Method for preparing high-purity trifluoroiodomethane

Abstract

The invention relates to a method for preparing high-purity trifluoroiodomethane. The present disclosure provides a method for purifying trifluoroiodomethane. The process comprises providing a process stream comprising trifluoroiodomethane, organic impurities, and acid impurities; reacting the process stream with an aqueous alkaline solution comprising water and at least one base selected from the group consisting of alkali metal carbonates and alkali metal hydroxides; and separating at least some of the organic impurities from the process stream.

Description

[0001] This application is a divisional application of the invention patent application with application date of December 3, 2019, application number 201980078943.7, and name “Method for preparing high-purity trifluoroiodomethane”. Technical Field

[0002] The present disclosure relates to a method for preparing high-purity trifluoroiodomethane (CF3I). Specifically, the present disclosure relates to a method for purifying trifluoroiodomethane to obtain high-purity trifluoroiodomethane in high yield. Background Art

[0003] Trifluoroiodomethane (CF3I), also known as perfluoromethyl iodide, trifluoromethyl iodide or iodotrifluoromethane, is a compound that can be used in commercial applications, such as as a refrigerant or fire extinguishing agent. CF3I is a low global warming potential molecule with almost no ozone depletion potential. CF3I can replace more environmentally harmful substances.

[0004] There are several known methods for preparing CF3I and compositions comprising CF3I. Many of these methods relate to direct catalytic iodination of suitable precursor compounds comprising CF3 groups. In many of these methods, the crude process stream comprising CF3I may also include organic impurities, acid impurities and water. For example, organic impurities may include fluorinated hydrocarbons and iodinated hydrocarbons, such as pentafluoroethane (HFC-125), hexafluoropropylene (HFO-1216), 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea), 1,1,3,3,3-pentafluoropropylene (HFO-1225zc), 1,1,1,3,3,3-hexafluoropropane (HFC-236fa) and / or methyl iodide (CH3I). Organic impurities may also include carbon dioxide (CO2). Organic impurities may be formed as byproducts during the preparation of CF3I, and / or may be present in reactants or other starting materials for the preparation of CF3I.

[0005] According to the U.S. Department of Agriculture, CH3I exhibits moderate to high acute toxicity by inhalation and ingestion. The specification for CH3I in high purity CF3I required for toxicity assessment is less than 5 ppm. The concentration of CH3I in the crude process stream can typically be about 1,000 ppm and can be as high as 5,000 ppm.

[0006] Acid impurities may include, for example, hydrogen fluoride (HF), hydrogen chloride (HCl), hydrogen iodide (HI) and / or trifluoroacetic acid (TFA). Acid impurities may be formed as byproducts during the preparation of CF3I, and / or may be present in reactants or other starting materials for the preparation of CF3I. The concentration of acid impurities in the crude process stream may be in the range of about 20ppm to about 100ppm. Water may also be present in reactants or other starting materials for the preparation of CF3I. The concentration of water in the crude process stream may be in the range of about 5ppm to about 100ppm. The presence of acid impurities and water in the crude process stream produces a corrosive medium, which may have a harmful effect on downstream processing equipment such as distillation towers, pumps, pipelines, sensors, storage tanks, etc. Corrosion resulting in equipment replacement and / or maintenance may reduce the overall efficiency of the purification process. High-purity CF3I must have no more than 1ppm of acid impurities and no more than 10ppm of water.

[0007] Therefore, there is a need for a purification process that can remove sufficient organic impurities (especially CH3I), acid impurities and water to produce high-purity CF3I. Summary of the invention

[0008] The present disclosure provides a method for purifying trifluoroiodomethane (CF3I) to obtain high-purity trifluoroiodomethane in high yield.

[0009] In one form thereof, the present disclosure provides a method for purifying trifluoroiodomethane. The method includes providing a process stream comprising trifluoroiodomethane, organic impurities, and acid impurities; reacting the process stream with an alkaline aqueous solution comprising water and at least one base selected from the group consisting of alkali metal carbonates and alkali metal hydroxides; and separating at least some of the organic impurities from the process stream.

[0010] In the reaction step, the at least one alkali may include an alkali carbonate. The concentration of the alkali carbonate in the alkaline aqueous solution may be from about 0.01 wt % to about 20 wt %. The concentration of the alkali carbonate in the alkaline aqueous solution may be from about 0.5 wt % to about 5 wt %. The alkali carbonate may include sodium carbonate.

[0011] The at least one base may include an alkali metal hydroxide. The concentration of the alkali metal hydroxide in the alkaline aqueous solution may be from about 0.01 wt % to about 20 wt %. The concentration of the alkali metal hydroxide in the alkaline aqueous solution may be from about 0.5 wt % to about 1 wt %. The alkali metal hydroxide may include potassium hydroxide.

[0012] During the reacting step, the temperature of the process stream may be from about 5°C to about 80°C, and the pressure of the process stream may be from about 1 psig to about 100 psig.

[0013] In the providing step, the organic impurities may include methyl iodide. The concentration of methyl iodide in the process stream may be reduced by about 1% to about 70% by the reacting step, based on the GC area % of the total organic compounds. The reacting step may be performed before the separating step. The reacting step may be performed after the separating step.

[0014] The method may also include an additional drying step immediately following the reacting step to remove at least some water from the process stream. After the reacting step, the drying step, and the separating step, the process stream may contain at least about 99% by weight trifluoroiodomethane, less than about 50 ppm iodomethane, less than about 100 ppm water, and less than about 20 ppm acid impurities. The method may be a continuous process.

[0015] In another form thereof, the present disclosure provides a method for purifying trifluoroiodomethane. The method includes providing a process stream comprising trifluoroiodomethane, organic impurities, and acid impurities; contacting the process stream with an acid reactant; and separating at least some of the organic impurities from the process stream.

[0016] The acid reactant may include an alumina adsorbent. During the contacting step, the process stream may be in a liquid phase, and the temperature of the process stream may be about -50°C to about 50°C, and the pressure of the process stream may be about 1 psig to about 100 psig. During the contacting step, the process stream may be in a gas phase, and the temperature of the process stream may be about -20°C to about 60°C, and the pressure of the process stream may be about 1 psig to about 100 psig.

[0017] The contacting step may be performed before the separating step. The contacting step may be performed after the separating step.

[0018] The method may also include an additional drying step immediately after the contacting step to remove at least some water from the process stream. After the contacting step, the drying step, and the separating step, the process stream may contain at least about 99% by weight trifluoroiodomethane, less than about 50 ppm iodomethane, less than about 100 ppm water, and less than about 20 ppm acid impurities.

[0019] The above and other features of the present disclosure and the manner of achieving the same will become more apparent and will be better understood by referring to the following description of the embodiments in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a process flow diagram showing one method for preparing high purity trifluoroiodomethane.

[0021] Figure 2 is a process flow diagram showing another method for preparing high purity trifluoroiodomethane.

[0022] Figure 3 is a process flow diagram showing another method for preparing high purity trifluoroiodomethane.

[0023] Figure 4 is a process flow diagram showing another method for preparing high purity trifluoroiodomethane. DETAILED DESCRIPTION

[0024] The present disclosure provides a method for purifying crude trifluoroiodomethane (CF3I) to obtain high-purity CF3I in high yield. It has been found that the neutralization of acids from process streams containing CF3I is particularly challenging because CF3I can chemically decompose when contacted with alkaline solutions typically used to neutralize acids, resulting in losses of CF3I product.

[0025] Acid impurities can be removed from a process stream by passing the process stream through a scrubber comprising an alkaline aqueous solution. It has been found that acid impurities can be effectively removed from a process stream without significantly decomposing the CF3I by passing a crude process stream comprising CF3I and acid impurities through a scrubber comprising an alkaline aqueous solution comprising water and at least one base within a defined concentration range. The base can be an alkali metal carbonate and / or an alkali metal hydroxide.

[0026] The alkaline aqueous solution may consist essentially of water and at least one base. The alkaline aqueous solution may consist essentially of water and at least one base.

[0027] The base may comprise an alkali metal hydroxide. The base may consist essentially of an alkali metal hydroxide. The base may consist of an alkali metal hydroxide. The alkali metal hydroxide may be selected from the group consisting of sodium hydroxide (NaOH), potassium hydroxide (KOH) and lithium hydroxide (LiOH) and combinations thereof. Preferably, the alkali metal hydroxide may comprise potassium hydroxide. More preferably, the alkali metal hydroxide may consist essentially of potassium hydroxide. Most preferably, the alkali metal hydroxide may consist of potassium hydroxide. The alkali metal hydroxide may consist essentially of sodium hydroxide. The alkali metal hydroxide may consist essentially of sodium hydroxide. The alkali metal hydroxide may consist essentially of lithium hydroxide. The alkali metal hydroxide may consist of lithium hydroxide.

