Process for preparing 2, 3, 3, 3-tetrafluoropropene

Abstract

The present invention relates to the technical field of chemistry, particularly to a 2, 3, 3, 3-tetrafluoropropene preparation method, which comprises: mixing a water-soluble metal salt containing a first metal auxiliary agent and chromium chloride hexahydrate to prepare a first solution, mixing the first solution with first ammonia water, and carrying out first calcination treatment on the obtained first precipitate to obtain a first chromium salt; mixing first chromium salt with graphite and silicon dioxide to obtain a first catalyst precursor, and performing fluorination activation treatment on the first catalyst precursor to obtain a first catalyst; the method comprises the following steps: under the action of a first catalyst, reacting 2-chloro-3, 3, 3-trifluoropropene with hydrogen fluoride to obtain 2, 3, 3, 3-tetrafluoropropene. According to the method, the process route is shortened, the use of highly toxic substances is avoided, the cost is reduced, the pollution to the environment is reduced, and meanwhile, the conversion rate of HCFO-1233xf and the selectivity of HFO-1234yf are improved.

Description

Technical Field

[0001] The present invention relates to the field of chemical technology, and in particular to a method for preparing 2,3,3,3-tetrafluoropropene. Background Art

[0002] With the increasing global awareness of environmental protection, traditional chlorofluorocarbons (CFCs) and hydrofluorocarbons (HFCs) are restricted due to their high global warming potential (GWP) and ozone depletion potential (ODP). Therefore, finding alternatives with low GWP and low ODP has become an important topic. 2,3,3,3-Tetrafluoropropene (HFO-1234yf) is considered an ideal refrigerant alternative for automotive air conditioners due to its extremely low GWP (GWP = 4) and ODP (ODP = 0), and is expected to replace the widely used 1,1,1,2-tetrafluoroethane (HFC-134a).

[0003] However, the preparation of HFO-1234yf currently faces the following challenges: (1) The purity of the raw materials for preparing HFO-1234yf, such as 1,1,1,2,3-pentachloropropane (HCC-240db) and 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf), will seriously affect the purity and yield of the product; (2) In the process of obtaining HFO-1234yf from HCFO-1233xf in one step, the conversion rate of HCFO-1233xf and the selectivity of HFO-1234yf are relatively low; or by a two-step method, converting HCFO-1233xf into 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb) and then preparing HFO-1234yf, but this process route is long and uses highly toxic substances such as SnCl4 and SbCl5; (3) Using ethylene and carbon tetrachloride as the initial raw materials to prepare HFO-1234yf, but this method requires multi-stage membrane separation and continuous reaction steps, the process route is long and complex, and uses rare metals Dy and Tm, without industrial advantages; (4) The current industrialized routes for HFO-1234yf include hexafluoropropene, trifluoropropene, and tetrachloropropene routes, but due to the relatively high prices of hexafluoropropene and trifluoropropene raw materials, the route costs are high. Summary of the Invention

[0004] Aiming at solving at least one of the technical problems in the related art to a certain extent, the present invention provides a method for preparing 2,3,3,3-tetrafluoropropene. This method uses a one-step method to convert HCFO-1233xf into HFO-1234yf, shortening the process route, avoiding the use of highly toxic substances, reducing costs, reducing environmental pollution, and at the same time increasing the conversion rate of HCFO-1233xf and the selectivity of HFO-1234yf.

[0005] To this end, the present invention provides a method for preparing 2,3,3,3-tetrafluoropropene, comprising:

[0006] Mixing a water-soluble metal salt containing a first metal promoter and chromium chloride hexahydrate to prepare a first solution, and mixing the first solution with first ammonia water to obtain a first precipitate;

[0007] Performing a first calcination treatment on the first precipitate to obtain a first chromium salt;

[0008] Mixing the first chromium salt with graphite and silica to obtain a first catalyst precursor;

[0009] Performing a fluorination activation treatment on the first catalyst precursor to obtain a first catalyst;

[0010] Reacting 2-chloro-3,3,3-trifluoropropene with hydrogen fluoride under the action of the first catalyst to obtain the 2,3,3,3-tetrafluoropropene.

[0011] To solve the deficiencies in the prior art, the present invention uses a specific catalyst in the process of converting HCFO-1233xf to HFO-1234yf. The catalyst is mainly composed of chromium oxide and is modified by other metal elements as promoters. Then, the modified chromium-based catalyst is mixed with silica and graphite to obtain a catalyst precursor. During the fluorination activation treatment, silica is converted into volatile silicon tetrafluoride, leaving vacant positions, resulting in a catalyst with a larger adsorption area, higher catalytic activity, and longer service life. This catalyst can effectively improve the conversion rate of HCFO-1233xf and the selectivity of HFO-1234yf.

