Synthetic method of trifluoroiodomethane

Abstract

The invention discloses a synthesis method of trifluoroiodomethane. The synthesis method comprises the following steps: mixing raw materials CF3H, an oxygen source and iodine steam, and performing catalytic reaction to obtain a first product; and removing unreacted raw materials from the first product, and then carrying out alkali washing and adsorption to obtain the product. By optimizing the synthesis method, optimization and improvement in multiple aspects such as control of reaction temperature and feed ratio are realized, the reaction yield is increased to 40% or above, and the CF3I selectivity is increased to 80% or above.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical engineering, and particularly relates to a method for synthesizing trifluoroiodomethane. Background Art

[0002] One of the main applications of trifluoroiodomethane (CF3I) is as a clean fire extinguishing agent for gas fire extinguishing systems. It has good fire extinguishing performance and can quickly extinguish fires without damaging precision equipment. Therefore, it is widely used in data centers, museums and archives, telecommunications equipment rooms, aircraft and ship fire extinguishing systems.

[0003] Trifluoroiodomethane (TFIO) is a refrigerant primarily replacing traditional Freon refrigerants (CFCs, HCFCs, and HFCs). It boasts excellent environmental performance, including an ODP of 0, a GWP of 0.4, and an atmospheric lifetime of less than 1.2 days. It is safe, non-toxic, flame-retardant, oil-soluble, and has excellent material compatibility. It has been designated by the United Nations as a key component of the third generation of environmentally friendly refrigerants.

[0004] The existing method for synthesizing CF3I has multiple, such as using trifluoromethane (CF3H) or trifluoroacetic acid (CF3COOH) and I2 as raw materials and using trifluoroacetyl compounds as raw material synthesis methods. The major problems existing in the synthesis of CF3I are: first, the iodine element is expensive, accounting for about 90% of the raw material cost, and the product yield is low, generally only about 20%; second, the required reaction temperature is high, about 550°C, which can cause carbon deposition on the catalyst, causing the catalyst life to decrease, which also leads to a rise in production costs. A series of problems such as easily generating a large amount of three wastes during the reaction process have greatly limited the industrial production of trifluoroiodomethane.

[0005] Therefore, in view of the above technical problems, it is necessary to provide a method for synthesizing trifluoroiodomethane.

[0006] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the Invention

[0007] The object of the present invention is to provide a method for synthesizing trifluoroiodomethane.

[0008] In order to achieve the above object, a specific embodiment of the present invention provides the following technical solutions:

[0009] The synthesis method of trifluoroiodomethane comprises: mixing raw materials CF3H, an oxygen source and iodine steam and then subjecting the mixture to a catalytic reaction to obtain a first product; removing unreacted raw materials from the first product, and then subjecting the first product to alkali washing and adsorption to obtain the product.

[0010] In one or more embodiments of the present invention, the catalyst for the catalytic reaction comprises a carrier and an alkali metal salt supported on the carrier, wherein the carrier is activated carbon or fluoride.

[0011] In one or more embodiments of the present invention, the alkali metal salt is selected from RbNO3 and CsNO3.

[0012] In one or more embodiments of the present invention, the loading amount of the alkali metal salt on the carrier is 3% - 5%.

[0013] In one or more embodiments of the present invention, the molar feed ratio of CF3H, iodine and oxygen is (2 - 4):1:(0.1 - 0.3).

[0014] In one or more embodiments of the present invention, the conditions for the catalytic reaction are: the reaction temperature is 500 - 550 °C, the reaction space velocity is 250 - 350 h -1 , and the reaction pressure is 0.1 - 0.35 bar.

[0015] In one or more embodiments of the present invention, the catalyst is activated, and the activation conditions are: in a nitrogen atmosphere, the activation temperature is 500 - 550 °C, and the activation time is 2 - 4 h.

[0016] In one or more embodiments of the present invention, an adsorbent for adsorption sampling activation, and the activation conditions of the adsorbent are: the activation temperature is 300 - 350 °C, and the activation time is 4 - 6 h.

[0017] In one or more embodiments of the present invention, the adsorbent is silica gel or 3A molecular sieve.

[0018] In one or more embodiments of the present invention, the oxygen source is a nitrogen-oxygen mixture or pure oxygen. The nitrogen-oxygen mixture is preferably air.

[0019] Compared with the prior art, the method for synthesizing trifluoroiodomethane of the present invention improves the reaction yield to more than 40% and the selectivity of CF3I to more than 80% through optimization and improvement in multiple aspects such as controlling the reaction temperature and feed ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0021] Figure 1 It is a flow chart of the trifluoroiodomethane synthesis experiment in one embodiment of the present invention. Detailed implementation mode

[0022] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

[0023] The synthesis method of trifluoroiodomethane of the present invention can be realized through the following technical solutions, as Figure 1 shown:

[0024] The first step: Solid iodine is completely liquefied in an iodine evaporator.