[0028] The crude process stream may also include organic impurities. It has been found that an alkaline aqueous solution in which the base includes an alkali metal hydroxide can also remove a significant percentage of the organic impurity CH3I. CH3I in the process stream can react with the alkali metal hydroxide in the alkaline aqueous solution in the scrubber to form methanol and an alkali metal iodide salt according to Equation 1 below:

[0029] Equation 1: CH3I+XOH→CH3OH+XI,

[0030] wherein XI is potassium iodide, sodium iodide or lithium iodide. Methanol and alkali metal iodide salts are readily soluble in alkaline aqueous solutions and are therefore removed from the process stream.

[0031] It has been found that CH3I undergoes the reaction of Equation 1 more readily than CF3I. Without being bound by any theory, it is believed that the difference in reactivity is due at least in part to the significantly greater solubility of CH3I in water than the solubility of CF3I in water.

[0032] The composition of organic compounds in a process stream can be measured by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) analysis. The plot areas for each organic compound provided by the GC analysis can be combined to provide the GC area percentage (GC area %) of the total organic compounds for each organic compound as a measure of the relative concentration of the organic compound in the process stream.

[0033] The concentration of CH3I in the process stream can be reduced by as little as about 1%, about 5%, about 10%, about 15%, about 20%, about 25%, about 30% or about 35% by a reaction step in which the alkaline aqueous solution comprises an alkali metal hydroxide, or can be as much as about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70% or about 80%, or in any range defined between any two of the foregoing values, such as, for example, about 1% to about 80%, about 5% to about 70%, about 10% to about 65%, about 15% to about 60%, about 20% to about 55%, about 25% to about 50%, about 30% to about 45% or about 35% to about 40%. Preferably, the concentration of CH3I in the process stream can be reduced by about 1% to about 70% by a reaction step. More preferably, the concentration of CH3I in the process stream can be reduced by about 5% to about 50% by a reaction step. Most preferably, the concentration of CH3I in the process stream is reduced by about 5% to about 30% by the reaction step.

[0034] As described below, although CH3I can be effectively removed from the process stream by distillation, removing a significant amount of CH3I by an alkaline aqueous solution prior to distillation can allow the distillation column to operate more efficiently. CH3I can represent the largest component of organic impurities in the process stream. Removing a significant portion of the organic impurities before the distillation column can increase the flow rate of the process stream through the distillation column and increase the rate at which high-purity CF3I can be produced. Alternatively or in addition, reducing organic impurities before the distillation column can allow the use of a smaller distillation column to obtain the desired production rate of high-purity CF3I.

[0035] Removing a significant amount of CH3I by the alkaline aqueous solution after distillation can also allow the distillation column to operate more efficiently because the distillation column does not have to be operated to produce the final desired purity of CF3I. Removing a significant portion of the organic impurities after distillation can increase the flow rate of the process stream through the distillation column because less organic impurities need to be removed. Alternatively or in addition, reducing organic impurities after the distillation column can allow a smaller distillation column to be used to obtain the desired high purity CF3I production rate.

[0036] It has also been found that at higher concentrations of alkali hydroxide, CF3I can react with the alkali hydroxide in the alkaline aqueous solution in the scrubber and decompose to form carbonyl fluoride, alkali fluoride salt, alkali iodide salt and water according to the following equation 2:

[0037] Equation 2: CF3I+2XOH→CF2O+XI+XF+H2O

[0038] Wherein XI is potassium iodide, sodium iodide or lithium iodide, and XF is potassium fluoride, sodium fluoride or lithium fluoride. Therefore, the concentration of alkali metal hydroxide in the alkaline aqueous solution must be strictly controlled to limit this decomposition of CF3I during the purification process and maintain the yield of CF3I.

[0039] The concentration of the alkali metal hydroxide (as a percentage of the total weight of the alkaline aqueous solution) can be as low as about 0.01 weight percent (wt %), about 0.02 wt %, about 0.05 wt %, about 0.1 wt %, about 0.2 wt %, about 0.5 wt %, or about 1 wt %, or as high as about 2 wt %, about 5 wt %, about 10 wt %, about 15 wt %, or about 20 wt %, or within any range defined between any two of the foregoing values, such as, for example, about 0.01 wt % to about 20 wt %, about 0.02 wt % to about 15 wt %, about 0.05 wt % to about 12 wt %, about 0.1 wt % to about 10 wt %, about 0.2 wt % to about 5 wt %, about 0.5 wt % to about 2 wt %, about 0.5 wt % to about 5 wt %, about 0.05 wt % to about 1 wt %, about 0.5 wt % to about 1 wt %, or about 0.1 wt % to about 5 wt %. Preferably, the concentration of the alkali metal hydroxide may be from about 0.1 wt % to about 5 wt %. More preferably, the concentration of the alkali metal hydroxide may be from about 0.5 wt % to about 1 wt %. Most preferably, the concentration of the alkali metal hydroxide may be about 0.5 wt %.

[0040] It has also been found that alkaline aqueous solutions in which the base comprises an alkali metal carbonate do not remove a significant percentage of the organic impurity CH3I, but do cause less significant decomposition of CF3I. Therefore, it may be preferred to use alkaline aqueous solutions in which the base comprises an alkali metal carbonate rather than an alkali metal hydroxide to retain more CF3I and to rely solely on separation methods to remove CH3I from the process stream, as described below.

[0041] The base may comprise an alkali carbonate. The base may consist essentially of an alkali carbonate. The base may consist of an alkali carbonate. The alkali carbonate may be selected from the group consisting of sodium carbonate (Na2CO3), potassium carbonate (K2CO3) and lithium carbonate (Li2CO3) and combinations thereof. Preferably, the alkali carbonate may comprise sodium carbonate. More preferably, the alkali carbonate may consist essentially of sodium carbonate. Most preferably, the alkali carbonate may consist essentially of sodium carbonate. The alkali carbonate may consist essentially of potassium carbonate. The alkali carbonate may consist essentially of potassium carbonate. The alkali carbonate may consist essentially of lithium carbonate. The alkali carbonate may consist of lithium carbonate.

[0042] The concentration of alkali carbonate (as a percentage of the total weight of the alkaline aqueous solution) can be as low as about 0.01 weight percent (wt%), about 0.02 wt%, about 0.05 wt%, about 0.1 wt%, about 0.2 wt%, about 0.5 wt% or about 1 wt%, or up to about 2 wt%, about 5 wt%, about 10 wt%, about 15 wt% or about 20 wt%, or in any range defined between any two of the foregoing values, such as, for example, about 0.01 wt% to about 20 wt%, about 0.02 wt% to about 15 wt%, about 0.05 wt% to about 12 wt%, about 0.1 wt% to about 10 wt%, about 0.2 wt% to about 5 wt%, about 0.5 wt% to about 2 wt%, or about 0.5 wt% to about 5 wt%. Preferably, the concentration of alkali carbonate can be about 0.1 wt% to about 10 wt%. More preferably, the concentration of alkali carbonate can be about 0.5 wt% to about 5 wt%. Most preferably, the concentration of the alkali metal carbonate may be about 5% by weight.

[0043] The contact time between the process stream and the alkaline aqueous solution is not particularly critical and can be as short as 0.5 seconds. The contact time can be much longer and still not cause significant decomposition of CF3I.

[0044] When passing through the scrubber, the process stream can be in the gas phase or the liquid phase. The pressure and temperature of the process stream passing through the scrubber should be strictly controlled to limit unwanted secondary reactions involving CF3I.

[0045] When passing through the scrubber, the temperature of the process stream may be as low as about 5°C, about 10°C, about 15°C, about 20°C, about 25°C, or about 30°C, or as high as about 40°C, about 50°C, about 60°C, about 70°C, or about 80°C, or any temperature within any range defined between any two of the foregoing values, such as, for example, about 5°C to about 80°C, about 10°C to about 70°C, about 15°C to about 60°C, about 20°C to about 50°C, about 25°C to about 40°C, or about 20°C to about 40°C. Preferably, the process stream temperature in the scrubber may be about 10°C to about 50°C. More preferably, the process stream temperature in the scrubber may be about 20°C to about 40°C.