[0012] According to an embodiment of the present invention, the first metal promoter includes at least one of La, Y, Zn, Co, Ni, Mg, Al, Fe, Ti, Sn, and Sb, and preferably at least two.

[0013] According to an embodiment of the present invention, the molar ratio of each metal element in the first metal promoter to the chromium element in the chromium chloride hexahydrate is independently (0.5 - 10):100, and preferably (0.5 - 5):100.

[0014] According to an embodiment of the present invention, the concentration of the first ammonia water is 10 - 20 wt%.

[0015] According to an embodiment of the present invention, the temperature of the first calcination treatment is 200 - 400 °C.

[0016] According to an embodiment of the present invention, the time of the first calcination treatment is 5 - 20 h.

[0017] According to an embodiment of the present invention, the mass ratio of the graphite to the first chromium salt is (1-10):100.

[0018] According to an embodiment of the present invention, the mass ratio of the silicon dioxide to the first chromium salt is (1-10):100.

[0019] According to an embodiment of the present invention, the 2-chloro-3,3,3-trifluoropropene reacts with hydrogen fluoride at 200-400 °C.

[0020] According to an embodiment of the present invention, the space velocity of the reaction of the 2-chloro-3,3,3-trifluoropropene with hydrogen fluoride is 600-1000 h -1 。

[0021] According to an embodiment of the present invention, the method further includes preparing the 2-chloro-3,3,3-trifluoropropene;

[0022] The preparation method of the 2-chloro-3,3,3-trifluoropropene includes:

[0023] Mix a water-soluble metal salt containing a second metal promoter and chromium chloride hexahydrate to prepare a second solution, and mix the second solution with second ammonia water to obtain a second precipitate;

[0024] Perform a second calcination treatment on the second precipitate to obtain a second chromium salt;

[0025] Mix the second chromium salt with graphite to obtain a second catalyst;

[0026] Under the action of the second catalyst, react 1,1,1,2,3-pentachloropropane with hydrogen fluoride to obtain the 2-chloro-3,3,3-trifluoropropene.

[0027] According to an embodiment of the present invention, the second metal promoter includes at least one of La, Y, Zn, Co, Ni, Mg, Al, Fe, Ti, Sn, and Sb.

[0028] According to an embodiment of the present invention, the molar ratio of the total molar number of each metal element in the second metal promoter to the molar number of chromium element in the chromium chloride hexahydrate is (0.5:100)-(10:100), preferably (0.5:100)-(5:100), and more preferably (0.5:100)-(1:100).

[0029] According to an embodiment of the present invention, the concentration of the second ammonia water is 10-20 wt%.

[0030] According to an embodiment of the present invention, the mass ratio of the graphite to the second chromium salt is (1-10):100.

[0031] According to an embodiment of the present invention, the 1,1,1,2,3-pentachloropropane reacts with hydrogen fluoride at 200-400°C.

[0032] According to an embodiment of the present invention, the space velocity of the reaction of 1,1,1,2,3-pentachloropropane with hydrogen fluoride is 240-800h -1 .

[0033] According to an embodiment of the present invention, the method further comprises preparing the 1,1,1,2,3-pentachloropropane;

[0034] The preparation method of 1,1,1,2,3-pentachloropropane comprises:

[0035] Under the action of a third catalyst, trichloroethylene and dichloromethane react to obtain the 1,1,1,2,3-pentachloropropane.

[0036] According to an embodiment of the present invention, the third catalyst includes a main catalyst and a co-catalyst;

[0037] The main catalyst includes iron powder and / or ferric chloride; the co-catalyst includes phosphate.

[0038] According to an embodiment of the present invention, the phosphate ester includes at least one of triethyl phosphate, tributyl phosphate, triethyl phosphite, and diethyl phosphate.

[0039] According to an embodiment of the present invention, the trichloroethylene reacts with dichloromethane at 0.3-1 MPa.

[0040] According to an embodiment of the present invention, the trichloroethylene reacts with dichloromethane at 90-150°C.

[0041] According to an embodiment of the present invention, the method further comprises preparing the trichloroethylene;

[0042] The preparation method of trichloroethylene comprises:

[0043] Chlorine is reacted with ethylene to obtain the trichloroethylene.

[0044] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0046] Figure 1 shows the mass spectrum of the product obtained in Example 1 of the present invention;

[0047] Figure 2 It shows the mass spectrum of the product obtained in Example 20 of the present invention. Detailed implementation manners

[0048] The embodiments of the present invention will be described in detail below. The embodiments described below are exemplary and are only used to explain the present invention and should not be construed as a limitation to the present invention.

