阅读说明：本技术 一种气相氟化制备1,1,2,2-四氟乙烷的方法 (Method for preparing 1,1,2, 2-tetrafluoroethane by gas phase fluorination ) 是由 段琦 王瑞英 魏刚 李丕永 王欢 丁莎莎 于 2020-12-30 设计创作，主要内容包括：本发明涉及一种气相氟化制备1,1,2,2-四氟乙烷的方法,属于有机氟化工技术领域。本发明的气相氟化制备1,1,2,2-四氟乙烷的制备方法,以1,1-二氟-2,2-二氯乙烷为原料,在氟化催化剂催化下,与无水氟化氢进行气相氟化反应制备1,1,2,2-四氟乙烷。目标产物的选择性和转化率高,反应可控,对设备无腐蚀,安全环保。制备利用的气相氟化催化剂比表面积大、催化活性高、稳定性好,适合用于气相氟化反应,尤其适合用于以1,1-二氟-2,2-二氯乙烷(R132a)为原料,在氟化催化剂作用下,与无水氟化氢进行气相氟化反应制备1,1,2,2-四氟乙烷(R134)。反应一步完成,流程短、制备工艺简单,便于控制、重复性好,可连续性投料,易于实现大规模工业化生产。(The invention relates to a method for preparing 1,1,2, 2-tetrafluoroethane by gas phase fluorination, belonging to the technical field of organic fluorine chemical industry. The preparation method of the 1,1,2, 2-tetrafluoroethane by gas phase fluorination takes 1, 1-difluoro-2, 2-dichloroethane as a raw material, and carries out gas phase fluorination reaction with anhydrous hydrogen fluoride under the catalysis of a fluorination catalyst to prepare the 1,1,2, 2-tetrafluoroethane. The selectivity and the conversion rate of a target product are high, the reaction is controllable, the equipment is not corroded, and the method is safe and environment-friendly. The prepared gas phase fluorination catalyst has large specific surface area, high catalytic activity and good stability, is suitable for gas phase fluorination reaction, and is particularly suitable for preparing 1,1,2, 2-tetrafluoroethane (R134) by using 1, 1-difluoro-2, 2-dichloroethane (R132 a) as a raw material and carrying out gas phase fluorination reaction with anhydrous hydrogen fluoride under the action of the fluorination catalyst. The reaction is completed in one step, the flow is short, the preparation process is simple, the control is convenient, the repeatability is good, the continuous feeding can be realized, and the large-scale industrial production is easy to realize.)

1. A method for preparing 1,1,2, 2-tetrafluoroethane by gas phase fluorination, which is characterized by comprising the following steps: the method comprises the following steps of taking 1, 1-difluoro-2, 2-dichloroethane as a raw material, and carrying out gas-phase fluorination reaction on the 1, 1-difluoro-2, 2-dichloroethane and anhydrous hydrogen fluoride under the catalysis of a fluorination catalyst to prepare the 1,1,2, 2-tetrafluoroethane, wherein the molar ratio of the anhydrous hydrogen fluoride to the 1, 1-difluoro-2, 2-dichloroethane is 5-20: 1.

2. A method for preparing 1,1,2, 2-tetrafluoroethane by gas phase fluorination, which is characterized in that the reaction conditions of the gas phase fluorination are as follows: the contact time is 5-20 s, the reaction temperature is 250-400 ℃, and the reaction pressure is 0.05-0.45 Mpa.

3. A method for preparing 1,1,2, 2-tetrafluoroethane by gas phase fluorination, which is characterized by comprising the following steps: the active carrier in the precursor of the gas-phase fluorination catalyst is any one or the combination of more of aluminum fluoride, calcium fluoride, magnesium fluoride or zirconium fluoride; the active component in the gas phase fluorination catalyst precursor is any one or combination of more of Cr, Zn, Cu, Co, Ni or Fe.

