A method for preparing 1,2-difluoroethylene from 2-chloro-1,1-difluoroethane resource utilization

Abstract

The application discloses a method for preparing 1,2-difluoroethylene from 2-chloro-1,1-difluoroethane resource utilization, and the method comprises the following steps: under the action of an M-N / Y catalyst, 2-chloro-1,1-difluoroethane is subjected to a gas phase dehydrochlorination reaction to obtain 1,2-difluoroethylene, wherein M is an active component, is a fluoride and / or chloride of at least one of K, Cs, Mg, Sr or Ba; N is a metal additive, is at least one of Ru, Rh, Pd, La, Ce or Pr; and Y is a carrier, is selected from activated carbon, graphene or metal fluoride. The preparation method has the advantages of mild reaction conditions, high selectivity of target products and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the preparation of 1,2-difluoroethylene, in particular to a method for preparing 1,2-difluoroethylene from 2-chloro-1,1-difluoroethane. BACKGROUND

[0002] 1,2-difluoroethylene (HFO-1132 for short), whose trans structure has a GWP value of 1.9 and whose cis structure has a GWP value of 1.5, is not only a polymer monomer but also a fourth-generation HFO refrigerant, which can be used in the fields of heat pumps, refrigeration, freezer units, etc. in combination with HFO-1234ze, trifluoroethylene, trifluoropropargyl, HFC-125, HFC-152a, HCFC-123, etc. It not only has excellent environmental protection performance, but also has refrigeration efficiency (COP) and freezing capacity comparable to widely used air conditioner refrigerants R410a, R32 and R134a. In addition, 1,2-difluoroethylene in combination with HFO-1234yf, etc. can also be used in vehicle air conditioners of hybrid electric vehicles, electric vehicles or hydrogen-powered vehicles. Therefore, 1,2-difluoroethylene has also become a research hotspot of current refrigerant substitutes.

[0003] At present, the dehydrohalogenation preparation route of 1,2-difluoroethylene is as follows:

[0004] I. Dehydrochlorination route of 1-chloro-1,2-difluoroethane (HCFC-142a)

[0005] Patent CN113166005A discloses a method for preparing 1,2-difluoroethylene by gas-phase dehydrochlorination of HCFC-142a under the action of a catalyst. When activated carbon is used as the catalyst, the raw material conversion rate is 89.6% at a reaction temperature of 700℃, and the HFO-1132 selectivity is 90.3%. The raw material conversion rate is only 21% at a reaction temperature of 450℃, and the HFO-1132 selectivity is 93.3%. When a CsCl / MgF2=10:90 mixed catalyst is used, the raw material conversion rate is 91% at a reaction temperature of 750℃, and the HFO-1132 selectivity is 80.3%. The raw material conversion rate is only 20.6% at a reaction temperature of 450℃, and the HFO-1132 selectivity is 99.6%.

[0006] II. Dehydrochlorination route of 2-chloro-1,1-difluoroethane (HCFC-142)

[0007] In this route, 1,2-difluoroethylene only exists as a byproduct, and the main product is 1,1-difluoroethylene. Patent CN110776394A discloses the use of a CrF3 / AC catalyst at 700℃, 2000h -1The HCFC-142 dehydrochlorination reaction was carried out under the condition, the raw material conversion rate was 92.3%, the 1,1-difluoroethylene selectivity was 70.2%, and the 1,2-difluoroethylene selectivity was only 10.6%.

[0008] Yuan Juanjuan in the paper ChemistrySelect 2020, 5, 5788-5793 found that under the condition of 1% K / AC as the catalyst and 600 DEG C, the HCFC-142 dehydrochlorination reaction, the raw material conversion rate was 47.7%, the 1,1-difluoroethylene selectivity was 48.4%, and the 1,2-difluoroethylene selectivity was only 21.9%.

[0009] Three, trifluoroethane (HFC-143) dehydrofluorination route

[0010] The patent CN112105594A discloses a method for preparing 1,2-difluoroethylene by dehydrofluorination of HFC-143 under the action of fluorinated CrO2 catalyst. When the reaction temperature is 400 DEG C, the raw material conversion rate is 98%, and the selectivity of HFO-1132 is 89% (E / Z = 19 / 81).

