Method and system for preparing trifluoroiodomethane and composition thereof

Abstract

In distilling trifluoroiodomethane, it is brought into contact with an alkaline medium as a pretreatment to remove hydrogen fluoride gas and carbon dioxide gas contained therein to reduce the load on a distillation process.SOLUTION: A process for producing trifluoroiodomethane, comprising the steps of: 1) reacting trifluoromethane with iodine in the presence of a solid catalyst and oxygen to obtain a reaction gas containing trifluoroiodomethane; 2) bringing the reaction gas obtained in the step 1) into contact with an alkaline medium; A step of obtaining a reaction gas by distilling the reaction gas obtained in the step of reacting and removing hydrogen fluoride and carbon dioxide that may be contained in the reaction gas with the alkaline medium and separating trifluoroiodomethane, trifluoromethane, and other components in the reaction gas.SELECTED DRAWING: None

Description

[Technical Field]

[0001] Trifluoroiodomethane is a valuable gas used in many industries, including as an etching gas, fire extinguisher, magnesium flame retardant, etc. Trifluoroiodomethane is produced from trifluoromethane and iodine in the presence of a catalyst, and after being purified by pressure distillation to remove impurities, it is filled into high-pressure cylinders and used in many industries. The present invention relates to a method and system for producing high-purity trifluoroiodomethane, which is used in many industries, and to compositions containing trifluoroiodomethane. [Background technology]

[0002] Trifluoroiodomethane is synthesized using trifluoromethane or trifluoroacetic acid as raw materials (Patent Document 1). However, after the reaction, impurities such as hydrogen fluoride and carbon dioxide are mixed in as by-products. In particular, when trifluoroacetic acid is used as the raw material, the purity of the product is extremely low because carbon dioxide gas (carbon dioxide) is produced as a by-product during decarboxylation in an amount equivalent to the product.

[0003] When synthesizing trifluoroiodomethane from trifluoromethane as a raw material, if the conversion rate from trifluoromethane to trifluoroiodomethane is low, a large amount of unreacted trifluoromethane remains in the reaction product after the reaction in addition to impurities such as hydrogen fluoride and carbon dioxide. Here, when producing the target product, trifluoroiodomethane, it is necessary to separate unreacted trifluoromethane together with the above-mentioned impurities from trifluoroiodomethane. In addition, the above-mentioned unreacted trifluoromethane needs to be recovered. This is because if the recovery of trifluoromethane is insufficient, the raw material consumption rate will deteriorate when the efficient conversion from the raw material trifluoromethane to the target product trifluoroiodomethane is insufficient, which will significantly affect the economic viability of the product.

[0004] Trifluoromethane is recovered by distillation, particularly pressurized distillation, in which the low boiling point component is extracted from the top of a distillation column and recovered in a raw material tank. However, if separation in the pressurized distillation column is insufficient, carbon monoxide and tetrafluoromethane present as light components may be mixed into the raw material tank, causing a decrease in the conversion rate of the reaction and a decrease in the product yield. Furthermore, trifluoromethane has an extremely high global warming potential of 14,800, and its release into the environment, including its inclusion in products, must be prevented as much as possible.

[0005] Therefore, there is a demand for a process for obtaining practically high-purity trifluoroiodomethane by further removing by-products or impurities that have not been completely removed in the production of trifluoroiodomethane.

[0006] Patent Document 2 lists organic impurities, acid impurities, and water as impurities that may be contained in the target product in some known processes for producing CF3I and compositions containing CF3I, and discloses that in order to remove these impurities, the reaction materials in the production process are reacted with 0.5% to 5% by weight of an alkali metal carbonate or 0.01% to 5% by weight of an alkali metal hydroxide. Patent Document 2 lists as organic impurities fluorinated and iodinated hydrocarbons such as pentafluoroethane (HFC-125), hexafluoropropene (HFO-1216), 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea), 1,1,3,3,3-pentafluoropropene (HFO-1225zc), 1,1,1,3,3,3-hexafluoropropane (HFC-236fa), and methyl iodide (CHI), as well as carbon dioxide (CO). Acid impurities include hydrogen fluoride (HF), hydrogen chloride (HCl), hydrogen iodide (HI), and trifluoroacetic acid (TFA). Patent Document 2 states that in order to improve defects such as corrosion caused by these impurities, the acid impurities must be kept to 1 ppm or less and the water content to 10 ppm or less, and that to produce high-purity CF3I, a purification process is required to sufficiently remove organic impurities (particularly CH3I), acid impurities, and water. As described above, it discloses that the reaction materials for the production process are reacted with 0.5% to 5% by weight of alkali metal carbonate or 0.01% to 5% by weight of alkali metal hydroxide.

[0007] However, even though trifluoroiodomethane is synthesized using trifluoromethane or trifluoroacetic acid as a raw material in the production process, the by-products and impurities generated in these processes can vary depending on various factors such as the reaction conditions and the purity of the raw materials. For example, when trifluoromethane is used as the raw material, there are the raw materials trifluoromethane (CF3H), iodine (I2), and by-products generated by the reaction between these. When trifluoroacetic acid is used as the raw material, there are the raw materials trifluoroacetic acid, iodine (I2), and by-products generated by the reaction between these. In particular, when using the raw material trifluoroacetic acid, carboxyl groups or carbon dioxide derived from acetic acid remain or are generated, which imposes a heavy burden on the removal of these. Thus, depending on the raw materials and by-products, it is desirable to optimize the impurity removal process. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 4547133 [Patent Document 2] Patent No. 7451527 Summary of the Invention [Problem to be solved by the invention]

[0009] In view of the above-mentioned background art, an object of the present invention is to provide a method and system for producing high-purity trifluoroiodomethane, which comprises contacting trifluoroiodomethane with an alkaline medium to remove impurities such as hydrogen fluoride and carbon dioxide contained therein, and then separating low-boiling-point impurities by a distillation operation such as pressurized distillation in a distillation step, as well as a composition containing trifluoroiodomethane. [Means for solving the problem]

[0010] As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that, in producing high-purity trifluoroiodomethane, high-purity trifluoroiodomethane can be produced efficiently by bringing trifluoroiodomethane into contact with an alkaline medium to remove contained impurities such as hydrogen fluoride (HF) and carbon dioxide (CO), and then separating low-boiling-point impurities in a distillation step by a distillation operation such as pressurized distillation; and further, that production efficiency can be improved by recovering trifluoromethane (CFH), a raw material for producing trifluoroiodomethane (CFI), and reusing this in the production of trifluoroiodomethane (CFI), which led to the completion of the present invention.

[0011] That is, the present invention relates to the following inventions. [1] A method for producing trifluoroiodomethane, characterized by being carried out by a process including the following steps 1), 2) and 3): 1) A step of reacting trifluoromethane with iodine in the presence of a solid catalyst and oxygen to obtain a reaction gas containing trifluoroiodomethane. 2) A step of contacting the reaction gas obtained in step 1) with an alkaline medium to react hydrogen fluoride and carbon dioxide that may be contained in the reaction gas with the alkaline medium to obtain a removed reaction gas. 3) Distilling the reaction gas obtained in step 2), Trifluoroiodomethane and Trifluoromethane and Other components in the reaction gas Separating the [2] The content ratios of the main impurities in the reaction gas obtained in step 2) in item [1], namely, (a) carbon dioxide (CO2), (b) hydrogen fluoride (HF), (c) tetrafluoromethane (CF4), and (d) carbon monoxide (CO) and (e) trifluoromethane (CF3H), based on peak areas determined by gas chromatography and / or ion chromatography, are (a) ≦0.001%, (b) ≦0.001%, (c) ≦10.0%, (d) ≦2.0%, and (e) ≦70.0%, respectively (provided that the sum of the peak areas of trifluoroiodomethane (CF3I) and (a) to (e) is 100%), Item [1] A method for producing trifluoroiodomethane. [3] The content ratios of the main impurities in the trifluoroiodomethane separated in step 3) in item [1], namely, (a) carbon dioxide (CO2), (b) hydrogen fluoride (HF), (c) tetrafluoromethane (CF4), and (d) carbon monoxide (CO) and (e) trifluoromethane (CF3H), determined by gas chromatography and / or ion chromatography, based on peak areas, are (a) ≦0.0005%, (b) ≦0.0005%, (c) ≦0.2%, (d) ≦0.2%, and (e) ≦0.1%, respectively, and trifluoroiodomethane (CF3I) is 99.5% or more (provided that the sum of the peak areas of trifluoroiodomethane (CF3I) and (a) to (e) is 100%). Item [1] A method for producing trifluoroiodomethane. [4] The content ratios of the main impurities in the trifluoromethane separated in step 3) in item [1], namely, (a) carbon dioxide (CO2), (b) hydrogen fluoride (HF), (c) tetrafluoromethane (CF4), and (d) carbon monoxide (CO) and (e) trifluoromethane (CF3H), based on peak areas determined by gas chromatography and / or ion chromatography, are (a) ≦0.0.0005%, (b) ≦0.0005%, (c) ≦8.0%, (d) ≦1.0%, and (e) ≧80.0%, respectively (however, the sum of the peak areas of (a) to (e) is 100%, excluding trifluoroiodomethane (CF3I)), Item [1] A method for producing trifluoroiodomethane. [5] A method for producing trifluoroiodomethane, wherein the trifluoroiodomethane separated in step 3) of item [1] is stored. [6] The method for producing trifluoroiodomethane according to item [1], wherein the trifluoromethane separated in step 3) is stored. [7] The method for producing trifluoroiodomethane according to item [1], wherein the trifluoromethane separated in step 3) of item [1] is recycled to step 1) of item [1]. [8] The method for producing trifluoroiodomethane according to item [1], wherein the stored trifluoromethane in item [3] is supplied to step 1) in item [1]. [9] A trifluoroiodomethane composition, characterized in that the content ratios of the major impurities in trifluoroiodomethane, namely (a) carbon dioxide (CO2), (b) hydrogen fluoride (HF), (c) tetrafluoromethane (CF4), and (d) carbon monoxide (CO) and (e) trifluoromethane (CF3H), based on peak areas determined by gas chromatography and / or ion chromatography, are (a) ≦0.0005%, (b) ≦0.0005%, (c) ≦0.2%, (d) ≦0.2%, and (e) ≦0.1%, respectively, and that trifluoroiodomethane (CF3I) is 99.5% or more (provided that the sum of the peak areas of trifluoroiodomethane (CF3I) and (a) to (e) is 100%).

