Method for co-producing 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene

Abstract

To provide a method for co-producing 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene.SOLUTION: A method comprises A1. a telomerization step and A2. a removal step. A1 is a telomerization step of subjecting monofluoromonochloromethane and trifluoroethylene to a telomerization reaction under the action of a telomerization catalyst to prepare 3-chloro-1,1,1,2-tetrafluoropropane, wherein the telomerization catalyst is selected from at least one halide of Al, Sb, Ti, Zr and Hf, and wherein the reaction employs a nonsolvent reaction, and A2 is a removal step of subjecting the 3-chloro-1,1,1,2-tetrafluoropropane to a dehydrochlorination reaction and a dehydrogenation reaction simultaneously under the action of an activated carbon supported noble metal catalyst to obtain 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene, wherein the activated carbon supported noble metal catalyst is at least one of Pd / activated carbon and Pt / activated carbon.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to the production of 2,3,3,3-tetrafluoropropene, and in particular to a method for producing 2,3,3,3-tetrafluoropropene by using trifluoroethylene as a raw material and undergoing a two-step reaction of telomerization and elimination (dehydrochlorination, dehydrofluorination, dehydrogenation, etc.). [Background technology]

[0002] 2,3,3,3-Tetrafluoropropene has zero ODP, a GWP value of <1, a lower Life Cycle Climate Performance (LCCP) than the conventional refrigerant HFC-134a, better system refrigeration performance than HFC-134a, and the same atmospheric decomposition products as HFC-134a, and is currently considered the most potential automotive refrigerant alternative and has been accepted by multiple mainstream automakers. Currently, the production routes for 2,3,3,3-tetrafluoropropene include several of the following:

[0003] 1. Hexafluoropropylene route: 2,3,3,3-tetrafluoropropene is produced using hexafluoropropylene as a raw material. The process is divided into four steps: (1) hydrogenating hexafluoropropylene with hydrogen gas to produce 1,1,1,2,3,3-hexafluoropropane (HFC-236ea), (2) catalytically dehydrofluorinating HFC-236ea to produce 1,1,1,2,3-pentafluoropropene (HFO-1225ye), (3) hydrogenating HFO-1225ye with hydrogen gas to produce 1,1,1,2,3-pentafluoropropane (HFC-245eb), and (4) catalytically dehydrofluorinating HFC-245eb to produce 2,3,3,3-tetrafluoropropene.

[0004] U.S. Patent US20070179324A and Chinese Patents CN101544536A, CN102267869A and CN102026947A all disclose methods for producing 2,3,3,3-tetrafluoropropene using hexafluoropropylene as a raw material through a four-step reaction of hydrogenation, dehydrofluorination, rehydrogenation and re-dehydrofluorination. These methods are characterized by a simple process and mature technology, but they have problems such as a large number of reaction steps, the need to separate and purify multiple intermediate products, complex process steps, large capital investment, low reaction yield, high separation costs and large energy consumption.

[0005] To address the shortcomings of the above patented technologies, Chinese Patent CN103449963B discloses a method for synthesizing 2,3,3,3-tetrafluoropropene through a multi-step continuous reaction using hexafluoropropylene as a raw material, enabling continuous production by directly reacting without separating intermediate products such as HFC-236ea, HFO-1225ye, and HFC-245eb. However, not separating and purifying the intermediate products means that impurities are constantly accumulating in the reaction mixture and being newly added, ultimately affecting the yield of the target product, 2,3,3,3-tetrafluoropropene, and at the same time increasing the difficulty of rectifying and separating the 2,3,3,3-tetrafluoropropene product.

[0006] Second, tetrachloropropene (TCP) route: Patent CN101395108B discloses a method for preparing 2,3,3,3-tetrafluoropropene by a three-step reaction using 1,1,2,3-tetrachloropropene as a raw material. The reaction steps are: (1) fluorination of 1,1,2,3-tetrachloropropene with HF in a gas phase to prepare 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf), with a selectivity of 80-96%; and (2) the production of Cr2O3 and FeCl3. The process involves (1) the addition reaction of HCFO-1233xf with HF to produce 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb) using SbCl5 as the catalyst, and (2) the gas-phase dehydrochlorination of HCFC-244bb over an activated carbon catalyst to produce the target product, 2,3,3,3-tetrafluoropropene. This process has complex reaction steps, making it unsuitable for industrial production, and has problems such as low conversion and high reaction temperatures.

[0007] U.S. Patent US20090099396 discloses a two-step process for producing 2,3,3,3-tetrafluoropropene using 1,1,2,3-tetrachloropropene as a raw material. The reaction steps include (1) liquid-phase fluorination of 1,1,2,3-tetrachloropropene with HF to produce 1,1,1,2,3-pentafluoropropane (HFC-245eb), using SbCl as a catalyst. While the conversion of TCP can reach 100%, the selectivity for HFC-245eb is only 53-59%, resulting in the generation of a large amount of by-products; and (2) liquid-phase dehydrofluorination of HFC-245eb in the presence of an alkali metal hydroxide to produce the target product, 2,3,3,3-tetrafluoropropene. This process has the advantage of fewer reaction steps and less capital investment, but suffers from low selectivity for the intermediate product, HFC-245eb, and significant difficulty in separating the by-products.

[0008] 3. Trifluoropropene route: Patent CN101979364A discloses a method for producing 2,3,3,3-tetrafluoropropene using 3,3,3-trifluoropropene as a raw material, and the reaction includes the steps of: (1) photocatalytic addition reaction of 3,3,3-trifluoropropene with chlorine gas to produce 1,2-dichloro-3,3,3-trifluoropropane, with a raw material conversion rate of 95% and a selectivity of 90%; (2) liquid-phase dehydrochlorination of 1,2-dichloro-3,3,3-trifluoropropane under the action of alkali metal hydroxide to produce 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf). (3) the addition reaction of HCFO-1233xf with HF to produce 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb) using SnCl4, TiCl4, and fluorosulfonic acid as catalysts, with a feedstock conversion of 95% and a selectivity of 90-96%; and (4) the liquid-phase dehydrochlorination of HCFC-244bb over an alkali metal catalyst to produce the target product, CF3CF=CH2, with a feedstock conversion of 95% and a selectivity of 90-95%. This process involves a long synthetic route, high equipment requirements for the first chlorination reaction, and the two-step dehalogenation reaction produces a large amount of waste liquid, resulting in a low overall reaction yield and high synthetic costs.

[0009] 4. Other routes: Asahi Glass Patent WO2011162341A discloses a method for producing 2,3,3,3-tetrafluoropropene by hydrogenation reduction using 1,1-dichloro-2,3,3,3-tetrafluoropropene (CFO-1214ya) as a raw material under the action of a palladium catalyst. However, this method has difficulties in controlling the degree of hydrogenation reduction, is prone to producing intermediates such as 1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd), 1-chloro-2,3,3,3-tetrafluoropropane (HCFC-244eb), and 2,3,3,3-tetrafluoropropane (HFC-254eb), as well as over-reduced products. It also has low product selectivity and requires complex post-treatment. Furthermore, the by-product HFC-254eb can undergo further dehydrofluorination during the alkaline washing process to produce 3,3,3-trifluoropropene (HFO-1243zf), which has a boiling point close to that of HFO-1234yf, further increasing the difficulty of impurity separation. While these problems can be alleviated by controlling the reaction temperature of the catalyst bed and the alkaline washing and absorption temperature, the extent of the improvement is unclear, and the process conditions are difficult to control, making it unsuitable for industrial scale. Summary of the Invention [Problem to be solved by the invention]

[0010] To solve the above technical problems, the present invention provides a method for producing 2,3,3,3-tetrafluoropropene by a two-step method, which has a simple process, mild reaction conditions, high product selectivity, and is suitable for industrial production. [Means for solving the problem]

[0011] The object of the present invention is achieved by the following technical solutions.