[0011] In the above raw material route, the raw material HCFC-142a is not easy to obtain, and at a high temperature of 700-750 DEG C, it has a good raw material conversion rate. Once the reaction temperature is reduced to 450 DEG C, the raw material conversion rate is only 20%. A higher reaction temperature requires higher requirements for industrial equipment and safety, and it is difficult to obtain a large amount of raw material, which is not suitable for industrial production. The reaction temperature of the raw material HFC-143 route is appropriate, the raw material conversion rate and product selectivity are also ideal, but the raw material is also difficult to obtain, and HCFC-142 needs to be obtained by fluorination of CHCl2CH2Cl (HCC-140) or CHCl=CHCl (HCO-1130), and then HCFC-142 is fluorinated to obtain HFC-143. However, the reaction conversion rate of HCFC-142 fluorination to prepare HCFC-143 is 70%, and the selectivity of HFC-143 is only 11%, which is too low in economic efficiency, and is also not suitable for industrial application. The raw material HCFC-142 is a by-product of the industrial 1,1-difluoroethane (HFC-152a) photochlorination process to prepare 1-chloro-1,1-difluoroethane (HCFC-142b), which is a very suitable raw material route for industrialization by recycling waste into treasure, but the main product obtained by HCFC-142 dehydrochlorination is 1,1-difluoroethylene, and the selectivity of 1,2-difluoroethylene is very low.

[0012] Therefore, it is necessary to propose a reaction route for preparing 1,2-difluoroethylene by recycling HCFC-142, which has very good industrial application prospect. SUMMARY

[0013] To solve the above technical problems, the present application provides a method for preparing 1,2-difluoroethylene from 2-chloro-1,1-difluoroethane, which has simple process and high selectivity of target product.

[0014] The object of the present application is achieved by the following technical solutions:

[0015] The method for preparing 1,2-difluoroethylene from 2-chloro-1,1-difluoroethane comprises: under the action of M-N / Y catalyst, 2-chloro-1,1-difluoroethane is subjected to gas phase dehydrochlorination reaction to obtain 1,2-difluoroethylene, wherein:

[0016] M is an active component, selected from fluoride and / or chloride of at least one of K, Cs, Mg, Sr or Ba;

[0017] N is a metal additive, selected from at least one of Ru, Rh, Pd, La, Ce or Pr;

[0018] Y is a carrier, selected from activated carbon, graphene or metal fluoride.

[0019] In order to increase the selectivity of the rearrangement reaction of the reactants, the active component M is preferably fluoride and / or chloride of at least one of K and Cs.

[0020] In order to strengthen the dechlorination selectivity of the active component of the catalyst and the synergistic effect with the carrier, the metal additive N is selected from at least one of Ru, Rh and Pd.

[0021] In order to improve the adsorption performance of organic chlorides, Y is preferably activated carbon.

[0022] Further, the loading amount of the active component M is 1-30%, and the loading amount of the metal additive N is 0.01%-2.0%. As a preferred, the loading amount of the active component M is 3-20%, and the loading amount of the metal additive N is 0.05-1.0%. More preferably, the loading amount of the active component M is 5-10%.

[0023] The reaction pressure of the method is normal pressure, the raw material 2-chloro-1,1-difluoroethane is vaporized after passing through a 80℃ vaporizer and then introduced into the reactor, the reaction temperature is 300-500℃, and the reaction space velocity is 100-1000h -1 . Preferably, the reaction temperature is 300-400℃, and the reaction space velocity is 120-600h -1 . The reaction is carried out in a tubular reactor made of corrosion-resistant Monel 400 or Inconel 600.

[0024] Under the M-N / Y catalyst and the reaction temperature condition described in the present application, especially under the condition that the reaction temperature is ≤400℃, the raw material 2-chloro-1,1-difluoroethane can be obviously promoted to undergo intramolecular rearrangement, and the transition state after rearrangement undergoes dehydrochlorination reaction to obtain 1,2-difluoroethylene, and the reaction equation is as follows:

[0025]

[0026] Under the condition that the reaction temperature exceeds the above reaction temperature range or is not under the action of the M-N / Y catalyst, the rearrangement reaction cannot be well induced to occur, and therefore 1,2-difluoroethylene cannot be obtained with high selectivity, that is, 1,2-difluoroethylene can only exist in the form of a byproduct.

