Preparation process of R-1234yf refrigerant based on heterogeneous catalyst

Abstract

The invention discloses a preparation process of an R-1234yf refrigerant based on a heterogeneous catalyst, and relates to the field of preparation of refrigerants. According to the method, tetrafluoroethylene and trichloromonofluoromethane are subjected to a reaction through a liquid phase reaction to generate an intermediate product CCl3CF2CF3 (CFC-215cb), then the CFC-215cb is subjected to a catalytic hydrodechlorination reaction to obtain CH3CF2CF3, and then the CH3CF2CF3 is subjected to a catalytic elimination reaction to generate the target product R-1234yf. According to the method, the self-developed catalyst is used as a liquid phase reaction catalyst, Pd / Pd-AlF3 is used as a hydrogenation catalyst, and AlF3, Cr2O3 or activated carbon is used as an elimination catalyst, so that efficient and environment-friendly R-1234yf preparation is realized under mild conditions, and the method has the advantages of high reaction selectivity, high yield and few byproducts.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of refrigerant preparation, in particular to a R-1234yf refrigerant preparation process based on a heterogeneous catalyst. BACKGROUND

[0002] With the intensification of global warming, the emission of greenhouse gases has become the focus of global attention. The use of refrigerants is one of the important sources of greenhouse gas emissions, especially traditional hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) such as R-134a, which have high global warming potential (GWP) and can exist in the atmosphere for a long time, causing greater harm to the environment. Therefore, the international community has imposed strict restrictions on the use and production of these high-GWP refrigerants through the Montreal Protocol and the Kigali Amendment, promoting the development and application of environmentally friendly refrigerants.

[0003] In recent years, the fourth generation of refrigerants has become the focus of industry development. Among them, R-1234yf, as a new low-GWP refrigerant, has been widely used in automotive air conditioning, household air conditioning, commercial refrigeration equipment, and light refrigeration equipment. R-1234yf has low GWP (about 4), zero ozone depletion potential (ODP), low toxicity, and no corrosiveness, etc. characteristics, especially in the field of automotive air conditioning, it is considered as the optimal solution to replace R-134a. In addition, R-1234yf has similar thermophysical properties to traditional refrigerants, and can be replaced and upgraded on existing equipment, and performs well in energy efficiency, meeting the increasingly stringent environmental regulations of countries around the world.

[0004] However, the existing R-1234yf preparation process still faces many challenges. In the industrial production process, the common preparation method relies on homogeneous catalytic reaction or traditional hydrogenation process. Although these processes can achieve the synthesis of R-1234yf, they have the following problems: usually involve complex multi-step reactions and expensive catalysts, and the yield and reaction selectivity need to be improved. In order to overcome the shortcomings of the prior art, it is urgent to develop a more efficient and low-cost R-1234yf preparation process.

[0005] Therefore, it is urgent to develop an efficient, low-energy and environmentally friendly R-1234yf preparation process. This not only can improve production efficiency and reduce cost, but also can reduce the impact on the environment, meeting the more stringent environmental regulations in the future. SUMMARY

[0006] The present application provides a R-1234yf preparation method based on tetrafluoroethylene and trichloromonofluoromethane as raw materials, which generates the target product R-1234yf through liquid phase reaction, hydrogenation dechlorination reaction and elimination reaction.

[0007] The specific technical solution is as follows:

[0008] A process for preparing R-1234yf refrigerant based on a heterogeneous catalyst, characterized in that it comprises the following steps:

[0009] A) Liquid phase reaction: tetrafluoroethylene (CF2=CF2) and trichloromonofluoromethane (CCl3F) are added to a reactor, and a reaction is carried out in the presence of a catalyst by controlling the temperature and pressure, to generate an intermediate product CCl3CF2CF3;

[0010] B) Hydrogenation reaction: hydrogen gas is introduced into CCl3CF2CF3 prepared in step A using a Pd or Pd / AlF3 catalyst under high temperature and high pressure for 2-6 hours to obtain CH3CF2CF3 through hydrogenation dechlorination reaction;

[0011] C) Elimination reaction: CH3CF2CF3 prepared in step B is subjected to an elimination reaction at high temperature through a catalyst to generate R-1234yf.