[0012] According to a first aspect, the present invention provides a method for producing 2,3,3,3-tetrafluoropropene by a two-step process, said method comprising: A1. Telomerization step: a step of producing 3-chloro-1,1,1,2-tetrafluoropropane by subjecting monofluoromonochloromethane and trifluoroethylene to a pressure telomerization reaction under the action of a telomerization catalyst, wherein the telomerization catalyst is a Lewis acid catalyst or a mixed catalyst of a Lewis acid catalyst and dichloromethane; A2. Dehydrochlorination step: Dehydrochlorinating 3-chloro-1,1,1,2-tetrafluoropropane under the catalytic action of activated carbon to obtain 2,3,3,3-tetrafluoropropene.

[0013] The reaction scheme for producing 2,3,3,3-tetrafluoropropene by the two-step process of the present invention is as follows:

[0014] [ka]

[0015] The Lewis acid catalyst of the present invention is at least one halide selected from the group consisting of Al, Sb, Ti, Zr, and Hf. Preferably, the Lewis acid catalyst is at least one selected from the group consisting of ZrCl4, HfCl4, TiCl4, AlCl3, AlF3, and SbF5. More preferably, the Lewis acid catalyst is ZrCl4 or HfCl4.

[0016] The telomerization reaction of the raw material monofluoromonochloromethane with trifluoroethylene in the present invention is carried out under pressurized conditions, and the raw material monofluoromonochloromethane partially or completely forms a liquid under the reaction conditions. In addition, since the 3-chloro-1,1,1,2-tetrafluoropropane produced by the telomerization reaction is liquid, step A1 of the present invention preferably employs a solvent-free reaction, thereby reducing the need for separation steps of intermediates and / or products.

[0017] The telomerization catalyst of the present invention may be a single Lewis acid catalyst or a mixed catalyst of a Lewis acid catalyst and dichloromethane. When a mixed catalyst is used, the Lewis acid catalyst dissociates and activates monofluoromonochloromethane, resulting in F - , CHCl + , Cl - , CH2F + Dichloromethane dissociates to form ions such as F - , CHCl + , Cl - , CH2F + suppressing the recombination of ions such as F - , CHCl + The directed telomerization reaction of ions with trifluoroethylene is ensured, and the telomerization product CF3CHFCH2Cl is obtained with high selectivity.

[0018] In chemical reactions, the compounding ratio between raw materials, the compounding ratio between raw materials and catalyst, reaction temperature, reaction time, etc. affect the reaction results, and the combination of multiple variables in particular has a significant effect on the reaction results.

[0019] In the telomerization step of the present invention, the molar ratio of monofluoromonochloromethane to trifluoroethylene is 1:0.1 to 1:10, more preferably 1:1 to 1:5. The amount of the Lewis acid catalyst used is 0.01 to 50 wt% of the mass of monofluoromonochloromethane, more preferably 0.1 to 10 wt% of the mass of monofluoromonochloromethane. When a mixed catalyst of a Lewis acid catalyst and dichloromethane is used, the molar blending ratio of dichloromethane to monofluoromonochloromethane is 1:0.01 to 1:10, more preferably 1:0.1 to 1:5.

[0020] The telomerization step of the present invention is carried out under pressurized conditions, with the reaction temperature being −30 to 100° C., the reaction pressure being 0.5 to 5.0 MPa, and the reaction time being 1 to 50 hours, more preferably 0 to 50° C., the reaction pressure being 0.8 to 3.0 MPa, and the reaction time being 5 to 10 hours.

[0021] The dehydrochlorination step of the present invention is carried out under the catalytic action of activated carbon, and the activated carbon is selected from fruit shell-based activated carbon, coal-based activated carbon, and wood-based activated carbon, preferably fruit shell-based activated carbon.

[0022] The dehydrochlorination step is carried out at a reaction temperature of 200 to 500°C, preferably 300 to 350°C.

[0023] In order to further improve the product purity of 2,3,3,3-tetrafluoropropene and reduce the difficulty of post-treatment, the 3-chloro-1,1,1,2-tetrafluoropropane obtained in the telomerization step is separated by rectification and then used in the dehydrochlorination step.

[0024] According to a second aspect, the present invention provides a method for the co-production of 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene, the method comprising: A1. Telomerization step: a step of producing 3-chloro-1,1,1,2-tetrafluoropropane by subjecting monofluoromonochloromethane and trifluoroethylene to a pressure telomerization reaction under the action of a telomerization catalyst, wherein the telomerization catalyst is a Lewis acid catalyst or a mixed catalyst of a Lewis acid catalyst and dichloromethane; A2. Desorption step: a step of simultaneously dehydrochlorinating and dehydrogenating 3-chloro-1,1,1,2-tetrafluoropropane under the action of a noble metal-supported activated carbon catalyst to obtain 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene, wherein the noble metal-supported activated carbon catalyst is at least one of Pd / AC and Pt / AC.

[0025] The reaction scheme of the co-production process of the present invention is as follows:

[0026] [ka]

[0027] The Lewis acid catalyst of the present invention is at least one halide selected from the group consisting of Al, Sb, Ti, Zr, and Hf. Preferably, the Lewis acid catalyst is at least one selected from the group consisting of ZrCl4, HfCl4, TiCl4, AlF3, AlCl3, and SbF5. More preferably, the Lewis acid catalyst is ZrCl4 or HfCl4.

[0028] The telomerization reaction of the raw material monofluoromonochloromethane with trifluoroethylene in the present invention is carried out under pressurized conditions, and the raw material monofluoromonochloromethane partially or completely forms a liquid under the reaction conditions. In addition, since the 3-chloro-1,1,1,2-tetrafluoropropane produced by the telomerization reaction is liquid, step A1 of the present invention preferably employs a solvent-free reaction, thereby reducing the need for separation steps of intermediates and / or products.

[0029] The telomerization catalyst of the present invention may be a single Lewis acid catalyst or a mixed catalyst of a Lewis acid catalyst and dichloromethane. When a mixed catalyst is used, the Lewis acid catalyst dissociates and activates monofluoromonochloromethane, resulting in F - , CHCl + , Cl - , CH2F + Dichloromethane dissociates to form ions such as F - , CHCl + , Cl - , CH2F + suppressing the recombination of ions such as F - , CHCl + The directed telomerization reaction of ions with trifluoroethylene is ensured, and the telomerization product CF3CHFCH2Cl is obtained with high selectivity.

[0030] In chemical reactions, the compounding ratio between raw materials, the compounding ratio between raw materials and catalyst, reaction temperature, reaction time, etc. affect the reaction results, and the combination of multiple variables in particular has a significant effect on the reaction results.

[0031] In the telomerization step of the present invention, the molar ratio of monofluoromonochloromethane to trifluoroethylene is 1:0.1 to 1:10, more preferably 1:1 to 1:5. The amount of the Lewis acid catalyst used is 0.01 to 50 wt% of the mass of monofluoromonochloromethane, more preferably 0.1 to 10 wt% of the mass of monofluoromonochloromethane. When a mixed catalyst of a Lewis acid catalyst and dichloromethane is used, the molar blending ratio of dichloromethane to monofluoromonochloromethane is 1:0.01 to 1:10, more preferably 1:0.1 to 1:5.

[0032] The telomerization step of the present invention is carried out under pressurized conditions, with the reaction temperature being −30 to 100° C., the reaction pressure being 0.5 to 5.0 MPa, and the reaction time being 1 to 50 hours, more preferably 0 to 50° C., the reaction pressure being 0.8 to 3.0 MPa, and the reaction time being 5 to 10 hours.

[0033] In the desorption step of the present invention, when the raw material 3-chloro-1,1,1,2-tetrafluoropropane is adsorbed onto the activated carbon under the action of a noble metal-supported activated carbon catalyst, a dehydrochlorination reaction occurs, and when the raw material 3-chloro-1,1,1,2-tetrafluoropropane is adsorbed onto the noble metal sites on the activated carbon, a dehydrogenation reaction occurs, thereby simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene.