[0049] It should be noted that the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. Further, in the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more.

[0050] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0051] To make it easier to understand the present invention, certain technical and scientific terms are specifically defined below. Unless otherwise clearly defined elsewhere in this document, all other technical and scientific terms used herein have the meanings commonly understood by those of ordinary skill in the art to which the present invention pertains.

[0052] In this document, the term "comprising" or "including" is an open expression, that is, it includes the content specified by the present invention, but does not exclude other aspects.

[0053] In this document, the terms "optionally", "optional" or "option" generally mean that the subsequent events or conditions may or may not occur, and this description includes the cases where the events or conditions occur and the cases where the events or conditions do not occur.

[0054] According to an embodiment of the present invention, the present invention provides a method for preparing 2,3,3,3-tetrafluoropropene, comprising:

[0055] (1) Mix a water-soluble metal salt containing a first metal promoter and chromium chloride hexahydrate to prepare a first solution, and mix the first solution with first ammonia water to obtain a first precipitate.

[0056] In this process, chromium(III) chloride hexahydrate reacts with ammonia water to obtain chromium hydroxide precipitate. At the same time, the acidity of the catalyst surface is adjusted by adding a first metal promoter, thereby improving the catalytic efficiency and the catalyst life.

[0057] According to specific embodiments of the present invention, the type of the first metal promoter is not particularly limited, and those skilled in the art can select according to actual needs. As some specific examples, it can be at least one of La, Y, Zn, Co, Ni, Mg, Al, Fe, Ti, Sn, Sb, preferably at least two of La, Y, Zn, Co, Ni, Mg, Al, Fe, Ti, Sn, Sb; more preferably, it is at least three of La, Y, Zn, Co, Ni, Mg, Al, Fe, Ti, Sn, Sb.

[0058] According to specific embodiments of the present invention, the type of the water-soluble metal salt containing the first metal promoter is also not particularly limited, including but not limited to metal chloride salts, metal nitrate salts, etc.

[0059] According to specific embodiments of the present invention, the molar ratio of each metal element in the first metal promoter to the chromium element in the chromium(III) chloride hexahydrate is not particularly limited, and those skilled in the art can select according to actual needs. As some specific examples, they can each independently be (0.5 - 10):100, preferably (0.5 - 5):100, such as 0.5:100, 1:100, 2:100, 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100, 10:100, etc., preferably 0.5:100, 3:100, 5:100. Among them, "the molar ratio of each metal element in the first metal promoter to the chromium element in the chromium(III) chloride hexahydrate is each independently (0.5 - 10):100" should be understood that the first metal promoter may contain at least one metal element, and the molar ratio of the molar number of each metal element to the chromium element in the chromium(III) chloride hexahydrate is each independently (0.5 - 10):100.

[0060] According to specific embodiments of the present invention, the concentration of the first ammonia water is not particularly limited, and those skilled in the art can select according to actual needs. As some specific examples, it can be 10 - 20 wt%. Thus, a chromium-based precipitate is obtained instead of a soluble complex.

[0061] (2) Perform a first calcination treatment on the first precipitate to obtain a first chromium salt.

[0062] In this process, the first precipitate undergoes high-temperature dehydration to become chromium oxide.

[0063] According to specific embodiments of the present invention, the temperature and time of the first calcination treatment are not particularly limited, and those skilled in the art can select according to actual needs. As some specific examples, it can be calcined at 200-400 °C; optionally, calcined for 5-20 h, for example, calcined at 200 °C, 250 °C, 300 °C, 350 °C, 400 °C; optionally, calcined for 1 h, 2 h, 3 h, 4 h, 5 h.

[0064] According to specific embodiments of the present invention, this step may further include: before the first calcination treatment of the first precipitate, a drying treatment is performed. The temperature and time of the drying treatment are not particularly limited, that is, the drying purpose can be achieved. For example, the drying treatment is carried out at 80-120 °C; optionally, the drying time is 5-12 h; for example, the drying treatment is carried out at 80 °C, 90 °C, 100 °C, 110 °C, 120 °C; optionally; the drying time is 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h.

[0065] (3) Mix the first chromium salt with graphite and silicon dioxide to obtain a first catalyst precursor.

[0066] Among them, graphite is used as a shaping aid, so that the first catalyst precursor is tableted.

[0067] According to specific embodiments of the present invention, the addition amount of the graphite is not particularly limited, and those skilled in the art can select according to actual needs. As some specific examples, the mass ratio of graphite to the first chromium salt is (1-10):100, such as 1:100, 2:100, 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100, 10:100, etc.; preferably 2:100.