[10] Alkaline medium contact unit: Inlet for receiving alkaline media a gas inlet for receiving a reactant gas Means for contacting the alkaline medium with the reaction gas Outlet for discharging reaction gas after treatment Piping for supplying the treated reaction gas to the distillation unit Distillation unit: A gas inlet for receiving the reaction gas after processing Means for distilling the reaction gas after treatment Storage tank for CF3I separated by distillation Storage tank for CF3H separated by distillation An outlet for discharging the distilled and separated CF3I Outlet for discharging the distilled and separated CF3H Piping for supplying the distilled and separated CF3H to the CF3H storage unit CF3H storage unit: Inlet for receiving distilled and separated CF3H Means for agitating the gas in the storage unit Outlet for discharging raw material CF3H Piping for supplying raw material CF3H to the mixing unit Mixed gas generator unit: Inlet for receiving raw material CF3H Inlet for receiving raw I2 solution A means for generating a mixed gas of CF3H and I2 by introducing the raw material CF3H into the raw material I2 solution. Outlet for discharging the generated mixed gas Piping for supplying mixed gas to the reaction unit Reaction Unit: Inlet for receiving mixed gases A method for generating CF3I by introducing a mixed gas into a packed solid catalyst An outlet for discharging the reaction gas containing the produced CF3I Piping for supplying reaction gas containing CF3I to the alkaline medium contact unit A trifluoroiodomethane production system comprising: [Effects of the Invention]

[0012] The present invention provides a method and system for producing high-purity trifluoroiodomethane, which comprises contacting trifluoroiodomethane with an alkaline medium to remove impurities such as hydrogen fluoride gas and carbon dioxide gas contained therein, and then separating low-boiling-point impurities through a distillation step using a distillation operation such as pressurized distillation, as well as a composition containing trifluoroiodomethane. INDUSTRIAL APPLICABILITY According to the present invention, by recycling the starting trifluoromethane, a composition containing trifluoroiodomethane can be provided with high efficiency, which is industrially useful. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic diagram showing a reaction vessel for contacting a raw material reaction gas with an alkaline medium, and the flow of the reaction gas and the alkaline medium, for producing high-purity trifluoroiodomethane according to the present invention. [Figure 2] FIG. 1 shows a schematic diagram of a distillation column in which the reaction gas is brought into contact with an alkaline medium, and the treated reaction gas is removed from the top of the reaction vessel, and then the reaction gas is pressurized and distilled to obtain the CF3I product. [Figure 3] Figure 3 shows the process from (i) mixed gas generation, (ii) alkaline medium treatment, and (iii) fractionation of the reaction gas by distillation. The figure shows (i) to (iii) as a schematic diagram. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention will be described in detail below with reference to the accompanying drawings.

[0015] <Method of producing high-purity trifluoroiodomethane> The method for producing high-purity trifluoroiodomethane of the present invention is characterized by being carried out by a process including the following steps 1), 2) and 3). 1) A step of reacting trifluoromethane with iodine in the presence of a solid catalyst and oxygen to obtain a reaction gas containing trifluoroiodomethane. 2) A step of contacting the reaction gas obtained in step 1) with an alkaline medium to react and remove hydrogen fluoride and carbon dioxide that may be contained in the reaction gas with the alkaline medium to obtain a reaction gas. 3) Distilling the reaction gas obtained in step 2), Trifluoroiodomethane and Trifluoromethane and Other components in the reaction gas Separating the

[0016] The present invention provides a method for efficiently producing high purity trifluoroiodomethane. This method contains trifluoroiodomethane and impurities derived from the raw materials and by-products produced by the reaction. Among these impurities, hydrogen fluoride (HF) and carbon dioxide (CO2) in particular are removed by contacting them with an alkaline medium and causing them to react. The remaining impurities, such as carbon tetrafluoride (CF) and carbon monoxide (CO), and the unreacted raw material trifluoromethane (CFH) are subjected to a subsequent distillation step, such as a pressure distillation operation, to be separated into trifluoroiodomethane (CFI), trifluoromethane (CFH), and other components in the reaction gas (carbon tetrafluoride (CF) and carbon monoxide (CO), etc.).

[0017] The trifluoroiodomethane (CF3I) separated in the distillation process is discharged from the outlet of the distillation column and sent to a storage tank, cylinder, etc. as a product.

[0018] The trifluoromethane (CFH) separated in the distillation process can be reused as a raw material for producing trifluoroiodomethane (CFI). To this end, it is supplied to a reaction raw material (CFH) storage tank and then supplied to a reaction tank for producing CFI product, where it is used to produce trifluoroiodomethane (CFI). In other words, the present invention relates to a method for producing high-purity trifluoroiodomethane (CFI) by recycling the separated trifluoromethane (CFH).

[0019] When trifluoromethane (CF3H) is recycled, as shown in Figure 3, it is supplied to the reaction raw material trifluoromethane (CF3H) storage tank (3), where it is mixed with fresh trifluoromethane (CF3H), and then supplied to the mixed gas generation tank (6) for use in the step of generating a mixed gas. Here, when storing trifluoromethane (CFH), mixing equipment such as a stirrer may be installed since the concentrations of the raw material CFH and the recovered CFH may differ. Furthermore, the recovered CFH may be purified by distillation again as necessary, and then supplied to a CFH storage tank (CFH storage unit).

[0020] The separated trifluoromethane (CF3H) can be stored in a storage tank or cylinder, or can be used as a product.

[0021] Although it is preferable to have a small amount of impurities, it is also preferable to avoid excessive purification treatment, which would significantly reduce the yield of the desired high-purity trifluoroiodomethane. Although excessive purification, for example, purification using multiple distillation steps, is possible, in consideration of equipment costs, operation management, and a reduction in the yield of the desired product, it is preferable to minimize the burden of the distillation steps.

[0022] The other components in the reaction gas separated in the distillation process, i.e., components other than trifluoroiodomethane (CF3I) and trifluoromethane (CF3H), are removed from the manufacturing process via waste (drain). These components do not need to be further separated into multiple components and may be disposed of together. If necessary, carbon dioxide (CO2) and carbon monoxide (CO) should be fixed so that they are not released into the atmosphere. Tetrafluoromethane (CF4) and hydrogen fluoride (HF) should be captured or fixed so that they are not released into the atmosphere, ground, rivers, oceans, etc.

[0023] The present invention relates to a method for separating components from a reaction gas containing trifluoroiodomethane by contacting the resulting reaction gas with an alkaline medium and then distilling the resulting reaction gas, from which hydrogen fluoride and carbon dioxide have been substantially removed. Therefore, it is important to control the production of the target product by analyzing and quantifying the components produced or remaining in the reaction. Specifically, the major impurities, unreacted raw materials, and the target product in the reaction gas are analyzed and quantified by gas chromatography (GC) and / or ion chromatography (IC).

[0024] Here, the reaction gas is brought into contact with an alkaline medium, and in the reaction gas from which hydrogen fluoride and carbon dioxide have been substantially removed, the content ranges of the major impurities in the reaction gas, namely (a) carbon dioxide (CO), (b) hydrogen fluoride (HF), (c) tetrafluoromethane (CF), and (d) carbon monoxide (CO), and the unreacted raw material (e) trifluoromethane (CFH), based on peak areas determined by gas chromatography and / or ion chromatography, are (a) ≦0.001%, (b) ≦0.001%, (c) ≦10.0%, (d) ≦2.0%, and (e) ≦70.0%, respectively (with the proviso that the sum of the peak areas of trifluoroiodomethane (CFI) and (a) to (e) is 100%).

