Method for continuously preparing trifluoroiodomethane

Abstract

The invention discloses a method for continuously preparing trifluoroiodomethane. The method specifically comprises the following steps: in a continuous reactor, in the presence of a fluorination catalyst and a dehydration catalyst, reacting carbonyl fluoride, hydrogen iodide and hydrogen fluoride at the reaction temperature of 100-400 DEG C to obtain trifluoroiodomethane. The preparation method has the advantages of few three wastes, environmental friendliness, suitability for industrial production and the like.

Description

Technical Field

[0001] The invention relates to the field of synthesis of trifluoroiodomethane, and in particular to a method for continuously preparing trifluoroiodomethane. Background Art

[0002] Trifluoroiodomethane is a colorless, odorless, non-flammable gas at room temperature and pressure, with good environmental performance (ODP = 0, 20-year GWP value is less than 5). As a fire extinguishing agent, trifluoroiodomethane has the characteristics of high fire extinguishing efficiency, good safety performance, high economic benefits, and no trace left after fire extinguishing. It is a preferred alternative to halon 1301 and plays an irreplaceable role in aviation, aerospace and other fields; as a refrigerant, trifluoroiodomethane has the characteristics of good oil solubility and material compatibility, and is considered to be one of the ideal substitutes for traditional Freon refrigerant components; as an insulating gas, trifluoroiodomethane has excellent insulating properties and is a new type of environmentally friendly insulating gas, which can replace SF6 in the power industry. In addition, trifluoroiodomethane also has broad application prospects in other fields such as fluorine-containing intermediates, semiconductor etching, and foaming agents.

[0003] In the prior art, there are many synthetic routes for trifluoroiodomethane, which mainly include trifluoroacetate, trifluoromethane and trifluoroacetyl chloride according to the process raw materials.

[0004] The literature J. Chem. Soc., 1951, No. 124, The Reactions of Metallic Salts of Acids with Halogens. Part I. The Reaction of Metal Trifluoroacetates with Iodine, Bromine, and Chlorine. discloses the reaction of metal trifluoroacetates (CF) in the presence of iodine. 3 COOM) is decarboxylated and iodinated to prepare trifluoroiodomethane, and trifluoroacetate and elemental iodine are heated together without a solvent to prepare trifluoroiodomethane. This method has the problems of expensive raw material silver trifluoroacetate and low reaction conversion rate.

[0005] Patent CN102464569B discloses a method for preparing low carbon number perfluoro iodoalkane, in which anhydrous perfluorocarboxylic acid silver salt R f CO 2 Ag and / or anhydrous perfluorocarboxylic acid copper salt (R f CO 2 ) 2 Under the action of Cu, anhydrous perfluorocarboxylate (R f CO 2)nM undergoes thermal decomposition reaction with elemental iodine to generate perfluoroalkyl iodide, and the thermal decomposition reaction temperature is 120-250° C. This method has the problems of high reaction temperature, easy material flushing, easy sublimation and blockage of iodine source, and difficulty in scale-up.

[0006] N.Nagasaki (Catalysis Today 88 (2004) 121–126) studied the preparation of trifluoroiodomethane by gas-phase iodination catalytic reaction using trifluoromethane and iodine as raw materials and alkali metals or alkaline earth metals as catalysts. Later, the reaction was improved by adding an appropriate amount of oxygen, which prolonged the catalyst life. However, there were still problems such as severe iodine corrosion and catalyst carbon deposition.

[0007] Patent CN113423681A discloses a gas phase reactant of trifluoroacetyl halide, hydrogen and iodine, heating the gas phase reactant, and reacting the heated gas phase reactant in the presence of a catalyst to produce trifluoroiodomethane. This method produces a colorless toxic gas CO as a byproduct and is environmentally unfriendly.

[0008] In summary, the existing preparation methods of trifluoroiodomethane have many side reactions, are environmentally unfriendly, have low product yields, poor selectivity, and other problems. Therefore, it is particularly important to find a preparation route for trifluoroiodomethane with less by-products, environmental friendliness, and suitable for industrial production. Summary of the invention

[0009] In order to solve the above technical problems, the present invention provides a method for preparing trifluoroiodomethane which has high reaction selectivity, is environmentally friendly and is suitable for industrial production.

[0010] The objective of the present invention is achieved through the following technical solutions:

[0011] A method for continuously preparing trifluoroiodomethane specifically comprises: in a continuous reactor, in the presence of a fluorination catalyst and a dehydration catalyst, carbonyl fluoride, hydrogen iodide and hydrogen fluoride react at a reaction temperature of 100° C. to 400° C. to obtain trifluoroiodomethane.