[0012] Further, the molar ratio of tetrafluoroethylene (CF2=CF2) to trichloromonofluoromethane (CCl3F) in step A is 1:0.8-1.2.

[0013] Further, the amount of catalyst in step A is 0.5-2% of the total mass of the reaction monomers, and the preparation method of the catalyst is as follows:

[0014] Material preparation: by weight

[0015] Vinyl boron anhydride pyridine complex: 0.05-0.3 parts;

[0016] (Ferrocenyl) hexanethiol: 30-60 parts;

[0017] Allyl dibutyltin chloride: 20-40 parts;

[0018] Ethylene diamine: 2-6 parts;

[0019] Dimethylformamide: 500-620 parts

[0020] Preparation steps:

[0021] K1. Mix the raw materials: mix the vinyl boron anhydride pyridine complex (vinyl boron anhydride pyridine complex CAS: 442850-89-7), (ferrocenyl) hexanethiol, allyl dibutyltin chloride, dimethylformamide according to the above proportions and mix uniformly;

[0022] K2. Heating reaction: the reactor is heated to 70-80℃, and the temperature range is maintained under stirring conditions, and the reaction is stirred for 10-20 hours; this step is critical, and the temperature and time need to be strictly controlled to ensure the activity and selectivity of the catalyst;

[0023] K3. Distillation to remove dimethylformamide; drying: the filtered catalyst is placed in a drying device for drying treatment to remove residual solvents and moisture; the dried catalyst is collected and stored in a sealed container to avoid moisture and contamination.

[0024] Further, the reaction temperature in step A is 15-40℃, and the reaction pressure is 0.1-0.5 MPa.

[0025] Further, the reaction temperature in step B is 100-400℃, and the reaction pressure is 1-3 MPa.

[0026] Further, the content of palladium in the Pd or Pd / AlF3 catalyst in step B is 1-10 wt%.

[0027] Further, the molar ratio of hydrogen to CCl3CF2CF3 in step B is 1-4:1.

[0028] Further, the catalyst in step C is AlF3, Cr2O3, or activated carbon catalyst.

[0029] Further, the elimination temperature in step C is 100-400℃.

[0030] The reaction mechanism of the catalyst in step A is:

[0031] 1. Mercapto-allyl addition reaction mechanism:

[0032] Under basic conditions, mercapto attacks allyl to form a new C-S bond, and a carbon anion intermediate is generated. Then, proton transfer or proton acquisition from the solvent is completed to complete the addition reaction.

[0033] 2. Reaction mechanism of catalytic tetrafluoroethylene and trichloromonofluoromethane:

[0034] The boron anhydride pyridine and butyl tin chloride groups in the catalyst interact with the substrate to reduce the activation energy and promote the reaction. Tetrafluoroethylene is first coordinated with the catalyst, then trichloromonofluoromethane is inserted, and the target product CCl3CF2CF3 is generated by elimination reaction.

[0035] 3. Advantages and mechanism of ferrocene, boron anhydride pyridine complex, and butyl tin chloride replacing fluorine modified aluminum trichloride as catalyst:

[0036] Advantages of the catalyst in step A:

[0037] Electronic effect and steric hindrance effect: the structure of ferrocene enhances the electronic density and steric hindrance effect of the catalyst, improves the catalytic activity and selectivity, and enhances the intermolecular interaction force of the catalyst, forms a stable and efficient catalytic system.

[0038] The boron anhydride pyridine complex and the butyl tin chloride reduce the activation energy of the reaction through the electronic effect, and promote the reaction to proceed.

[0039] Compared with the prior art, the present application has the following advantages:

[0040] 1. High selectivity: the generation of by-products is small during the reaction, and the purity of R-1234yf can reach more than 99%.

[0041] 2. High yield: the yield of R-1234yf can reach more than 95% under the optimized reaction conditions.