[0025] As described above, the amounts of impurities and unreacted raw materials in the production of trifluoroiodomethane (CF3I) are listed as content ratios based on peak areas determined by gas chromatography and / or ion chromatography. Trifluoromethane (CF3H) is reacted with iodine to produce trifluoroiodomethane (CF3I), When the resulting trifluoroiodomethane (CF3I) is contacted with an alkaline medium; (a) Carbon dioxide (CO2) is preferably 0.0010% or less (≦0.0010%), more preferably 0.0005% or less (≦0.0005%), and particularly preferably 0.0002% or less (≦0.0002%). (b) Hydrogen fluoride (HF) is preferably 0.0010% or less (≦0.0010%), more preferably 0.0005% or less (≦0.0005%), and particularly preferably 0.0002% or less (≦0.0002%). (c) Tetrafluoromethane (CF4) is preferably 10.0% or less (≦10.0%), more preferably 8.0% or less (≦8.0%), and particularly preferably 5.0% or less (≦5.0%). (d) Carbon monoxide (CO) is preferably 2.0% or less (≦2.0%), more preferably 1.5% or less (≦1.5%), and particularly preferably 1.0% or less (≦1.0%). (e) Trifluoromethane (CF3H) is preferably 70.0% or less (≦70.0%), more preferably 65.0% or less (≦65.0%), and even more preferably 60.0% or less (≦60.0%). However, the sum of the peak areas of trifluoroiodomethane (CF3I) and (a) to (e) is set to 100%.

[0026] For quantification, the elution position (elution time) of the peak detected in the analysis chart by gas chromatography and / or ion chromatography, the peak area, etc. can be determined, and then converted into a weight equivalent value, for example.

[0027] In gas chromatography (GC) analysis, the peak areas provided by the GC analysis for each compound may be combined with integration by an information processing means built into or external to the GC analysis to provide the GC area percentage (GC area %) of all compounds relative to each of the analyte compounds as a measure of the relative concentration of the compound in the reaction gas. A mass spectrometer may also be used to identify the analyte compounds, if desired. For quantitative analysis, the GC peak area may be regarded as a weight and used as a relative weight conversion value.

[0028] When a compound contains halogens such as fluorine, they can be liberated by dissolving them in water and then quantified by ion chromatography. Ion chromatography (IC) analysis calculates the concentration of specific ions, especially fluorine (F) ions, in the target compound. By combining this with gas chromatography (GC) analysis, the composition of trifluoroiodomethane (CF3I) and impurities can be quantified.

[0029] In the method for producing CF3I of the present invention, an alkaline medium is contacted with a reaction gas containing trifluoroiodomethane (CF3I), and carbon dioxide (CO2) and hydrogen fluoride (HF) that may be contained in the reaction gas are reacted and removed. When the components of the reaction gas after contact with the alkaline medium are measured by gas chromatography and / or ion chromatography, it is preferable that the components fall within the above-mentioned ranges. In particular, carbon dioxide (CO2) and hydrogen fluoride (HF) in the reaction gas can be removed by reaction with an alkaline medium, reducing the burden on the subsequent distillation process.

[0030] In the present invention, after the contact step with the alkaline medium, the reaction gas is distilled, particularly pressure distilled, to separate trifluoroiodomethane (CF3I), trifluoromethane (CF3H) and other gas components. Therefore, the present invention provides a method for producing trifluoroiodomethane, characterized in that the peak area content ratios of the major impurities in the separated trifluoroiodomethane (CF3I), namely, (a) carbon dioxide (CO2), (b) hydrogen fluoride (HF), (c) tetrafluoromethane (CF4), and (d) carbon monoxide (CO) and (e) trifluoromethane (CF3H), determined by gas chromatography and / or ion chromatography, are (a) ≦0.0005%, (b) ≦0.0005%, (c) ≦0.2%, (d) ≦0.2%, and (e) ≦0.1%, respectively, and that trifluoroiodomethane (CF3I) accounts for 99.5% or more (provided that the sum of the peak areas of trifluoroiodomethane (CF3I) and (a) to (e) is 100%).

[0031] As described above, the amounts of impurities and unreacted raw materials in the production of trifluoroiodomethane (CF3I) are listed as content ratios based on peak areas determined by gas chromatography and / or ion chromatography. When trifluoroiodomethane (CF3I) after contact with alkaline medium is separated from trifluoromethane (CF3H) and other components by distillation; (a) Carbon dioxide (CO2) is preferably 0.0005% or less (≦0.0005%), more preferably 0.0003% or less (≦0.0003%), and particularly preferably 0.0001% or less (≦0.0001%). (b) Hydrogen fluoride (HF) is preferably 0.0005% or less (≦0.0005%), more preferably 0.0003% or less (≦0.0003%), and particularly preferably 0.0001% or less (≦0.0001%). (c) Tetrafluoromethane (CF4) is preferably 0.2% or less (≦0.2%), more preferably 0.15% or less (≦0.15%), and particularly preferably 0.1% or less (≦0.1%). (d) Carbon monoxide (CO) is preferably 0.2% or less (≦0.2%), more preferably 0.15% or less (≦0.15%), and particularly preferably 1.0% or less (≦1.0%). (e) Trifluoromethane (CF3H) is preferably 0.1% or less (≦0.1%), more preferably 0.09% or less (≦0.09%), and particularly preferably 0.08% or less (≦0.08%). Trifluoroiodomethane (CF3I) is preferably 99.5% or more (≧99.5%), and more preferably 99.7% or more (≧99.7%). However, the sum of the peak areas of trifluoroiodomethane (CF3I) and (a) to (e) is set to 100%.

[0032] When separating trifluoroiodomethane (CF3I) by distillation, hydrogen fluoride (HF), which has a higher boiling point than trifluoroiodomethane (CF3I), is removed by reaction with an alkaline medium in the previous step, and carbon dioxide (CO2) is also removed, reducing the burden of the distillation step.In particular, since the major impurities other than hydrogen fluoride (HF), carbon dioxide (CO2), tetrafluoromethane (CF4), carbon monoxide (CO), and the unreacted raw material trifluoromethane (CF3H), are all lower in concentration than trifluoroiodomethane (CF3I), the distillation step can be performed under pressure, which makes it easy to condense the evaporated components, allowing for a rational design of the process. The trifluoroiodomethane (CF3I) obtained in this manner has a high purity of 99.5% or more, and can be supplied to a cylinder or storage tank as a product.

[0033] In the present invention, after a reaction gas containing trifluoroiodomethane (CF3I) is obtained, the reaction gas is contacted with an alkaline medium, and then the reaction gas is distilled, particularly pressure distillation, to separate trifluoroiodomethane (CF3I), trifluoromethane (CF3H), and other gas components. Therefore, this is a method for producing trifluoroiodomethane, characterized in that the content ratios of the major impurities in the separated trifluoromethane (CF3H), namely, (a) carbon dioxide (CO2), (b) hydrogen fluoride (HF), (c) tetrafluoromethane (CF4), and (d) carbon monoxide (CO) and (e) trifluoromethane (CF3H), based on peak area determined by gas chromatography and / or ion chromatography, are (a) ≦0.0.0005%, (b) ≦0.0005%, (c) ≦10.0%, (d) ≦2.0%, and (e) ≧80.0%, respectively (however, the sum of the peak areas of (a) to (e) excluding trifluoroiodomethane (CF3I) is 100%).

[0034] As described above, the amounts of impurities and unreacted raw materials in the production of trifluoroiodomethane (CF3I) are listed as content ratios based on peak areas determined by gas chromatography and / or ion chromatography. When trifluoromethane (CF3H) after contact with an alkaline medium is separated from trifluoromethane (CF3H) and other components by distillation; (a) Carbon dioxide (CO2) is preferably 0.0005% or less (≦0.0005%), more preferably 0.0003% or less (≦0.0003%), and particularly preferably 0.0001% or less (≦0.0001%). (b) Hydrogen fluoride (HF) is preferably 0.0005% or less (≦0.0005%), more preferably 0.0003% or less (≦0.0003%), and particularly preferably 0.0001% or less (≦0.0001%). (c) Tetrafluoromethane (CF4) is preferably 8.0% or less (≦8.0%), more preferably 6.0% or less (≦6.0%), and particularly preferably 5.0% or less (≦5.0%). (d) Carbon monoxide (CO) is preferably 1.0% or less (≦1.0%), more preferably 0.8% or less (≦0.8%), and particularly preferably 0.7% or less (≦0.7%). (e) Trifluoromethane (CF3H) is preferably 80.0% or more (≧80.0%), more preferably 90.0% or more (≧90.0%), and particularly preferably 93.0% or more (≧93.0%). However, the sum of the peak areas of trifluoroiodomethane (CF3I) and (a) to (e) is set to 100%.

[0035] When separating trifluoromethane (CF3H) by distillation, hydrogen fluoride (HF), which has a higher boiling point than trifluoroiodomethane (CF3H), is removed by reaction with an alkaline medium in the previous step, and carbon dioxide (CO2) is also removed, reducing the burden of the distillation step.In particular, the major impurities other than hydrogen fluoride (HF), tetrafluoromethane (CF4) and carbon monoxide (CO), both of which have lower boiling points than trifluoromethane (CF3H), and carbon dioxide (CO2), which has a boiling point close to that of trifluoromethane (CF3H), are mostly removed in the previous step.Furthermore, the distillation operation can be performed under pressure, which makes it easy to condense the evaporated components, allowing for a rational design of the process. The trifluoromethane (CF3H) obtained in this way has a high purity of 90.0% or more, and can be supplied to a cylinder or storage tank as a product such as a CF3-forming agent.