[0034] The noble metal-supported activated carbon catalyst can be produced by a conventional method as long as the noble metal-supported activated carbon catalyst of the present invention can be obtained. Preferably, the present invention is produced by an impregnation method, B1. Carrier pretreatment: A step of drying activated carbon at 90 to 120 ° C for 12 hours or more; B2. Metal salt impregnation: impregnating the pretreated activated carbon under vacuum or atmospheric pressure conditions with a soluble salt solution of Pd or Pt; B3. A step of drying the activated carbon after impregnation, wherein the drying temperature is 90 to 120 ° C and the drying time is 12 hours or more; B4. The dried activated carbon is reduced with a hydrogen-nitrogen mixed gas to obtain the noble metal-supported activated carbon catalyst, wherein the volume ratio of hydrogen gas in the hydrogen-nitrogen mixed gas is 5 to 50% and the reduction temperature is 150 to 300°C.

[0035] In the noble metal-supported activated carbon catalyst, the amount of Pd and Pt supported is 0.1 to 5.0 wt %, and preferably the amount is 0.5 to 1.5 wt %.

[0036] The desorption step of the present invention is a gas-solid phase reaction, in which 3-chloro-1,1,1,2-tetrafluoropropane is vaporized and then loaded into a catalyst bed layer with nitrogen gas to carry out the desorption reaction, and the raw material volumetric space velocity of the desorption reaction is 50 to 300 h -1 and the volume ratio of N2 / 3-chloro-1,1,1,2-tetrafluoropropane is (0.5 to 3.0):1, preferably (1.5 to 2.0):1.

[0037] In the desorption step of the present invention, the reaction temperature is 300 to 600°C, and preferably the reaction temperature is 400 to 450°C.

[0038] By adjusting the process for preparing the noble metal-loaded activated carbon catalyst, the amount of noble metal loaded in the catalyst, and the reaction conditions, the product distribution of the A2 elimination step can be adjusted within a certain range. Generally, the A2 elimination step yields 30-90% 2,3,3,3-tetrafluoropropene and 10-50% 1-chloro-2,3,3,3-tetrafluoropropene. Preferably, the products of the elimination step contain 50-60% 2,3,3,3-tetrafluoropropene and 30-50% 1-chloro-2,3,3,3-tetrafluoropropene, with the remainder being by-products such as 1-chloro-3,3,3-trifluoropropene.

[0039] To further reduce the difficulty of post-treatment, the 3-chloro-1,1,1,2-tetrafluoropropane obtained in the telomerization step is subjected to rectification and then used in the desorption step.

[0040] According to a third aspect, the present invention further provides a method for the co-production of 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene, the method comprising: A1. Telomerization step: a step of producing 3-chloro-1,1,1,2-tetrafluoropropane by subjecting monofluoromonochloromethane and trifluoroethylene to a pressure telomerization reaction under the action of a telomerization catalyst, wherein the telomerization catalyst is a Lewis acid catalyst or a mixed catalyst of a Lewis acid catalyst and dichloromethane; A2. Dehydrohalogenation step: simultaneously dehydrochlorinating and dehydrofluorinating 3-chloro-1,1,1,2-tetrafluoropropane in the presence of a composite dehalogenation catalyst to obtain 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene, wherein the composite dehalogenation catalyst is made from an oxide or fluoride of at least one of Al, Mg, and Cr, and activated carbon powder.

[0041] The oxide or fluoride of at least one of Al, Mg, and Cr is at least one selected from Al2O3, AlF3, MgF2, and Cr2O3, and the activated carbon powder is selected from fruit shell-based activated carbon, coal-based activated carbon, and wood-based activated carbon.

[0042] The reaction scheme of the co-production process of the present invention is as follows:

[0043] [ka]

[0044] The Lewis acid catalyst of the present invention is at least one halide selected from the group consisting of Al, Sb, Ti, Zr, and Hf. Preferably, the Lewis acid catalyst is at least one selected from the group consisting of ZrCl4, HfCl4, TiCl4, AlF3, AlCl3, and SbF5. More preferably, the Lewis acid catalyst is ZrCl4 or HfCl4.

[0045] The telomerization reaction of the raw material monofluoromonochloromethane with trifluoroethylene in the present invention is carried out under pressurized conditions, and the raw material monofluoromonochloromethane partially or completely forms a liquid under the reaction conditions. In addition, since the 3-chloro-1,1,1,2-tetrafluoropropane produced by the telomerization reaction is liquid, step A1 of the present invention preferably employs a solvent-free reaction, thereby reducing the need for separation steps of intermediates and / or products.

[0046] The telomerization catalyst of the present invention may be a single Lewis acid catalyst or a mixed catalyst of a Lewis acid catalyst and dichloromethane. When a mixed catalyst is used, the Lewis acid catalyst dissociates and activates monofluoromonochloromethane, resulting in F - , CHCl + , Cl - , CH2F + Dichloromethane dissociates to form ions such as F - , CHCl + , Cl- , CH2F + suppressing the recombination of ions such as F - , CHCl + The directed telomerization reaction of ions with trifluoroethylene is ensured, and the telomerization product CF3CHFCH2Cl is obtained with high selectivity.

[0047] In chemical reactions, the compounding ratio between raw materials, the compounding ratio between raw materials and catalyst, reaction temperature, reaction time, etc. affect the reaction results, and the combination of multiple variables in particular has a significant effect on the reaction results.

[0048] In the telomerization step of the present invention, the molar ratio of monofluoromonochloromethane to trifluoroethylene is 1:0.1 to 1:10, more preferably 1:1 to 1:5. The amount of the Lewis acid catalyst used is 0.01 to 50 wt% of the mass of monofluoromonochloromethane, more preferably 0.1 to 10 wt% of the mass of monofluoromonochloromethane. When a mixed catalyst of a Lewis acid catalyst and dichloromethane is used, the molar blending ratio of dichloromethane to monofluoromonochloromethane is 1:0.01 to 1:10, more preferably 1:0.1 to 1:5.

[0049] The telomerization step of the present invention is carried out under pressurized conditions, with the reaction temperature being −30 to 100° C., the reaction pressure being 0.5 to 5.0 MPa, and the reaction time being 1 to 50 hours, more preferably 0 to 50° C., the reaction pressure being 0.8 to 3.0 MPa, and the reaction time being 5 to 10 hours.

[0050] In the dehydrohalogenation step of the present invention, under the action of a composite dehalogenation catalyst, 3-chloro-1,1,1,2-tetrafluoropropane is adsorbed onto activated carbon to undergo a dehydrochlorination reaction, and 3-chloro-1,1,1,2-tetrafluoropropane is adsorbed onto Al2O3 and / or AlF3 and / or MgF2 and / or Cr2O3 to undergo a dehydrofluorination reaction, thereby simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene.

[0051] The composite dehalogenation catalyst of the present invention can be produced by a conventional method as long as the composite dehalogenation catalyst of the present invention can be obtained. Preferably, the composite dehalogenation catalyst of the present invention is produced by a co-mixing method, B1. Mixing: Mixing Al2O3 and / or AlF3 and / or MgF2 and / or Cr2O3 with activated carbon powder in a mass ratio of (0.01-0.25):1 and thoroughly mixing by mechanical stirring or ball milling; B2. Sifting: Sifting the mixed material to remove uneven parts of the mixture; B3. Forming: The sieved material is sent to a tablet press to form tablets; B4. The molded catalyst is dried and the composite dehalogenation catalyst, such as AlO 3- and producing catalysts such as AC, AlF3-AC, MgF2-AC and Cr2O3-AC.

[0052] The B3 molding step can be performed in the form of a column, a sheet, or the like, and there is no specific limitation to the shape.

[0053] The drying treatment in step B4 is generally carried out at 90°C to 120°C for 12 hours or more.