[0042] 3. Environmental protection: the catalyst used in the process has good regeneration property, reduces waste discharge, and the by-products in the hydrogenation and elimination reactions can be effectively treated, meeting the environmental protection requirements.

[0043] 4. Economy: the reaction is carried out under relatively mild conditions, the energy consumption is low, the catalyst consumption is small, and the production cost is effectively reduced. DETAILED DESCRIPTION

[0044] The following will be further described in detail through specific embodiments:

[0045] The test method involved in the present application is as follows:

[0046] 1. Product purity detection: the purity of R-1234yf is analyzed by using gas chromatography (GC), and the generation of by-products is detected.

[0047] 2. Yield calculation: yield = (actual product mass / theoretical product mass) * 100%

[0048] Example 1

[0049] An R-1234yf refrigerant preparation process based on a heterogeneous catalyst, characterized in that it comprises the following steps:

[0050] A) Liquid phase reaction: tetrafluoroethylene (CF2=CF2) and trichloromonofluoromethane (CCl3F) are added to a reactor, and the reaction is carried out under the control of temperature and pressure in the presence of a catalyst to generate an intermediate product CCl3CF2CF3.

[0051] B) Hydrogenation reaction: hydrogenation dechlorination reaction of CC13CF2CF3 prepared in step A with hydrogen gas using Pd catalyst at high temperature and high pressure for 2h to obtain CH3CF2CF3;

[0052] C) Elimination reaction: elimination reaction of CH3CF2CF3 prepared in step B at high temperature through catalyst to generate R-1234yf.

[0053] The molar ratio of tetrafluoroethylene (CF2=CF2) to trichloromonofluoromethane (CC13F) in step A is 1:0.8.

[0054] The amount of catalyst in step A is 0.5% of the total mass of the reaction monomer, and the preparation method of the catalyst is:

[0055] Material preparation:

[0056] Vinyl boronate pyridine complex: 0.05g;

[0057] (Ferrocenyl)hexanethiol: 30g;

[0058] Allyl dibutyltin chloride: 20g;

[0059] Ethylene diamine: 2g;

[0060] Dimethylformamide: 500g

[0061] Preparation steps:

[0062] K1. Mix raw materials: mix vinyl boronate pyridine complex (vinyl boronate pyridine complex CAS: 442850-89-7), (ferrocenyl)hexanethiol, allyl dibutyltin chloride, dimethylformamide according to the above proportions;

[0063] K2. Heat reaction: heat the reaction kettle to 70°C and maintain the temperature range under stirring conditions for 10 hours of stirring reaction; this step is critical and requires strict control of temperature and time to ensure the activity and selectivity of the catalyst;

[0064] K3. Distillation to remove dimethylformamide; drying: place the filtered catalyst in a drying device for drying treatment to remove residual solvents and moisture; collect and store the dried catalyst in a sealed container to avoid moisture and contamination.

[0065] The reaction temperature in step A is 15°C, and the reaction pressure is 0.1 MPa.

[0066] The reaction temperature in step B is 100°C, and the reaction pressure is 1 MPa.

[0067] The content of palladium in the Pd catalyst in step B is 2wt%.

[0068] The molar ratio of hydrogen gas to CCl3CF2CF3 in step B is 1:1.

[0069] The catalyst in step C is AlF.

[0070] The elimination temperature in step C is 100°C.

[0071] The yield of R-1234yf in this example is 96.2% and the purity of the product is 99.89% according to the analysis.

[0072] Example 2

[0073] A process for preparing R-1234yf refrigerant based on a heterogeneous catalyst, characterized in that it comprises the following steps:

[0074] A) Liquid phase reaction: tetrafluoroethylene (CF2=CF2) and trichloromonofluoromethane (CCl3F) are added to a reactor and reacted in the presence of a catalyst under controlled temperature and pressure to produce an intermediate product CCl3CF2CF3;

[0075] B) Hydrogenation reaction: Pd / AlF3 catalyst is used to introduce hydrogen gas into the CCl3CF2CF3 prepared in step A under high temperature and high pressure for 4 hours of hydrogenation dechlorination reaction to obtain CH3CF2CF3;

[0076] C) Elimination reaction: CH3CF2CF3 prepared in step B is subjected to elimination reaction under high temperature through a catalyst to produce R-1234yf.