[0036] Furthermore, as shown in Figure 3, trifluoromethane (CF3H) can be recovered and sent to a storage tank for the reactant trifluoromethane (CF3H), where it can be reused as a raw material for the production of trifluoroiodomethane (CF3I). This reuse allows it to be incorporated into the trifluoroiodomethane (CF3I) production process, in which unreacted trifluoroiodomethane (CF3I) is recycled. This not only reduces the cost of raw materials used, but also reduces the burden of waste disposal by incorporating a trifluoromethane (CF3H) recycling process into the production process. In other words, this process is also favorable from the perspective of the SDGs (Sustainable Development Goals).

[0037] <Removal of impurities in reaction gas using alkaline medium> In the present invention, the alkaline medium refers to an agent for removing impurities present in a container containing trifluoroiodomethane (CF3I), and removes the major impurities (a) carbon dioxide (CO2) and (b) hydrogen fluoride (HF) by reacting them with the impurities. These boiling points (at atmospheric pressure) are (a) carbon dioxide (CO2) at -78.5°C and (b) hydrogen fluoride (HF) at 19.54°C, which is higher than the boiling point of trifluoroiodomethane (CF3I), which is -22.5°C, reducing the operational complexity of the subsequent distillation step. Furthermore, since the boiling point of (a) carbon dioxide (CO2) is -78.5°C and the boiling point of the unreacted raw material (e) trifluoromethane (CF3H) is -82.1°C, precise distillation operations are required. However, the burden of distillation operations can be reduced by contacting the reaction gas, which is the pre-distillation step, with an alkaline medium to cause a reaction, and removing (a) carbon dioxide (CO2) together with (b) hydrogen fluoride (HF).

[0038] FIG. 1 is a schematic diagram showing a reaction vessel (1) for contacting a raw material reaction gas (11) with an alkaline medium (10) for the production of high-purity trifluoroiodomethane according to the present invention, and the flow of the reaction gas (11) and the alkaline medium (10). The reaction gas (11) is supplied from the bottom of the reaction vessel (1), and the alkaline medium (10) is supplied from the top of the reaction vessel (1). After the reaction, the treated reaction gas (11) is removed from the top of the reaction vessel (1). Although not shown, the alkaline medium (10) that has come into contact with the reaction gas (11) is discharged from the reaction vessel (1) through an outlet (not shown) provided at the bottom of the reaction vessel (1) or at an appropriate location.

[0039] 1, there are various variations depending on the type of alkaline medium used and the method of contacting the reaction gas with the alkaline medium in the reaction vessel, and these can be selected appropriately. Examples are shown below, but the present invention is not limited to these examples.

[0040] 2 shows a schematic diagram of the distillation column (2) in which the reaction gas (11) is contacted with the alkaline medium (10) in FIG. 1, and the treated reaction gas (12) is then removed from the top of the reaction vessel (1), and the treated reaction gas (12) is then distilled under pressure to produce a CF3I product (13). After distillation, the treated reaction gas (12) is removed from the top of the distillation column (2) and produced as a CF3I product (13). Although not shown, when the treated reaction gas (12) is distilled under pressure, components other than CF3I in the treated reaction gas (12) are discharged from the distillation column (2) through an outlet (not shown) provided at the bottom of the distillation column (2) or at an appropriate position. The CF3I product (13) is transferred to the next process, such as filling into a cylinder or a storage tank.

[0041] Figure 3 consists of (i) mixed gas generation, (ii) alkaline medium treatment, and (iii) fractionation of the reaction gas by distillation. The figure shows (i) to (iii) schematically. (i) Iodine (I2) solution (15) from the reactant iodine (I2) solution storage tank (4) is supplied to the mixed gas generation tank (6), and CF3H from the reactant trifluoromethane (CF3H) storage tank (3) is also supplied to the mixed gas generation tank (6), to obtain a mixed gas (17) of CF3H (gas) and generated iodine (I2). If the reactant iodine (I2) solution (15) is charged in advance in the mixed gas generation tank (6), the reactant iodine (I2) solution storage tank (4) becomes unnecessary, and the corresponding part shown in Figure 3 may be omitted. (ii) This mixed gas (17) is fed to the reaction vessel (5) and heated in the presence of a solid catalyst (not shown) packed in the reaction vessel (5) to react the mixed gas (17) to produce trifluoroiodomethane (CF3I), which, together with other gas components, is used as a reaction gas and fed to the alkaline medium treatment vessel (1). At the same time, the alkaline medium (10) is also fed to the alkaline medium treatment vessel (1) to bring the two into contact with each other, and mainly carbon dioxide (CO2) and hydrogen fluoride (HF) are reactively removed by the alkaline medium (10). (iii) The reaction gas (12) after treatment with the alkaline medium (10) is taken out from the top of the alkaline medium treatment tank (1) and fed to the distillation column (2), where the reaction gas (12) after treatment is distilled under pressure to separate CF3I, CF3H, and other components, and then treated as follows: a) to c). a) Trifluoroiodomethane (CF3I) is discharged from the top of the distillation column (2) and becomes the CF3I product (13). For example, although not shown, it can be filled into a cylinder or a storage tank. b) After being recovered, trifluoromethane (CF3H) is supplied to the reaction raw material trifluoromethane (CF3H) storage tank (3). Trifluoromethane (CF3H) can also be used as a CF3 group introduction agent, and therefore, although not shown, it can be stored by filling it into a cylinder or a storage tank. c) Other components are vented (venting means not shown).

[0042] As mentioned above, unreacted CF3H can be effectively removed from the reaction gas by distillation. However, CF3H can also be separated from CF3I by distillation and reused as a raw material.

[0043] In the present invention, specific examples of the alkaline medium include alkali metal hydroxides, such as potassium hydroxide (KOH), sodium hydroxide (NaOH), and lithium hydroxide (LiOH), with potassium hydroxide (KOH) being preferred. These may be used alone or in combination, and may be dissolved in water to form an aqueous solution.

[0044] In the present invention, the concentration of the alkaline medium used is 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, or 50 wt%, or, for example, 5 wt% to 50 wt%, 10 wt% to 50 wt%, 15 wt% to 50 wt%, 20 wt% to 50 wt%, 25 wt% to 50 wt%, 30 wt% to 45 wt%, or 35 wt% to 40 wt%, etc., and the reaction step containing the alkali metal hydroxide within any range defined between any two of the above values ​​is preferably a concentration that can remove impurities in the reaction gas and can particularly reduce the burden on the subsequent distillation step.

[0045] Impurities can be removed from the reaction gas by passing the reaction gas containing the impurities and trifluoroiodomethane (CF3I) through a reaction vessel for contacting the reaction gas with an alkaline medium. The reaction vessel and reaction conditions used in the present invention allow for effective removal of impurities from the reaction gas without significant decomposition of trifluoroiodomethane (CF3I).

[0046] Zeolite, such as basic zeolite, can also be used as the alkaline medium in the present invention. Zeolites with large pore volumes are preferred in terms of reaction efficiency, and synthetic zeolites such as X-type and A-type zeolites, or natural zeolites can be used. Furthermore, since the zeolite is expected to be used by filling it into a reaction vessel or the like, not only powdered zeolite but also granulated zeolite containing an extender or other binder can be used. Granulated zeolite can be prepared by appropriately using known techniques. Alternatively, zeolite, synthetic polymers or other agents may be used as a carrier, which may be coated with an alkaline medium such as an alkali metal hydroxide or alkali metal, and then packed in a reaction vessel as a solid. As these alkaline media, alkali metal hydroxides, particularly potassium hydroxide (KOH), are preferably used in view of impurity removal performance, economy, ease of use, and burden on production facilities.

[0047] As the solid alkaline medium, zeolites, particularly basic zeolites, can be used. In the present invention, the removal of impurities by reacting zeolite with a reaction gas containing CF3I and small amounts of impurities such as CF3H, CO2, and HF is believed to depend not only on the reactivity with basic zeolite but also on its adsorption characteristics. For this reason, zeolites with relatively large pores are preferably used, such as synthetic zeolites of type X, type Y, and type L, or equivalent natural zeolites.

[0048] The contact time between the reaction gas and the alkaline medium can vary depending on various factors, such as the size and shape of the reaction vessel, the flow rate of the reaction gas, and the pressure during the reaction. For example, in Example 1 of this specification, the reaction gas was introduced from the bottom of a reaction vessel with an inner diameter of 105 mm and a height of 3 m (internal volume: 26.0 liters) at a gas introduction rate of 37 L / min. The residence time in this case was 42 seconds. By shortening this residence time, that is, by increasing the flow rate of the reaction gas, the efficiency of removing impurities in the reaction gas by reaction with the alkaline medium increases, but there is a possibility that the reaction may become insufficient. On the other hand, although the efficiency of reactive removal increases if there is sufficient residence time, depending on the type of alkaline medium used, for example, when a base such as sodium hydroxide (NaOH) or potassium hydroxide (KOH) is used, alcohol may be produced as an impurity due to the decomposition of CFI.