[0025] The second step: The raw materials CF3H and oxygen source are introduced into the iodine evaporator through mass flow meters, mixed evenly and then introduced into a Hastelloy reaction tube for catalytic reaction.

[0026] The third step: The unreacted iodine vapor is cooled and recovered through an iodine recovery device.

[0027] The fourth step: The reaction product is alkali-washed through a two-stage alkali washer, dried by an adsorption column and then enters a GC-MS for analysis, and the tail gas is collected by cryogenic cooling with liquid nitrogen.

[0028] Preferably, a catalyst is filled in the Hastelloy reaction tube, the catalyst carrier is activated carbon or fluoride, and the supported active component is an alkali metal salt (RbNO3, CsNO3, etc.).

[0029] Preferably, the alkali washer is filled with a 5% - 30% KOH solution.

[0030] Preferably, the adsorption column is filled with silica gel or 3A molecular sieve.

[0031] Preferably, the molar feed ratio of CF3H, iodine and oxygen is (2 - 4):1:(0.1 - 0.3), the reaction temperature is 500 - 550 °C, the reaction space velocity is 250 - 350 h -1 , and the reaction pressure is 0.1 - 0.35 bar.

[0032] Preferably, the catalyst activation: in a nitrogen atmosphere, the activation temperature is 500 - 550 °C, and the activation time is 2 - 4 h. Preferably, the adsorbent activation: the activation temperature is 300 - 350 °C, and the activation time is 4 - 6 h.

[0033] Examples 1 - 3

[0034] The first step: Solid iodine is completely liquefied in an iodine evaporator.

[0035] Step 2: Feed the raw materials CF3H and nitrogen-oxygen mixture (79:21) into the iodine evaporator through a mass flowmeter. After mixing evenly, introduce them into a Hastelloy reaction tube for catalytic reaction. The catalyst is 1 mm activated carbon supported RbNO3 with a loading of 3.5%. The catalyst is activated in a nitrogen atmosphere at an activation temperature of 500 °C for 2 h.

[0036] Step 3: Cool and recover the unreacted iodine vapor through an iodine recovery device.

[0037] Step 4: The reaction products are washed with a 5% KOH solution in a two-stage alkali scrubber, dried by an adsorption column of 3A molecular sieve (activation temperature: 300 °C, activation time: 4 h), and then enter a GC-MS for analysis and product collection. The tail gas is collected by cryogenic cooling with liquid nitrogen.

[0038] Among them, some parameters are sequentially as follows: the catalytic reaction temperatures are 500 °C, 525 °C, and 550 °C respectively; the reaction space velocities are 200 h -1 、250 h -1 、300 h -1 respectively; the reaction pressures are 0.1 bar, 0.2 bar, and 0.35 bar respectively; the feed ratios (CF3H:I2:O2) are 3.5:1:0.25, 3.5:1:0.3, and 3:1:0.25 respectively.

[0039] The reaction products are analyzed using a gas chromatography-mass spectrometry instrument (GC-MS). The component information and their contents are shown in Table 1. Reaction yield = (amount of CF3H raw material consumed to produce CF3I) / (amount of CF3H raw material) * 100%. Table 1. Component information of reaction products in Examples 1 - 3

[0040]

[0041]

[0042] Control Example 1: The reaction temperature is 600 °C, and other conditions are the same as those in Example 2.

[0043] Control Example 2: The feed ratio (CF3H:I2:O2) is 3.5:1:0.05, and other conditions are the same as those in Example 1.

[0044] As shown in Table 2, increasing the reaction temperature results in more side reaction products; decreasing the amount of oxygen leads to severe carbon deposition on the catalyst, a decline in the catalytic effect, and a decrease in both the reaction yield and selectivity.

[0045] Table 2. Component information of reaction products in control examples

[0046] Raw material components (%) Comparative Example 1 Comparative Example 2 <![CDATA[CF4]]> 10.56 2.12 <![CDATA[CO2]]> 0.26 0.17 <![CDATA[C2F6]]> 5.23 0.66 <![CDATA[CF3H]]> 29.85 48.77 <![CDATA[C3F8]]> 0.88 0.11 <![CDATA[C2HF5]]> 0.33 0.27 <![CDATA[CF3I]]> 50.69 46.63 <![CDATA[C2F5I]]> 2.03 1.23 Reaction yield 32.5％ 35.7％ <![CDATA[CF3I selectivity]]> 62.7％ 64.1％

[0047] Examples 4-6 are correspondingly different from Examples 1-3 only in that: catalyst activation: in a nitrogen atmosphere, the activation temperature is 525 °C, and the activation time is 3 h.