[0054] In the composite dehalogenation catalyst of the present invention, when Al2O3 is co-mixed with activated carbon powder, the Al2O3 content is 1.0 to 20 wt% of the total catalyst weight; when AlF3 is co-mixed with activated carbon powder, the AlF3 content is 1.0 to 20 wt% of the total catalyst weight; when MgF2 is co-mixed with activated carbon, the MgF2 content is 1.0 to 20 wt% of the total catalyst weight; and when Cr2O3 is co-mixed with activated carbon, the Cr2O3 content is 1.0 to 20 wt% of the total catalyst weight.

[0055] The dehydrohalogenation step of the present invention is a gas-solid phase reaction, in which 3-chloro-1,1,1,2-tetrafluoropropane is vaporized and then loaded into a catalyst bed with nitrogen gas to carry out the dehydrohalogenation reaction, and the raw material volumetric space velocity of the dehydrohalogenation reaction is 50 to 300 h -1 and the volume ratio of N2 / 3-chloro-1,1,1,2-tetrafluoropropane is (0.5 to 3.0):1, preferably (1.5 to 2.0):1.

[0056] The reaction temperature of the dehydrohalogenation step of the present invention is 300 to 500°C, and preferably the reaction temperature is 350 to 450°C.

[0057] By adjusting the preparation process of the composite dehalogenation catalyst, the content of the active component in the catalyst, and the reaction conditions, the product distribution in the dehydrohalogenation step can be adjusted within a certain range. Generally, the dehydrohalogenation step yields 10-50% 2,3,3,3-tetrafluoropropene and 10-70% 1-chloro-3,3,3-trifluoropropene. Preferably, the product of the elimination step contains 20-40% 2,3,3,3-tetrafluoropropene and 30-60% 1-chloro-3,3,3-trifluoropropene, with the remainder being unknown by-products.

[0058] To further reduce the difficulty of post-treatment, the 3-chloro-1,1,1,2-tetrafluoropropane obtained in the telomerization step is separated by rectification and then used in the dehydrohalogenation step. [Effects of the Invention]

[0059] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0060] The present invention uses monofluoromonochloromethane and trifluoroethylene as raw materials, and obtains 3-chloro-1,1,1,2-tetrafluoropropane by pressure telomerization under the action of a Lewis acid catalyst or a mixed catalyst of a Lewis acid catalyst and dichloromethane. 2,3,3,3-tetrafluoropropene can be obtained by producing 2,3,3,3-tetrafluoropropene from 3-chloro-1,1,1,2-tetrafluoropropane in the presence of an activated carbon catalyst, or by simultaneously dehydrochlorinating and dehydrogenating 3-chloro-1,1,1,2-tetrafluoropropane in the presence of a noble metal-supported activated carbon catalyst to co-produce 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene, or by simultaneously dehydrochlorinating and dehydrofluorinating 3-chloro-1,1,1,2-tetrafluoropropane in the presence of a composite dehalogenation catalyst to co-produce 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene. The three methods for producing 2,3,3,3-tetrafluoropropene provided by the present invention have the advantages of simple processes, mild reaction conditions, high selectivity for telomerization products and target products, etc., and are suitable for industrial expansion. DETAILED DESCRIPTION OF THE INVENTION

[0061] The present invention will be further described below with reference to specific examples, but the present invention is not limited to these specific embodiments. Those skilled in the art should recognize that the present invention encompasses all alternatives, modifications, and equivalents that may fall within the scope of the claims.

[0062] According to a first aspect of an embodiment of the present invention, there is provided a method for producing 2,3,3,3-tetrafluoropropene by a two-step process. Example 1.1 This example provides a method for producing 2,3,3,3-tetrafluoropropene by a double-step method, which includes a telomerization step and a dehydrochlorination step, and is specifically as follows:

[0063] 1. Telomerization step A1. A 250 mL Inconel alloy autoclave was used as the reactor. 3.0 g of HfCl4 and 20.0 g of dichloromethane were added to the reactor. After sealing the reactor, 1.0 MPa of nitrogen gas was introduced to replace the air inside the reactor. This was repeated three times. A2. After the air replacement in the reactor is completed, 19.9 g (0.29 mol) of monofluoromonochloromethane and 24.6 g (0.30 mol) of trifluoroethylene are poured in succession. A3. The reaction temperature is set to 10°C, the stirring speed is set to 300 rpm, and the initial reaction pressure is set to 0.9 MPa. As the reaction progresses, the pressure is gradually reduced. The reaction time is set to 10 hours. A4. After the reaction is completed, the unreacted gaseous raw materials trifluoroethylene and / or monofluoromonochloromethane, as well as a small amount of telomerization products and dichloromethane, are collected, and the materials in the reactor are subjected to solid-liquid separation treatment such as filtration or distillation. The solid is the Lewis acid catalyst (HfCl4), and the liquid is dichloromethane and telomerization products. 3-chloro-1,1,1,2-tetrafluoropropane with a purity of 99.9% is obtained by rectification and separation, which is used in the dehydrochlorination reaction.

[0064] The unreacted vapor phase raw material and the separated Lewis acid catalyst can be recycled back to the telomerization step.

[0065] Analysis of the gaseous and liquid phase substances by gas chromatography showed that the conversion of monofluoromonochloromethane was 76.5%, the selectivity for 3-chloro-1,1,1,2-tetrafluoropropane was 81.2%, and the main by-product was 1-chloro-1,1,2,3-tetrafluoropropane with a selectivity of 15.3%, with small amounts of other by-products.

[0066] Second, dehydrochlorination step B1. An Inconel alloy reaction tube with an inner diameter of 19 mm and a length of 800 mm is used as a fixed-bed reactor. A 20 mL volume of coconut shell activated carbon with a particle size of 10-20 mesh is filled in the center of the fixed-bed reactor. The reactor is connected to a reaction line and purged with nitrogen gas at a flow rate of 100 mL / min. B2. Set the reaction temperature to 350°C and the heating rate to 5°C / min, and start heating the reactor. B3. After the catalyst bed reaches the reaction temperature, adjust the nitrogen gas flow rate to 20 mL / min, and simultaneously continuously flow 99.9% pure 3-chloro-1,1,1,2-tetrafluoropropane into the fixed-bed reactor at a rate of 5.0 g / h to start the reaction. B4. Online GC and GC / MS analysis of the gas mixture leaving the reactor revealed a conversion of 3-chloro-1,1,1,2-tetrafluoropropane of 99.6% and a selectivity for the product 2,3,3,3-tetrafluoropropene of 99.3%. Example 1.2 This example provides a method for preparing 2,3,3,3-tetrafluoropropene, and the operation is the same as in Example 1.1, except that in the telomerization step, ZrCl4 is used instead of HfCl4, and the amount used is 4.0g, the amount of monofluoromonochloromethane is increased to 39.7g (0.58mol), and the amount of trifluoroethylene is increased to 71.3g (0.87mol), and other conditions are unchanged.

[0067] Gas chromatography analysis of the gas and liquid phase materials from the telomerization step showed that the conversion of monofluoromonochloromethane was 99.0%, the selectivity of 3-chloro-1,1,1,2-tetrafluoropropane was 89.9%, and the main by-product was 1-chloro-1,1,2,3-tetrafluoropropane with a selectivity of 5.3%, with small amounts of other by-products. Example 1.3 This example provides a method for preparing 2,3,3,3-tetrafluoropropene, and the operation is the same as in Example 1.2, except that in the telomerization step, dichloromethane is not used, and the amount of trifluoroethylene used is increased to 95.1g (1.16mol), and at the same time, the reaction temperature is increased to 30°C, and the initial reaction pressure is increased to 1.5MPa, and other conditions are unchanged.

[0068] Gas chromatography analysis of the gas and liquid phase materials from the telomerization step showed that the conversion of monofluoromonochloromethane was 99.5%, the selectivity of 3-chloro-1,1,1,2-tetrafluoropropane was 88.1%, and the main by-product was 1-chloro-1,1,2,3-tetrafluoropropane with a selectivity of 4.1%, with small amounts of other by-products. Example 1.4 This example provides a method for preparing 2,3,3,3-tetrafluoropropene, and the procedure is the same as in Example 1.2, except that in the telomerization step, AlCl3 is used instead of ZrCl4, and the amount used remains the same, 4.0g; at the same time, dichloromethane is not used, and the amount of trifluoroethylene is reduced to 52.5g (0.64mol); other conditions remain unchanged.