[0046] When passing through the scrubber, the pressure of the process stream can be as low as about 1 psig, about 2 psig, about 3 psig, about 5 psig, about 10 psig, about 20 psig, about 25 psig or about 30 psig, or up to about 40 psig, about 50 psig, about 60 psig, about 70 psig, about 80 psig, about 90 psig or about 100 psig, or any pressure in any range limited between any two aforementioned values, such as for example about 1 psig to about 100 psig, about 2 psig to about 90 psig, about 3 psig to about 80 psig, about 5 psig to about 70 psig, about 5 psig to about 60 psig, about 5 psig to about 50 psig, about 5 psig to about 40 psig or about 5 psig to about 50 psig. Preferably, the process stream pressure in the scrubber can be about 3 psig to about 80 psig. More preferably, the process stream pressure in the scrubber can be about 5 psig to about 50 psig.

[0047] Alternatively or in addition, acid impurities may be removed from the process stream by passing the process stream through an adsorption column comprising an acid activator.An acid activator is a material that adsorbs acids.

[0048] The acid-activated agent may include at least one adsorbent selected from the group consisting of aluminum oxide, alkali metal oxides, alkaline earth metal oxides, metal hydroxides, aluminosilicate minerals, zirconium oxide, and silicon dioxide. The acid-activated agent may be an adsorbent selected from the group consisting of aluminum oxide, alkali metal oxides, alkaline earth metal oxides, metal hydroxides, aluminosilicate minerals, zirconium oxide, silicon dioxide, and combinations thereof.

[0049] It has been discovered that by passing a process stream containing CF3I through an adsorption column containing an acid activating agent that does not induce or detrimentally affect the decomposition of CF3I, acid impurities in the process stream can be effectively removed without significantly reducing the yield of CF3I.

[0050] The acid activator may include alumina. The acid activator may consist essentially of alumina. The acid activator may consist of alumina. The alumina may include one or more types of alumina. The alumina may be an activated alumina, such as, for example, P-188 or CLR-204 purchased from Honeywell (UOP LLC, Des Plaines, IL), HF-200XP purchased from BASF, Iselin, NJ, or an alumina catalyst support purchased from Alfa Aesar, Haverhill, MA.

[0051] The contact time between the process stream and the adsorption column containing the acid activator is not particularly critical and can be as short as 0.5 seconds. The contact time can be much longer and still not cause significant decomposition of CF3I.

[0052] When passing through an adsorption column containing an acid activator, the process stream may be in the gas phase or the liquid phase.

[0053] When passing through the adsorption tower in the liquid phase, the temperature of the process stream can be as low as about -50°C, about -45°C, about -40°C, about -35°C, about -30°C, about -25°C, about -20°C, or about -15°C, or as high as about -10°C, about -5°C, about 0°C, about 5°C, about 10°C, about 15°C, about 20°C, about 25°C, about 30°C, about 35°C, about 40°C, about 45°C, or about 50°C, or any temperature in any range defined between any two of the foregoing values, such as, for example, about -50°C to about 50°C, about -40°C to about 45°C, about -30°C to about 40°C, about -25°C to about 35°C, about -10°C to about 30°C, or about 0°C to about -25°C. Preferably, the temperature of the process stream in the adsorption tower may be about 0°C to about 35°C. More preferably, the temperature of the process stream in the adsorption tower may be about 10°C to about 30°C.

[0054] When passing through the adsorption tower in the liquid phase, the pressure of the process stream can be as low as about 1 psig, about 5 psig, about 10 psig, about 20 psig, about 25 psig or about 30 psig, or as high as about 40 psig, about 50 psig, about 60 psig, about 70 psig, about 80 psig, about 90 psig or about 100 psig, or any pressure within any range defined between any two of the foregoing values, such as, for example, about 1 psig to about 100 psig, about 5 psig to about 90 psig, about 10 psig to about 80 psig, about 15 psig to about 70 psig, about 20 psig to about 60 psig, about 25 psig to about 50 psig, about 30 psig to about 40 psig or about 20 psig to about 50 psig. Preferably, the process stream pressure in the adsorption tower can be about 10 psig to about 90 psig. More preferably, the process stream pressure in the adsorption tower can be about 20 psig to about 50 psig.

[0055] When passing through the adsorption tower in the gas phase, the temperature of the process stream can be as low as about -20°C, about -15°C, about -10°C, about -5°C, about 0°C, about 5°C, about 10°C, or about 15°C, or as high as about 20°C, about 25°C, about 30°C, about 35°C, about 40°C, about 45°C, about 50°C, about 55°C, or about 60°C, or any temperature in any range defined between any two of the foregoing values, such as, for example, about -20°C to about 60°C, about -10°C to about 50°C, about 0°C to about 40°C, about 10°C to about 30°C, about -5°C to about 50°C, or about 15°C to about 40°C. Preferably, the temperature of the process stream in the adsorption tower may be about -5°C to about 50°C. More preferably, the temperature of the process stream in the adsorption tower may be about 15°C to about 40°C.

[0056] When passing through the adsorption tower in the gas phase, the pressure of the process stream can be as low as about 1 psig, about 5 psig, about 10 psig, about 20 psig, about 25 psig or about 30 psig, or as high as about 40 psig, about 50 psig, about 60 psig, about 70 psig, about 80 psig, about 90 psig or about 100 psig, or any pressure within any range defined between any two of the foregoing values, such as, for example, about 1 psig to about 100 psig, about 5 psig to about 90 psig, about 10 psig to about 80 psig, about 15 psig to about 70 psig, about 20 psig to about 60 psig, about 25 psig to about 50 psig, about 30 psig to about 40 psig or about 20 psig to about 50 psig. Preferably, the process stream pressure in the adsorption tower can be about 10 psig to about 90 psig. More preferably, the process stream pressure in the adsorption tower can be about 15 psig to about 80 psig.

[0057] Water can be removed from the process stream by a drying step. The drying step may include contacting the process stream with a desiccant. The desiccant may include at least one adsorbent selected from the group consisting of anhydrous calcium chloride, anhydrous calcium sulfate, concentrated sulfuric acid, silicon dioxide, activated carbon and zeolite. The desiccant may be selected from the group consisting of anhydrous calcium chloride, anhydrous calcium sulfate, concentrated sulfuric acid, silicon dioxide, activated carbon, zeolite and a combination thereof. The desiccant may preferably be a 3A molecular sieve. It has been found that the 3A molecular sieve does not induce or is not conducive to the decomposition of CF3I.

[0058] The drying step is preferably performed immediately after the acid impurities are removed from the process stream. This allows the water collected in the scrubber to be removed as well as any moisture present in the crude CF3I process stream when the acid impurities are removed from the process stream by passing the process stream through a scrubber containing an alkaline aqueous solution.

[0059] When the acid impurities are removed from the process stream by passing the process stream through an adsorption column containing an acid activator, it is also preferred to carry out a drying step immediately after the acid impurities are removed from the process stream. This allows the water generated when the acid impurities are removed from the process stream as well as any water present in the crude CF3I process stream to be removed.

[0060] Organic impurities can be removed from the process stream by a separation step. The separation step can include distilling the process stream. The distillation process stream can include a first distillation and a second distillation. The first distillation can remove organic impurities with a boiling point lower than CF3I from the process stream. Such low-boiling organic impurities can include, for example, CO2. The second distillation can remove organic impurities with a boiling point higher than CF3I from the process stream. Such high-boiling organic impurities can include, for example, CH3I. Separating CH3I from a process stream containing CF3I by distillation can be preferred because the boiling point of CH3I under standard conditions is 42°C, which is much higher than the boiling point of CF3I under standard conditions of -22°C.

[0061] Alternatively or in addition, the distillation process may include a single distillation, wherein organic impurities having a boiling point lower than CF3I are removed through an overhead stream, and then CF3I is obtained through the overhead stream, while organic impurities having a boiling point higher than CF3I are concentrated in a reboiler.

[0062] The distillation of the process stream can be carried out in a continuous process or a batch process. A single distillation may be more suitable for a batch process, while a distillation process including a first distillation and a second distillation may be more suitable for a continuous process.

