Catalysts and processes for the production of 1,2-difluoroethene from 2-chloro-1,1-difluoroethane

Abstract

Catalysts and processes for the production of 1,2-difluoroethene from 2-chloro-1,1-difluoroethane. The present application provides a supported catalyst comprising a first catalytic component selected from the group consisting of aluminum fluoride, chromium fluoride, cobalt fluoride, ferrous fluoride and ferric fluoride supported on a support, and a second catalyst component selected from the group consisting of potassium fluoride, cesium fluoride, magnesium fluoride and calcium fluoride. The present application also provides a process for the production of 1,2-difluoroethene by catalytic cracking of 2-chloro-1,1-difluoroethane using the catalyst. The technical solution of the present application can greatly improve the conversion rate of HCFC-142, which is an industrial byproduct of no value, and obtain high-value target product 1,2-difluoroethene with high selectivity.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of chemical industry, more particularly to a novel supported catalyst and a catalytic cracking reaction process using the same. BACKGROUND

[0002] Fluorine-containing vinyl compounds are a large class of fluorine-containing compounds known in the industry, common compounds include 1-fluoroethylene, 1,1-difluoroethylene, chlorotrifluoroethylene, trifluoroethylene, tetrafluoroethylene, etc. Tetrafluoroethylene has always been the core raw material monomer of fluorine-containing polymer products. The latest research found that 1,2-difluoroethylene has the potential to be a new generation of refrigerants with lower global warming potential (GWP), or can be used for solvent, blowing agent and other purposes. However, on the other hand, there are still some fluorine-containing olefins that have not found suitable industrial or commercial applications so far, which brings great pressure on environmental protection and cost.

[0003] For example, 2-chloro-1,1-difluoroethane (HCFC-142) is an isomer of 1-chloro-1,1-difluoroethane (HCFC-142b), and is also an inevitable by-product in the large-scale production of HCFC-142b in industry. At present, HCFC-142 has not found a suitable industrial application value, and the large amount of by-product 2-chloro-1,1-difluoroethane (HCFC-142) produced in the production process brings considerable pressure on environmental protection, storage and waste treatment of related enterprises. In order to solve this problem, researchers have so far invested a lot of time and effort in research, hoping to develop an efficient, simple and low-cost process to turn the worthless HCFC-142 into valuable fluorine-containing hydrocarbon products. One of the technologies is to catalytically crack 2-chloro-1,1-difluoroethane (HCFC-142) to obtain cracking products such as 1,2-difluoroethylene, which have significant commercial value. However, the existing processes have many problems. First, the conversion rate of HCFC-142 is relatively low, often only about 20-40%, which cannot achieve truly efficient catalytic conversion. Such a low conversion rate cannot meet the requirements of commercialization. Secondly, catalytic cracking will inevitably produce a large amount of non-target products, such as 1,1-difluoroethylene, 2-chloro-1-fluoroethylene, and other fluorine-containing (chlorine-containing) olefins or alkanes, etc. Moreover, the proportion of these low-value non-target products is often not low, sometimes it can be as high as 60% or more, which seriously compresses the selectivity of the target product 1,2-difluoroethylene. Even some catalytic cracking processes do not produce 1,2-difluoroethylene target product at all, and these process technologies do not have actual industrialization prospects.

[0004] In addition, there are some studies that attempt to use 1-chloro-1,1-difluoroethane (HCFC-142b) as a raw material to synthesize the target product 1,2-difluoroethylene by catalytic cracking. However, 1-chloro-1,1-difluoroethane (HCFC-142b) itself is a raw material with clear industrial use, which is usually used to synthesize 1,1-difluoroethylene (VDF) by a high-temperature cracking process without using a catalyst, and further to scale production of PVDF polymers. From the industrial benefit point of view, the path of HCFC-142b catalytic cracking to synthesize 1,2-difluoroethylene does not have a good enough commercial prospect. In addition, it is very important that the catalytic process, conditions and catalyst design that can achieve excellent conversion rate and target product selectivity in the catalytic cracking of HCFC-142b will have very poor raw material conversion rate and target product selectivity when used for the catalytic cracking of HCFC-142, so the catalytic cracking technology developed for 1-chloro-1,1-difluoroethane (HCFC-142b) is of no reference significance for the catalytic cracking of HCFC-142.