[0069] Gas chromatography analysis of the gas and liquid phase materials from the telomerization step showed that the conversion of monofluoromonochloromethane was 99.6%, the selectivity of 3-chloro-1,1,1,2-tetrafluoropropane was 75.5%, and the main by-product was 1-chloro-1,1,2,3-tetrafluoropropane with a selectivity of 15.9%, with small amounts of other by-products. Example 1.5 This embodiment provides a method for preparing 2,3,3,3-tetrafluoropropene, and the operation is the same as that of Example 1.1. The only difference is that in step A2 of telomerization step, monofluoromonochloromethane and trifluoroethylene are successively introduced into the autoclave, and then high-purity high-pressure nitrogen gas is used to pressurize the autoclave, and the pressure inside the autoclave is increased from 0.9 MPa to 3.0 MPa. Other conditions remain unchanged.

[0070] Gas chromatography analysis of the gas and liquid phase materials from the telomerization step showed that the conversion of monofluoromonochloromethane was 99.8%, the selectivity of 3-chloro-1,1,1,2-tetrafluoropropane was 88.6%, and the main by-product was 1-chloro-1,1,2,3-tetrafluoropropane with a selectivity of 7.6%, with small amounts of other by-products. Example 1.6 This example provides a method for producing 2,3,3,3-tetrafluoropropene. The operation is the same as in Example 1.1, except that in the dehydrochlorination step, 10-20 mesh coal-based activated carbon is used instead of coconut shell-based activated carbon.

[0071] Chromatographic analysis of the dehydrochlorination product revealed that the conversion of 3-chloro-1,1,1,2-tetrafluoropropane was 99.2%, and the selectivity for the product, 2,3,3,3-tetrafluoropropene, reached 95.1%. Example 1.7 This example provides a method for producing 2,3,3,3-tetrafluoropropene, and the operation is the same as in Example 1.1, except that in the dehydrochlorination step, the reaction temperature is reduced to 300°C.

[0072] Chromatographic analysis of the dehydrochlorination showed a conversion of 3-chloro-1,1,1,2-tetrafluoropropane of 75.8% with a selectivity to the product 2,3,3,3-tetrafluoropropene of 99.2%. Example 1.8 This example provides a method for producing 2,3,3,3-tetrafluoropropene, and the operation is the same as in Example 1.1, except that in the dehydrochlorination step, the reaction temperature is reduced to 320°C.

[0073] Chromatographic analysis of the dehydrochlorination product revealed that the conversion of 3-chloro-1,1,1,2-tetrafluoropropane was 86.9% and the selectivity for the product, 2,3,3,3-tetrafluoropropene, was 99.1%. (Comparative Example 1.1) This comparative example provides a method for preparing 2,3,3,3-tetrafluoropropene. The procedure is the same as in Example 1.1, except that trichloromethane is used instead of dichloromethane in an amount of 20.0 g, and other conditions are unchanged.

[0074] Chromatographic analysis of the material after the telomerization step reaction showed that the conversion of monofluoromonochloromethane was 86.9%, the selectivity of 3-chloro-1,1,1,2-tetrafluoropropane was 46.2%, and a large amount of dichloromethane, a disproportionation product of monofluoromonochloromethane, was produced, with a selectivity of 40.3%, and there were also small amounts of other telomerization by-products. (Comparative Example 1.2) This comparative example provides a method for preparing 2,3,3,3-tetrafluoropropene. The procedure is the same as in Example 1.1, except that ZnCl2 is used instead of HfCl4 in an amount of 3.0 g, and other conditions are unchanged.

[0075] Chromatographic analysis of the material after the telomerization step reaction revealed that the conversion rate of monofluoromonochloromethane was 20.8%, and the target product, 3-chloro-1,1,1,2-tetrafluoropropane, was not produced. (Comparative Example 1.3) This comparative example provides a method for preparing 2,3,3,3-tetrafluoropropene, and the operation is the same as in Example 1.1, except that HfCl4 and dichloromethane are not added, and other conditions are unchanged.

[0076] Chromatographic analysis of the material after the telomerization step reaction revealed that the conversion rate of monofluoromonochloromethane was 7.7%, and that the target product, 3-chloro-1,1,1,2-tetrafluoropropane, was not produced, with only a small amount of dichloromethane, a disproportionation product of monofluoromonochloromethane, being produced.

[0077] According to a second aspect of the present invention, there is provided a method for the co-production of 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene. (Production Example 2.1) 6.0 mL of chloropalladium acid solution (concentration: 0.033 g Pd / mL) was diluted uniformly with 80.0 mL of distilled water, and the above impregnation solution was added to 20.0 g of pretreated (dried at 120°C for 12 hours) activated carbon. The mixture was impregnated for 12 hours or more and then dried at 120°C for 12 hours to obtain a 1% wt. Pd / AC catalyst designated as cat2.1. (Example 2.2) 9.2 mL of chloropalladium acid solution (concentration: 0.033 g Pd / mL) was diluted uniformly with 80.0 mL of distilled water, and the above impregnation solution was added to 20.0 g of pretreated (dried at 120°C for 12 hours) activated carbon. The impregnation was continued for 12 hours or more, and then dried at 120°C for 12 hours to obtain a 1.5 wt.% Pd / AC catalyst designated as cat2.2. (Example 2.3) 0.35 g of PtCl4 was dissolved in 80.0 mL of distilled water, and the above impregnation solution was added to 20.0 g of pretreated (dried at 120 °C for 12 h) activated carbon. The mixture was impregnated for 12 hours or more and then dried at 120 °C for 12 hours to obtain a 1 wt.% Pt / AC catalyst designated as cat2.3. (Example 2.4) 0.52 g of PtCl4 was dissolved in 80.0 mL of distilled water, and the above impregnation solution was added to 20.0 g of pretreated (dried at 120 °C for 12 h) activated carbon. The mixture was impregnated for 12 hours or more and then dried at 120 °C for 12 hours to obtain a 1.5 wt.% Pt / AC catalyst designated as cat2.4. Example 2.1 This embodiment provides a method for simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene, which includes a telomerization step and a desorption step, and is specifically as follows:

[0078] 1. Telomerization step A1. A 250 mL Inconel alloy autoclave was used as the reactor. 3.0 g of HfCl4 and 20.0 g of dichloromethane were added to the reactor. After sealing the reactor, nitrogen gas of 1.0 MPa or more was introduced to replace the air inside the reactor. This was repeated three times. A2. After the air replacement in the reactor is completed, 19.9 g (0.29 mol) of monofluoromonochloromethane and 24.6 g (0.30 mol) of trifluoroethylene are poured in succession. A3. The reaction temperature is set to 10°C, the stirring speed is set to 300 rpm, and the initial reaction pressure is set to 0.9 MPa. As the reaction progresses, the pressure is gradually reduced. The reaction time is set to 10 hours. A4. After the reaction is completed, the unreacted gaseous raw materials trifluoroethylene and / or monofluoromonochloromethane, as well as a small amount of telomerization products and dichloromethane, are collected, and the materials in the reactor are subjected to solid-liquid separation treatment such as filtration or distillation. The solid is the Lewis acid catalyst (HfCl4), and the liquid is dichloromethane and telomerization products. 3-chloro-1,1,1,2-tetrafluoropropane with a purity of 99.9% is obtained by rectification and separation, which is used in the desorption step.

[0079] The unreacted vapor phase raw material and the separated Lewis acid catalyst can be recycled back to the telomerization step.

[0080] Analysis of the gaseous and liquid phase substances by gas chromatography showed that the conversion of monofluoromonochloromethane was 76.5%, the selectivity for 3-chloro-1,1,1,2-tetrafluoropropane was 81.2%, and the main by-product was 1-chloro-1,1,2,3-tetrafluoropropane with a selectivity of 15.3%, with small amounts of other by-products.