[0049] In this way, the process of removing impurities in the reaction vessel should be designed in relation to the load on the subsequent distillation process. As mentioned above, there are various methods for contacting the reaction gas with the alkaline medium, and an efficient method can be selected depending on the settings. For example, when a solid catalyst such as basic zeolite is used, the impurities are likely to be removed by the adsorption properties of the zeolite, making the decomposition of CF3I less likely to occur. However, the efficiency of impurity removal will need to be further investigated. On the other hand, when high concentrations of sodium hydroxide (NaOH) or potassium hydroxide (KOH) are used, it is expected that the efficiency of reactive removal of CO2 and HF will increase, but care must be taken to prevent the decomposition of CF3I. As described above, there may be conditions that conflict with the removal of impurities from the reaction gas and the production efficiency of high-purity CF3I. Therefore, it is preferable to set optimal conditions while taking into consideration the effects, as seen in the examples of this specification.

[0050] When the reactant gas and alkaline medium come into contact in the reaction vessel, if the alkaline medium is a base such as aqueous sodium hydroxide, a gas-liquid reaction occurs between the gaseous reactant gas and the liquid alkaline medium. In this case, the reaction occurs at the gas-liquid interface, or in the liquid if the reactant gas is dissolved in the liquid alkaline medium. Therefore, assuming the reaction is more efficient, By breaking the liquid into small droplets and increasing the surface area per unit volume, the opportunity for contact with the reactant gas can be increased. For example, a mist generator can be used to atomize the liquid, or the liquid can be passed through a solid object with tiny pores to create a microfluidic solution, or the liquid can be pressurized and sprayed onto a solid object with tiny cavities. In order to increase the density of CF3I in the reaction gas, the reaction vessel is pressurized to increase the gas density. - To increase the contact efficiency of the reactant gas, the gas movement is accelerated. To achieve this, it is advisable to increase the reaction temperature. However, increasing the reaction temperature may accelerate the decomposition of CF3I, and the temperature control of the reaction vessel requires high temperature control, which increases the equipment cost. - To increase the contact efficiency of the reactant gas, the gas movement is accelerated. To achieve this, the supply rate of the reactant gas to the reaction vessel is increased. In this case, equipment to increase the supply rate is required, which increases the equipment cost. It is advisable to design the equipment with the above points in mind and install appropriate facilities.

[0051] When the reactant gas and alkaline medium come into contact in the reaction vessel, if the alkaline medium is a solid such as basic zeolite, a gas-solid reaction occurs between the gaseous reactant gas and the solid basic zeolite. In this case, the reaction occurs at the interface between the gas and the solid, or when the reactant gas penetrates into the pores of the solid basic zeolite. Therefore, assuming the reaction is more efficient, To reduce the size of solids, it is advisable to powder them or to pulverize granular materials to make them finer. However, care must be taken when filling small powders into equipment, as they may become pressurized or the density may increase, causing problems. When the particle size is small, such as in powders, increasing the surface area per unit volume increases the chance of contact with the reaction gas. In order to increase the density of CF3I in the reaction gas, the reaction vessel is pressurized to increase the gas density. In this case, it is necessary to set conditions so that the liquid zeolite is packed densely and is not crushed by the pressure. - To increase the contact efficiency of the reactant gas, the gas movement is accelerated. To achieve this, it is advisable to increase the reaction temperature. However, increasing the reaction temperature may accelerate the decomposition of CF3I, and high temperature control is required to control the temperature of the reaction vessel, which increases the equipment cost. - To increase the contact efficiency of the reactant gas, the gas movement is accelerated. To achieve this, the supply rate of the reactant gas to the reaction vessel is increased. In this case, equipment to increase the supply rate is required, which increases the equipment cost. It is advisable to design the equipment with the above points in mind and install appropriate facilities.

[0052] When the reaction gas and alkaline medium contact each other in the reaction vessel, the reaction temperature is 15°C, 20°C, 25°C, 30°C, 40°C, or 50°C, or a temperature in any range defined between any two of the above temperatures, such as 15°C to 50°C, 20°C to 50°C, 25°C to 40°C, or 20°C to 40°C. Preferably, the reaction temperature is 20°C to 40°C.

[0053] <Separation of reaction gas components by distillation> The method for producing high-purity trifluoroiodomethane of the present invention comprises a step of contacting trifluoroiodomethane containing impurities with an alkaline medium to remove them by reaction, and a step of purifying the obtained trifluoroiodomethane by pressure distillation.

[0054] Impurities such as CF3H contained in the reaction gas can be removed by a distillation step following the reaction step. In particular, it is preferable to carry out pressurized distillation to remove impurities with a boiling point lower than that of the target product, CF3I. The distillation step may include not only a first distillation but also a second distillation, if necessary. The first distillation can remove impurities having a boiling point lower than that of CF3I from the treated reaction gas after the reaction step. Such low boiling point impurities can include, for example, CF3H, CO2, CF4, CO, etc. The second distillation can remove impurities from the reaction gas that have a boiling point higher than that of CF3I, such as HF.

[0055] The distillation of the reaction gas in the distillation step following the reaction step can be carried out either as a continuous process or a batch process. A single distillation may be more suitable for a batch process, while a distillation process comprising a first distillation and a second distillation may be more suitable for a continuous process.

[0056] Of course, the first distillation and the second distillation can be carried out in a single distillation column, but impurities with higher and lower boiling points than the boiling point of the target product, CF3I, may be present, requiring more precise distillation operations.

[0057] <Trifluoroiodomethane composition> The trifluoroiodomethane composition of the present invention is characterized in that the content ratios of the major impurities in trifluoroiodomethane, namely (a) carbon dioxide (CO), (b) hydrogen fluoride (HF), (c) tetrafluoromethane (CF), and (d) carbon monoxide (CO), and (e) trifluoromethane (CFH), based on peak areas determined by gas chromatography and / or ion chromatography, are (a) ≦0.0005%, (b) ≦0.0005%, (c) ≦0.2%, (d) ≦0.2%, and (e) ≦0.1%, respectively, and that trifluoroiodomethane (CFI) is 99.7% or more (with the proviso that the sum of the peak areas of trifluoroiodomethane (CFI) and (a) to (e) is 100%).

[0058] By the above-described method for producing high-purity trifluoroiodomethane, a composition containing trifluoroiodomethane can be obtained. The trifluoroiodomethane composition preferably has the following specifications based on peak areas determined by gas chromatography and / or ion chromatography: (a) Carbon dioxide (CO2) is preferably 0.0005% or less (≦0.0005%), more preferably 0.0003% or less (≦0.0003%), and particularly preferably 0.0001% or less (≦0.0001%). (b) Hydrogen fluoride (HF) is preferably 0.0005% or less (≦0.0005%), more preferably 0.0003% or less (≦0.0003%), and particularly preferably 0.0001% or less (≦0.0001%). (c) The content of tetrafluoromethane (CF4) is preferably 0.2% or less (≦0.2%), more preferably 0.15% or less (≦0.15%), and particularly preferably 0.1% or less (≦0.1%). (d) Carbon monoxide (CO) is preferably 0.2% or less (≦0.2%), more preferably 0.15% or less (≦0.15%), and particularly preferably 0.1% or less (≦0.1%). (e) Trifluoroiodomethane (CF3H) is preferably 0.08% or less (≦0.08%), more preferably 0.04% or less (≦0.04%), and particularly preferably 0.02% or less (≦0.02%). It is preferable that the trifluoroiodomethane content is 99.7% or more. However, the sum of the peak areas of trifluoroiodomethane and the above (a) to (c) is set to 100%.

[0059] <Trifluoroiodomethane production system> The trifluoroiodomethane production system of the present invention is composed of an alkaline medium contact unit, a distillation unit, a CF3H storage unit, an I2 gas generation unit, a mixing unit, and a reaction unit. It may also be equipped with a control system that controls the coordination of these units. Specifically, the system is as follows. Alkaline medium contact unit: Inlet for receiving alkaline media a gas inlet for receiving a reactant gas Means for contacting the alkaline medium with the reaction gas Outlet for discharging reaction gas after treatment Piping for supplying the treated reaction gas to the distillation unit Distillation unit: A gas inlet for receiving the reaction gas after processing Means for distilling the reaction gas after treatment Storage tank for CF3I separated by distillation Storage tank for CF3H separated by distillation An outlet for discharging the distilled and separated CF3I Outlet for discharging the distilled and separated CF3H Piping for supplying the distilled and separated CF3H to the CF3H storage unit CF3H storage unit: Inlet for receiving distilled and separated CF3H Means for agitating the gas in the storage unit Outlet for discharging raw material CF3H Piping for supplying raw material CF3H to the mixing unit Mixed gas generator unit: Inlet for receiving raw material CF3H Inlet for receiving raw I2 solution A means for generating a mixed gas of CF3H and I2 by introducing the raw material CF3H into the raw material I2 solution. Outlet for discharging the generated mixed gas Piping for supplying mixed gas to the reaction unit Reaction Unit: Inlet for receiving mixed gases A method for generating CF3I by introducing a mixed gas into a packed solid catalyst An outlet for discharging the reaction gas containing the produced CF3I Piping for supplying reaction gas containing CF3I to the alkaline medium contact unit A trifluoroiodomethane production system comprising:

[0060] In order to control the cooperation of these units, a control system may be provided that adjusts at least one of the gas pressure, gas temperature, and gas supply flow rate of the I gas supplied to the reaction unit based on the I gas concentration in the mixed gas generation unit, and that adjusts at least one of the gas pressure, gas temperature, and gas supply flow rate of the CFH-containing source gas supplied to the reaction unit based on the CFH concentration in a CFH storage tank.