[0068] According to specific embodiments of the present invention, the addition amount of the silicon dioxide is not particularly limited, and those skilled in the art can select according to actual needs. As some specific examples, the mass ratio of silicon dioxide to the first chromium salt is (1-10):100, such as 1:100, 2:100, 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100, 10:100, etc., preferably 3:100.

[0069] According to specific embodiments of the present invention, this step may specifically include: mixing the first chromium salt with graphite and silicon dioxide, and performing granulation and shaping to obtain the first catalyst precursor.

[0070] (4) Perform fluorination activation treatment on the first catalyst precursor to obtain a first catalyst.

[0071] In this process, silicon dioxide is converted into volatile silicon tetrafluoride, leaving vacancies at the positions of silicon dioxide, and a first catalyst with a larger adsorption area, higher catalytic activity, and longer service life is obtained.

[0072] According to specific embodiments of the present invention, the fluorination activation treatment preferably uses HF to activate the first catalyst precursor. For example, the first catalyst is obtained by activating with HF at 200 - 400 °C; optionally, the activation treatment time is 4 - 8 h. For example, activation is carried out with HF at 200 °C, 250 °C, 300 °C, 350 °C, 400 °C; optionally, the activation treatment time is 4 h, 5 h, 6 h, 7 h, 8 h, etc.

[0073] (5) Under the action of the first catalyst, 2-chloro-3,3,3-trifluoropropene reacts with hydrogen fluoride to obtain the 2,3,3,3-tetrafluoropropene.

[0074] The reaction process of this step is as follows:

[0075]

[0076] This first catalyst can improve the conversion rate of HCFO-1233xf and the selectivity of HFO-1234yf.

[0077] According to specific embodiments of the present invention, the molar ratio of HF to HCFO-1233xf is not particularly limited, and those skilled in the art can select according to actual needs. As some specific examples, (5:1)-(20:1) can be selected, such as 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1, etc.; preferably 10:1.

[0078] According to specific embodiments of the present invention, the reaction temperature and space velocity of HF and HCFO-1233xf are not particularly limited, and those skilled in the art can select according to actual needs. As some specific examples, the reaction temperature of HF and HCFO-1233xf is 200–400 °C, such as 200 °C, 250 °C, 300 °C, 350 °C, 400 °C, etc.; the space velocity is 600 - 1000 h -1 , such as 600 h -1 、700 h -1 、800 h -1 、900 h -1 、1000 h -1 etc.; preferably 350 °C, and the space velocity is 800 h -1Among them, the "space velocity" should be understood as the ratio of the total volume (or total mass) of the HCFO-1233xf and HF mixed gas passing through the catalyst bed layer per unit time to the total volume (or total mass) of the catalyst.

[0079] According to a specific embodiment of the present invention, this step can be carried out by the following method:

[0080] Load the activated catalyst into the fluorination reactor, and simultaneously introduce HF and HCFO-1233xf into the reaction tube at a molar ratio of (5:1)-(20:1). The temperature of the reaction tube is 200-400 °C, and the space velocity is 600-1000 h -1 The mixed gas passing through the catalyst is washed, tested, and collected.

[0081] According to a specific embodiment of the present invention, the method further includes preparing the 2-chloro-3,3,3-trifluoropropene;

[0082] The preparation method of the 2-chloro-3,3,3-trifluoropropene includes:

[0083] Mix a water-soluble metal salt containing a second metal promoter and chromium chloride hexahydrate to prepare a second solution, and mix the second solution with second ammonia water to obtain a second precipitate;

[0084] Perform a second calcination treatment on the second precipitate to obtain a second chromium salt;

[0085] Mix the second chromium salt with graphite to obtain a second catalyst;

[0086] Under the action of the second catalyst, react 1,1,1,2,3-pentachloropropane (HCC-240db) with hydrogen fluoride to obtain the 2-chloro-3,3,3-trifluoropropene.

[0087] Specifically, the process of obtaining HCFO-1233xf from HCC-240db is shown by the following formula:

[0088]

[0089] Specifically, the preparation of the second catalyst is relatively similar to the aforementioned first catalyst.

[0090] Specifically, the second metal promoter includes but is not limited to La, Y, Zn, Co, Ni, Mg, Al, Fe, Ti, Sn, Sb.

[0091] Specifically, the molar ratio of the total number of moles of each metal element in the second metal promoter to the number of moles of chromium element in chromium chloride hexahydrate is (0.5:100)-(10:100), preferably (0.5:100)-(5:100), more preferably (0.5:100)-(1:100), such as 0.5:100, 1:100, 2:100, 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100, 10:100, etc.