[0005] Therefore, it is urgent to develop a completely new process that uses the by-product 2-chloro-1,1-difluoroethane (HCFC-142), which has no commercial value, as a raw material to convert it into high-value products such as 1,2-difluoroethylene in a simple, convenient and low-cost manner, and more importantly, to achieve excellent raw material conversion rate of 2-chloro-1,1-difluoroethane (HCFC-142) and excellent selectivity of high-value target product 1,2-difluoroethylene. SUMMARY

[0006] In order to solve the above problems, the applicant has developed a novel catalytic cracking technology through long-term and in-depth research, which is particularly designed for 2-chloro-1,1-difluoroethane (HCFC-142) as a raw material, can be carried out using simple conventional cracking equipment, has the advantages of high raw material conversion rate and excellent selectivity of target product, thereby completing the present application.

[0007] The first aspect of the present application provides a supported catalyst comprising a first catalytic component and a second catalytic component supported on a support,

[0008] The support is selected from at least one of activated carbon, molecular sieve, zeolite, amorphous alumina and porous ceramic;

[0009] The first catalytic component is selected from at least one of aluminum fluoride, chromium (III) fluoride, cobalt (II) fluoride, ferrous (II) fluoride and iron (III) fluoride;

[0010] The second catalytic component is selected from at least one of potassium fluoride, cesium fluoride, magnesium fluoride and calcium fluoride.

[0011] The weight ratio of the first catalytic component to the second catalytic component is 1:0.4 to 1:5, and the weight ratio of the weight of the carrier to the total weight of the first catalytic component and the second catalytic component is carrier:(first catalytic component + second catalytic component) = 1:0.01 to 1:0.6.

[0012] According to one embodiment of the first aspect of the present application, the weight ratio of the first catalytic component to the second catalytic component is 1:0.5 to 1:2.5.

[0013] According to one embodiment of the first aspect of the present application, the weight ratio of the weight of the carrier to the total weight of the first catalytic component and the second catalytic component is carrier:(first catalytic component + second catalytic component) = 1:0.1 to 1:0.5.

[0014] According to one embodiment of the first aspect of the present application, the first catalytic component is chromium fluoride, aluminum fluoride or cobalt fluoride; and the second catalytic component is cesium fluoride, magnesium fluoride, calcium fluoride, or a combination of magnesium fluoride and calcium fluoride.

[0015] The second aspect of the present application provides a method for preparing 1,2-difluoroethylene from 2-chloro-1,1-difluoroethane, which comprises: in the presence of the catalyst of the present application, allowing 2-chloro-1,1-difluoroethane to undergo a catalytic cracking reaction in a reactor to generate 1,2-difluoroethylene.

[0016] According to one embodiment of the second aspect of the present application, a mixed reaction gas of 2-chloro-1,1-difluoroethane and an inert carrier gas is input into the reactor, and in the presence of the catalyst, 2-chloro-1,1-difluoroethane is allowed to undergo a catalytic cracking reaction to generate 1,2-difluoroethylene.

[0017] According to one embodiment of the second aspect of the present application, the inert carrier gas is selected from at least one of the following: nitrogen, helium, neon, argon.

[0018] According to one embodiment of the second aspect of the present application, the molar ratio of 2-chloro-1,1-difluoroethane to inert carrier gas is 1:0.5 to 1:12.

[0019] According to one embodiment of the second aspect of the present application, the space velocity of the mixed reaction gas is 200-3000 hours -1 .

[0020] According to one embodiment of the second aspect of the present application, the inert carrier gas is nitrogen, and the molar ratio of 2-chloro-1,1-difluoroethane to inert carrier gas is 1:3 to 1:8.