4. A method for preparing 1,1,2, 2-tetrafluoroethane by gas phase fluorination, which is characterized by comprising the following steps: the mass of the active carrier in the gas phase fluorination catalyst is 80-90% of the mass of the catalyst; the mass of the active component is 10-20% of the mass of the catalyst.

5. A method for preparing 1,1,2, 2-tetrafluoroethane by gas phase fluorination, which is characterized by comprising the following steps: the specific surface area of the active carrier in the precursor of the gas phase fluorination catalyst is more than 100m²(ii)/g, the average pore diameter is 2nm to 10 nm.

6. A process for the vapor phase fluorination of 1,1,2, 2-tetrafluoroethane according to any one of claims 1 to 5 wherein:

the active carrier in the precursor of the gas phase fluorination catalyst is aluminum fluoride, magnesium fluoride and calcium fluoride, and the active components are Cr, Zn and Fe; the mass ratio of the materials is aluminum fluoride: magnesium fluoride: calcium fluoride: cr: zn: fe =70:10:5:5:5:5, the specific surface area of the gas phase fluorination catalyst is 120-230 m²(iv) g, the average pore diameter is 4.5nm to 9.0 nm.

7. A process for the vapor phase fluorination of 1,1,2, 2-tetrafluoroethane according to any one of claims 1 to 5 wherein: 1, 1-difluoro-2, 2-dichloroethane is taken as a raw material, under the action of a fluorination catalyst, the molar ratio of anhydrous hydrogen fluoride to 1, 1-difluoro-2, 2-dichloroethane is 10:1, the contact time is 10s, the reaction temperature is 300 ℃, and the reaction pressure is 0.2 MPa.

8. A process for the vapor phase fluorination of 1,1,2, 2-tetrafluoroethane as claimed in any one of claims 1 to 5, wherein said vapor phase fluorination catalyst is prepared by a process comprising the steps of:

1) preparing corresponding aqueous solution of active component chloride according to a ratio, then soaking the mixture of the active carrier in the aqueous solution of the chloride, drying, roasting in an inert gas atmosphere, and extruding for forming to prepare a catalyst precursor for later use;

2) introducing gas hydrogen fluoride into the precursor prepared in the step 1) at the temperature of 300-350 ℃ for fluorination reaction to prepare the gas phase fluorination catalyst.

9. The process for preparing 1,1,2, 2-tetrafluoroethane by gas phase fluorination as claimed in claim 8, wherein the drying of step 1) is followed by calcination in an inert gas atmosphere of: drying at 120 deg.C for 12h, and calcining at 400 deg.C under nitrogen protection for 10 h.

10. A process for the vapor phase fluorination of 1,1,2, 2-tetrafluoroethane according to claim 8 wherein: the fluorination time of the hydrofluorination of the vent in the step 2) is 8 h.

Technical Field

The invention relates to a preparation method for preparing 1,1,2, 2-tetrafluoroethane by gas phase fluorination, belonging to the technical field of organic fluorine chemical industry.

Background

1,1,2, 2-tetrafluoroethane (HFC-134, R134) with the molecular formula CHF₂-CHF₂The refrigerant is an isomer of R134a, has no flammability, no toxicity and no pungent smell, has a boiling point of-23 ℃, has zero ODP (ozone depleting potential) and a GWP (global warming potential) value which is far less than R134a, and is a very potential substitute refrigerant. As a basic raw material of a novel Freon-substituted refrigerating mixed working medium, the refrigerant has good use value in the aspect of refrigeration industry, and the Chinese patent CN109046335A reports that the refrigerating coefficient of 1,1,2, 2-tetrafluoroethane is high, and the refrigerant has higher effect on a heat pump than other refrigerants. R134 is reported in chinese patents CN106662369A, CN108676547A as a component of the working fluid of high temperature heat pumps. As a novel environment-friendly refrigerant, the refrigerant has good market prospect.