[0092] Specifically, the concentration of the second ammonia water is 10-20 wt%, thereby ensuring the formation of chromium hydroxide precipitate rather than soluble complexes, etc.

[0093] Specifically, before the second calcination treatment of the second precipitate, drying treatment can also be carried out, for example, drying at 80-120 °C for 5-12 h, and then calcining at 200-400 °C for 5-20 h to obtain the second chromium salt.

[0094] Specifically, the mass ratio of graphite to the second chromium salt is (1-10):100, for example, 1:100, 2:100, 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100, 10:100, etc.; preferably 2:100, thereby enabling the catalyst to be formed. Among them, the step of mixing the second chromium salt and graphite to obtain the second catalyst may further include: mixing the second chromium salt and graphite for granulation and forming to obtain the second catalyst. In addition, activation treatment can also be carried out after granulation and forming, for example, activating with HF at 200-400 °C for 4-8 h to obtain the second catalyst.

[0095] Specifically, the molar ratio of HF to HCC-240db is not particularly limited, and those skilled in the art can select according to actual needs. As some specific examples, (5:1)-(20:1) can be selected, such as 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1, etc.; preferably 10:1.

[0096] Specifically, the reaction temperature and space velocity of HCC-240db and HF are not particularly limited, and those skilled in the art can select according to actual needs. As some specific examples, the reaction temperature of HCC-240db and HF is 200-400 °C; the space velocity is 240-800 h -1 , such as 240 h -1 , 300 h -1 , 350 h -1 , 400 h -1 , 450 h -1 , 500 h-1 , 550 h -1 , 600 h -1 , 650 h -1 , 700 h -1 , 750 h -1 , 800 h -1 etc.; preferably 300 °C, and the space velocity is 240 h -1 , 600 h -1 or 800 h -1 .

[0097] Specifically, the step of obtaining HCFO-1233xf from HCC-240db can be carried out by the following method:

[0098] Load the activated second catalyst into the fluorination reactor, and simultaneously introduce HF and HCC-240db into the reaction tube at a molar ratio of (5:1)-(20:1). The temperature of the reaction tube is 200-400 °C, and the space velocity is 240-800 h -1 . The mixed gas after passing through the catalyst is washed, tested, and collected.

[0099] According to a specific embodiment of the present invention, the method further includes preparing the 1,1,1,2,3-pentachloropropane;

[0100] The preparation method of the 1,1,1,2,3-pentachloropropane includes:

[0101] React trichloroethylene with dichloromethane under the action of a third catalyst to obtain the 1,1,1,2,3-pentachloropropane.

[0102] Specifically, the process of obtaining HCC-240db from trichloroethylene and dichloromethane is shown in the following formula:

[0103]

[0104] Specifically, the third catalyst includes a main catalyst and a promoter;

[0105] The main catalyst includes, but is not limited to, iron powder and / or ferric chloride.

[0106] According to a specific embodiment of the present invention, the main catalyst includes at least iron powder.

[0107] According to a specific embodiment of the present invention, when the main catalyst includes both iron powder and ferric chloride, the molar ratio of iron powder to ferric chloride is 1:1-5:1, such as 1:1, 2:1, 3:1, 4:1, 5:1, etc.

[0108] The cocatalyst includes, but is not limited to, phosphate esters; preferably at least one of triethyl phosphate, tributyl phosphate, triethyl phosphite, and diethyl phosphate.

[0109] According to specific embodiments of the present invention, the molar ratio of the main catalyst to the cocatalyst is 1:1 - 1:2, for example, it can be 1:1, 1:1.5, 1:2.

[0110] The molar ratio of dichloromethane to trichloroethylene is 1:1 - 1:4, for example, 1:1, 1:2, 1:3, 1:4.

[0111] Specifically, the preparation method of 1,1,1,2,3 - pentachloropropane may further dissolve trichloroethylene and dichloromethane in a solvent for subsequent reactions. The type of the solvent is not particularly limited and includes, but is not limited to, acetonitrile.

[0112] Specifically, the reaction of trichloroethylene and dichloromethane is preferably carried out in an inert gas (such as nitrogen), and the reaction pressure is preferably 0.3 - 1 MPa, for example, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1 MPa, etc.; optionally, the reaction temperature is preferably 90 - 150 °C, for example, 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, etc.

[0113] Specifically, the preparation method of 1,1,1,2,3 - pentachloropropane may further include separating the obtained crude product, such as extraction and liquid - liquid separation, rectification, etc.