[0063] After reacting with an alkaline aqueous solution and / or contacting with an acid activator to remove at least some acid impurities, drying the process stream to remove at least some water, and separating at least some organic impurities from the process stream, the concentration of CF3I in the purified process stream may be greater than about 99% by weight. Preferably, the concentration of CF3I in the purified process stream may be greater than about 99.5% by weight. More preferably, the concentration of CF3I in the purified process stream may be greater than about 99.9% by weight. Most preferably, the concentration of CF3I in the purified process stream may be greater than about 99.99% by weight.

[0064] After reacting with an alkaline aqueous solution and / or contacting with an acid activator to remove at least some acid impurities, drying the process stream to remove at least some water, and separating at least some organic impurities from the process stream, the concentration of CH3I in the purified process stream may be less than about 50 parts per million (ppm). Preferably, the concentration of CH3I in the purified process stream may be less than about 20 ppm. More preferably, the concentration of CH3I in the purified process stream may be less than about 10 ppm. Most preferably, the concentration of CH3I in the purified process stream may be less than about 5 ppm.

[0065] After reacting with the alkaline aqueous solution and / or contacting with an acid activator to remove at least some of the acid impurities, drying the process stream to remove at least some of the water, and separating at least some of the organic impurities from the process stream, the concentration of acid impurities in the purified process stream may be less than about 20 parts per million (ppm). Preferably, the concentration of acid impurities in the purified process stream may be less than about 10 ppm. More preferably, the concentration of acid impurities in the purified process stream may be less than about 5 ppm. Most preferably, the concentration of acid impurities in the purified process stream may be less than about 1 ppm.

[0066] After reacting with the alkaline aqueous solution and / or contacting with an acid activator to remove at least some of the acid impurities, drying the process stream to remove at least some of the water, and separating at least some of the organic impurities from the process stream, the concentration of water in the purified process stream may be less than about 100 parts per million (ppm). Preferably, the concentration of water in the purified process stream may be less than about 50 ppm. More preferably, the concentration of water in the purified process stream may be less than about 30 ppm. Most preferably, the concentration of water in the purified process stream may be less than about 10 ppm.

[0067] It has been found that the purified process stream prepared as described above can obtain a high purity CF3I product. The method produces good process yields and is suitable for the production of CF3I on a commercial scale.

[0068] Figure 1 FIG. 1 is a process flow diagram showing a method 10 for producing high purity CF3I. Figure 1 As shown, the process 10 may include a crude process stream 12 and an alkaline aqueous solution 14 flowing into a scrubber 16. The crude process stream 12 and the alkaline aqueous solution 14 may be as described above. The alkaline aqueous solution 14 may react with the crude process stream 12 within the scrubber 16 to neutralize and dissolve acid impurities present in the crude process stream 12, thereby forming a first intermediate process stream 18. The reacted alkaline aqueous solution 14 with the neutralized and dissolved acid impurities may flow out of the scrubber via a scrubber waste stream 20 for disposal or recycling.

[0069] The first intermediate process stream 18 may flow to an adsorption tower 22. The adsorption tower 22 may contain any of the above-mentioned desiccants. When the first intermediate process stream 18 contacts the desiccant in the adsorption tower 22, the desiccant adsorbs the water in the first intermediate process stream 18 to produce a dry second intermediate process stream 24.

[0070] The second intermediate process stream 24 may flow to a first distillation column 26. The first distillation column 26 may be configured to separate organic impurities having a boiling point lower than CF3I from the second intermediate process stream 24. The separated organic impurities having a boiling point lower than CF3I may be removed via a volatile organic overhead stream 30. CF3I and the remaining organic impurities may flow from the bottom of the first distillation column 26 to form a third intermediate process stream 32.

[0071] The third intermediate process stream 32 may flow to a second distillation column 34. The second distillation column 34 may be configured to separate organic impurities having a boiling point higher than CF3I from the third intermediate process stream 32. High purity CF3I is collected from the overhead product process stream 36, as described above. Organic impurities having a boiling point higher than CF3I, such as CH3I, may flow out of the bottom of the second distillation column 34 to form a non-volatile organic waste stream 38.

[0072] Figure 2 FIG. 4 is a process flow diagram showing another method 40 for producing high purity CF3I. Figure 2 As shown, the process 40 may include a crude process stream 42 flowing into a first distillation column 44. The crude process stream 42 may be as described above. The first distillation column 44 may be configured to separate organic impurities having a boiling point lower than CF3I from the crude process stream 42. The separated organic impurities having a boiling point lower than CF3I may be removed via a volatile organic overhead stream 46. CF3I and the remaining organic impurities may flow out of the bottom of the first distillation column 44 to form a first intermediate process stream 48.

[0073] The first intermediate process stream 48 may flow to a second distillation column 50. The second distillation column 50 may be configured to separate organic impurities having a boiling point higher than CF3I from the first intermediate process stream 48 to form a second intermediate process stream 52 from the top of the second distillation column 50. Organic impurities having a boiling point higher than CF3I, such as CH3I, may flow out from the bottom of the second distillation column 50 to form a non-volatile organic waste stream 54.

[0074] The second intermediate process stream 52 and the alkaline aqueous solution 56 may flow into a scrubber 58. The alkaline aqueous solution may be as described above. The alkaline aqueous solution 56 may react with the second intermediate process stream 52 within the scrubber 58 to neutralize and dissolve the acid impurities present in the second intermediate process stream 52, thereby forming a third intermediate process stream 60. The reacted alkaline aqueous solution 56 with the neutralized and dissolved acid impurities may flow out of the scrubber through a scrubber waste stream 62 for disposal or recycling.

[0075] The third intermediate process stream 60 may flow to an adsorption column 64. The adsorption column 64 may contain any of the above-described desiccants. When the third intermediate process stream 60 contacts the desiccant within the adsorption column 64, the desiccant adsorbs the water in the third intermediate process stream 60 to produce a dry, high-purity CF3I process stream 66, as described above.

[0076] Figure 3 FIG. 6 is a process flow diagram showing another method 68 for producing high purity CF3I. Figure 3 As shown, the method 68 may include a crude process stream 70 and an adsorption tower 72. The crude process stream 70 may be as described above. The adsorption tower 72 may include a first acid activator 74, a second acid activator 76, and a desiccant 78. The first acid activator 74 may be any one of the above-mentioned acid activators, such as, for example, alumina P-188. The second acid activator 76 may be any one of the above-mentioned acid activators, as long as it is different from the first acid activator 74. The second acid activator 76 may be, for example, alumina CLR-204. It may be preferred to use more than one acid activator because different acid activators may have greater affinity for different acid impurities. The desiccant 78 may be any one of the above-mentioned desiccants, such as, for example, 3A molecular sieves.

[0077] The crude process stream 70 may flow into an adsorption column 72 and contact a first acid activator 74 and then a second acid activator 76 to remove at least some acid impurities from the crude process stream 70. The crude process stream 70 may then contact a desiccant 78 to remove at least some water from the crude process stream 70, thereby producing a first intermediate process stream 80.

[0078] The first intermediate process stream 80 may flow to a first distillation column 82. The first distillation column 82 may be configured to separate organic impurities having a boiling point lower than CF3I from the first intermediate process stream 80. The separated organic impurities having a boiling point lower than CF3I may be removed via a volatile organic overhead stream 84. CF3I and remaining organic impurities may flow out of the bottom of the first distillation column 82 to form a second intermediate process stream 86.

[0079] The second intermediate process stream 86 may flow to a second distillation column 88. The second distillation column 88 may be configured to separate organic impurities having a boiling point higher than CF3I from the second intermediate process stream 86. High purity CF3I is collected from the overhead product process stream 90, as described above. Organic impurities having a boiling point higher than CF3I, such as CH3I, may flow out of the bottom of the second distillation column 88 to form a non-volatile organic waste stream 92.

[0080] Figure 4 FIG. 9 is a process flow diagram showing another method 94 for producing high purity CF3I. Figure 4As shown, the process 94 may include a crude process stream 96 flowing into a first distillation column 98. The crude process stream 96 may be as described above. The first distillation column 98 may be configured to separate organic impurities having a boiling point lower than CF3I from the crude process stream 96. The separated organic impurities having a boiling point lower than CF3I may be removed via a volatile organic overhead stream 100. CF3I and the remaining organic impurities may flow from the bottom of the first distillation column 98 to form a first intermediate process stream 102.