[0081] Second, the desorption step B1. An Inconel alloy reaction tube with an inner diameter of 19 mm and a length of 800 mm is used as a fixed-bed reactor. A 20 mL volume of Cat2.1 is filled in the center of the fixed-bed reactor, connected to the reaction line, and purged with nitrogen gas at a flow rate of 100 mL / min. B2. Set the reaction temperature to 450°C and the heating rate to 5°C / min, and start heating the reactor. B3. After the catalyst bed reaches the reaction temperature, adjust the nitrogen gas flow rate to 20 mL / min. At the same time, use a peristaltic pump to continuously flow 99.9% pure 3-chloro-1,1,1,2-tetrafluoropropane into the fixed-bed reactor at a rate of 5.0 g / h to start the reaction. B4. The gas mixture flowing out of the reactor was kept at a constant temperature and analyzed online by GC and GC / MS. The conversion rate of 3-chloro-1,1,1,2-tetrafluoropropane was 96.8%, the content of 2,3,3,3-tetrafluoropropene in the product was 56.3%, and the content of 1-chloro-2,3,3,3-tetrafluoropropene was 31.4%. Example 2.2 This example provides a method for simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene. The procedure is the same as in Example 2.1, except that in the telomerization step, ZrCl4 is used instead of HfCl4, and the amount used is 4.0 g, the amount of monofluoromonochloromethane is increased to 39.7 g (0.58 mol), and the amount of trifluoroethylene is increased to 71.3 g (0.87 mol), and other conditions are unchanged.

[0082] Gas chromatography analysis of the gas and liquid phase materials from the telomerization step showed that the conversion of monofluoromonochloromethane was 99.0%, the selectivity of 3-chloro-1,1,1,2-tetrafluoropropane was 89.9%, and the main by-product was 1-chloro-1,1,2,3-tetrafluoropropane with a selectivity of 5.3%, with small amounts of other by-products. Example 2.3 This example provides a method for simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene, and the operation is the same as in Example 2.2, except that in the telomerization step, dichloromethane is not used, and the amount of trifluoroethylene used is increased to 95.1g (1.16mol), while the reaction temperature is increased to 30°C, and the initial reaction pressure is increased to 1.5MPa, and other conditions are unchanged.

[0083] Gas chromatography analysis of the gas and liquid phase materials from the telomerization step showed that the conversion of monofluoromonochloromethane was 99.5%, the selectivity of 3-chloro-1,1,1,2-tetrafluoropropane was 88.1%, and the main by-product was 1-chloro-1,1,2,3-tetrafluoropropane with a selectivity of 4.1%, with small amounts of other by-products. Example 2.4 This example provides a method for simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene. The procedure is the same as in Example 2.2, except that in the telomerization step, AlCl3 is used instead of ZrCl4, and the amount used remains the same, at 4g; at the same time, dichloromethane is not used, and the amount of trifluoroethylene is reduced to 52.5g (0.64mol); other conditions remain unchanged.

[0084] Gas chromatography analysis of the gas and liquid phase materials from the telomerization step showed that the conversion of monofluoromonochloromethane was 99.6%, the selectivity of 3-chloro-1,1,1,2-tetrafluoropropane was 75.5%, and the main by-product was 1-chloro-1,1,2,3-tetrafluoropropane with a selectivity of 15.9%, with small amounts of other by-products. Example 2.5 This example provides a method for simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene. The operation is the same as in Example 2.1, except that in step A2 of the telomerization step, monofluoromonochloromethane and trifluoroethylene are introduced into the autoclave in advance, and high-purity high-pressure nitrogen gas is used to pressurize the autoclave, increasing the pressure inside the autoclave from 0.9 MPa to 3.0 MPa. Other conditions remain unchanged.

[0085] Gas chromatography analysis of the gas and liquid phase materials from the telomerization step showed that the conversion of monofluoromonochloromethane was 99.8%, the selectivity of 3-chloro-1,1,1,2-tetrafluoropropane was 88.6%, and the main by-product was 1-chloro-1,1,2,3-tetrafluoropropane with a selectivity of 7.6%, with small amounts of other by-products. Example 2.6 This example provides a method for the simultaneous production of 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene, and the procedure is the same as in Example 2.1, except that cat2.3 is used instead of cat2.1 in the elimination step.

[0086] Chromatographic analysis of the elimination reaction product showed that the conversion of 3-chloro-1,1,1,2-tetrafluoropropane was 89.3%, the content of 2,3,3,3-tetrafluoropropene in the product was 90.3%, and the content of 1-chloro-2,3,3,3-tetrafluoropropene was 7.7%. Example 2.7 This example provides a method for the simultaneous production of 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene. The procedure is the same as in Example 2.1, except that the amount of cat2.1 used in the elimination step is increased to 40 mL.

[0087] Chromatographic analysis of the elimination reaction product showed that the conversion of 3-chloro-1,1,1,2-tetrafluoropropane was 95.8%, the content of 2,3,3,3-tetrafluoropropene in the product was 65.7%, and the content of 1-chloro-2,3,3,3-tetrafluoropropene was 26.8%. Example 2.8 This example provides a method for the simultaneous production of 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene, and the procedure is the same as in Example 2.1, except that in the elimination step, cat2.2 is used instead of cat2.1.

[0088] Chromatographic analysis of the elimination reaction product showed that the conversion of 3-chloro-1,1,1,2-tetrafluoropropane was 70.1%, the content of 2,3,3,3-tetrafluoropropene in the product was 39.2%, and the content of 1-chloro-2,3,3,3-tetrafluoropropene was 28.5%. Example 2.9 This example provides a method for simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene. The procedure is the same as in Example 2.1, except that the reaction temperature in the elimination step is 400°C.

[0089] Chromatographic analysis of the elimination reaction product showed that the conversion of 3-chloro-1,1,1,2-tetrafluoropropane was 96.7%, the content of 2,3,3,3-tetrafluoropropene in the product was 85.2%, and the content of 1-chloro-2,3,3,3-tetrafluoropropene was 10.3%. (Comparative Example 2.1) This comparative example provides a method for simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene. The procedure is the same as in Example 2.1, except that trichloromethane is used in an amount of 20.0 g instead of dichloromethane, and other conditions are unchanged.

[0090] Chromatographic analysis of the material after the telomerization step reaction showed that the conversion of monofluoromonochloromethane was 86.9%, the selectivity of 3-chloro-1,1,1,2-tetrafluoropropane was 46.2%, and a large amount of dichloromethane, a disproportionation product of monofluoromonochloromethane, was produced, with a selectivity of 40.3%, and there were also small amounts of other telomerization by-products. (Comparative Example 2.2) This comparative example provides a method for simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene. The procedure is the same as in Example 2.1, except that ZnCl2 is used instead of HfCl4 in an amount of 3.0 g, and other conditions are unchanged.

[0091] Chromatographic analysis of the material after the telomerization step reaction revealed that the conversion rate of monofluoromonochloromethane was 20.8%, and the target product, 3-chloro-1,1,1,2-tetrafluoropropane, was not produced. (Comparative Example 2.3) This comparative example provides a method for simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene. The procedure is the same as in Example 2.1, except that HfCl4 and dichloromethane are not added, and other conditions remain unchanged.

[0092] Chromatographic analysis of the material after the telomerization step reaction revealed that the conversion rate of monofluoromonochloromethane was 7.7%, and that the target product, 3-chloro-1,1,1,2-tetrafluoropropane, was not produced, with only a small amount of dichloromethane, a disproportionation product of monofluoromonochloromethane, being produced. (Comparative Example 2.4) This comparative example provides a method for simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene. The procedure is the same as in Example 2.1, except that in the desorption step, pretreated activated carbon (dried at 120°C for 12 hours) is used instead of cat2.1, and other conditions remain unchanged.