[0114] Specifically, the preparation of 1,1,1,2,3 - pentachloropropane can be carried out by the following method:

[0115] Add the main catalyst (a combination of reduced iron powder and ferric chloride) into a high - pressure reactor, and then perform the evacuation and filling operation on the high - pressure reactor, that is, use a vacuum pump to evacuate the high - pressure reactor to a negative pressure, and then introduce nitrogen. Repeat this operation three times to reduce the oxygen content in the reactor. Then add the cocatalyst (phosphate ester), acetonitrile, dichloromethane, and trichloroethylene, use nitrogen for inert gas protection and keep the pressure within the range of 0.3 - 1 MPa, and react at 90 - 150 °C for 2 - 7 h. After the reaction, perform suction filtration, extraction and liquid - liquid separation, and rectification to obtain the product HCC - 240db.

[0116] According to specific embodiments of the present invention, the method further includes preparing the trichloroethylene;

[0117] The preparation method of the trichloroethylene includes:

[0118] React chlorine with ethylene to obtain the trichloroethylene.

[0119] Thus, the preparation of HFO-1234yf can use ethylene and chlorine as raw materials, and has a lower cost compared to the currently industrialized hexafluoropropylene and trifluoropropylene routes.

[0120] Specifically, the reaction process is as follows:

[0121]

[0122] Specifically, the molar ratio of chlorine to ethylene is not particularly limited, and those skilled in the art can select according to actual needs. As some specific examples, it can be 10:1 - 30:1. The reaction temperature is preferably 100 - 300 °C, and the space velocity is preferably 600 - 1500 h -1 . This process can also be carried out under the action of a catalyst, such as FeCl3 / C catalyst, etc.

[0123] Specifically, a series of by-products will be generated in this process, mainly tetrachloroethylene, vinyl chloride, and dichloroethylene. The obtained crude product can be separated, such as by distillation, etc., to obtain the main product trichloroethylene and less by-product tetrachloroethylene.

[0124] The following will explain the solution of the present invention in combination with embodiments. Those skilled in the art will understand that the following embodiments are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. For those not specified in the embodiments in terms of specific technology or conditions, they shall be carried out according to the technology or conditions described in the literature in this field or according to the product instructions. For reagents or instruments not specified in terms of the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0125] Example 1 uses the method provided by the present invention to prepare 2,3,3,3-tetrafluoropropene

[0126] (1) Mix 500 g of chromium chloride hexahydrate, a water-soluble metal salt containing a first metal promoter, and 9.6 L of deionized water to form solution A. Among them, the water-soluble metal salt containing the first metal promoter is cobalt chloride hexahydrate, and it is added in a ratio of 5:100 of the metal element contained therein to Cr in chromium chloride hexahydrate. Mix 714 mL of ammonia water and 3.3 L of deionized water to form solution B, and then slowly add solution A to B to form a first precipitate, and then dry the first precipitate at 120 °C for 12 h;

[0127] (2) Calcinate the dried first precipitate at 400 °C for 5 h to obtain a first chromium salt (147.01 g). Add graphite and silica to the first chromium salt in a ratio of 2:100 of the mass of graphite to the first chromium salt and 3:100 of the mass of silica to the first chromium salt, mix them and granulate to form a first catalyst precursor. Then activate the first catalyst precursor with HF at 400 °C for 8 h to obtain a first catalyst (chromium-based catalyst);

[0128] (3) Charge 100 mL of the activated first catalyst (chromium-based catalyst) into the fluorination reactor. Simultaneously introduce HF and 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf) into the reaction tube at a molar ratio of 15:1. The temperature of the reaction tube is 350 °C and the space velocity is 800 h -1 . The mixed gas after being catalyzed by the first catalyst is washed, tested, and collected. The collected gas is tested by mass spectrometry to obtain Figure 1 , which is consistent with HFO-1234yf.

[0129] The differences between Examples 2-19, Comparative Example 1 and Example 1 are shown in Table 1. At the same time, the conversions of HCFO-1233xf and the selectivities of HFO-1234yf in Examples 1-19 and Comparative Example 1 are detected by GC:

[0130] Conversion rate = 100% - percentage of peak area of raw material;

[0131] Selectivity = percentage of peak area of product / (100% - percentage of peak area of raw material).

[0132] The test results are shown in Table 1. The results show that the method provided by the present invention can significantly improve the conversion rate of HCFO-1233xf and the selectivity of HFO-1234yf.

[0133] Table 1

[0134]

[0135] Among them, " / " means none.