[0048] Table 3. Component information of the reaction products in Examples 4-6

[0049]

[0050]

[0051] Examples 7-9 are correspondingly different from Examples 1-3 only in that: catalyst activation: in a nitrogen atmosphere, the activation temperature is 550 °C, and the activation time is 4 h.

[0052] Table 4. Component information of the reaction products in Examples 7-9

[0053] Raw material components (%) Example 7 Example 8 Example 9 <![CDATA[CF4]]> 2.57 2.38 2.30 <![CDATA[CO2]]> 0.49 0.6 1.92 <![CDATA[C2F6]]> 0.39 0.49 0.09 <![CDATA[CF3H]]> 37.87 40.25 35.00 <![CDATA[C3F8]]> 0.05 0.07 0.38 <![CDATA[C2HF5]]> 0.25 0.26 0.07 <![CDATA[CF3I]]> 55.86 52.96 56.00 <![CDATA[C2F5I]]> 2.47 2.91 2.70 Reaction yield 44.3％ 48.6％ 51.2％ <![CDATA[CF3I selectivity]]> 87.4％ 83.9％ 86.3％

[0054] Examples 10-12 are correspondingly different from Examples 1-3 only in adsorbent activation: the activation temperature is 325 °C, and the activation time is 5 h.

[0055] Table 5. Component information of the reaction products in Examples 10-12

[0056]

[0057]

[0058] Examples 13-15 are correspondingly different from Examples 1-3 only in that: adsorbent activation: the activation temperature is 350 °C, and the activation time is 6 h.

[0059] Table 6. Component information of the reaction products in Examples 13-15

[0060] Raw material components (%) Example 13 Example 14 Example 15 <![CDATA[CF4]]> 3.13 2.15 3.75 <![CDATA[CO2]]> 0.13 0.16 0.13 <![CDATA[C2F6]]> 0.67 0.56 0.62 <![CDATA[CF3H]]> 33.02 35.89 34.03 <![CDATA[C3F8]]> 0.09 0.08 0.07 <![CDATA[C2HF5]]> 0.28 0.25 0.34 <![CDATA[CF3I]]> 58.69 57.02 56.95 <![CDATA[C2F5I]]> 3.92 3.81 4.01 Reaction yield 42.5％ 45.6％ 44.7％ <![CDATA[CF3I selectivity]]> 82.7％ 84.4％ 80.6％

[0061] Examples 16-18 are correspondingly different from Examples 7-9 only in that: the catalyst is 1 mm activated carbon supported RbNO3, and the loadings are 1%, 3%, and 6% respectively.

[0062] Table 7. Component information of the reaction products in Examples 16-18

[0063]

[0064]

[0065] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, in any regard, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention.

[0066] In addition, it should be understood that although this specification is described in terms of embodiments, not every embodiment only contains an independent technical solution. This narrative manner of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for synthesizing trifluoroiodomethane, comprising: Mixing raw materials CF3H, an oxygen source, and iodine vapor, and then performing a catalytic reaction to obtain a first product; After the first product is subjected to removal of unreacted raw materials, it is then subjected to alkali washing and adsorption to obtain the product.

2. The synthesis method of trifluoroiodomethane according to claim 1, wherein, The catalyst for the catalytic reaction includes a carrier and an alkali metal salt supported on the carrier, wherein the carrier is activated carbon or a fluoride.

3. The synthesis method of trifluoroiodomethane according to claim 2, wherein The alkali metal salt is selected from RbNO3 and CsNO3.

4. The synthesis method of trifluoroiodomethane according to claim 2, wherein The loading amount of the alkali metal salt on the carrier is 3% - 5%.

5. The synthesis method of trifluoroiodomethane according to claim 1, wherein, The molar feed ratio of CF3H, iodine, and oxygen is (2 - 4):1:(0.1 - 0.3).

6. The synthesis method of trifluoroiodomethane according to claim 1, wherein The conditions of the catalytic reaction are as follows: the reaction temperature is 500 to 550 °C, the reaction space velocity is 250 to 350 h -1 , and the reaction pressure is 0.1 to 0.35 bar.

7. The synthesis method of trifluoroiodomethane according to claim 2, wherein The catalyst is activated, and the activation conditions are: in a nitrogen atmosphere, the activation temperature is 500 - 550 °C, and the activation time is 2 - 4 h.

8. The method for synthesizing trifluoroiodomethane according to claim 1, wherein The adsorbent for adsorption sampling is activated, and the activation conditions of the adsorbent are: the activation temperature is 300 - 350 °C, and the activation time is 4 - 6 h.

9. The synthesis method of trifluoroiodomethane according to claim 8, wherein The adsorbent is silica gel or 3A molecular sieve.

10. The method for synthesizing trifluoroiodomethane according to claim 1, characterized in that, The oxygen source is a nitrogen-oxygen mixture or pure oxygen.

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