[0081] The first intermediate process stream 102 may flow to the second distillation column 104. The second distillation column 104 may be configured to separate organic impurities having a boiling point higher than CF3I from the first intermediate process stream 102 to form a second intermediate process stream 106 from the top of the second distillation column 104. Organic impurities having a boiling point higher than CF3I, such as CH3I, may flow out from the bottom of the second distillation column 104 to form a non-volatile organic waste stream 108.

[0082] The second intermediate process stream 106 may flow into an adsorption tower 110. The adsorption tower 110 may include a first acid activator 112, a second acid activator 114, and a desiccant 116. The first acid activator 112 may be any of the above-mentioned acid activators, such as, for example, alumina P-188. The second acid activator 114 may be any of the above-mentioned acid activators, as long as it is different from the first acid activator 112. The second acid activator 114 may be, for example, alumina CLR-204. The desiccant 116 may be any of the above-mentioned desiccants, such as, for example, 3A molecular sieves.

[0083] As the second intermediate process stream 106 flows into the adsorption column 110 and contacts the first acid activator 112 and then the second acid activator 114, at least some of the acid impurities are removed from the second intermediate process stream 106. The second intermediate process stream 106 may then contact a desiccant 116 to remove at least some of the water from the second intermediate process stream 106, thereby producing a dry, high purity CF3I process stream 118, as described above.

[0084] Although the present invention has been described with respect to exemplary designs, the present invention may be further modified within the spirit and scope of the present disclosure. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains.

[0085] As used herein, the phrase "in any range defined between any two preceding values" literally means that any range can be selected from any two values ​​listed before such phrase, regardless of whether these values ​​are in the lower part of the list or in the upper part of the list. For example, a pair of values ​​can be selected from two lower values, two higher values, or a lower value and an upper value.

[0086] Example

[0087] Example 1: Effect of Alkali Metal Hydroxide Concentration on Crude CF3I

[0088] In this embodiment, the influence of alkali metal hydroxide concentration on rough CF according to above-mentioned equations 1 and 2 is shown.At room temperature, the rough starting material of 100g amount by 99.88GC area %CF3I, 0.08GC area %CH3I and 0.04GC area % other organic impurities is loaded into six 150ml cylinders.Before loading the rough starting material, six cylinders are evacuated.Prepare six different test solutions that potassium hydroxide concentration changes from 0 wt % to 20 wt %.Each of the six test solutions is added to each of the six cylinders with an amount of 50ml.At room temperature, the average pressure in the sample cylinder is 70psig.Six cylinders are shaken at room temperature for five days.Five days are much longer than the typical process contact time, but five days are selected to provide a clearer indication of the relative influence of various potassium hydroxide concentrations on the rough starting material.

[0089] After five days, take out the sample of water layer and the sample of organic layer from each of six cylinders.Analyze six water layer samples by ion chromatography to determine the amount of fluoride generated during the interaction between rough CF3I and six kinds of test solutions.The results are shown in the following table 1.Analyze six organic layer samples by GC to determine the concentration change of CF3I, CH3I and other organic impurities.The results are shown in Table 2.

[0090] Table 1 has been listed for each of six potassium hydroxide concentrations, normalized to the CF3I crude amount of fluoride concentration in ppm. Control sample shows the total free fluoride in the crude CF3I. By using the fluoride concentration measured by ion chromatography divided by the gross mass of CF3I in the crude sample measured by GC, each sample is normalized.

[0091] Table 1

[0092] KOH concentration (weight %) Fluoride concentration (ppm) 0(Control) 0.2 0.5 10.5 1 16.7 5 18 10 54.7 20 78.3

[0093] As shown in Table 1, at potassium hydroxide concentrations above about 0.5 wt %, the fluoride concentration increased by more than 10 ppm relative to a control sample not exposed to potassium hydroxide. It is believed that the increase in fluoride is entirely due to the decomposition of CF3I. Therefore, in order to maintain a high CF3I yield throughout the purification process, a potassium hydroxide concentration of about 0.01 wt % to about 0.5 wt % may be preferred.

[0094] Table 2 lists the concentrations of CF3I, CH3I, and other organic impurities for each of the six KOH concentrations.

[0095] Table 2

[0096]

[0097] As shown in Table 2, at potassium hydroxide concentrations above about 1 wt %, a significant portion of the CH3I present in the crude CF3I is removed by the potassium hydroxide solution. Therefore, to remove a significant amount of CH3I, a potassium hydroxide concentration of about 1 wt % to about 20 wt % may be preferred. Considering Tables 1 and 2 simultaneously, when balancing the preservation of CF3I with the removal of CH3I, a potassium hydroxide concentration of about 0.5 wt % to about 5 wt % may be preferred.

[0098] Example 2: Effect of Alkali Metal Carbonate Concentration on Crude CF3I

[0099] In this embodiment, the influence of alkali carbonate concentration on rough CF according to above-mentioned equations 1 and 2 is shown.At room temperature, the rough starting material of 100g amount by 99.88GC area %CF3I, 0.08GC area %CH3I and 0.03GC area % other organic impurities is loaded into six 150ml cylinders.Before loading the rough starting material, six cylinders are evacuated.Prepare six different test solutions that sodium carbonate concentration changes from 0 wt % to 20 wt %.Each of the six test solutions is added to each of the six cylinders with the amount of 50ml.At room temperature, the average pressure in the sample cylinder is 70psig.Six cylinders are shaken at room temperature for five days.Five days are much longer than the typical process contact time, but five days are selected to provide a clearer indication of the relative influence of various sodium carbonate concentrations on the rough starting material.

[0100] After five days, a sample of the water layer and a sample of the organic layer were taken out from each of the six cylinders. The six water layer samples were analyzed by ion chromatography to determine the amount of fluoride generated during the interaction between the crude CF3I and the six test solutions. The results are shown in Table 3.

[0101] Table 3 lists the fluoride concentration in ppm normalized to the amount of crude CF3I for each of the six sodium carbonate concentrations.

[0102] Table 3

[0103] <![CDATA[Concentration of Na2CO3 (wt%)]]> Fluoride concentration (ppm) 0(Control) 0.2 0.5 0.4 1 2 5 5.2 10 46.4 20 59.6

[0104] As shown in Table 3, above the sodium carbonate concentration between about 5% and 10% by weight, the fluoride concentration increases by more than 10 ppm relative to the control sample not exposed to sodium carbonate. It is believed that the increase in fluoride is entirely due to the decomposition of CF3I. Therefore, in order to maintain a high CF3I yield throughout the purification process, it may be preferred that the sodium carbonate concentration is about 0.5% to about 5% by weight.

[0105] Six organic layer samples are analyzed by GC to determine CF3I, CH3I and other organic impurities concentration changes. No significant difference is observed between six organic layer samples. Therefore, even sodium carbonate solution is not significantly affected by CH3I concentration at a concentration up to 20 % by weight. Without being bound by any theory, it is believed that the reactivity difference between potassium hydroxide and sodium carbonate in removing CH3I can be attributed to the following fact: hydroxide ion is a better nucleophilic substance than carbonate ion, and is easy to replace with CH3I. This same impact can also explain why potassium hydroxide is observed to decompose CF3I at a concentration lower than sodium carbonate.

[0106] Example 3: Removal of acid impurities and water from crude CF3I using alumina

[0107] In this embodiment, the effectiveness of aluminum oxide in removing acid impurities from crude CF3I was demonstrated. An adsorption column made of 24-inch long, three-quarter-inch diameter perfluoroalkoxy alkane polymer tubes was prepared by including a P-188 aluminum oxide layer, a CLR-204 aluminum oxide layer, and a 3A molecular sieve layer. Each layer was about eight inches long. An additional indicative anhydrous calcium sulfate thin layer was inserted into the 3A molecular sieve layer to indicate when the 3A molecular layer was exhausted. The column was wrapped in foil to prevent interaction with light.

[0108] About 30 pounds of crude CF3I were circulated through the column in the liquid phase. The crude CF3I was passed through two alumina layers into the column and exited through a 3A molecular sieve layer. The crude CF3I was circulated through the column for seven days. Seven days is much longer than the typical process contact time, but seven days were selected to provide a clearer indication of the relative impact of the two alumina layers on the crude starting material.

[0109] After seven days, the acid impurity concentration and water concentration of the crude CF3I sample were analyzed. The acid impurity concentration was measured by acid-base titration. The water concentration was measured by Karl-Fisher titration. The results are shown in Table 4 below.