[0012] The reaction formula of the present invention is: COF 2 +HI+HF→CF 3 I+H 2 O.

[0013] The invention adopts carbonyl fluoride, hydrogen iodide and hydrogen fluoride as raw materials to prepare trifluoroiodomethane in a continuous reactor, which can not only effectively solve the problems of high-temperature material impact and iodine source sublimation blocking reaction equipment in the prior art, but also has high reaction selectivity and few side reactions.

[0014] Specifically, the fluorination catalyst can promote the dehydration reaction of the reaction of the present invention, the dehydration catalyst can promote the halogenation reaction, and the fluorination catalyst and the dehydration catalyst can jointly improve the reaction selectivity of trifluoroiodomethane in the reaction system of the present invention and reduce the production of by-products such as tetrafluoromethane and difluorodiiodomethane.

[0015] The fluorination catalyst is a metal fluoride or a supported catalyst in which a metal fluoride is supported on a carrier; preferably, it is a supported catalyst in which a metal fluoride is supported on a carrier, and the carrier is a molecular sieve.

[0016] Specifically, the fluorination catalyst is selected from at least one of chromium fluoride, aluminum fluoride, calcium fluoride, iron fluoride, zinc fluoride, cobalt fluoride, nickel fluoride, antimony fluoride, magnesium fluoride, tantalum fluoride, niobium fluoride, titanium fluoride, zirconium fluoride, molybdenum fluoride or vanadium fluoride. Preferably, the fluorination catalyst is selected from at least one of chromium fluoride, aluminum fluoride, calcium fluoride, antimony fluoride or magnesium fluoride.

[0017] The preparation method of the supported catalyst of metal fluoride supported on a carrier specifically comprises: drying and removing water from the molecular sieve, adding the molecular sieve into the metal fluoride solution and stirring; and drying and calcining to obtain the supported catalyst of metal fluoride supported on the carrier.

[0018] The dehydration catalyst is selected from at least one of active metal oxides, heteropoly acid salts, calcium phosphate, zinc aluminate, activated carbon, molecular sieves or zeolites. The metal oxide is selected from at least one of aluminum oxide, silicon oxide, thorium oxide, zirconium oxide, manganese oxide, iron oxide, cobalt oxide, nickel oxide, copper oxide or zinc oxide. The heteropoly acid salt is silver phosphotungstate or potassium dodecamolybdate phosphate.

[0019] The mass ratio of the fluorination catalyst to the dehydration catalyst is 1:(0.1-10), preferably 1:(0.5-5).

[0020] The molar ratio of carbonyl fluoride, hydrogen iodide and hydrogen fluoride is 1:(1-3):(1-5), and the molar ratio is preferably 1:(1-2):(1-3).

[0021] The reaction temperature is preferably 200°C to 400°C; more preferably 200°C to 300°C.

[0022] The reaction time is 5s to 180s, preferably 8s to 120s.

[0023] The continuous reactor of the present invention is a tubular reactor or a microreactor.

[0024] The mixed gas obtained by the reaction of the present invention is separated into trifluoroiodomethane, and the remaining gas is returned to the reaction to continue the reaction.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The reaction selectivity of the present invention is high, the by-product is small, the environment is friendly, and it is suitable for industrial production;

[0027] 2. The present invention is a continuous reaction, and the raw materials that have not reacted completely can be recycled, and the overall yield is high. DETAILED DESCRIPTION

[0028] The present invention is further described below in conjunction with specific embodiments, but the present invention is not limited to these specific embodiments. Those skilled in the art should recognize that the present invention covers all possible alternatives, improvements and equivalents within the scope of the claims.

[0029] In the embodiment of the present invention, gas chromatography analysis is adopted, and the analytical instrument is Shimadzu GC-2014; chromatographic column: CP-Sil8CB (50m X 0.2mm X 0.330um). GC analysis method: detector temperature 200°C, vaporization chamber temperature 200°C, column temperature: 40°C (5min) 10°C / min 100°C (3min) 10°C / min 200°C (4min); carrier gas (N) flow rate 1.05mL / min, air flow rate 300mL / min, hydrogen flow rate 30mL / min, split ratio 30:1, injection volume 0.2mL.

[0030] Example 1

[0031] Chromium fluoride and molecular sieve are respectively loaded into a tubular reactor, and the tubular reactor is protected by nitrogen. After the temperature is raised to 300°C, the nitrogen is stopped, and carbonyl fluoride, hydrogen iodide, and hydrogen fluoride are continuously introduced. The molar ratio of carbonyl fluoride, hydrogen iodide, and hydrogen fluoride is controlled to be 1:1.2:1.2, the material residence time is 10s, the reaction pressure is 0.01MPa, and the mixed gas obtained by the reaction is washed with alkali, dried, and distilled to obtain trifluoroiodomethane product.