[0021] According to an embodiment of the second aspect of the present application, the reaction temperature of the catalytic cracking reaction is 360-720°C.

[0022] According to an embodiment of the second aspect of the present application, the reaction pressure of the catalytic cracking reaction is 0.1-1.0 MPa.

[0023] According to an embodiment of the second aspect of the present application, the reactor is selected from the group consisting of a tubular reactor, a shell-and-tube reactor, and a microchannel reactor.

[0024] According to an embodiment of the second aspect of the present application, the conversion of 2-chloro-1,1-difluoroethane is at least 78%, and the selectivity of 1,2-difluoroethene is at least 55%. DETAILED DESCRIPTION

[0025] "Ranges" disclosed herein are defined, for each specific range by a lower limit and an upper limit, the lower and upper limits defining the boundaries in the specific range. Ranges defined by the lower and upper limits can be inclusive or exclusive of the end values, and can be arbitrarily combined, i.e., any lower limit can be combined with any upper limit to form a range. For example, if the ranges 60-120 and 80-110 are listed, it is understood that the ranges 60-110 and 80-120 are also contemplated. Also, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4 and 5 are listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise stated, a numerical range "a-b" indicates a shorthand way of describing each and every intervening real number, a and b, between the upper and lower boundary values. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed herein, "0-5" is merely a shorthand way of describing these numerical combinations. Also, when it is stated that a parameter is an integer ≥ 2, it is equivalent to disclose that the parameter is, for example, the integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0026] In the present application, all embodiments and preferred embodiments mentioned herein can be combined with each other to form new technical solutions, unless otherwise specified.

[0027] In the present application, all technical features and preferred features mentioned herein can be combined with each other to form new technical solutions, unless otherwise specified.

[0028] In the present application, if there is no special description, all the steps mentioned in the text can be carried out in sequence or randomly, but preferably in sequence. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method mentioned in the text can also comprise step (c), which means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0029] In the present application, if there is no special description, "including" and "containing" mentioned in the text means open, which can also be closed. For example, "including" and "containing" can mean that other components not listed can also be included or contained, or only the listed components can be included or contained.

[0030] In the description herein, it is necessary to point out that, unless otherwise specified, "above", "below" include the number, and "one or several" means two or more.

[0031] In the description herein, unless otherwise specified, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or A and B are both true (or exist).

[0032] In the present application, if there is no special description, the percentage (%) or the part refers to the percentage by weight or the weight part of the composition.

[0033] In the present application, if there is no special description, the sum of the contents of the components in the composition is 100%.

[0034] In the present application, if there is no special description, the sum of the parts of the components in the composition can be 100 parts by weight.

[0035] In the present application, unless otherwise specified, "combination thereof" means a multi-component mixture of the elements, such as two, three, four, and up to the maximum possible multi-component mixture.

[0036] Unless otherwise specified, the term "one" used in the present application means "at least one".

[0037] One of the invention points of the present application is to develop a supported catalyst having at least two kinds of fluoride catalytically active components, and to use the supported catalyst in a process for the catalytic cleavage of 2-chloro-1,1-difluoroethane to produce 1,2-difluoroethylene, whereby an excellent conversion of 2-chloro-1,1-difluoroethane and selectivity of the target product 1,2-difluoroethylene are achieved.

[0038] According to one embodiment of the present application, the starting material used in the present application is 2-chloro-1,1-difluoroethane (HCFC-142), and the target product is 1,2-difluoroethylene. It is known in the art that in the catalytic cleavage reaction of fluorine-containing olefins, particularly fluorine-containing ethylene, the types of starting material and target product have a very great influence on the selection of process parameters and catalysts, and a technical solution designed for a certain specific starting material and / or target product is completely useless for the design of another specific starting material and / or target product.