[0110] Table 4

[0111] Material Acidity in HCl (ppm) Water (ppm) <![CDATA[Initial crude CF3I]]> 91.2 15.6 <![CDATA[Crude CF3I after 7 days]]> 6.5 1.8

[0112] The crude CF3I samples were also analyzed by GC to determine the concentration changes of CF3I, CH3I and other organic impurities. The results are shown in Table 5.

[0113] Table 5

[0114]

[0115] Considering Tables 4 and 5 together, the adsorption column containing alumina and desiccant significantly reduced acid impurities and water while not causing measurable decomposition of CF3I.

[0116] Example 4: Distillation of crude CF3I

[0117] In this example, the effectiveness of distillation in removing CH3I from crude CF3I is demonstrated. 180 pounds of crude starting material are charged to the reboiler of the distillation column, which consists of 99.4 GC area % CF3I, 0.4 GC area % CH3I and 0.2 GC area % other organic impurities. The distillation column is operated at a pressure in the range of 60 psig to 80 psig, a temperature in the range of 30°C to 40°C and a pressure difference of 10 inches to 30 inches of water column. The distillation rate is in the range of 0.5 pounds / hour to 3 pounds / hour.

[0118] About 5 to 10 pounds of non-condensable gases and low boiling impurities are removed through the overhead stream, followed by CF3I. The purity of CF3I is greater than 99.99%, and the content of CH3I is less than 5 ppm. The yield of distillation is in the range of 90% to 97%. CH3I and other high boiling impurities are concentrated in the reboiler. After distillation, about 2 pounds to 5 pounds of organic impurities are collected from the reboiler.

[0119] Example 5: Purification of crude CF3I

[0120] In this example, the effectiveness of the purification method is demonstrated. A crude feed of 11,323 pounds was bubbled into 1,382 pounds of a 0.52 wt% KOH aqueous solution. The crude feed consisted of CF3I (99.78 GC area %), CH3I (0.15 GC area %), and other substances (0.07 GC area %), with a total acidity of 50 ppm and a water content of 15 ppm. The source tank containing the crude feed was maintained at a temperature of about 30°C, while the crude feed was charged into a caustic tank containing a 0.5 wt% KOH solution at a flow rate of about 5 pounds per minute by a pressure differential. The crude feed was bubbled into the 0.5 wt% KOH solution as a gas. Assuming that in any case the crude feed (gas) only contacts about 10% of the 0.5 wt% KOH solution in the tank, a flow rate of about 5 pounds per minute corresponds to a contact time of about 27.64 minutes. The resulting exhaust gas stream from the caustic tank is passed through a tank filled with A drying column of molecular sieves is then solidified in the reboiler of a distillation column.

[0121] During distillation in the distillation tower, cold water between about 2°C and 5°C is circulated through the condenser at the top of the distillation tower while the reboiler temperature is maintained between about 10°C and 20°C. During distillation, 283 pounds of non-condensable gases and low-boiling impurities are passed through the overhead stream, followed by 10,312 pounds of CF3I at a rate of about 250 pounds / h. The resulting CF3I is measured by GC and found to have a purity greater than 99.99% by weight, a CH3I concentration of less than 5ppm, a total acid concentration of less than 0.1ppm, and a moisture concentration of less than 5ppm. About 390 pounds of higher boiling impurities are recovered from the reboiler. The material balance of the comprehensive purification process is about 97%, and the yield is about 91%. Ion chromatographic analysis of a 0.5% by weight KOH solution after contact with the crude feed shows the presence of about 10ppm of fluoride ions. This indicates that in the caustic tank containing 0.5 wt % KOH solution, only a small amount of CF3I reacted with KOH during the acid removal step despite the longer contact time.

[0122] aspect

[0123] Aspect 1 is a method for purifying trifluoroiodomethane, the method comprising: providing a process stream comprising trifluoroiodomethane, organic impurities, and acid impurities; reacting the process stream with an alkaline aqueous solution comprising water and at least one base selected from the group consisting of alkali metal carbonates and alkali metal hydroxides; and separating at least some of the organic impurities from the process stream.

[0124] Aspect 2 is a method according to aspect 1, wherein the alkaline aqueous solution consists essentially of water and the at least one base, and the at least one base is selected from the group consisting of alkali metal carbonates and alkali metal hydroxides.

[0125] Aspect 3 is a method according to aspect 2, wherein the alkaline aqueous solution consists of water and the at least one base, and the at least one base is selected from the group consisting of alkali metal carbonates and alkali metal hydroxides.

[0126] Aspect 4 is a method according to any one of aspects 1 to 3, wherein in the reacting step, the base comprises an alkali metal carbonate.

[0127] Aspect 5 is a method according to aspect 4, wherein in the reacting step, the base consists essentially of alkali metal carbonate.

[0128] Aspect 6 is a method according to aspect 4, wherein in the reacting step, the base consists of an alkali metal carbonate.

[0129] Aspect 7 is a method according to any one of aspects 4 to 6, wherein the concentration of the alkali metal carbonate in the basic aqueous solution is about 0.01 wt % to about 20 wt %.

[0130] Aspect 8 is a method according to any one of aspects 4-6, wherein the concentration of the alkali metal carbonate in the basic aqueous solution is about 0.1 wt % to about 10 wt %.

[0131] Aspect 9 is a method according to any one of aspects 4-6, wherein the concentration of the alkali metal carbonate in the basic aqueous solution is about 0.5 wt % to about 5 wt %.

[0132] Aspect 10 is a method according to any one of aspects 4-6, wherein the concentration of the alkali metal carbonate in the basic aqueous solution is about 5 wt %.

[0133] Aspect 11 is a method according to any one of aspects 4 to 10, wherein the alkali metal carbonate is selected from the group consisting of sodium carbonate, potassium carbonate, lithium carbonate, and combinations thereof.

[0134] Aspect 12 is a method according to aspect 11, wherein the alkali metal carbonate comprises sodium carbonate.

[0135] Aspect 13 is a method according to any one of aspects 11 or 12, wherein the alkali metal carbonate comprises potassium carbonate.

[0136] Aspect 14 is a method according to any one of aspects 11-13, wherein the alkali metal carbonate comprises lithium carbonate.

[0137] Aspect 15 is a method according to aspect 11, wherein the alkali metal carbonate consists essentially of sodium carbonate.

[0138] Aspect 16 is a method according to aspect 11, wherein the alkali metal carbonate consists of sodium carbonate.

[0139] Aspect 17 is a method according to aspect 11, wherein the alkali metal carbonate consists essentially of potassium carbonate.

[0140] Aspect 18 is a method according to aspect 11, wherein the alkali metal carbonate consists of potassium carbonate.

[0141] Aspect 19 is a method according to aspect 11, wherein the alkali metal carbonate consists essentially of lithium carbonate.

[0142] Aspect 20 is a method according to aspect 11, wherein the alkali metal carbonate consists of lithium carbonate.

[0143] Aspect 21 is a method according to any one of aspects 1-3, wherein in the reacting step, the base comprises an alkali metal hydroxide.

[0144] Aspect 22 is a method according to aspect 21, wherein in the reacting step, the base consists essentially of an alkali metal hydroxide.

[0145] Aspect 23 is a method according to aspect 21, wherein in the reacting step, the base consists of an alkali metal hydroxide.

[0146] Aspect 24 is a method according to any one of aspects 21-23, wherein the concentration of the alkali metal hydroxide in the basic aqueous solution is about 0.01 wt % to about 20 wt %.

[0147] Aspect 25 is a method according to any one of aspects 21-23, wherein the concentration of the alkali metal hydroxide in the basic aqueous solution is about 0.1 wt % to about 5 wt %.

[0148] Aspect 26 is a method according to any one of aspects 21-23, wherein the concentration of the alkali metal hydroxide in the basic aqueous solution is about 0.5 wt % to about 1 wt %.

[0149] Aspect 27 is a method according to any one of aspects 21-23, wherein the concentration of the alkali metal hydroxide in the basic aqueous solution is about 0.5 wt%.

[0150] Aspect 28 is a method according to any one of aspects 21-27, wherein the alkali metal hydroxide is selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, and combinations thereof.

[0151] Aspect 29 is a method according to aspect 28, wherein the alkali metal hydroxide comprises sodium hydroxide.

[0152] Aspect 30 is a method according to any one of aspects 28 or 29, wherein the alkali metal hydroxide comprises potassium hydroxide.

[0153] Aspect 31 is a method according to any one of aspects 28-30, wherein the alkali metal hydroxide comprises lithium hydroxide.