[0027] The research reason is that:

[0028] The F atom of the raw material 2-chloro-1,1-difluoroethane (HCFC-142) in the present application is located on the α-C of the molecule, and the Cl atom is located on the β-C. Through DFT theoretical calculation, it is found that under the reaction temperature of 800K, the 1,2-HCl elimination reaction of the molecule needs to overcome the energy barrier of 70.9KJ / mol, the 1,2-HF elimination reaction needs to overcome the energy barrier of 68.1KJ / mol, and the 1,2-FCl exchange rearrangement needs to overcome the energy barrier of 66.3KJ / mol. It can be known that HCFC-142 is more prone to dehydrofluorination reaction and fluorine-chlorine rearrangement reaction. The Z-2,1-HCl elimination reaction of the transition state substance after rearrangement needs to overcome the energy barrier of 58.3KJ / mol, the E-2,1-HCl elimination reaction needs to overcome the energy barrier of 59.1KJ / mol, and the dehydrochlorination reaction after rearrangement is relatively easy. According to the theoretical calculation and research results, the possible mechanism of the HCl elimination reaction after the rearrangement of HCFC-142 is as follows:

[0029]

[0030] It is further found through research that the acidity and alkalinity of the catalyst have a significant influence on the selectivity of the reaction product. The acidic catalyst is helpful for breaking the C-F bond, the reaction active site is located at the acidic site, and thus the dehydrogen fluoride reaction occurs. The basic catalyst is helpful for breaking the C-Cl bond, the reaction active site is located at the basic site, and thus the dehydrogen chloride reaction occurs. The M-N / Y catalyst in the present application has a suitable acid-base strength, promotes the occurrence of intramolecular rearrangement, and thus improves the selectivity of 1,2-difluoroethylene.

[0031] The M-N / Y catalyst described in the present application is formed by impregnating and loading the active component and the metal additive into the carrier in equal volume, and specifically includes the following steps: a metal additive impregnation step, a hydrogen reduction step and an active component impregnation step.

[0032] Specifically, the hydrogen reduction step is carried out in a reducing atmosphere with a hydrogen volume concentration of 1-20%, for 5-15 hours, at a reduction temperature of 150-300°C. Preferably, the hydrogen reduction step is carried out in a reducing atmosphere with a hydrogen volume concentration of 5-10%, for 5-10 hours, at a reduction temperature of 200-250°C.

[0033] In a preferred embodiment, the M-N / Y catalyst is prepared by the following steps:

[0034] S1. Metal assistant impregnation: according to the loading amount, the metal assistant chloride is weighed, and according to the saturated water absorption amount of the activated carbon (40-60 mesh, specific surface area 1000-1500 g / cm 2 ) carrier pretreated by 5% dilute nitric acid, the metal assistant chloride is dissolved in an appropriate amount of deionized water, and the well-dissolved metal assistant chloride aqueous solution is dropwise impregnated on the activated carbon carrier, and after ultrasonic impregnation for 0.1-1 hour, it is continuously impregnated at room temperature for 12-24 hours;

[0035] S2. Hydrogen reduction: after the impregnated activated carbon carrier is dried at 120°C, it is transferred to a hydrogen reduction reaction furnace, and after reduction in a reducing atmosphere with a hydrogen volume concentration of 5% for about 10 hours, an activated carbon-supported metal assistant element is obtained;

[0036] S3. Active component impregnation: according to the loading amount, the active component precursor is weighed, an appropriate amount of deionized water is added to dissolve uniformly, and then the activated carbon-supported metal assistant element is added to the active component precursor aqueous solution, which is continuously heated and stirred at 40-60°C for 8-12 hours, and then placed in an ultrasonic device for ultrasonic treatment for 0.1-1 hour; after that, it is placed at room temperature for 10-24 hours and transferred to a 120°C oven for drying for 4-6 hours, and then calcined at 400°C in a nitrogen atmosphere for 3-5 hours to obtain the M-N / Y catalyst.

[0037] In the reaction product of the preparation of 1,2-difluoroethylene from 2-chloro-1,1-difluoroethane, 1,2-difluoroethylene, 1,1-difluoroethylene and 1-chloro-2-fluoroethylene are included. Among them, 1,2-difluoroethylene includes cis-1,2-difluoroethylene and trans-1,2-difluoroethylene, and byproduct 1-chloro-2-fluoroethylene also includes cis-1-chloro-2-fluoroethylene and trans-1-chloro-2-fluoroethylene.

[0038] Further, the selectivity of 1,1-difluoroethylene in the reaction product is not higher than 10%, and further, the selectivity of 1,1-difluoroethylene in the reaction product is not higher than 5%.