[0093] Chromatographic analysis of the elimination reaction product showed that the conversion of 3-chloro-1,1,1,2-tetrafluoropropane was 99.7%, the content of 2,3,3,3-tetrafluoropropene in the product was 99.0%, and no 1-chloro-2,3,3,3-tetrafluoropropene was produced. (Comparative Example 2.5) This comparative example provides a method for simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene. The procedure is the same as in Example 2.1, except that Al2O3 is used instead of cat2.1, and other conditions are unchanged.

[0094] Chromatographic analysis of the elimination reaction products showed that the conversion of 3-chloro-1,1,1,2-tetrafluoropropane was 50.1%, the content of 2,3,3,3-tetrafluoropropene in the products was 3.1%, and the content of 1-chloro-3,3,3-trifluoropropene was 62.2%, meaning that no 1-chloro-2,3,3,3-tetrafluoropropene was produced.

[0095] According to a third aspect of an embodiment of the present invention, there is provided a method for the co-production of 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene. (Production Example 3.1) In this example, a co-mixed catalyst of Cr2O3 and activated carbon powder, Cr2O3-AC, is produced. The production steps are as follows: S1. Mixing Cr2O3 and coconut shell activated carbon powder in a mass ratio of 1 / 9, and then mixing the mixed materials in a ball mill to uniformly disperse each component; S2. Sifting the mixed material to remove any inhomogeneous parts of the mixture; S3. The sieved material is sent to a tablet press to form tablets to produce a pillar-shaped catalyst; S4. The molded catalyst is dried at 120°C for 12 hours to produce a Cr2O3-AC catalyst designated as cat3.1. (Example 3.2) The procedure of this preparation is the same as that of Preparation 3.1, except that AlF3 is used instead of Cr2O3 to produce the AlF3-AC catalyst designated cat3.2. (Example 3.3) The procedure of this preparation example is the same as that of Preparation Example 3.1, except that the mass ratio of Cr2O3 to activated carbon is changed to 1 / 4, and a Cr2O3-AC catalyst designated as cat3.3 is prepared and obtained. Example 3.1 This example provides a method for simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene, which includes a telomerization step and a dehydrohalogenation step, and is specifically as follows:

[0096] 1. Telomerization step A1. A 250 mL Inconel alloy autoclave was used as the reactor. 3.0 g of HfCl4 and 20.0 g of dichloromethane were added to the reactor. After sealing the reactor, nitrogen gas of 1.0 MPa or more was introduced to replace the air inside the reactor. This was repeated three times. A2. After the air replacement in the reactor is completed, 19.9 g (0.29 mol) of monofluoromonochloromethane and 24.6 g (0.30 mol) of trifluoroethylene are poured in succession. A3. The reaction temperature is set to 10°C, the stirring speed is set to 300 rpm, and the initial reaction pressure is set to 0.9 MPa. As the reaction progresses, the pressure is gradually reduced. The reaction time is set to 10 hours. A4. After the reaction is completed, the unreacted gaseous raw materials trifluoroethylene and / or monofluoromonochloromethane, as well as a small amount of telomerization products and dichloromethane, are collected, and the materials in the reactor are subjected to solid-liquid separation treatment such as filtration or distillation. The solid is the Lewis acid catalyst (HfCl4), and the liquid is dichloromethane and telomerization products. 3-chloro-1,1,1,2-tetrafluoropropane with a purity of 99.9% is obtained by rectification and separation, which is used in the dehydrohalogenation step.

[0097] The unreacted vapor phase raw material and the separated Lewis acid catalyst can be recycled back to the telomerization step.

[0098] Analysis of the gaseous and liquid phase substances by gas chromatography showed that the conversion of monofluoromonochloromethane was 76.5%, the selectivity for 3-chloro-1,1,1,2-tetrafluoropropane was 81.2%, and the main by-product was 1-chloro-1,1,2,3-tetrafluoropropane with a selectivity of 15.3%, with small amounts of other by-products.

[0099] Second, dehydrohalogenation step B1. An Inconel alloy reaction tube with an inner diameter of 19 mm and a length of 800 mm is used as a fixed-bed reactor. A volume of 20 mL of Cat3.1 is filled in the middle of the fixed-bed reactor, connected to the reaction line, and purged with nitrogen gas at a flow rate of 100 mL / min. B2. Set the reaction temperature to 350°C and the heating rate to 5°C / min, and start heating the reactor. B3. After the catalyst bed reaches the reaction temperature, adjust the nitrogen gas flow rate to 20 mL / min, and simultaneously continuously flow 99.9% pure 3-chloro-1,1,1,2-tetrafluoropropane into the fixed-bed reactor at a rate of 5.0 g / h to start the reaction. B4. The gas mixture discharged from the reactor was kept at a constant temperature and analyzed online by GC and GC / MS. The conversion rate of 3-chloro-1,1,1,2-tetrafluoropropane reached 88.7%, the content of 2,3,3,3-tetrafluoropropene in the product reached 24.1%, and the content of 1-chloro-3,3,3-trifluoropropene reached 58.7%. Example 3.2 This example provides a method for simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene. The procedure is the same as in Example 3.1, except that in the telomerization step, ZrCl4 is used instead of HfCl4, and the amount used is 4.0 g, the amount of monofluoromonochloromethane is increased to 39.7 g (0.58 mol), and the amount of trifluoroethylene is increased to 71.3 g (0.87 mol), and other conditions are unchanged.

[0100] Gas chromatography analysis of the gas and liquid phase materials from the telomerization step showed that the conversion of monofluoromonochloromethane was 99.0%, the selectivity of 3-chloro-1,1,1,2-tetrafluoropropane was 89.9%, and the main by-product was 1-chloro-1,1,2,3-tetrafluoropropane with a selectivity of 5.3%, with small amounts of other by-products. Example 3.3 This example provides a method for simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene. The operation is the same as in Example 3.2, except that in the telomerization step, dichloromethane is not used, and the amount of trifluoroethylene is increased to 95.1g (1.16mol), while the reaction temperature is increased to 30°C, and the initial reaction pressure is increased to 1.5MPa. Other conditions remain unchanged.

[0101] Gas chromatography analysis of the gas and liquid phase materials from the telomerization step showed that the conversion of monofluoromonochloromethane was 99.5%, the selectivity of 3-chloro-1,1,1,2-tetrafluoropropane was 88.1%, and the main by-product was 1-chloro-1,1,2,3-tetrafluoropropane with a selectivity of 4.1%, with small amounts of other by-products. Example 3.4 This example provides a method for simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene. The procedure is the same as in Example 3.2, except that in the telomerization step, AlCl3 is used instead of ZrCl4, and the amount used remains the same at 4.0g; at the same time, dichloromethane is not used, and the amount of trifluoroethylene is reduced to 52.5g (0.64mol); other conditions remain unchanged.

[0102] Gas chromatography analysis of the gas and liquid phase materials from the telomerization step showed that the conversion of monofluoromonochloromethane was 99.6%, the selectivity of 3-chloro-1,1,1,2-tetrafluoropropane was 75.5%, and the main by-product was 1-chloro-1,1,2,3-tetrafluoropropane with a selectivity of 15.9%, with small amounts of other by-products. Example 3.5 This example provides a method for simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene. The operation is the same as in Example 3.1, except that in step A2 of the telomerization step, monofluoromonochloromethane and trifluoroethylene are sequentially introduced into the autoclave, and then high-purity high-pressure nitrogen gas is used to pressurize the autoclave, increasing the pressure inside the autoclave from 0.9 MPa to 3.0 MPa. Other conditions remain unchanged.

[0103] Gas chromatography analysis of the gas and liquid phase materials from the telomerization step showed that the conversion of monofluoromonochloromethane was 99.8%, the selectivity of 3-chloro-1,1,1,2-tetrafluoropropane was 88.6%, and the main by-product was 1-chloro-1,1,2,3-tetrafluoropropane with a selectivity of 7.6%, with small amounts of other by-products. Example 3.6 This example provides a method for the simultaneous production of 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene. The procedure is the same as in Example 3.1, except that cat. 3.2 is used instead of cat. 3.1 in the dehydrohalogenation step.