[0154] Aspect 32 is a method according to aspect 28, wherein the alkali metal hydroxide consists essentially of sodium hydroxide.

[0155] Aspect 33 is a method according to aspect 28, wherein the alkali metal hydroxide consists of sodium hydroxide.

[0156] Aspect 34 is a method according to aspect 28, wherein the alkali metal hydroxide consists essentially of potassium hydroxide.

[0157] Aspect 35 is a method according to aspect 28, wherein the alkali metal hydroxide consists of potassium hydroxide.

[0158] Aspect 36 is a method according to aspect 28, wherein the alkali metal hydroxide consists essentially of lithium hydroxide.

[0159] Aspect 37 is a method according to aspect 28, wherein the alkali metal hydroxide consists of lithium hydroxide.

[0160] Aspect 38 is a method according to any one of aspects 1-37, wherein in the reacting step, the temperature of the process stream is about 5°C to about 80°C.

[0161] Aspect 39 is a method according to any one of aspects 1-37, wherein in the reacting step, the temperature of the process stream is about 10°C to about 50°C.

[0162] Aspect 40 is a method according to any one of aspects 1-37, wherein in the reacting step, the temperature of the process stream is about 20°C to about 40°C.

[0163] Aspect 41 is a method according to any one of aspects 1-40, wherein in the reacting step, the pressure of the process stream is about 1 psig to about 100 psig.

[0164] Aspect 42 is a method according to any one of aspects 1-40, wherein in the reacting step, the pressure of the process stream is about 3 psig to about 80 psig.

[0165] Aspect 43 is a method according to any one of aspects 1-40, wherein in the reacting step, the pressure of the process stream is about 5 psig to about 50 psig.

[0166] Aspect 44 is a method according to any one of aspects 1-43, wherein the method is a continuous process.

[0167] Aspect 45 is a method according to any one of aspects 1-43, wherein the method is a batch process.

[0168] Aspect 46 is a method according to any one of aspects 1-45, wherein in the providing step, the organic impurities include methyl iodide and the base includes an alkali metal hydroxide, and the concentration of the methyl iodide in the process stream is reduced by about 1% to about 70% by the reacting step in terms of GC area % of total organic compounds.

[0169] Aspect 47 is a method according to any one of Aspects 1-45, wherein in the providing step, the organic impurities include methyl iodide and the base includes an alkali metal hydroxide, and the concentration of the methyl iodide in the process stream is reduced by about 5% to about 50% by the reacting step in terms of GC area % of total organic compounds.

[0170] Aspect 48 is a method according to any one of aspects 1-45, wherein in the providing step, the organic impurities include methyl iodide and the base includes an alkali metal hydroxide, and the concentration of the methyl iodide in the process stream is reduced by about 5% to about 30% by the reacting step in terms of GC area % of total organic compounds.

[0171] Aspect 49 is a method according to any one of aspects 1-46, wherein the reacting step is performed before the separating step.

[0172] Aspect 50 is a method according to any one of aspects 1-46, wherein the reacting step is performed after the separating step.

[0173] Aspect 51 is a method according to any one of aspects 1-48, further comprising an additional drying step immediately after the reacting step to remove at least some of the water from the process stream.

[0174] Aspect 52 is a method according to aspect 51, wherein the drying step comprises contacting the process stream with a desiccant.

[0175] Aspect 53 is a method according to aspect 52, wherein the desiccant comprises at least one adsorbent selected from the group consisting of anhydrous calcium chloride, anhydrous calcium sulfate, concentrated sulfuric acid, silica, activated carbon, and zeolite.

[0176] Aspect 54 is a method according to aspect 51, wherein the drying step comprises passing the process stream through at least one 3A molecular sieve.

[0177] Aspect 55 is a method according to any one of aspects 1-54, wherein after the reacting step, the drying step, and the separating step, the process stream comprises at least about 99 weight percent trifluoroiodomethane.

[0178] Aspect 56 is a method according to any one of aspects 1-54, wherein after the reacting step, the drying step, and the separating step, the process stream comprises at least about 99.5 wt% trifluoroiodomethane.

[0179] Aspect 57 is a method according to any one of aspects 1-54, wherein after the reacting step, the drying step, and the separating step, the process stream comprises at least about 99.9 weight percent trifluoroiodomethane.

[0180] Aspect 58 is a method according to any one of aspects 1-52, wherein after the reacting step, the drying step, and the separating step, the process stream comprises at least about 99.99 wt% trifluoroiodomethane.

[0181] Aspect 59 is a method according to any one of aspects 1-58, wherein after the reacting step, the drying step, and the separating step, the process stream contains less than about 50 ppm of methyl iodide.

[0182] Aspect 60 is a method according to any one of aspects 1-58, wherein after the reacting step, the drying step, and the separating step, the process stream comprises less than about 20 ppm of methyl iodide.

[0183] Aspect 61 is a method according to any one of aspects 1-58, wherein after the reacting step, the drying step, and the separating step, the process stream contains less than about 10 ppm of methyl iodide.

[0184] Aspect 62 is a method according to any one of aspects 1-58, wherein after the reacting step, the drying step, and the separating step, the process stream contains less than about 5 ppm of methyl iodide.

[0185] Aspect 63 is a method according to any one of aspects 1-62, wherein after the reacting step, the drying step, and the separating step, the process stream contains less than about 20 ppm of acid impurities.

[0186] Aspect 64 is a method according to any one of aspects 1-62, wherein after the reacting step, the drying step, and the separating step, the process stream contains less than about 10 ppm of acid impurities.

[0187] Aspect 65 is a method according to any one of aspects 1-62, wherein after the reacting step, the drying step, and the separating step, the process stream contains less than about 5 ppm of acid impurities.

[0188] Aspect 66 is a method according to any one of aspects 1-62, wherein after the reacting step, the drying step, and the separating step, the process stream contains less than about 1 ppm of acid impurities.

[0189] Aspect 67 is a method according to any one of aspects 1-66, wherein after the reacting step, the drying step, and the separating step, the process stream contains less than about 100 ppm water.

[0190] Aspect 68 is a method according to any one of aspects 1-66, wherein after the reacting step, the drying step, and the separating step, the process stream contains less than about 50 ppm water.

[0191] Aspect 69 is a method according to any one of aspects 1-66, wherein after the reacting step, the drying step, and the separating step, the process stream contains less than about 30 ppm water.

[0192] Aspect 70 is a method according to any one of aspects 1-66, wherein after the reacting step, the drying step, and the separating step, the process stream contains less than about 10 ppm water.

[0193] Aspect 71 is a method according to any one of aspects 1-70, wherein the separating step comprises distilling the process stream.

[0194] Aspect 72 is a method according to aspect 71, wherein distilling the process stream comprises a first distillation to remove organic impurities having a boiling point lower than CF3I from the process stream, and a second distillation to remove organic impurities having a boiling point higher than CF3I from the process stream.

[0195] Aspect 73 is a method according to aspect 71, wherein distilling the process stream comprises removing organic impurities having a boiling point lower than CF3I through a top stream, and then obtaining CF3I through the top stream, while organic impurities having a boiling point higher than CF3I are concentrated in a reboiler.

[0196] Aspect 74 is a method for purifying trifluoroiodomethane, the method comprising: providing a process stream comprising trifluoroiodomethane, organic impurities, and acid impurities; contacting the process stream with an acid reactant; and separating at least some of the organic impurities from the process stream.

[0197] Aspect 75 is a method according to aspect 74, wherein the acid reactant comprises at least one adsorbent selected from the group consisting of aluminum oxide, alkali metal oxides, alkaline earth metal oxides, metal hydroxides, aluminosilicate minerals, zirconium oxide and silicon dioxide.

[0198] Aspect 76 is a method according to aspect 74, wherein the acid reactant comprises aluminum oxide.

[0199] Aspect 77 is a method according to any one of aspects 74-76, wherein in the contacting step, the process stream is in a liquid phase and the temperature of the process stream is about -50°C to about 50°C.

[0200] Aspect 78 is a method according to any one of aspects 74-76, wherein in the contacting step, the process stream is in a liquid phase and the temperature of the process stream is about 0°C to about 35°C.

[0201] Aspect 79 is a method according to any one of aspects 74-76, wherein in the contacting step, the process stream is in a liquid phase and the temperature of the process stream is about 10°C to about 30°C.

[0202] Aspect 80 is a method according to any one of aspects 74-79, wherein in the contacting step, the process stream is in a liquid phase and the pressure of the process stream is about 1 psig to about 100 psig.