[0039] After the reaction is completed, the system includes, in addition to the reaction product, raw material 2-chloro-1,1-difluoroethane. The boiling point of the raw material 2-chloro-1,1-difluoroethane is 35℃, the boiling point of 1,1-difluoroethylene (VDF) is -84℃, the boiling point of E-2-chloro-1-fluoroethylene is -4℃, the boiling point of Z-2-chloro-1-fluoroethylene is 16℃, the boiling point of E-1,2-difluoroethylene is -53℃, and the boiling point of Z-1,2-difluoroethylene is -26℃. The boiling points of the substances are quite different, and pure E-1,2-difluoroethylene and Z-1,2-difluoroethylene products can be obtained by ordinary rectification.

[0040] Specifically, the reaction product after the reaction is completed is introduced into an acid mist purification tower to remove acidic gases such as HF and HCl, and then is enriched in the distillation tower pot, and 1,2-difluoroethylene products are obtained by separation through a three-stage rectification tower. The condensation temperature at the top of the first-stage rectification tower is -80 to -60℃, so as to collect a small amount of vinylidene fluoride (boiling point -84℃) in the reaction product; the condensation temperature at the top of the second-stage rectification tower is set to -50 to -10℃, so as to collect 1,2-difluoroethylene products (E: -53℃, Z: -26℃); and the temperature at the top of the third-stage rectification tower is set to 16 to 30℃, so as to collect 2-chloro-1-fluoroethylene (E: -4℃, Z: 16℃).

[0041] The 2-chloro-1,1-difluoroethane described in the present application is a by-product of the industrial photochlorination of 1,1-difluoroethane (HFC-152a) to prepare 1-chloro-1,1-difluoroethane (HCFC-142b), and the resource utilization of 2-chloro-1,1-difluoroethane can be well realized through the above-mentioned mode.

[0042] Compared with the prior art, the present application has the beneficial effects including:

[0043] 1. The raw material 2-chloro-1,1-difluoroethane (HCFC-142) of the present application is cheap and easy to obtain, which can be obtained from the by-product of the industrial production of HCFC-142b. Through resource recycling, it can not only be converted into a fluorine-containing olefin monomer with high added value and environmental friendliness, but also can greatly reduce the production and by-product treatment cost of enterprises;

[0044] 2. The process route of the present application is simple, the reaction temperature is low, the reaction energy consumption is low, the single-pass yield of the reaction is high, and the selectivity of the target product is high;

[0045] 3. In the reaction product of the present application, a 1,2-difluoroethylene product with high purity can be obtained through a rectification purification process, and the unreacted raw material can be recycled and reused. DETAILED DESCRIPTION

[0046] The application will be further described in conjunction with specific examples, but the application is not limited to these specific examples. Those skilled in the art should recognize that the application encompasses all alternatives, modifications and equivalents possible within the scope of the claims.

[0047] Preparation Example 1: Preparation of 1.0% Ru / AC catalyst

[0048] 0.1035 g of RuCl3was weighed and dissolved in about 2 mL of deionized water to form an aqueous RuCl3solution. In order to accelerate the dissolution, the solution was heated at a temperature of 30-50°C. Then the above aqueous solution was added dropwise to the surface of 5 g of activated carbon carrier (the activated carbon has a mesh size of 40-60 mesh and a specific surface area of 1000-1500 g / cm 2 , and the activated carbon was washed with 5% dilute nitric acid to remove ash before use), and was immersed at room temperature for 16 hours and then was placed in an oven at 120°C for drying. Finally, the activated carbon supported RuCl3catalyst was transferred to a hydrogen reduction reactor, and was reduced at a hydrogen concentration of 5% and a reduction temperature of 230°C for about 10 hours to obtain a 1.0% Ru / AC catalyst.

[0049] Preparation Example 2: Preparation of 5% CsF-1% Ru / AC catalyst

[0050] This preparation example was based on Preparation Example 1. 0.2857 g of CsF solid powder was weighed and dissolved in an appropriate amount of deionized water to form a transparent aqueous solution at a temperature of 50°C. 5 g of the 1% Ru / AC catalyst prepared in Preparation Example 1 was added to the aqueous solution, and was stirred for 12 hours and ultrasonically treated for 0.5 h before being transferred to an oven for drying for 6 hours. Finally, the catalyst was calcined at 400°C in a nitrogen atmosphere for 4 hours to obtain a 5% CsF-1% Ru / AC catalyst.