[0136] Example 20 prepares HCFO-1233xf by the method provided by the present invention

[0137] (1) First, mix 500 g of chromium chloride hexahydrate, a water-soluble metal salt containing a second metal promoter, and 9.6 L of deionized water to form solution A. Among them, the water-soluble metal salt containing the second metal promoter is lanthanum chloride heptahydrate, which is added in a molar ratio of element La to element Cr in chromium chloride hexahydrate of 1:100. Mix 714 mL of ammonia water and 3.3 L of deionized water to form solution B. Then slowly add solution A to B to form a second precipitate, and then dry the second precipitate at 120 °C for 12 h;

[0138] (2) The dried second precipitate was calcined at 400 °C for 5 h to obtain the second chromium salt (152.82 g). Graphite was added to the second chromium salt according to the mass ratio of graphite to the second chromium salt of 2:100, and they were mixed and granulated to obtain the second catalyst precursor. Subsequently, the second catalyst precursor was activated with HF at 400 °C for 8 h to obtain the second catalyst (chromium-based catalyst);

[0139] (3) 100 mL of the activated second catalyst (chromium-based catalyst) was loaded into the fluorination reactor. HF and HCC-240db were simultaneously introduced into the reaction tube at a molar ratio of 15:1. The temperature of the reaction tube was 300 °C, and the space velocity was 240 h -1 . The mixed gas after being catalyzed by the second catalyst was washed, tested, and collected. The collected gas was tested by mass spectrometry to obtain Figure 2 , which was consistent with HCFO-1233xf.

[0140] The differences between Examples 21-28, Comparative Examples 2-4 and Example 20 are shown in Table 1. At the same time, the conversion rate of HCC-240db and the selectivity of HCFO-1233xf in each example and comparative example were detected by GC:

[0141] Conversion rate = 100% - proportion of peak area of raw material, Selectivity = proportion of peak area of product / (100% - proportion of peak area of raw material)

[0142] Catalyst life: cumulative duration when (initial conversion rate of catalyst - final conversion rate of catalyst) ≤ 5%.

[0143] The test results are shown in Table 2. The results show that the catalyst obtained by the method provided by the present invention has a longer life, and at the same time, the conversion rate of HCC-240db and the selectivity of HCFO-1233xf can be improved.

[0144] Table 2

[0145]

[0146] Among them, " / " means none.

[0147] Example 29 Preparation of HCC-240db

[0148] (1) Chlorine and ethylene were introduced into the chlorination reactor together at a molar ratio of 20:1, and the space velocity was 900 h -1 , and the temperature was 200 °C. In the chlorination tower, the crude product was generated under the action of the catalyst, and the catalyst was FeCl3 / C catalyst. The crude product after the reaction was rectified to obtain trichloroethylene and tetrachloroethylene. Among them, the conversion rate of ethylene was 100%, the yield of trichloroethylene was 81%, the yield of tetrachloroethylene was 16%, and other by-products were vinyl chloride and dichloroethylene;

[0149] (2) Add the main catalyst (10.3 g of iron powder and 29.8 g of ferric chloride) into the high-pressure reactor. Subsequently, conduct the evacuation and filling operations on the high-pressure reactor. Then add the cocatalyst (67.0 g of triethyl phosphate), 16.9 g of acetonitrile, 500 g of dichloromethane, and 483 g of trichloroethylene. Use nitrogen for inert gas protection and keep the pressure at 0.5 MPa. React at 100 °C for 5 h. After the reaction is completed, perform suction filtration, extraction and liquid separation, and rectification to obtain the product HCC-240db.

[0150] The differences between Examples 30 - 36 and Example 29 and the reaction yields of step (2) are shown in Table 3. The results show that the method provided by the present invention can ensure a relatively high yield of HCC-240db.

[0151] Table 3

[0152] Experiment number Main catalyst Promoter Reaction yield Example 29 <![CDATA[Fe powder (10.3 g), FeCl3 (29.8 g)]]> Triethyl phosphate (67.0 g) 93％ Example 30 <![CDATA[Fe powder (10.3 g), FeCl3 (29.8 g)]]> Tributyl phosphate (97.9 g) 96％ Example 31 <![CDATA[Fe powder (10.3 g), FeCl3 (29.8 g)]]> Triethyl phosphite (61.1 g) 87％ Example 32 <![CDATA[Fe powder (10.3 g), FeCl3 (29.8 g)]]> Diethyl phosphate (56.7 g) 81％ Example 33 Fe powder (20.5 g) Triethyl phosphate (67.0 g) 91％ Example 34 Fe powder (20.5 g) Tributyl phosphate (97.9 g) 95％ Example 35 Fe powder (20.5 g) Triethyl phosphite (61.1 g) 93％ Example 36 Fe powder (20.5 g) Diethyl phosphate (56.7 g) 84％