[0032] A sample was taken from the alkali washing outlet of the tubular reactor, and the product composition was analyzed by gas chromatography: 98.5% of trifluoroiodomethane, 1.2% of tetrafluoromethane, 0.1% of difluorodiiodomethane, and 0.2% of other components.

[0033] After calculation, the single-pass yield was 83.1% based on carbonyl fluoride.

[0034] Example 2

[0035] The operation of Example 2 is the same as that of Example 1, except that the catalyst is changed to aluminum fluoride and zeolite, and other operations remain unchanged.

[0036] A sample was taken from the alkali washing outlet of the tubular reactor, and the product composition was analyzed by gas chromatography: 98.1% of trifluoroiodomethane, 1.4% of tetrafluoromethane, 0.2% of difluorodiiodomethane, and 0.3% of other components.

[0037] After calculation, the single-pass yield was 82.7% based on carbonyl fluoride.

[0038] Example 3

[0039] The operation of Example 3 is the same as that of Example 1, except that the nitrogen flow is stopped after the temperature is raised to 400° C., and other operations remain unchanged.

[0040] A sample was taken from the alkali washing outlet of the tubular reactor, and the product composition was analyzed by gas chromatography: 98.3% of trifluoroiodomethane, 1.2% of tetrafluoromethane, 0.2% of difluorodiiodomethane, and 0.3% of other components.

[0041] After calculation, the single-pass yield was 83.5% based on carbonyl fluoride.

[0042] Example 4

[0043] The operation of Example 4 is the same as that of Example 1, except that the molar ratio of carbonyl fluoride, hydrogen iodide, and hydrogen fluoride is changed to 1:1.5:1.2, and other operations remain unchanged.

[0044] A sample was taken from the alkali washing outlet of the tubular reactor, and the product composition was analyzed by gas chromatography: 98.3% of trifluoroiodomethane, 1.0% of tetrafluoromethane, 0.3% of difluorodiiodomethane, and 0.4% of other components.

[0045] After calculation, the single-pass yield was 81.5% based on carbonyl fluoride.

[0046] Example 5

[0047] The operation of Example 5 is the same as that of Example 1, except that the reaction pressure is changed to 0 MPa, and other operations remain unchanged.

[0048] A sample was taken from the alkali washing outlet of the tubular reactor, and the product composition was analyzed by gas chromatography: 97.5% of trifluoroiodomethane, 1.5% of tetrafluoromethane, 0.5% of difluorodiiodomethane, and 0.5% of other components.

[0049] After calculation, the single-pass yield was 82.1% based on carbonyl fluoride.

[0050] Example 6

[0051] Step A: Dry the 4A molecular sieve in a forced air drying oven at 120°C for 4 hours, remove moisture, add it to a magnesium fluoride solution, stir it magnetically at room temperature for 6 hours, and evaporate it to dryness with stirring; then dry it in an oven at 120°C for 12 hours, and calcine it in air at 400°C for 4 hours to obtain a magnesium fluoride supported catalyst.

[0052] Step B: The operation is the same as in Example 1, except that the catalyst is changed to a magnesium fluoride supported catalyst and a molecular sieve, and the other operations remain unchanged.

[0053] A sample was taken from the alkali washing outlet of the tubular reactor, and the product composition was analyzed by gas chromatography: 99.3% of trifluoroiodomethane, 0.5% of tetrafluoromethane, 0.1% of difluorodiiodomethane, and 0.1% of other components.

[0054] After calculation, the single-pass yield was 92.4% based on carbonyl fluoride.

[0055] Example 7

[0056] The operation of Example 7 is the same as that of Example 1, except that the remaining gas after separating trifluoroiodomethane from the mixed gas obtained in the reaction of Example 1 is collected and used as a raw material after supplementing the ratio, that is, the molar ratio of carbonyl fluoride, hydrogen iodide, and hydrogen fluoride is 1:1.2:1.2, and other operations remain unchanged.

[0057] A sample was taken from the alkali washing outlet of the tubular reactor, and the product composition was analyzed by gas chromatography: 97.1% of trifluoroiodomethane, 2.3% of tetrafluoromethane, 0.2% of difluorodiiodomethane, and 0.4% of other components.

[0058] After calculation, the single-pass yield was 82.8% based on carbonyl fluoride.

