain) was used as a catalyst.
• Example 5 ⁇ -Alumina (product name "FGL-30", manufactured by Iwatani Chemical Industries, Ltd.) was used as a catalyst.
• Example 6 ⁇ -alumina (product name "FGL-40", manufactured by Iwatani Chemical Industries, Ltd.) was used as a catalyst.
• Example 7 ⁇ -alumina (product name "C500", manufactured by Nippon Light Metals Co., Ltd.) was used as a catalyst.
• Example 8 ⁇ -alumina (product name "LT303D", manufactured by Nippon Light Metal Co., Ltd.) was used as a catalyst.
• Example 9 ⁇ -alumina (product name "AKQ-10", manufactured by Sumitomo Chemical Co., Ltd.) was used as a catalyst.
• Example 10 ⁇ -alumina (product name "SA51161", manufactured by Saint-Gobain) was used as a catalyst.
• Example 11 ⁇ -alumina (product name "SA5561", manufactured by Saint-Gobain) was used as a catalyst.
• Example 12 ⁇ -alumina (product name "SA5218", manufactured by Saint-Gobain) was used as a catalyst.
• Example 13 ⁇ -alumina (product name "SA5252", manufactured by Saint-Gobain) was used as the catalyst.
• Elemental analysis of each catalyst was performed using a Rigaku Corporation ZSX Primus II (scanning X-ray fluorescence analyzer) under conditions of X-ray output of 50 kV, 72 mA, measurement area of 20 mm ⁇ , and measurement time of 30 minutes.
• the results of elemental analysis of the catalysts used in Examples 1 to 13 are shown in Table 1. The values in the table are mass %, and blank spaces indicate that the corresponding element was below the detection limit.
• the product gas (hereinafter also referred to as "reactor outlet gas”) extracted from the reactor outlet 10 hours after the start of the reaction was analyzed by gas chromatography. Specifically, a column (product name "DB-1301”, Agilent, length 60 m, inner diameter 0.25 mm, film thickness 1 ⁇ m) was attached to a gas chromatograph (product name "GC6850”, Agilent) and analyzed. The conversion rate of HFC-134a and the selectivity of HFO-1123 were calculated using the molar amount calculated from the area ratio (GCArea%) of the reactor outlet gas.
• Examples 1 to 9 include a step of producing a fluoroolefin represented by formula (2) by contacting a fluorocarbon represented by formula (1) with a catalyst, and the alumina-containing catalyst satisfies at least one of the following: (I) the total content of alkali metal elements and alkaline earth metal elements is 100 ppm by mass or less; and (II) the Si content is 1000 ppm by mass or less. Therefore, it was found that the conversion rate was higher than that of the conventional method. On the other hand, in Examples 10 to 13 which did not satisfy either (I) or (II), the conversion rate was significantly lower than that in Examples 1 to 9. In addition, in Examples 10 to 13, the selectivity was also significantly lower than that in Examples 1 to 9.

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