The earliest reports of R134 synthesis started in 1936, and R134 synthesis was proposed during the study of fluoro derivatives of ethane and ethylene. The synthesis route adopted in the actual industrial production of 1,1,2, 2-tetrafluoroethane in the prior art mainly utilizes a tetrachloroethylene route and a fluorination hydrogenation route. The R134 is synthesized by using tetrafluoroethylene and hydrogen as raw materials, the process is simple, but because tetrafluoroethylene has the problem of easy self-polymerization, explosion is easy to cause, long-distance transportation cannot be realized, R134 can be produced only near a tetrafluoroethylene raw material factory, the moisture content and the oxygen content need to be strictly controlled, the reaction temperature for synthesizing R134 is not too high, and the reaction pressure is also suitable to be carried out at low pressure or normal pressure. Patent CN101591218B proposes a method for synthesizing R134 by using palladium as a catalyst in a mixed gas of tetrafluoroethylene and hydrogen, wherein the pressure reaches 0.5MPa, the reaction temperature reaches 300 ℃, the tetrafluoroethylene is olefin which is easy to self-polymerize, accidents are easily caused by high temperature and high pressure, the reaction is not easy to control, and the safe production is difficult to realize.

The R134 is synthesized by fluorination reaction of anhydrous hydrogen fluoride in a fluorination hydrogenation route, and the process has the main problems of low conversion rate and a large amount of corrosive hydrogen fluoride circulation, so that the equipment investment is large and the operating conditions are harsh. Chinese patentCN101591218B proposes a method for synthesizing R134 by using mixed gas of tetrafluoroethylene and hydrogen and palladium as a catalyst, and as the pressure reaches 0.5MPa and the reaction temperature reaches 300 ℃, tetrafluoroethylene is olefin which is easy to polymerize, accidents are easily caused by high temperature and high pressure, the reaction is not easy to control, and safe production is difficult to realize. Song tin gem "New Process for synthesizing R134 and R134 a" reported in the text, the reaction temperature was 80-100 deg.C, V (C)₂F4):V(H₂) 1 (2-4) has higher yield, C₂F₄The conversion of (a) is about 80%. Because the reaction releases heat, heat is difficult to take away in industrial application, temperature control is carried out by means of reactor conduction, the local temperature of the catalyst is greatly increased, the service life of the catalyst is influenced, the reaction selectivity is seriously reduced, and therefore the production cost is increased, and the market competitiveness of products is influenced.

Aiming at the technical defects of the prior art that the reaction condition is harsh, the safe production control is difficult to realize, the conversion rate is low, the catalyst and equipment investment cost is high and the like in industrial production, the preparation method of the gas phase fluorination method 1,1,2, 2-tetrafluoroethane, which has the advantages of mild reaction condition, simple method and easy realization of industrial production, needs to be developed urgently.

Disclosure of Invention

In order to overcome the technical defects of multiple reaction steps, harsh reaction conditions, difficulty in realizing safe production control, low yield, high equipment investment, high cost, unsuitability for industrial production and the like in the prior art, the invention provides a preparation method of 1,1,2, 2-tetrafluoroethane by a gas phase fluorination method, which takes 1, 1-difluoro-2, 2-dichloroethane (R132 a) as a raw material and carries out gas phase fluorination reaction with anhydrous hydrogen fluoride under the action of a fluorination catalyst to prepare the 1,1,2, 2-tetrafluoroethane (R134). The method has the advantages of mild reaction conditions and simple method, and is suitable for industrial production.

In order to achieve the purpose, the technical scheme adopted by the invention for solving the technical problems is as follows:

the method for preparing 1,1,2, 2-tetrafluoroethane through gas phase fluorination comprises the step of carrying out gas phase fluorination reaction on 1, 1-difluoro-2, 2-dichloroethane serving as a raw material and anhydrous hydrogen fluoride under the catalysis of a fluorination catalyst to prepare 1,1,2, 2-tetrafluoroethane, wherein the molar ratio of the anhydrous hydrogen fluoride to the 1, 1-difluoro-2, 2-dichloroethane is 5-20: 1.