[0061] In the trifluoroiodomethane production system of the present invention, the alkaline medium contact unit brings into contact in an alkaline medium treatment tank an alkaline medium introduced through an inlet for receiving an alkaline medium with a reaction gas introduced through a gas inlet for receiving a reaction gas, i.e., a reaction gas containing CF3I obtained by heating a mixed gas of CF3H and I2 in the presence of a solid catalyst, and obtains a treated reaction gas after reactively removing carbon dioxide (CO2), hydrogen fluoride (HF), etc. that can react with the alkaline medium. Regarding the method of contacting the alkaline medium with the reaction gas, if the alkaline medium is a liquid or liquid droplets, the reaction will be between a liquid and a gas, so it is advisable to ensure sufficient contact between the two by stirring or the like in the alkaline medium treatment tank. Furthermore, if the alkaline medium is a solid such as zeolite, the reaction will be between a solid and a gas, so it is advisable to move the solid sufficiently within the alkaline medium treatment tank to ensure sufficient contact between the two. Furthermore, if the alkaline medium is a solid such as zeolite, it may be difficult to continuously introduce a solid such as zeolite into the alkaline medium treatment tank, so it is also possible to fill the alkaline medium treatment tank with a solid such as zeolite in advance.

[0062] In the trifluoroiodomethane production system of the present invention, the distillation unit is a step in which the reaction gas after contact treatment with an alkaline medium introduced from a gas inlet for receiving the reaction gas after treatment is distilled to separate CF3I, CF3H, and other components (CF4, CO, etc.). Although the reaction gas after treatment with an alkaline medium contains very little carbon dioxide (CO2) and hydrogen fluoride (HF), it still contains impurities such as tetrafluoromethane (CF4) and carbon monoxide (CO) in addition to CF3I and the unreacted raw material CF3H, and these must be separated. Since the boiling points of each compound are particularly low, it is preferable to perform pressurized distillation to promote condensation during the distillation process. This allows for efficient separation of CF3I, CF3H, and other components (CF4, CO, etc.). The CF3I separated by distillation is discharged from an outlet and sent to a storage tank such as a tank or cylinder, where it is made into a product. The CF3H separated by distillation is discharged from an outlet, and if it is to be reused, it is sent to a CF3H storage unit and recycled. CF3H may also be used as a CF3 conversion agent, so it can be sent to a storage tank such as a tank or cylinder and made into a product.

[0063] In the trifluoroiodomethane production system of the present invention, the CF3H storage unit not only stores the raw material CF3H, but also stores CF3H supplied through an inlet for receiving CF3H separated by distillation. Here, the raw material CF3H and the CF3H separated by distillation differ in concentration and other components contained therein, so it is advisable to thoroughly mix them in the raw material CF3H storage tank to make their composition as uniform as possible.

[0064] In the trifluoroiodomethane production system of the present invention, the mixed gas generation unit is a process in which CFH gas from an inlet for receiving raw material CFH is introduced into raw material I2 solution from an inlet for receiving raw material I2 solution, thereby generating a mixed gas of CF3H and I2. The generated mixed gas is supplied to the reaction unit through an outlet.

[0065] In the trifluoroiodomethane production system of the present invention, the reaction unit is a step in which a mixed gas from an inlet for receiving the mixed gas and a solid catalyst packed in a reaction vessel are heated to obtain CF3I. There are no limitations on the solid catalyst as long as it can convert a mixed gas of CF3H and I2 into CF3I, but a solid catalyst supporting an alkali metal is preferably used. The reaction gas containing the produced CF3I is discharged from an outlet for discharge and is supplied to an alkaline medium contact unit. [Example]

[0066] Examples of the present invention will be described below, but the present invention is not limited to these examples.

[0067] The conditions of the apparatus used for the analysis were as follows: <Materials used> The materials used in this example are listed below, and are either commercially available or Helium gas Dry air carbon dioxide Sodium hydroxide (NaOH) Potassium hydroxide (KOH) Zeolite (X-type zeolite)

[0068] <Analysis by gas chromatography (GC)> A sample was injected, and the GC purity (based on area %) was calculated based on the peaks in the analysis chart. Equipment: Shimadzu Corporation GC-2014 <Analysis by ion chromatography (IC)> A sample was injected and the fluorine content in the reaction gas was analyzed. Apparatus: Agilent 1260

[0069] Synthesis Example 1 A 105mm diameter Hastelloy C vertical reactor equipped with a stirring blade and thermometer was filled with 1 kg of alkali metal-supported solid catalyst. The temperature of the catalyst layer in the reactor was then raised to 440°C while the stirring blade was rotating. A mixed gas of 6.1 kg / hr CHF3 and 11 kg / hr I2 was supplied from the top of the reactor to react, and the reaction gas was continuously withdrawn from the bottom of the reactor. The linear velocity was 84 cm / min. Iodine was prepared by bubbling trifluoromethane (CHF3) into liquid iodine to generate a mixed gas of CHF3 and iodine (I2), which was then supplied to the reaction system.

[0070] After the reaction, the reaction gas was cooled through a cooler and separated into gas and solid. The gas was washed with water and analyzed by gas chromatography and ion chromatography. Analysis of the reaction gas 10 hours after the start of the reaction revealed the following: CF3I = 30.6 wt% (weight %), CF3H = 53.3, CF4 = 4.6 wt%, CO = 1.0 wt%, CO2 = 5.0 wt%, HF = 5.5 wt%. The analysis results are also shown in Table 1.

[0071] Example 1 A 105mm diameter Hastelloy C vertical reactor equipped with a stirring blade and thermometer was filled with 1 kg of alkali metal-supported solid catalyst. The temperature of the catalyst layer in the reactor was then raised to 440°C while the stirring blade was rotating. A mixed gas of CF3H4 = 6.1 kg / hr and I2 = 11 kg / hr was supplied from the top of the reactor to react, and the reaction gas was continuously withdrawn from the bottom of the reactor. The linear velocity was 84 cm / min. Iodine was prepared by bubbling CF3H into liquid iodine to generate a mixed gas of trifluoromethane and iodine, which was then supplied to the reaction system.

[0072] After the reaction, the reaction gas was cooled through a cooler and separated into gas and solid. The gas was washed with water and analyzed by gas chromatography and ion chromatography. Analysis of the reaction gas 10 hours after the start of the reaction revealed the following gas proportions: CF3H = 30.6 wt%, CF3I = 53.3 wt%, CF4 = 4.6 wt%, CO = 1.0 wt%, CO2 = 5.0 wt%, and HF = 5.5 wt%.

[0073] The resulting reaction gas was then introduced into a gas scrubber with an inner diameter of 100 mm and a height of 3 m from the bottom at a gas introduction rate of 37 L / min. On the other hand, a 10 wt% (weight %) aqueous solution of sodium hydroxide was introduced from the top of the tower at a rate of 0.18 kg / min, and after sufficient gas-liquid contact had occurred inside the tower, the washed gas was extracted from the top of the tower and analyzed by gas chromatography and ion chromatography. Analysis of the resulting reaction gas revealed the following gas proportions: CF3I = 34.1 wt%, CF3H = 59.6 wt%, CF4 = 5.1 wt%, CO = 1.1 wt%, CO2 = 0.0003 wt%, and HF = 0.0003 wt%. The analysis results of the reaction gas after treatment with this alkaline medium are also shown in Table 1.

[0074] Furthermore, the obtained gas was sent to a pressure distillation column to recover unreacted trifluoromethane (CF3H) and simultaneously obtain the product trifluoroiodomethane (CF3I). The product composition was CF3I = 99.7 wt%, CF3H = 0.08 wt%, CF4 = 0.1 wt%, CO = 0.1 wt%, CO2 = 0.0004 wt%, and HF = 0.0004 wt%. The analytical results of the product CF3I after this distillation are also shown in Table 2.

[0075] On the other hand, analysis of the recovered gas revealed the following gas proportions: CF3H = 92.6 wt%, CF4 = 6.5 wt%, CO = 0.9 wt%, CO2 = less than 0.0001 wt% (<0.0001 wt%), HF = less than 0.0001 wt% (<0.0001 wt%). The analysis results of CF3H (recovered gas) after this distillation are also shown in Table 3. The recovered gas was sent to a raw material tank for continuous operation.

[0076] Example 2 The same procedure as in Example 1 was repeated except that the 10 wt % aqueous sodium hydroxide solution used in Example 1 was replaced with a 5 wt % aqueous potassium hydroxide solution.

[0077] Analysis of the resulting reaction gas revealed the following gas proportions: CF3I = 34.1 wt%, CF3H = 59.6 wt%, CF4 = 5.1 wt%, CO = 1.1 wt%, CO2 = 0.0002 wt%, and HF = 0.0002 wt%. The analysis results of the reaction gas after treatment with this alkaline medium are also shown in Table 1.