[0039] According to one embodiment of the present application, in the catalytic cleavage process of the present application, the conversion of 2-chloro-1,1-difluoroethane (HCFC-142) is ≥ 60%, for example ≥ 65%, or ≥ 68%, or ≥ 70%, or ≥ 72%, or ≥ 75%, or ≥ 78%, or ≥ 80%, or ≥ 82%, or ≥ 85%, or ≥ 88%, or ≥ 90%, or ≥ 91%, or ≥ 92%, or ≥ 93%, or ≥ 94%, or ≥ 95%, or ≥ 96%, or in the range of 75-97%, or the conversion is within the numerical range obtained by combining any two of the above-mentioned end values with each other, and the above-mentioned percentage is a molar percentage calculated based on the molar amount of the 2-chloro-1,1-difluoroethane (HCFC-142) starting material participating in the reaction.

[0040] According to one embodiment of the present application, in the catalytic cleavage process of the present application, the selectivity of the target product 1,2-difluoroethylene is ≥ 55%, for example ≥ 60%, or ≥ 62%, or ≥ 65%, or ≥ 68%, or ≥ 70%, or ≥ 72%, or ≥ 75%, or ≥ 78%, or ≥ 80%, or ≥ 82%, or ≥ 85%, or ≥ 88%, or ≥ 90%, or in the range of 60-95%, or in the range of 65-92%, or the selectivity of the target product 1,2-difluoroethylene is within the numerical range obtained by combining any two of the above-mentioned end values with each other, and the above-mentioned percentage is a molar percentage calculated based on the total molar amount of all products produced by catalytic cleavage.

[0041] According to one embodiment of the present application, the supported catalyst comprises a support and a first catalytic component and a second catalytic component supported on the support. The support is selected from at least one of activated carbon, molecular sieve, zeolite, amorphous alumina and porous ceramic, for example the support can be activated carbon.

[0042] According to another embodiment of the present application, the first catalytic component can be selected from at least one of aluminum fluoride, chromium (III) fluoride, cobalt (II) fluoride, ferrous (II) fluoride and iron (III) fluoride, for example the first catalytic component can be aluminum fluoride, chromium (III) fluoride or cobalt (II) fluoride.

[0043] According to another embodiment of the present application, the second catalytic component can be selected from at least one of potassium fluoride, cesium fluoride, magnesium fluoride, calcium fluoride; for example the second catalytic component can be cesium fluoride, magnesium fluoride, calcium fluoride, a combination of cesium fluoride and calcium fluoride, a combination of cesium fluoride and magnesium fluoride, or a combination of calcium fluoride and magnesium fluoride. According to one embodiment of the present application, for the case that the second catalytic component comprises a combination of two fluorides (for example a combination of cesium fluoride and calcium fluoride, or a combination of cesium fluoride and magnesium fluoride, or a combination of calcium fluoride and magnesium fluoride), the weight ratio of the two fluorides (for example the weight ratio of cesium fluoride and calcium fluoride, or the weight ratio of cesium fluoride and magnesium fluoride, or the weight ratio of calcium fluoride and magnesium fluoride) is 1:10 to 10:1, for example 1:9 to 9:1, or 1:8 to 8:1, or 1:7 to 7:1, or 1:5 to 5:1, or 1:4 to 4:1, or 1:3 to 3:1, or 1:2 to 2:1, or 1:1 to 3:2, or within a numerical range obtained by combining any two of the above-mentioned end values.

[0044] According to one embodiment of the present application, in the catalyst of the present application, the weight ratio of the first catalytic component to the second catalytic component is 1:0.4 to 1:5, for example it can be 1:0.5 to 1:4.5, or 1:0.6 to 1:4, or 1:0.7 to 1:3.5, or 1:0.8 to 1:3, or 1:0.8 to 1:2.5, or 1:0.9 to 1:2.2, or 1:1 to 1:2, or 1:1.2 to 1:1.8, or 1:1.3 to 1:1.5, or within a numerical range obtained by combining any two of the above-mentioned end values.