[0051] Preparation Example 3: Preparation of 1% CsF-1% Ru / AC catalyst

[0052] This preparation example was based on Preparation Example 1. 0.0577 g of CsF solid powder was weighed and dissolved in an appropriate amount of deionized water to form a transparent aqueous solution at a temperature of 50°C. 5 g of the 1% Ru / AC catalyst prepared in Preparation Example 1 was added to the aqueous solution, and was stirred for 12 hours and ultrasonically treated for 0.5 h before being transferred to an oven for drying for 6 hours. Finally, the catalyst was calcined at 400°C in a nitrogen atmosphere for 4 hours to obtain a 1% CsF-1% Ru / AC catalyst.

[0053] Preparation Example 4: Preparation of 10% CsF-1% Ru / AC catalyst

[0054] Preparation Example 4: 10% CsF-1% Ru / AC catalyst preparation

[0055] Preparation Example 5: 5% KF-1% Ru / AC

[0056] This preparation example was carried out on the basis of Preparation Example 1. 0.3914 g of KF solid powder was weighed and dissolved in an appropriate amount of deionized water at 50°C to form a transparent aqueous solution; 5 g of 1.0% Ru / AC catalyst prepared in Preparation Example 1 was added to the aqueous solution, and stirring was continued for 12 hours and ultrasonic treatment was performed for 0.5 h before being transferred to an oven for drying for 6 hours; finally, calcination was performed at 400°C in a nitrogen atmosphere for 4 hours to obtain a 5% KF-1% Ru / AC catalyst.

[0057] Preparation Example 6: 1% Pd / AC catalyst preparation

[0058] 0.0843 g of PdCl2 was weighed and dissolved in about 2 mL of deionized water and 10 mL of 5% dilute hydrochloric acid to form a PdCl2 aqueous solution; in order to accelerate the dissolution rate, the solution was heated and dissolved at a temperature of 30-50°C and ultrasonic treatment was performed for 0.5 h; then the above aqueous solution was added dropwise to the surface of 5 g of activated carbon carrier (the activated carbon mesh size was 40-60 mesh, and the specific surface area was 1000-1500 g / cm 2 , and the activated carbon was washed with 5% mass concentration of dilute nitric acid to remove ash before use), and the impregnation was performed at room temperature for 16 hours before being placed in an oven at 120°C for drying; finally, the activated carbon-supported PdCl2 catalyst was transferred to a hydrogen reduction reaction furnace, and reduction was performed at a hydrogen gas volume concentration of 5% and a reduction temperature of 230°C for about 10 hours to obtain a 1.0% Pd / AC catalyst.

[0059] Preparation Example 7: 5% CsF-1% Pd / AC catalyst preparation

[0060] This preparation example was carried out on the basis of Preparation Example 6. 0.2587 g of CsF solid powder was weighed and dissolved in an appropriate amount of deionized water at 50°C to form a transparent aqueous solution; 5 g of 1% Pd / AC catalyst prepared in Preparation Example 6 was added to the aqueous solution, and stirring was continued for 12 hours and ultrasonic treatment was performed for 0.5 h before being transferred to an oven for drying for 6 hours; finally, calcination was performed at 400°C in a nitrogen atmosphere for 4 hours to obtain a 5% CsF-1% Pd / AC catalyst.

[0061] Example 1

[0062] 5mL of 5% CsF-1% Ru / AC catalyst particles (catalyst mesh size 40-60 mesh) were charged into a 10mm inner diameter fixed bed reactor for catalytic pyrolysis of gas phase. HCFC-142 raw material (purity 99% or more) was vaporized by a 80°C vaporizer and passed through the 300°C catalyst bed of pre-fluorination catalyst for 2h, then the temperature was raised to 350°C and the reaction was carried out for 180h -1 The pyrolysis reaction was carried out at atmospheric pressure and the temperature of the catalyst bed was recorded. After the reaction products were washed with water and alkali to remove HCl and HF, the components were analyzed by gas chromatography, and the conversion of the raw material and the selectivity of the target product were calculated based on the consumption of HCFC-142. The results are shown in Table 1.

[0063] Example 2

[0064] The operation of this example was the same as that of Example 1, except that the reaction temperature was 350°C and the reaction space velocity was 240h -1 , and the others were unchanged.