Preferably, the reaction conditions of the gas phase fluorination are as follows: the contact time is 5-20 s, the reaction temperature is 250-400 ℃, and the reaction pressure is 0.05-0.45 Mpa.

Preferably, the active carrier in the precursor of the gas-phase fluorination catalyst is any one or more of aluminum fluoride, calcium fluoride, magnesium fluoride or zirconium fluoride; the active component in the gas phase fluorination catalyst precursor is composed of any one or more of Cr, Zn, Cu, Co, Ni or Fe.

Preferably, the using amount of the active carrier in the gas phase fluorination catalyst is 80-90% of the mass of the catalyst; the dosage of the active component is 10-20% of the mass of the catalyst.

Preferably, the specific surface area of the active carrier in the precursor of the gas-phase fluorination catalyst is more than 100m²(iii) a metal fluoride having a mesoporous structure with an average pore diameter of 2nm to 10 nm.

Preferably, the active carrier in the precursor of the gas-phase fluorination catalyst is composed of aluminum fluoride, magnesium fluoride and calcium fluoride, and the active component is composed of Cr, Zn and Fe; wherein the weight ratio of each substance is aluminum fluoride: magnesium fluoride: calcium fluoride: cr: zn: fe weight ratio of 70:10:5:5:5:5, metal fluoride having specific surface area of 120-²(iv) g, the average pore diameter is 4.5nm to 9.0 nm.

The preparation method of the gas phase fluorination catalyst comprises the following steps:

1) preparing corresponding aqueous solution of active component chloride according to the proportion, then dipping the mixture of the active carrier in the aqueous solution of the chloride, roasting in an inert gas atmosphere after drying, and finally extruding and forming to prepare the catalyst precursor.

2) And (2) carrying out hydrofluorination on the precursor prepared in the step 1) at the temperature of 300-350 ℃ by using a gas-permeable body to prepare the gas-phase fluorination catalyst.

Preferably, the step 1) is dried at 120 ℃ for 12 hours and then roasted at 400 ℃ for 10 hours under the protection of nitrogen.

Preferably, the precursor prepared in the step 2) is subjected to hydrofluorination for 8 hours at the temperature of 300-350 ℃.

The invention has the beneficial technical effects that:

1. the method for preparing 1,1,2, 2-tetrafluoroethane by gas phase fluorination takes 1, 1-difluoro-2, 2-dichloroethane (R132 a) as a raw material, and carries out gas phase fluorination reaction with anhydrous hydrogen fluoride under the action of a fluorination catalyst to prepare the 1,1,2, 2-tetrafluoroethane (R134), and the target product has high selectivity and conversion rate, controllable reaction, no corrosion to equipment, safety and environmental protection.

2. The method for preparing 1,1,2, 2-tetrafluoroethane by gas phase fluorination has the advantages of large specific surface area, high catalytic activity and good stability of the gas phase fluorination catalyst, is suitable for gas phase fluorination reaction, and is particularly suitable for preparing 1,1,2, 2-tetrafluoroethane (R134) by gas phase fluorination reaction of 1, 1-difluoro-2, 2-dichloroethane (R132 a) serving as a raw material and anhydrous hydrogen fluoride under the action of the fluorination catalyst.

3. The method for preparing the 1,1,2, 2-tetrafluoroethane by gas phase fluorination has the advantages of one-step reaction completion, short flow, simple preparation process, convenient control, good repeatability, continuous feeding and easy realization of large-scale industrial production.

Detailed Description

The present invention is further illustrated by the following examples, which are not intended to limit the invention.