[0077] The molar ratio of tetrafluoroethylene (CF2=CF2) to trichloromonofluoromethane (CCl3F) in step A is 1:1.

[0078] The amount of catalyst in step A is 1% of the total mass of the reaction monomers, and the preparation method of the catalyst is:

[0079] Material preparation:

[0080] Vinyl boronic anhydride pyridine complex: 0.1 g;

[0081] (Ferrocenyl)hexanethiol: 40 g;

[0082] Allyl dibutyltin chloride: 30 g;

[0083] Ethylene diamine: 4 g;

[0084] Dimethylformamide: 540 g

[0085] Preparation steps:

[0086] K1. Mixed raw materials: Ethylene boron anhydride pyridine complex (ethylene boron anhydride pyridine complex CAS: 442850-89-7), (ferrocene) hexamethylene mercaptan, allyl dibutyltin chloride, and dimethylformamide are mixed evenly in the above proportions.

[0087] K2. Heating reaction: Heat the reactor to 75°C and maintain this temperature range under stirring for 15 hours; this step is critical and requires strict control of temperature and time to ensure the activity and selectivity of the catalyst;

[0088] K3. Distillation to remove dimethylformamide; Drying: Place the filtered catalyst into a drying device for drying to remove residual solvent and moisture; Collect the dried catalyst and store it in a sealed container to avoid moisture and contamination.

[0089] In step A, the reaction temperature is 25°C and the reaction pressure is 0.3 MPa.

[0090] In step B, the reaction temperature is 200℃ and the reaction pressure is 2MPa.

[0091] In step B, the palladium content in the Pd / AlF3 catalyst is 5 wt%.

[0092] In step B, the molar ratio of hydrogen to CCl3CF2CF3 is 2:1.

[0093] The catalyst used in step C is AlF3.

[0094] The elimination temperature in step C is 200℃.

[0095] Analysis and calculations show that the yield of R-1234yf in this case is 97.1%, and the product purity is 99.93%.

[0096] Example 3

[0097] A process for preparing R-1234yf refrigerant based on a heterogeneous catalyst, characterized by comprising the following steps:

[0098] A) Liquid phase reaction: Tetrafluoroethylene (CF2=CF2) and trichlorofluoromethane (CCl3F) are added to the reactor. In the presence of a catalyst, the temperature and pressure are controlled to carry out the reaction and generate the intermediate product CCl3CF2CF3.

[0099] B) Hydrogenation reaction: Under high temperature and high pressure, using a Pd catalyst, hydrogen gas is introduced and reacted with the CCl3CF2CF3 prepared in step A to carry out a hydrogenation and dechlorination reaction for 4 hours to obtain CH3CF2CF3.

[0100] C) Elimination reaction: The CH3CF2CF3 obtained in step B is subjected to an elimination reaction at high temperature with a catalyst to generate R-1234yf.

[0101] In step A, the molar ratio of tetrafluoroethylene (CF2=CF2) to trichlorofluoromethane (CCl3F) is 1:1.

[0102] In step A, the amount of catalyst is 1.5% of the total mass of the reactants. The catalyst is prepared as follows:

[0103] Materials preparation:

[0104] Ethylene boric anhydride pyridine complex: 0.2g;

[0105] (Ferrocene-based)hexamethylene mercaptan: 50g;

[0106] Allyl dibutyltin chloride: 30g;

[0107] Ethylenediamine: 5g;

[0108] Dimethylformamide: 580g

[0109] Preparation steps:

[0110] K1. Mixed raw materials: Ethylene boron anhydride pyridine complex (ethylene boron anhydride pyridine complex CAS: 442850-89-7), (ferrocene) hexamethylene mercaptan, allyl dibutyltin chloride, and dimethylformamide are mixed evenly in the above proportions.