[0065] Example 3

[0066] The operation of this example was the same as that of Example 1, except that the reaction temperature was 400°C and the reaction space velocity was 180h -1 , and the others were unchanged.

[0067] Example 4

[0068] The operation of this example was the same as that of Example 1, except that the reaction temperature was 400°C and the reaction space velocity was 240h -1 , and the others were unchanged.

[0069] Example 5

[0070] The operation of this example was the same as that of Example 1, except that the reaction temperature was 500°C and the reaction space velocity was 180h -1 , and the others were unchanged.

[0071] Example 6

[0072] The operation of this example was the same as that of Example 1, except that the reaction temperature was 500°C and the reaction space velocity was 240h -1 , and the others were unchanged.

[0073] Example 7

[0074] The operation of this example was the same as that of Example 1, except that the reaction temperature was 500°C and the reaction space velocity was 360h -1 , and the others were unchanged.

[0075] Example 8

[0076] The operation of this example is the same as Example 1, except that the catalyst is replaced by 5 mL of 1% CsF-1% Ru / AC catalyst pellets, the reaction temperature is 400°C, and the reaction space velocity is 240 h -1 , and the others are unchanged.

[0077] Example 9

[0078] The operation of this example is the same as Example 1, except that the catalyst is replaced by 5 mL of 1% CsF-1% Ru / AC catalyst pellets, the reaction temperature is 500°C, and the reaction space velocity is 240 h -1 , and the others are unchanged.

[0079] Example 10

[0080] The operation of this example is the same as Example 1, except that the catalyst is replaced by 5 mL of 10% CsF-1% Ru / AC catalyst pellets, the reaction temperature is 400°C, and the reaction space velocity is 240 h -1 , and the others are unchanged.

[0081] Example 11

[0082] The operation of this example is the same as Example 1, except that the reaction temperature is 300°C, and the reaction space velocity is 240 h -1 , and the others are unchanged.

[0083] Example 12

[0084] The operation of this example is the same as Example 1, except that the reaction temperature is 250°C, and the reaction space velocity is 240 h -1 , and the others are unchanged.

[0085] Example 13

[0086] The operation of this example is the same as Example 1, except that the catalyst is replaced by 5 mL of 5% KF-1% Ru / AC catalyst pellets, the reaction temperature is 400°C, and the reaction space velocity is 240 h -1 , and the others are unchanged.

[0087] Example 14

[0088] The operation of this example is the same as Example 1, except that the catalyst is replaced by 5 mL of 5% CsF-1% Pd / AC catalyst pellets, the reaction temperature is 400°C, and the reaction space velocity is 240 h -1 , and the others are unchanged.

[0089] Comparative Example 1

[0090] The operation of this example is the same as Example 1, except that the catalyst is replaced by 5 mL of 1.0% Ru / AC catalyst pellets, the reaction temperature is 350°C, and the reaction space velocity is 240 h-1 , and the others are the same.

[0091] Comparative Example 2

[0092] The operation of this comparative example is the same as Comparative Example 1, except that the reaction temperature is 400°C and the reaction space velocity is 240 h -1 , and the others are the same.

[0093] Comparative Example 3

[0094] The operation of this comparative example is the same as Comparative Example 1, except that the reaction temperature is 500°C and the reaction space velocity is 240 h -1 , and the others are the same.

[0095] Comparative Example 4

[0096] The operation of this comparative example is the same as Comparative Example 1, except that the catalyst is replaced with 5 mL of 5.0% CsF / AC catalyst particles, the reaction temperature is 400°C, and the reaction space velocity is 240 h -1 , and the others are the same.

[0097] Comparative Example 5

[0098] The operation of this comparative example is the same as Comparative Example 1, except that the catalyst is replaced with 5 mL of 1.0% Pd / AC catalyst particles, the reaction temperature is 400°C, and the reaction space velocity is 240 h -1 , and the others are the same.

[0099] Comparative Example 6

[0100] The operation of this comparative example is the same as Comparative Example 1, except that the catalyst is replaced with 5 mL of 5.0% KF / AC catalyst particles, the reaction temperature is 400°C, and the reaction space velocity is 240 h -1 , and the others are the same.