Preparation of the catalyst: aluminum fluoride in the reference catalyst: magnesium fluoride: calcium fluoride: cr: zn: preparing corresponding CrCl with Fe weight ratio of 70:10:5:5:5:5₃、ZnCl₂And FeCl₃Then soaking a mixture of aluminum fluoride, magnesium fluoride and calcium fluoride in a chloride aqueous solution, drying at 120 ℃ for 12h, then roasting at 400 ℃ for 10h under the protection of nitrogen, and finally extruding and forming to obtain the catalyst precursor. And (3) introducing gas hydrogen fluoride into the precursor at the temperature of 300-350 ℃ for hydrofluorination for 8h to obtain the gas-phase fluorination catalyst.

Example 1:

60ml of a fluorination catalyst is loaded into a stainless steel fixed bed tubular reactor, 1-difluoro-2, 2-dichloroethane and hydrogen fluoride are introduced for reaction, the molar ratio of the hydrogen fluoride to the 1-difluoro-2, 2-dichloroethane is controlled to be 5:1, the contact time is 5s, the reaction temperature is 250 ℃, after 12 hours of reaction, the reaction product is washed by water and alkali, and the conversion rate of R132a and the selectivity of R134 are analyzed by gas chromatography, and the results are shown in Table 1.

Example 2:

the reaction conditions were the same as in example 1 except that the contact time was changed to 10s and the reaction temperature was changed to 300 ℃ on the basis of example 1, and the reaction results are shown in Table 1.

Example 3:

the reaction conditions were the same as in example 1 except that the contact time was changed to 20s and the reaction temperature was changed to 400 ℃ on the basis of example 1, and the reaction results are shown in Table 1.

Example 4:

the molar ratio of hydrogen fluoride to 1-difluoro-2, 2-dichloroethane was changed to 10:1 based on example 1, the reaction temperature was 300 ℃, the other reaction conditions were the same as in example 1, and the reaction results are shown in Table 1.

Example 5:

the reaction conditions were the same as in example 1 except that the molar ratio of hydrogen fluoride to 1-difluoro-2, 2-dichloroethane was changed to 10:1, the contact time was 10s, and the reaction temperature was 400 ℃ on the basis of example 1, and the reaction results were as shown in Table 1.

Example 6:

the reaction conditions were the same as in example 1 except that the molar ratio of hydrogen fluoride to 1-difluoro-2, 2-dichloroethane was changed to 10:1 based on example 1, the contact time was 20s, and the reaction temperature was 250 deg.C, and the reaction results were as shown in Table 1.

Example 7:

the molar ratio of hydrogen fluoride to 1-difluoro-2, 2-dichloroethane was changed to 20:1 based on example 1, the reaction temperature was 400 ℃, the other reaction conditions were the same as in example 1, and the reaction results are shown in Table 1.

Example 8:

the molar ratio of hydrogen fluoride to 1-difluoro-2, 2-dichloroethane was varied to 20:1 on the basis of example 1, the contact time was 10s, the reaction conditions were otherwise the same as in example 1, and the reaction results are shown in Table 1.

Example 9:

the reaction conditions were the same as in example 1 except that the molar ratio of hydrogen fluoride to 1-difluoro-2, 2-dichloroethane was changed to 20:1 based on example 1, the contact time was 20s, and the reaction temperature was 300 deg.C, and the reaction results were as shown in Table 1.

TABLE 1 comparison of reaction conditions and target product Selectivity and conversion for examples 1-9

As can be seen from the experimental results in table 1, the methods for preparing 1,1,2, 2-tetrafluoroethane by gas phase fluorination according to the present invention have the advantages that the conversion rate of R132b is more than 96%, the selectivity of R134 is more than 70%, and the selectivity and the conversion rate of the target product are high in examples 1 to 9. The preparation process is simple, convenient to control, good in repeatability, capable of continuously feeding and easy to realize large-scale industrial production.

It should be noted that the above-mentioned preferred embodiments are merely illustrative of the technical concepts and features of the present invention, and are intended to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.