[0111] K2. Heating reaction: Heat the reactor to 75°C and maintain this temperature range under stirring for 15 hours; this step is critical and requires strict control of temperature and time to ensure the activity and selectivity of the catalyst;

[0112] K3. Distillation to remove dimethylformamide; Drying: Place the filtered catalyst into a drying device for drying to remove residual solvent and moisture; Collect the dried catalyst and store it in a sealed container to avoid moisture and contamination.

[0113] In step A, the reaction temperature is 30°C and the reaction pressure is 0.4 MPa.

[0114] In step B, the reaction temperature is 300℃ and the reaction pressure is 2MPa.

[0115] In step B, the palladium content in the Pd catalyst is 7.5 wt%.

[0116] In step B, the molar ratio of hydrogen to CCl3CF2CF3 is 3:1.

[0117] The catalyst in step C is Cr2O3.

[0118] The elimination temperature in step C is 300℃.

[0119] Analysis and calculation show that the yield of R-1234yf in this case is 96.8%, and the product purity is 99.95%.

[0120] Example 4

[0121] A process for preparing R-1234yf refrigerant based on a heterogeneous catalyst, characterized by comprising the following steps:

[0122] A) Liquid phase reaction: Tetrafluoroethylene (CF2=CF2) and trichlorofluoromethane (CCl3F) are added to the reactor. In the presence of a catalyst, the temperature and pressure are controlled to carry out the reaction and generate the intermediate product CCl3CF2CF3.

[0123] B) Hydrogenation reaction: Under high temperature and high pressure, using a Pd / AlF3 catalyst, hydrogen gas was introduced to carry out a hydrogenation and dechlorination reaction with the CCl3CF2CF3 prepared in step A for 6 hours to obtain CH3CF2CF3.

[0124] C) Elimination reaction: The CH3CF2CF3 obtained in step B is subjected to an elimination reaction at high temperature with a catalyst to generate R-1234yf.

[0125] In step A, the molar ratio of tetrafluoroethylene (CF2=CF2) to trichlorofluoromethane (CCl3F) is 1:1.2.

[0126] In step A, the amount of catalyst is 2% of the total mass of the reactants. The catalyst is prepared as follows:

[0127] Materials preparation:

[0128] Ethyleneborane pyridine complex: 0.3g;

[0129] (Ferrocene-based)hexamethylene mercaptan: 60g;

[0130] Allyl dibutyltin chloride: 40g;

[0131] Ethylenediamine: 6g;

[0132] Dimethylformamide: 620g

[0133] Preparation steps:

[0134] K1. Mixed raw materials: Ethylene boron anhydride pyridine complex (ethylene boron anhydride pyridine complex CAS: 442850-89-7), (ferrocene) hexamethylene mercaptan, allyl dibutyltin chloride, and dimethylformamide are mixed evenly in the above proportions.

[0135] K2. Heating reaction: Heat the reactor to 80°C and maintain this temperature range under stirring for 20 hours; this step is critical and requires strict control of temperature and time to ensure the activity and selectivity of the catalyst;

[0136] K3. Distillation to remove dimethylformamide; Drying: Place the filtered catalyst into a drying device for drying to remove residual solvent and moisture; Collect the dried catalyst and store it in a sealed container to avoid moisture and contamination.

[0137] In step A, the reaction temperature is 40°C and the reaction pressure is 0.5 MPa.

[0138] In step B, the reaction temperature is 400℃ and the reaction pressure is 3MPa.

[0139] In step B, the palladium content in the Pd / AlF3 catalyst is 10 wt%.

[0140] In step B, the molar ratio of hydrogen to CCl3CF2CF3 is 4:1.

[0141] The catalyst in step C is Cr2O3.

[0142] The elimination temperature in step C is 400℃.

[0143] Analysis and calculation show that the yield of R-1234yf in this case is 97.4%, and the product purity is 99.97%.

[0144] Comparative Example 1

[0145] The difference between this comparative example and Example 1 is as follows:

[0146] In step A, no ethylene boric anhydride pyridine complex is added during the preparation of the catalyst.

[0147] Analysis and calculation show that the yield of R-1234yf in this case is 94.7%, and the product purity is 99.12%.