[0078] Furthermore, the obtained gas was sent to a pressure distillation column to recover unreacted trifluoromethane (CF3H) and simultaneously obtain the product trifluoroiodomethane (CF3I). The product composition was CF3I = 99.7 wt%, CF3H = 0.08 wt%, CF4 = 0.1 wt%, CO = 0.1 wt%, CO2 = 0.0003 wt%, and HF = 0.0003 wt%. The analytical results of the product CF3I after this distillation are also shown in Table 2.

[0079] On the other hand, analysis of the recovered gas revealed the following gas proportions: CF3H = 93.2 wt%, CF4 = 5.5 wt%, CO = 0.7 wt%, CO2 = less than 0.0001 wt% (<0.0001 wt%), HF = less than 0.0001 wt% (<0.0001 wt%). The analysis results of CF3H (recovered gas) after this distillation are also shown in Table 3. The recovered gas was sent to a raw material tank for continuous operation.

[0080] Example 3 The same procedure as in Example 1 was repeated except that the 10% aqueous sodium hydroxide solution in Example 1 was replaced with a 10% aqueous potassium hydroxide solution.

[0081] Analysis of the resulting reaction gas revealed the following gas proportions: CF3I = 34.1 wt%, CF3H = 59.6 wt%, CF4 = 5.1 wt%, CO = 1.1 wt%, CO2 = 0.0001 wt%, and HF = 0.0001 wt%. The analysis results of the reaction gas after treatment with this alkaline medium are also shown in Table 1.

[0082] Furthermore, the obtained gas was sent to a pressure distillation column to recover unreacted trifluoromethane (CF3H) and simultaneously obtain the product trifluoroiodomethane (CF3I). The product composition was CF3I = 99.7 wt%, CF3H = 0.08 wt%, CF4 = 0.1 wt%, CO = 0.1 wt%, CO2 = less than 0.0001 wt% (<0.0001 wt%), HF = less than 0.0001 wt% (<0.0001 wt%). The analytical results of the product CF3I after this distillation are also shown in Table 2.

[0083] On the other hand, analysis of the recovered gas revealed the following gas proportions: CF3H = 93.2 wt%, CF4 = 5.5 wt%, CO = 0.7 wt%, CO2 = less than 0.0001 wt% (<0.0001 wt%), HF = less than 0.0001 wt% (<0.0001 wt%). The analysis results of CF3H (recovered gas) after this distillation are also shown in Table 3. The recovered gas was sent to a raw material tank for continuous operation.

[0084] Example 4 The same procedure as in Example 1 was repeated except that the 10% aqueous sodium hydroxide solution used in Example 1 was replaced with a 30% aqueous potassium hydroxide solution.

[0085] Analysis of the resulting reaction gas revealed the following gas proportions: CF3I = 34.1 wt%, CF3H = 59.6 wt%, CF4 = 5.1 wt%, CO = 1.1 wt%, CO2 = 0.0001 wt%, and HF = 0.0001 wt%. The analysis results of the reaction gas after treatment with this alkaline medium are also shown in Table 1.

[0086] Furthermore, the obtained gas was sent to a pressure distillation column to recover unreacted trifluoromethane (CF3H) and simultaneously obtain the product trifluoroiodomethane (CF3I). The product composition was CF3I = 99.7 wt%, CF3H = 0.08 wt%, CF4 = 0.1 wt%, CO = 0.1 wt%, CO2 = less than 0.0001 wt% (<0.0001 wt%), HF = less than 0.0001 wt% (<0.0001 wt%). The analytical results of the product CF3I after this distillation are also shown in Table 2.

[0087] On the other hand, analysis of the recovered gas revealed the following gas proportions: CF3H = 93.2 wt%, CF4 = 5.5 wt%, CO = 0.7 wt%, CO2 = less than 0.0001 wt% (<0.0001 wt%), HF = less than 0.0001 wt% (<0.0001 wt%). The analysis results of CF3H (recovered gas) after this distillation are also shown in Table 3. The recovered gas was sent to a raw material tank for continuous operation.

[0088] Example 5 The 10% aqueous sodium hydroxide solution used in Example 1 was replaced with basic zeolite (granular X-type zeolite, average particle size 100 μm, manufactured by Tosoh Corporation), which was previously packed into the tower in a volume equivalent to 1 / 10 of the internal volume. The reaction gas was introduced into the tower from the bottom at a gas introduction rate of 37 L / min. The reaction gas was brought into contact with the basic zeolite previously packed into the tower, and the reaction gas was stirred by bringing the two into contact so that the reaction gas would spray up the zeolite. The gas was then extracted from the top of the tower and analyzed by gas chromatography and ion chromatography.

[0089] Analysis of the resulting reaction gas revealed the following gas proportions: CF3I = 34.1 wt%, CF3H = 59.6 wt%, CF4 = 5.1 wt%, CO = 1.1 wt%, CO2 = 0.0004 wt%, and HF = 0.0004 wt%. The analysis results of the reaction gas after treatment with this alkaline medium are also shown in Table 1.

[0090] Furthermore, the obtained gas was sent to a pressure distillation column to recover unreacted trifluoromethane (CF3H) and simultaneously obtain the product trifluoroiodomethane (CF3I). The product composition was CF3I = 99.7 wt%, CF3H = 0.08 wt%, CF4 = 0.1 wt%, CO = 0.1 wt%, CO2 = 0.0005 wt%, and HF = 0.0005 wt%. The analytical results of the product CF3I after this distillation are also shown in Table 2.

[0091] On the other hand, analysis of the recovered gas revealed the following gas proportions: CF3H = 93.2 wt%, CF4 = 5.5 wt%, CO = 0.7 wt%, CO2 = 0.0002 wt%, HF = less than 0.0001 wt% (<0.0001 wt%). The analysis results of CF3H (recovered gas) after this distillation are also shown in Table 3. The recovered gas was sent to a raw material tank for continuous operation.

[0092] Comparative Example 1 The 10 wt % aqueous sodium hydroxide solution used in Example 1 was not used. Therefore, the reaction gas was introduced from the bottom of the tower at a gas introduction rate of 37 L / min. After stirring the reaction gas introduced inside the tower, the gas was extracted from the top of the tower and analyzed by gas chromatography and ion chromatography.

[0093] Analysis of the resulting reaction gas revealed the following gas proportions: CF3I = 30.6 wt%, CF3H = 53.3 wt%, CF4 = 4.6 wt%, CO = 1.0 wt%, CO2 = 5.0 wt%, and HF = 5.5 wt%. The analysis results of the reaction gas after treatment with this alkaline medium are also shown in Table 1.

[0094] Furthermore, the obtained gas was sent to a pressure distillation column to recover unreacted trifluoromethane (CF3H) and simultaneously obtain trifluoroiodomethane (CF3I). The composition of this product was CF3I = 89.7 wt%, CF3H = 0.08 wt%, CF4 = 0.1 wt%, CO = 0.1 wt%, CO2 = 9.4 wt%, and HF = 0.6 wt%. The analytical results of the product CF3I after this distillation are also shown in Table 2.

[0095] On the other hand, analysis of the recovered gas revealed the following gas proportions: CF3H = 87.5 wt%, CF4 = 5.5 wt%, CO = 0.7 wt%, CO2 = 5.1 wt%, HF = 1.1 wt%. The analysis results of CF3H (recovered gas) after this distillation are also shown in Table 3. The recovered gas was sent to a raw material tank for continuous operation.

[0096] Comparative Example 2 The same procedure as in Example 1 was repeated except that the 10 wt % aqueous sodium hydroxide solution in Example 1 was replaced with a 2 wt % aqueous sodium hydroxide solution.

[0097] Analysis of the resulting reaction gas revealed the following gas proportions: CF3I = 34.1 wt%, CF3H = 59.6 wt%, CF4 = 5.1 wt%, CO = 1.1 wt%, CO2 = 0.002 wt%, and HF = 0.001 wt%. The analysis results of the reaction gas after treatment with this alkaline medium are also shown in Table 1.

[0098] Furthermore, the obtained gas was sent to a pressure distillation column to recover unreacted trifluoromethane (CF3H) and simultaneously obtain trifluoroiodomethane (CF3I). The composition of this product was CF3I = 99.7 wt%, CF3H = 0.08 wt%, CF4 = 0.1 wt%, CO = 0.1 wt%, CO2 = 0.0010 wt%, and HF = less than 0.0010 wt%. The analytical results of the product CF3I after this distillation are also shown in Table 2.

[0099] On the other hand, analysis of the recovered gas revealed the following gas proportions: CF3H = 93.2 wt%, CF4 = 5.5 wt%, CO = 0.7 wt%, CO2 = 0.002 wt%, HF = less than 0.0001 wt% (<0.0001 wt%). The analysis results of CF3H (recovered gas) after this distillation are also shown in Table 3. The recovered gas was sent to a raw material tank for continuous operation.

[0100] Comparative Example 3 The same procedure as in Example 1 was repeated except that the 10 wt % aqueous sodium hydroxide solution in Example 1 was replaced with a 2 wt % aqueous potassium hydroxide solution.