[0059] Comparative Example 1

[0060] The operation of Comparative Example 1 is the same as that of Example 1, except that the catalyst is changed to chromium fluoride, and other operations remain unchanged.

[0061] Sampling was taken at the alkali washing outlet of the tubular reactor, and the product composition was analyzed by gas chromatography: 5.36% of trifluoroiodomethane, 74.64% of tetrafluoromethane, 1.8% of difluorodiiodomethane, and 18.2% of other components.

[0062] After calculation, the single-pass yield was 3.1% based on carbonyl fluoride.

[0063] Comparative Example 2

[0064] The operation of Comparative Example 1 is the same as that of Example 1, except that the catalyst is replaced by molecular sieve, and other operations remain unchanged.

[0065] The product composition of the sample taken at the alkali washing outlet of the tubular reactor and analyzed by gas chromatography was as follows: no product generation was monitored.

[0066] Comparative Example 3

[0067] 20 g of potassium trifluoroacetate, 6.2 g of copper iodide and 36.7 g of iodine were added to a 300 mL autoclave reactor (equipped with a condenser), 60 mL of sulfolane was added to the reactor, and the reactant mixture was heated to about 175° C. to react to produce trifluoroiodomethane product and by-products.

[0068] Sampling was taken at the outlet of the tubular reactor, and the product composition was analyzed by gas chromatography: the crude trifluoroiodomethane content was 50.7%, the trifluoromethane content was 47.0%, and the others were 2.3%.

[0069] According to calculation, based on elemental iodine, the conversion rate of elemental iodine is 92.5%, the selectivity is 34.48%, and the yield is 31.9%.

[0070] Comparative Example 4

[0071] Trifluoroacetyl chloride and anhydrous hydrogen iodide in a molar ratio of 1:1 are passed through a preheater and heated to about 100°C, and then passed into a stainless steel reaction tube with a diameter of 3 / 8 inch (9.5 mm) and a length of 6 inches (152 mm), the tube is filled with activated carbon, and heated to a reaction temperature of 350°C. The material residence time is 20S, and the reaction produces trifluoroiodomethane product and by-products.

[0072] Sampling was taken at the outlet of the tubular reactor, and the product composition was analyzed by gas chromatography: trifluoromethane content was 5.0%, trifluoroacetyl chloride was 81.79%, trifluoroiodomethane was 5.61%, and others were 7.6%.

[0073] After calculation, the single-pass yield was 5.2% based on hydrogen iodide.

Claims

1. A method for continuously preparing trifluoroiodomethane, Features: In a continuous reactor, in the presence of a fluorination catalyst and a dehydration catalyst, carbonyl fluoride, hydrogen iodide and hydrogen fluoride react at a reaction temperature of 100° C. to 400° C. to obtain trifluoroiodomethane.

2. The method according to claim 1, Features: The fluorination catalyst is a metal fluoride or a supported catalyst in which the metal fluoride is supported on a carrier.

3. The method according to claim 2, Features: The fluorination catalyst is selected from at least one of chromium fluoride, aluminum fluoride, calcium fluoride, iron fluoride, zinc fluoride, cobalt fluoride, nickel fluoride, antimony fluoride, magnesium fluoride, tantalum fluoride, niobium fluoride, titanium fluoride, zirconium fluoride, molybdenum fluoride or vanadium fluoride.

4. The method according to claim 2, Features: The fluorination catalyst is a supported catalyst in which metal fluoride is supported on a carrier, and the carrier is a molecular sieve.

5. The method according to claim 1, Features: The dehydration catalyst is selected from at least one of metal oxides, heteropoly acid salts, calcium phosphate, zinc aluminate, activated carbon, molecular sieves or zeolites.

6. The method according to claim 5, Features: The metal oxide is selected from at least one of aluminum oxide, silicon oxide, thorium oxide, zirconium oxide, manganese oxide, iron oxide, cobalt oxide, nickel oxide, copper oxide or zinc oxide; and the heteropoly acid salt is silver phosphotungstate or potassium dodecamolybdate phosphate.

7. The method according to claim 1, Features: The molar ratio of the fluorination catalyst to the dehydration catalyst is 1:(0.1-10).

8. The method according to claim 1, Features: The molar ratio of carbonyl fluoride, hydrogen iodide and hydrogen fluoride is 1:(1-3):(1-5).

9. The method according to claim 1, Features: The reaction temperature is 200°C to 400°C.

10. The method according to claim 1, Features: The reaction obtains a mixed gas from which trifluoroiodomethane is separated, and the remaining gas is returned to the reaction to continue the reaction.