[0101] Table 1, Reaction Analysis Results

[0102]

[0103]

[0104] As can be seen from Table 1, at a reaction temperature of 300-400℃, doping of noble metals such as Ru and Pd into alkali metal fluoride (such as CsF) can improve the selectivity of single-component alkali metal fluoride to 1,2-difluoroethylene, and strengthen the interaction between the active component of the catalyst and the carrier, thereby increasing the reaction conversion rate to a certain extent. When the reaction temperature is lower than 250℃, the conversion rate of the raw material and the selectivity of the target product 1-2-difluoroethylene are very low; when the reaction temperature is higher than 500℃, the trend of C-F bond breaking in the raw material molecule is significantly greater than that of F-Cl rearrangement reaction, thereby resulting in that the reaction product at a high temperature of 500℃ is mainly dehydrochlorination product 2-chloro-1-fluoroethylene. This may indicate that the intramolecular rearrangement of 2-chloro-1,1-difluoroethane to obtain 1,2-difluoroethylene requires a suitable reaction temperature range and the action of a suitable reaction catalyst to become the dominant reaction.

Claims

1. A method for the resource utilization of 2-chloro-1,1-difluoroethane to produce 1,2-difluoroethylene, characterized in that: The method comprises: obtaining 1,2-difluoroethylene by gas phase dehydrochlorination reaction of 2-chloro-1,1-difluoroethane under the action of an M-N / Y catalyst, the reaction pressure is normal pressure, and the reaction temperature is 300-400 DEG C, wherein: M is an active component, selected from at least one of fluorides and / or chlorides of K and Cs; N is a metal additive, selected from at least one of Ru, Rh and Pd; Y is a carrier, selected from activated carbon; The loading amount of the active component M is 1-30%, and the loading amount of the metal additive N is 0.01-2.0%.

2. The method of claim 1 for the resource utilization of 2-chloro- 1,1-difluoroethane to produce 1,2-difluoroethylene, characterized by: The loading amount of the active component M is 3-20%, and the loading amount of the metal additive N is 0.05-1.0%.

3. The method of claim 1 for the resource utilization of 2-chloro-1,1 -difluoroethane to produce 1,2-difluoroethene, characterized in that: The raw material 2-chloro-1,1 -difluoroethane was passed into the reactor after being vaporized by a 80°C vaporizer, and the reaction space velocity was 100-1000h -1 .

4. The method of claim 3 for the resource utilization of 2-chloro- 1,1-difluoroethane to produce 1,2-difluoroethylene, characterized by: The reaction pressure is normal pressure, the reaction temperature is 300-400°C, and the reaction space velocity is 120-600h -1 .

5. The method of claim 1 for the resource utilization of 2-chloro- 1,1-difluoroethane to produce 1,2-difluoroethylene, characterized by: The M-N / Y catalyst is formed by loading the active component and the metal additive into the carrier by equal-volume impregnation, and specifically comprises: a metal additive impregnation step, a hydrogen reduction step and an active component impregnation step.

6. The method of claim 5 for the resource utilization of 2-chloro- 1,1-difluoroethane to produce 1,2-difluoroethylene, characterized by: The hydrogen reduction step is performed under a reduction atmosphere with a hydrogen volume concentration of 1-20%, the reduction time is 5-15 h, and the reduction temperature is 150 DEG C-300 DEG C.

7. The method of claim 1, wherein the 2-chloro-1,1-difluoroethane resource utilization to make 1,2-difluoroethylene is characterized by: In the reaction product, the 1,2-difluoroethylene includes cis-1,2-difluoroethylene and trans-1,2-difluoroethylene.

8. The method of claim 7 for the resource utilization of 2-chloro-1,1 -difluoroethane to produce 1,2-difluoroethene, characterized in that: The selectivity of 1,1-difluoroethylene in the reaction product is not higher than 10%.

9. The method of claim 1 for the resource utilization of 2-chloro- 1,1-difluoroethane to produce 1,2-difluoroethylene, characterized by: The reaction is performed in a tubular reactor made of Monel 400 or Inconel 600.

10. The method of claim 1 for the resource utilization of 2-chloro- 1,1-difluoroethane to produce 1,2-difluoroethylene, characterized by: The 2-chloro-1,1-difluoroethane is a by-product of the industrial photochlorination of 1,1-difluoroethane to prepare 1-chloro-1,1-difluoroethane.

11. The method of 2-chloro-1,1 -difluoroethane resource utilization to make 1,2- difluoroethylene according to claim 1, characterized in that: The reaction product is post-treated to obtain 1,2-difluoroethylene product by acid removal and rectification.

Images