[0101] Analysis of the resulting reaction gas revealed the following gas proportions: CF3I = 34.1 wt%, CF3H = 59.6 wt%, CF4 = 5.1 wt%, CO = 1.1 wt%, CO2 = 0.0015 wt%, and HF = 0.001 wt%. The analysis results of the reaction gas after treatment with this alkaline medium are also shown in Table 1.

[0102] Furthermore, the obtained gas was sent to a pressure distillation column to recover unreacted trifluoromethane (CF3H) and simultaneously obtain trifluoroiodomethane (CF3I). The composition of this product was CF3I = 99.7 wt%, CF3H = 0.08 wt%, CF4 = 0.1 wt%, CO = 0.1 wt%, CO2 = 0.0008 wt%, and HF = 0.0005 wt%. The analytical results of the product CF3I after this distillation are also shown in Table 2.

[0103] On the other hand, analysis of the recovered gas revealed the following gas proportions: CF3H = 93.2 wt%, CF4 = 5.5 wt%, CO = 0.7 wt%, CO2 = 0.002 wt%, HF = less than 0.0001 wt% (<0.0001 wt%). The analysis results of CF3H (recovered gas) after this distillation are also shown in Table 3. The recovered gas was sent to a raw material tank for continuous operation.

[0104] [Table 1]

[0105] [Table 2]

[0106] [Table 3]

[0107] The results shown in Tables 1 to 3 reveal the following. 1) According to Table 1, the amounts of carbon dioxide (CO2) and hydrogen fluoride (HF) were lower in Comparative Examples 1-3 than in Examples 1-5. This indicates that these components in the reaction gas reacted and were removed by contact with the alkaline medium. This significantly reduces the burden on the subsequent distillation process. Although Comparative Examples 2 and 3 also use an alkaline medium, the amount is insufficient, so a certain amount of carbon dioxide (CO2) and hydrogen fluoride (HF) remains in the reaction gas, which is a burden in the distillation process. 2) Table 2 shows that high-purity CF3I can be obtained by distilling the reaction gas after alkaline medium treatment. However, in Comparative Example 1, the reaction gas was not brought into contact with an alkaline medium, and in Comparative Examples 2 and 3, treatment was performed with a low-concentration alkaline medium. Therefore, a certain amount of carbon dioxide (CO2) and hydrogen fluoride (HF) remained in the reaction gas, and they could not be successfully separated from CF3I. 3) Table 3 shows the results of component analysis when CF3I, CF3H, and other components are separated in the distillation process and CF3H is recovered. In Examples 1-5, carbon dioxide (CO2) and hydrogen fluoride (HF) are sufficiently reduced, and the recovered CF3H can be recycled as a raw material for the production of CF3I. On the other hand, in Comparative Examples 1-3, a certain amount of carbon dioxide (CO2) and hydrogen fluoride (HF) remain in the reaction gas, and further purification may be required for use as a CF3-reducing agent. [Industrial Applicability]

[0108] The present invention provides a method, production system, and composition for producing high-purity trifluoroiodomethane with high purity, high yield, and high production efficiency. [Explanation of symbols]

[0109] 1. Alkaline medium treatment tank 2. Distillation tower 3. Reaction raw material trifluoromethane (CF3H) storage tank 4. Reaction raw material iodine (I2) solution storage tank 5. Reaction tank 6. Mixed gas generation tank 10 Alkaline medium 11 Reactive gas 12 Reaction gas after treatment 13 CF3I Products 14 Raw material trifluoromethane (CF3H) 15 Raw iodine (I2) solution 16 Recovered trifluoromethane (CF3H) 17 Mixture of iodine (I2) and trifluoromethane (CF3H) gas

Claims

1. A method for producing trifluoroiodomethane, characterized by being carried out by a process including the following steps 1), 2) and 3): 1) A step of reacting trifluoromethane with iodine in the presence of a solid catalyst and oxygen to obtain a reaction gas containing trifluoroiodomethane. 2) A step of contacting the reaction gas obtained in step 1) with an alkaline medium to react hydrogen fluoride and carbon dioxide that may be contained in the reaction gas with the alkaline medium to obtain a removed reaction gas. 3) Distilling the reaction gas obtained in step 2), Trifluoroiodomethane and Trifluoromethane and Other components in the reaction gas Separating the

2. The main impurities in the reaction gas obtained in step 2) of claim 1 are: (a) carbon dioxide (CO ２ ), (b) hydrogen fluoride (HF), (c) tetrafluoromethane (CF ４ ), and (d) carbon monoxide (CO) and (e) trifluoromethane (CF ３ The content ratios of trifluoroiodomethane (CF), trifluoroiodomethane (CF), and HCl based on peak areas determined by gas chromatography and / or ion chromatography are (a) ≦0.001%, (b) ≦0.001%, (c) ≦10.0%, (d) ≦2.0%, and (e) ≦70.0%, respectively. ３ The sum of the peak areas of (I) and (a) to (e) is 100%. The method for producing trifluoroiodomethane according to claim 1.

3. The main impurities in the trifluoroiodomethane separated in step 3) of claim 1 are (a) carbon dioxide (CO ２ ), (b) hydrogen fluoride (HF), (c) tetrafluoromethane (CF ４ ), and (d) carbon monoxide (CO) and (e) trifluoromethane (CF ３ H) as determined by gas chromatography and / or ion chromatography on a peak area basis are (a) ≦0.0005%, (b) ≦0.0005%, (c) ≦0.2%, (d) ≦0.2%, and (e) ≦0.1%, respectively, and trifluoroiodomethane (CF ３ I) to 99.5% or more (excluding trifluoroiodomethane (CF ３ The sum of the peak areas of (I) and (a) to (e) is 100%. The method for producing trifluoroiodomethane according to claim 1.

4. The main impurities in the trifluoromethane separated in step 3) of claim 1 are (a) carbon dioxide (CO ２ ), (b) hydrogen fluoride (HF), (c) tetrafluoromethane (CF ４ ), and (d) carbon monoxide (CO) and (e) trifluoromethane (CF ３ The content ratios of trifluoroiodomethane (CF), based on the peak area determined by gas chromatography and / or ion chromatography, are (a) ≦0.0.0005%, (b) ≦0.0005%, (c) ≦8.0%, (d) ≦1.0%, and (e) ≧80.0%, respectively (provided that trifluoroiodomethane (CF ３ The sum of the peak areas of (a) to (e) is 100%, excluding (I), The method for producing trifluoroiodomethane according to claim 1.

5. The method for producing trifluoroiodomethane according to claim 1, wherein the trifluoroiodomethane separated in step 3) is stored.

6. 2. The method for producing trifluoroiodomethane according to claim 1, wherein the trifluoromethane separated in step 3) is stored.

7. 2. The method for producing trifluoroiodomethane according to claim 1, wherein the trifluoromethane separated in step 3) of claim 1 is recycled to step 1) of claim 1.

8. 3. The method for producing trifluoroiodomethane according to claim 1, wherein the stored trifluoromethane is supplied to step 1) of claim 1.

9. The major impurities in trifluoroiodomethane are: (a) carbon dioxide (CO ２ ), (b) hydrogen fluoride (HF), (c) tetrafluoromethane (CF ４ ), and (d) carbon monoxide (CO) and (e) trifluoromethane (CF ３ H) as determined by gas chromatography and / or ion chromatography on a peak area basis are (a) ≦0.0005%, (b) ≦0.0005%, (c) ≦0.2%, (d) ≦0.2%, and (e) ≦0.1%, respectively, and trifluoroiodomethane (CF ３ I) to 99.5% or more (excluding trifluoroiodomethane (CF ３ The sum of the peak areas of (I) and (a) to (e) is 100%.

10. Alkaline medium contact unit: Inlet for receiving alkaline media a gas inlet for receiving a reactant gas Means for contacting the alkaline medium with the reaction gas Outlet for discharging reaction gas after treatment Piping for supplying the treated reaction gas to the distillation unit Distillation unit: A gas inlet for receiving the reaction gas after processing Means for distilling the reaction gas after treatment CF separated by distillation ３ I reservoir CF separated by distillation ３ H storage tank CF separated by distillation ３ Outlet for discharging I CF separated by distillation ３ Outlet for discharging H CF separated by distillation ３ H to CF ３ Piping for supplying to the H storage unit CF ３ H storage unit: CF separated by distillation ３ Entrance to accept H Means for agitating the gas in the storage unit Raw material CF ３ Outlet for discharging H Raw material CF ３ Piping for supplying H to the mixing unit Mixed gas generation unit: Raw material CF ３ Entrance to accept H Raw material I ２ Inlet for receiving the solution Raw material CF ３ H is raw material I ２ CF ３ H and I ２ A means for generating a mixed gas with Outlet for discharging the generated mixed gas Piping for supplying mixed gas to the reaction unit Reaction unit: Inlet for receiving mixed gases The mixed gas is introduced into the packed solid catalyst. ３ Means for generating I Generated CF ３ an outlet for discharging the reaction gas containing I CF ３ Piping for supplying a reaction gas containing I to an alkaline medium contact unit A trifluoroiodomethane production system comprising:

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