[0148] Comparative Example 2

[0149] The difference between this comparative example and Example 1 is as follows:

[0150] In step A, allyl dibutyltin chloride is not added during the preparation of the catalyst.

[0151] Analysis and calculation show that the yield of R-1234yf in this case is 94.4%, and the product purity is 98.90%.

[0152] The preparation process of this invention significantly improves the yield and purity of R-1234yf through multi-step catalytic reactions, solving the problems of low efficiency and numerous by-products in the prior art, and has broad application prospects.

[0153] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific materials and properties is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A process for preparing R-1234yf refrigerant based on a heterogeneous catalyst, characterized in that, Includes the following steps: A) Liquid phase reaction: Tetrafluoroethylene (CF2=CF2) and trichlorofluoromethane (CCl3F) are added to the reactor. In the presence of a catalyst, the temperature and pressure are controlled to carry out the reaction and generate the intermediate product CCl3CF2CF3. B) Hydrogenation reaction: Under high temperature and high pressure, using Pd or Pd / AlF3 catalyst, hydrogen gas is introduced to carry out a hydrogenation and dechlorination reaction with CCl3CF2CF3 prepared in step A for 2-6 hours to obtain CH3CF2CF3. C) Elimination reaction: The CH3CF2CF3 obtained in step B is subjected to an elimination reaction at high temperature with a catalyst to generate R-1234yf.

2. The preparation process of R-1234yf refrigerant based on a heterogeneous catalyst according to claim 1, characterized in that: In step A, the molar ratio of tetrafluoroethylene (CF2=CF2) to trichlorofluoromethane (CCl3F) is 1:0.8-1.

2.

3. The preparation process of R-1234yf refrigerant based on a heterogeneous catalyst according to claim 1, characterized in that: In step A, the amount of catalyst is 0.5-2% of the total mass of the reactants. The catalyst preparation method is as follows: Material preparation: by weight Ethylene boric anhydride pyridine complex: 0.05-0.3 parts; (Ferrocene-based)hexamethylene mercaptan: 30-60 parts; Allyl dibutyltin chloride: 20-40 parts; Ethylenediamine: 2-6 parts; Dimethylformamide: 500-620 parts Preparation steps: K1. Mixed raw materials: Mix ethylene boron anhydride pyridine complex, (ferrocene) hexamethylene mercaptan, allyl dibutyltin chloride, and dimethylformamide evenly according to the above proportions; K2. Heating reaction: Heat the reactor to 70-80℃ and maintain this temperature range under stirring for 10-20 hours; this step is critical and requires strict control of temperature and time to ensure the activity and selectivity of the catalyst; K3. Distillation to remove dimethylformamide; Drying: Place the filtered catalyst into a drying device for drying to remove residual solvent and moisture; Collect the dried catalyst and store it in a sealed container to avoid moisture and contamination.

4. The preparation process of R-1234yf refrigerant based on a heterogeneous catalyst according to claim 1, characterized in that: In step A, the reaction temperature is 15-40℃ and the reaction pressure is 0.1-0.5MPa.

5. The preparation process of R-1234yf refrigerant based on a heterogeneous catalyst according to claim 1, characterized in that: In step B, the reaction temperature is 100-400℃ and the reaction pressure is 1-3MPa.

6. The preparation process of R-1234yf refrigerant based on a heterogeneous catalyst according to claim 1, characterized in that: In step B, the palladium content in the Pd or Pd / AlF3 catalyst is 1-10 wt%.

7. The preparation process of R-1234yf refrigerant based on a heterogeneous catalyst according to claim 1, characterized in that: In step B, the molar ratio of hydrogen to CCl3CF2CF3 is 1-4:

1.

8. The preparation process of R-1234yf refrigerant based on a heterogeneous catalyst according to claim 1, characterized in that: The catalyst in step C is AlF3, Cr2O3, or activated carbon catalyst.

9. The preparation process of R-1234yf refrigerant based on a heterogeneous catalyst according to claim 1, characterized in that: The elimination temperature in step C is 100-400℃.