[0045] According to one embodiment of the present application, in the catalyst of the present application, the weight ratio of the weight of the support to the total weight of the first and second catalytic components is support:(first catalytic component + second catalytic component) = 1 : 0.01 to 1 : 0.6, for example, the ratio can be 1 : 0.05 to 1 : 0.55, or 1 : 0.1 to 1 : 0.5, or 1 : 0.15 to 1 : 0.45, or 1 : 0.20 to 1 : 0.40, or 1 : 0.25 to 1 : 0.35, or 1 : 0.30 to 1 : 0.32, or within a range defined by any two of the above-mentioned end values in combination with each other.

[0046] According to one embodiment of the present application, the dual catalytic component supported catalyst of the present application can be prepared by a solution impregnation-deposition process. For example, the catalyst of the present application can be synthesized by the following method: first, prepare a corresponding aqueous solution of soluble metal salt, which includes nitrate, sulfate, phosphate, hydrochloride (metal chloride) or the like of the corresponding metal, preferably nitrate. Use the nitrate to prepare an aqueous solution in the desired proportion, add various supports to the aqueous solution of soluble nitrate to form a suspension, then add fluoride ions to the suspension, for example, in the form of an aqueous solution of ammonium fluoride, thereby converting the soluble metal salt into the corresponding metal ion fluoride which is not easily soluble in water or insoluble in water, and sufficient stirring is carried out during the above process so that the metal ion fluoride is generated in or dispersed in the support, and the system continues to be stirred (for example, stirring for 0.5-24 hours, or 1-20 hours, or 1.5-16 hours, or 2-12 hours, or 2-6 hours, or 2-4 hours), then heated to remove water (for example, heated at a temperature of 100-160°C to remove water, or the heating temperature can be 100-120°C), followed by calcination (for example, calcination at a temperature of 120-550°C, or the calcination temperature can be 150-520°C, or can be 160-400°C, or can be 180-300°C, or can be 200-250°C), and the duration of calcination can be 0.5-12 hours, for example, 1-10 hours, or 2-8 hours, or 3-6 hours, or 4-5 hours, thereby obtaining the catalyst of the present application. According to one embodiment of the present application, the above heating and calcination can be carried out in an air atmosphere or in an inert atmosphere, for example, heating can be carried out in air or in nitrogen.

[0047] The catalytic cracking reaction of the present application can be carried out in any suitable reactor, for example, the reactor used can include a tubular reactor, a pipe reactor, and a microchannel reactor. According to one exemplary embodiment of the present application, the catalytic cracking reaction is carried out using a tubular reactor.

[0048] According to one embodiment of the present application, the catalyst of the present application is packed in a reactor, the 2-chloro-1,1-difluoroethane (HCFC-142) raw material is mixed with inert gas at a molar ratio of 1:0.5 to 1:12, heated by a preheater and then fed into the reactor at a space velocity of 200-3000 hours -1 at a temperature of 360-720°C and a pressure of 0.1-1.0 MPa to carry out the catalytic cracking reaction.

[0049] According to one exemplary embodiment of the present application, after the catalyst is packed in the reactor, the packed catalyst is also dried, for example, the drying step can include feeding inert gas into the reactor and heating the reactor to 150-250°C (for example, 180-220°C, or 190-210°C) while continuously feeding the inert gas to dry the catalyst. For example, the duration of the catalyst drying can be 10 minutes to 24 hours, for example, 30 minutes to 20 hours, or 1-16 hours, or 2-12 hours, or 3-8 hours, or 4-5 hours, or the duration of the drying can be within the range of values obtained by combining any two of the above-mentioned end values with each other.

[0050] According to one embodiment of the present application, the inert gas used in the above-mentioned drying step and reaction process includes a gas that does not have any negative effect on the activity of the catalyst of the present application and the catalytic cracking reaction, for example, it can include nitrogen, helium, neon, argon, etc., and nitrogen is preferably used.

[0051] According to one embodiment of the present application, the molar ratio of the 2-chloro-1,1-difluoroethane (HCFC-142) raw material to the inert gas can be 1:1 to 1:10, for example, 1:2 to 1:9, or 1:3 to 1:8, or 1:4 to 1:7, or 1:5 to 1:6, or within the range of values obtained by combining any two of the above-mentioned end values with each other.