[0104] Chromatographic analysis of the dehydrohalogenation reaction product showed that the conversion of 3-chloro-1,1,1,2-tetrafluoropropane was 92.9%, the content of 2,3,3,3-tetrafluoropropene in the product was 20.3%, and the content of 1-chloro-3,3,3-trifluoropropene was 58.7%. Example 3.7 This example provides a method for the simultaneous production of 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene. The procedure is the same as in Example 3.1, except that the amount of cat. 3.1 used in the dehydrohalogenation step is increased to 40 mL.

[0105] Chromatographic analysis of the dehydrohalogenation reaction product showed that the conversion of 3-chloro-1,1,1,2-tetrafluoropropane was greater than 95.9%, the content of 2,3,3,3-tetrafluoropropene in the product was 16.1%, and the content of 1-chloro-3,3,3-trifluoropropene was 44.6%. Example 3.8 This example provides a method for simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene. The procedure is the same as in Example 3.1, except that the reaction temperature in the dehydrohalogenation step is 450°C.

[0106] Chromatographic analysis of the dehydrohalogenation reaction product showed that the conversion of 3-chloro-1,1,1,2-tetrafluoropropane was 98.3%, the content of 2,3,3,3-tetrafluoropropene in the product was 15.9%, and the content of 1-chloro-3,3,3-trifluoropropene was 60.0%. (Comparative Example 3.1) This comparative example provides a method for simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene. The procedure is the same as in Example 3.1, except that trichloromethane is used in place of dichloromethane in an amount of 20 g, and other conditions remain unchanged.

[0107] Chromatographic analysis of the material after the telomerization step reaction showed that the conversion of monofluoromonochloromethane was 86.9%, the selectivity of 3-chloro-1,1,1,2-tetrafluoropropane was 46.1%, and a large amount of dichloromethane, a disproportionation product of monofluoromonochloromethane, was produced, with a selectivity of 40.3%, and there were also small amounts of other telomerization by-products. (Comparative Example 3.2) This comparative example provides a method for simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene. The procedure is the same as in Example 3.1, except that ZnCl2 is used in place of HfCl4 in an amount of 3.0 g, and other conditions remain unchanged.

[0108] Chromatographic analysis of the material after the telomerization step reaction revealed that the conversion rate of monofluoromonochloromethane was 20.8%, and the target product, 3-chloro-1,1,1,2-tetrafluoropropane, was not produced. (Comparative Example 3.3) This comparative example provides a method for simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene. The procedure is the same as in Example 3.1, except that HfCl4 and dichloromethane are not added, and other conditions remain unchanged.

[0109] Chromatographic analysis of the material after the telomerization step reaction revealed that the conversion rate of monofluoromonochloromethane was 7.6%, and that the target product, 3-chloro-1,1,1,2-tetrafluoropropane, was not produced, with only a small amount of dichloromethane, a disproportionation product of monofluoromonochloromethane, being produced. (Comparative Example 3.4) This comparative example provides a method for simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene. The procedure is the same as in Example 3.1, except that in the dehydrohalogenation step, pretreated coconut shell-based activated carbon (dried at 120°C for 12 hours) is used instead of cat. 3.1. Other conditions remain unchanged.

[0110] Chromatographic analysis of the dehydrohalogenation reaction product showed that the conversion of 3-chloro-1,1,1,2-tetrafluoropropane exceeded 99.7%, the content of 2,3,3,3-tetrafluoropropene in the product was 99.0%, and no 1-chloro-3,3,3-trifluoropropene was produced. (Comparative Example 3.5) This comparative example provides a method for simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-3,3,3-trifluoropropene. The procedure is the same as in Example 3.1, except that Pd / AC catalyst (Pd loading: 1 wt%) is used instead of cat3.1, and other conditions are unchanged.

[0111] Chromatographic analysis of the dehydrohalogenation reaction product showed that the conversion of 3-chloro-1,1,1,2-tetrafluoropropane was 83.5%, the content of 2,3,3,3-tetrafluoropropene in the product was 96.4%, the content of 1-chloro-2,3,3,3-tetrafluoropropene was 1.3%, and no 1-chloro-3,3,3-trifluoropropene was produced.

Claims

1. A method for simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene, comprising: A1. Telomerization step: A step of producing 3-chloro-1,1,1,2-tetrafluoropropane by subjecting monofluoromonochloromethane and trifluoroethylene to a pressure telomerization reaction under the action of a telomerization catalyst, wherein the telomerization catalyst is a Lewis acid catalyst or a mixed catalyst of a Lewis acid catalyst and dichloromethane, and the Lewis acid catalyst is at least one halide selected from Al, Sb, Ti, Zr, and Hf, and the A1. telomerization step is a step of employing a solvent-free reaction; A2. A desorption step: a step of simultaneously dehydrochlorinating and dehydrogenating 3-chloro-1,1,1,2-tetrafluoropropane under the action of a noble metal-supported activated carbon catalyst to obtain 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene, wherein the noble metal-supported activated carbon catalyst is at least one of Pd / AC and Pt / AC, A method for simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene, characterized in that the amount of Pd or Pt supported on a precious metal-supported activated carbon catalyst is 0.1 to 5.0 wt %, and 30 to 90% of 2,3,3,3-tetrafluoropropene and 10 to 50% of 1-chloro-2,3,3,3-tetrafluoropropene are obtained by the A2 elimination step.

2. The Lewis acid catalyst is ZrCl ４ , HfCl ４ , TiCl ４ , AlF ３ , AlCl ３ , SbF ５ 2. The method for simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene according to claim 1, wherein the solvent is at least one selected from the group consisting of:

3. the molar blending ratio of the monofluoromonochloromethane to trifluoroethylene is 1:0.1 to 1:10; the Lewis acid catalyst is 0.01 wt % to 50 wt % of the mass of the monofluoromonochloromethane; the molar blending ratio of dichloromethane to monofluoromonochloromethane is 1:0.01 to 1:10; 2. The method for simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene according to claim 1, wherein the pressurized telomerization reaction is carried out at a temperature of −30 to 100° C. under a pressure of 0.5 to 5.0 MPa, and the reaction time is 1 to 50 hours.

4. The noble metal-supported activated carbon catalyst is produced by an impregnation method, B1. Carrier pretreatment: A step of drying activated carbon at 90 to 120 ° C for 12 hours or more; B2. Metal salt impregnation: adopting a soluble salt solution of Pd or Pt to impregnate the pretreated activated carbon under vacuum or atmospheric pressure conditions; B3. Drying the impregnated activated carbon, the drying temperature is 90 to 120°C, and the drying time is 12 hours or more; B4. The method for simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene according to claim 1, wherein the dried activated carbon is reduced with a hydrogen-nitrogen mixed gas to obtain the noble metal-supported activated carbon catalyst, wherein the volume ratio of hydrogen gas in the hydrogen-nitrogen mixed gas is 5 to 50%, and the reduction temperature is 150 to 300°C.

5. After vaporizing 3-chloro-1,1,1,2-tetrafluoropropane, it is loaded into the catalyst bed layer with nitrogen gas to carry out the desorption reaction, and the raw material volumetric space velocity of the desorption reaction is 50 to 300 h －１ and N ２ / 3-chloro-1,1,1,2-tetrafluoropropane volume ratio is (0.5 to 3.0):1, The desorption step is carried out at a reaction temperature of 300 to 600°C, The method for simultaneously producing 2,3,3,3-tetrafluoropropene and 1-chloro-2,3,3,3-tetrafluoropropene according to claim 1, characterized in that the 3-chloro-1,1,1,2-tetrafluoropropane obtained in the telomerization step is separated by rectification and then used in the desorption step.

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