[0153] In the description of this specification, the descriptions referring to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0154] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing 2,3,3,3-tetrafluoropropene, characterized in that, Comprising: Mixing a water-soluble metal salt containing a first metal promoter and chromium chloride hexahydrate to prepare a first solution, and mixing the first solution with first ammonia water to obtain a first precipitate; Performing a first calcination treatment on the first precipitate to obtain a first chromium salt; Mixing the first chromium salt with graphite and silicon dioxide to obtain a first catalyst precursor; Performing a fluorination activation treatment on the first catalyst precursor to obtain a first catalyst; Reacting 2-chloro-3,3,3-trifluoropropene with hydrogen fluoride under the action of the first catalyst to obtain the 2,3,3,3-tetrafluoropropene.

2. The method according to claim 1, wherein The first metal promoter includes at least one of La, Y, Zn, Co, Ni, Mg, Al, Fe, Ti, Sn, Sb, and is preferably at least two.

3. The method according to claim 1, characterized in that, The molar ratio of each metal element in the first metal promoter to the chromium element in the chromium chloride hexahydrate is independently (0.5 - 10):100, preferably (0.5 - 5):

100.

4. The method according to claim 1, characterized in that, The concentration of the first ammonia water is 10 - 20 wt%.

5. The method according to claim 1, characterized in that, The temperature of the first calcination treatment is 200 - 400 °C; Optionally, the time of the first calcination treatment is 5 - 20 h.

6. The method according to claim 1, characterized in that, The mass ratio of the graphite to the first chromium salt is (1 - 10):100; Optionally, the mass ratio of the silicon dioxide to the first chromium salt is (1 - 10):

100.

7. The method according to claim 1, wherein The 2-chloro-3,3,3-trifluoropropene reacts with hydrogen fluoride at 200 - 400 °C; Optionally, the space velocity of the reaction of 2-chloro-3,3,3-trifluoropropene with hydrogen fluoride is 600-1000 h -1 .

8. The method according to claim 1, wherein The method further includes preparing the 2-chloro-3,3,3-trifluoropropene; The preparation method of the 2-chloro-3,3,3-trifluoropropene includes: Mixing a water-soluble metal salt containing a second metal promoter and chromium chloride hexahydrate to prepare a second solution, and mixing the second solution with second ammonia water to obtain a second precipitate; Performing a second calcination treatment on the second precipitate to obtain a second chromium salt; Mixing the second chromium salt with graphite to obtain a second catalyst; Reacting 1,1,1,2,3-pentachloropropane with hydrogen fluoride under the action of the second catalyst to obtain the 2-chloro-3,3,3-trifluoropropene; Optionally, the second metal promoter includes at least one of La, Y, Zn, Co, Ni, Mg, Al, Fe, Ti, Sn, Sb; Optionally, the total molar ratio of each metal element in the second metal promoter to the chromium element in the chromium chloride hexahydrate is (0.5:100) - (10:100), preferably (0.5:100) - (5:100), more preferably (0.5:100) - (1:100); Optionally, the concentration of the second ammonia water is 10 - 20 wt%; Optionally, the mass ratio of the graphite to the second chromium salt is (1 - 10):100; Optionally, the 1,1,1,2,3-pentachloropropane reacts with hydrogen fluoride at 200 - 400 °C; Optionally, the space velocity of the reaction of 1,1,1,2,3-pentachloropropane with hydrogen fluoride is 240 - 800 h -1 .

9. The method according to claim 8, wherein The method further includes preparing the 1,1,1,2,3-pentachloropropane; The preparation method of the 1,1,1,2,3-pentachloropropane includes: Under the action of a third catalyst, trichloroethylene is reacted with dichloromethane to obtain the 1,1,1,2,3-pentachloropropane; Optionally, the third catalyst comprises a main catalyst and a co-catalyst; The main catalyst comprises iron powder and / or ferric chloride; the co-catalyst comprises a phosphate ester; Optionally, the phosphate ester comprises at least one of triethyl phosphate, tributyl phosphate, triethyl phosphite, and diethyl phosphate; Optionally, the reaction of trichloroethylene and dichloromethane is carried out at 0.3 - 1 MPa; Optionally, the reaction of trichloroethylene and dichloromethane is carried out at 90 - 150 °C.

10. The method according to claim 9, wherein The method further comprises preparing the trichloroethylene; The preparation method of the trichloroethylene comprises: Reacting chlorine gas with ethylene to obtain the trichloroethylene.

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