[0203] Aspect 81 is a method according to any one of aspects 74-79, wherein in the contacting step, the process stream is in a liquid phase and the pressure of the process stream is about 10 psig to about 90 psig.

[0204] Aspect 82 is a method according to any one of aspects 74-79, wherein in the contacting step, the process stream is in a liquid phase and the pressure of the process stream is about 20 psig to about 50 psig.

[0205] Aspect 83 is a method according to any one of aspects 74-76, wherein in the contacting step, the process stream is in a gas phase and the temperature of the process stream is about -20°C to about 60°C.

[0206] Aspect 84 is a method according to any one of aspects 74-76, wherein in the contacting step, the process stream is in a gas phase and the temperature of the process stream is about -5°C to about 50°C.

[0207] Aspect 85 is a method according to any one of aspects 74-76, wherein in the contacting step, the process stream is in a gas phase and the temperature of the process stream is about 15°C to about 40°C.

[0208] Aspect 86 is a method according to any one of aspects 74-76 and 83-85, wherein in the contacting step, the process stream is in a gas phase and the pressure of the process stream is about 1 psig to about 100 psig.

[0209] Aspect 87 is a method according to any one of aspects 74-76 and 83-85, wherein in the contacting step, the process stream is in a gas phase and the pressure of the process stream is about 10 psig to about 90 psig.

[0210] Aspect 88 is a method according to any one of aspects 74-76 and 83-85, wherein in the contacting step, the process stream is in a gas phase and the pressure of the process stream is about 15 psig to about 80 psig.

[0211] Aspect 89 is a method according to any one of aspects 74-88, wherein the method is a continuous process.

[0212] Aspect 90 is a method according to any one of aspects 74-88, wherein the method is a batch process.

[0213] Aspect 91 is a method according to any one of aspects 74-90, wherein the contacting step is performed before the separating step.

[0214] Aspect 92 is a method according to any one of aspects 74-90, wherein the contacting step is performed after the separating step.

[0215] Aspect 93 is a method according to any one of aspects 74-92, further comprising an additional drying step immediately after the contacting step to remove at least some of the water from the process stream.

[0216] Aspect 94 is a method according to aspect 93, wherein the drying step comprises contacting the process stream with a desiccant.

[0217] Aspect 95 is a method according to aspect 94, wherein the desiccant comprises at least one adsorbent selected from the group consisting of anhydrous calcium chloride, anhydrous calcium sulfate, concentrated sulfuric acid, silica, activated carbon, and zeolite.

[0218] Aspect 96 is a method according to aspect 93, wherein the drying step comprises passing the process stream through at least one 3A molecular sieve.

[0219] Aspect 97 is a method according to any one of Aspects 74-96, wherein after the contacting step, the drying step and the separating step, the process stream contains at least about 99 weight percent trifluoroiodomethane, less than about 50 ppm iodomethane, less than about 100 ppm water and less than about 20 ppm acid impurities.

[0220] Aspect 98 is a method according to any one of aspects 74-97, wherein after the reacting step, the drying step, and the separating step, the process stream comprises at least about 99 weight percent trifluoroiodomethane.

[0221] Aspect 99 is a method according to any one of aspects 74-97, wherein after the reacting step, the drying step, and the separating step, the process stream comprises at least about 99.5 wt% trifluoroiodomethane.

[0222] Aspect 100 is a method according to any one of aspects 74-97, wherein after the reacting step, the drying step, and the separating step, the process stream comprises at least about 99.9 wt% trifluoroiodomethane.

[0223] Aspect 101 is a method according to any one of aspects 74-97, wherein after the reacting step, the drying step, and the separating step, the process stream comprises at least about 99.99 weight percent trifluoroiodomethane.

[0224] Aspect 102 is a method according to any one of aspects 74-101, wherein after the reacting step, the drying step, and the separating step, the process stream contains less than about 50 ppm of methyl iodide.

[0225] Aspect 103 is a method according to any one of aspects 74-101, wherein after the reacting step, the drying step, and the separating step, the process stream contains less than about 20 ppm of methyl iodide.

[0226] Aspect 104 is a method according to any one of aspects 74-101, wherein after the reacting step, the drying step, and the separating step, the process stream comprises less than about 10 ppm of methyl iodide.

[0227] Aspect 105 is a method according to any one of aspects 74-101, wherein after the reacting step, the drying step, and the separating step, the process stream contains less than about 5 ppm of methyl iodide.

[0228] Aspect 106 is a method according to any one of aspects 74-105, wherein after the reacting step, the drying step, and the separating step, the process stream contains less than about 20 ppm of acid impurities.

[0229] Aspect 107 is a method according to any one of aspects 74-105, wherein after the reacting step, the drying step, and the separating step, the process stream contains less than about 10 ppm of acid impurities.

[0230] Aspect 108 is a method according to any one of aspects 74-105, wherein after the reacting step, the drying step, and the separating step, the process stream contains less than about 5 ppm of acid impurities.

[0231] Aspect 109 is a method according to any one of aspects 74-105, wherein after the reacting step, the drying step, and the separating step, the process stream contains less than about 1 ppm of acid impurities.

[0232] Aspect 110 is a method according to any one of aspects 74-109, wherein after the reacting step, the drying step, and the separating step, the process stream contains less than about 100 ppm water.

[0233] Aspect 111 is a method according to any one of aspects 74-109, wherein after the reacting step, the drying step, and the separating step, the process stream contains less than about 50 ppm water.

[0234] Aspect 112 is a method according to any one of aspects 74-109, wherein after the reacting step, the drying step, and the separating step, the process stream contains less than about 30 ppm water.

[0235] Aspect 113 is a method according to any one of aspects 74-109, wherein after the reacting step, the drying step, and the separating step, the process stream contains less than about 10 ppm water.

[0236] Aspect 114 is a method according to any one of aspects 74-113, wherein the separating step comprises distilling the process stream.

[0237] Aspect 115 is a method according to aspect 114, wherein distilling the process stream comprises a first distillation to remove organic impurities having a boiling point lower than CF3I from the process stream, and a second distillation to remove organic impurities having a boiling point higher than CF3I from the process stream.

[0238] Aspect 115 is a method according to aspect 114, wherein distilling the process stream comprises removing organic impurities having a boiling point lower than CF3I through a top stream, and then obtaining CF3I through the top stream, while organic impurities having a boiling point higher than CF3I are concentrated in a reboiler.

Claims

1. A method for purifying trifluoroiodomethane, the method comprising: providing a process stream comprising trifluoroiodomethane, organic impurities, and acid impurities; reacting the process stream with an alkaline aqueous solution comprising water and at least one base selected from the group consisting of alkali metal carbonates and alkali metal hydroxides; and At least some of the organic impurities are separated from the process stream.

2. The method of claim 1, wherein in the reacting step, the at least one base comprises an alkali metal carbonate.

3. The method of claim 2, wherein the concentration of the alkali metal carbonate in the alkaline aqueous solution is from about 0.01 wt% to about 20 wt%.

4. The method of claim 2, wherein the alkali metal carbonate comprises sodium carbonate.

5. The method of claim 1, wherein in the reacting step, the at least one base comprises an alkali metal hydroxide.

6. The method of claim 5, wherein the concentration of the alkali metal hydroxide in the alkaline aqueous solution is from about 0.01 wt% to about 20 wt%.

7. The process of any one of claims 1-6, further comprising the additional step of drying to remove at least some of the water from the process stream immediately after the reacting step, wherein after the reacting step, the drying step, and the separating step, the process stream comprises at least about 99 weight percent trifluoroiodomethane, less than about 50 ppm iodomethane, less than about 100 ppm water, and less than about 20 ppm acid impurities.

8. A method for purifying trifluoroiodomethane, the method comprising: providing a process stream comprising trifluoroiodomethane, organic impurities, and acid impurities; contacting the process stream with an acid reactant; as well as At least some of the organic impurities are separated from the process stream.

9. The method of claim 8, wherein the acid reactant comprises an alumina adsorbent.

10. The process of any one of claims 8 or 9, further comprising the additional step of drying to remove at least some of the water from the process stream immediately after the contacting step, wherein after the contacting step, the drying step, and the separating step, the process stream comprises at least about 99 weight percent trifluoroiodomethane, less than about 50 ppm methyl iodide, less than about 100 ppm water, and less than about 20 ppm acid impurities.

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