[0052] According to another embodiment of the present application, the preheating temperature of the 2-chloro-1,1-difluoroethane (HCFC-142) raw material and the inert gas is 150-350°C, for example, 160-340°C, or 170-330°C, or 180-320°C, or 190-310°C, or 200-300°C, or 210-290°C, or 220-280°C, or 230-270°C, or 240-260°C, or 240-250°C, or within the range of values obtained by combining any two of the above-mentioned end values with each other.

[0053] According to another embodiment of the present application, the space velocity of the mixture of 2-chloro- 1,1-difluoroethane (HCFC-142) feedstock and inert gas into the reactor is in the range of 200 to 3000 hours -1 , for example in the range of 300 to 2900 hours -1 , or in the range of 500 to 2600 hours -1 , or in the range of 600 to 2200 hours -1 , or in the range of 700 to 2200 hours -1 , or in the range of 800 to 2000 hours -1 , or in the range of 900 to 1600 hours -1 , or in the range of 1000 to 1500 hours -1 , or in the range of 1000 to 1200 hours -1 , or in the range of any two of the above-mentioned end values in combination.

[0054] According to an optional embodiment of the present application, after starting the feed of the mixture of 2-chloro- 1,1-difluoroethane (HCFC-142) feedstock and inert gas into the reactor, the catalyst in the reactor can first be activated at a lower temperature while the mixture is being fed, for example the activation temperature can be in the range of 150 to 350°C, for example in the range of 160 to 340°C, or in the range of 170 to 330°C, or in the range of 180 to 320°C, or in the range of 190 to 310°C, or in the range of 200 to 300°C, or in the range of 210 to 290°C, or in the range of 220 to 280°C, or in the range of 230 to 270°C, or in the range of 240 to 260°C, or in the range of 240 to 250°C, or in the range of any two of the above-mentioned end values in combination; the duration of the activation can be in the range of 0.5 to 2 hours, for example in the range of 0.6 to 1.9 hours, or in the range of 0.8 to 1.8 hours, or in the range of 1 to 1.6 hours, or in the range of 1.2 to 1.5 hours, or in the range of any two of the above-mentioned end values in combination. After the activation step, the temperature in the reactor is increased to the reaction temperature, and the catalytic cleavage reaction is started.

[0055] According to another independent embodiment of the present application, instead of the activation step, after starting the feed of the mixture of 2-chloro- 1,1-difluoroethane (HCFC-142) feedstock and inert gas into the reactor, the temperature in the reactor is directly increased to the reaction temperature, and the catalytic cleavage reaction is started.

[0056] According to another embodiment of the present application, the reaction temperature in the reactor can be 360-720°C, for example 380-700°C, 400-680°C, or 420-660°C, or 450-650°C, or 480-620°C, or 500-600°C, or 520-580°C, or 540-550°C, or within a range defined by any two of the above-mentioned values in combination.

[0057] According to another embodiment of the present application, the pressure in the reactor can be 0.1-1.0 MPa, for example 0.2-0.9 MPa, or 0.3-0.8 MPa, or 0.4-0.7 MPa, or 0.5-0.6 MPa, or within a range defined by any two of the above-mentioned values in combination.

[0058] According to one embodiment of the present application, after the catalytic cracking reaction is carried out in the reactor, the product mixture produced by the reactor can be subjected to subsequent treatment of the products, for example, the acidic gases contained in the product mixture, such as hydrogen fluoride, hydrogen chloride, etc., can be neutralized and removed by alkali absorption, and the inorganic salt components can be removed. The organic components in the product mainly include the target product 1,2-difluoroethylene, also include a certain amount of the main by-product 1,1-difluoroethylene and 2-chloro-1-fluoroethylene, unreacted raw material 2-chloro-1,1-difluoroethane (HCFC-142), and possibly contain a small amount of other components. These components can be effectively separated and purified by using processes such as rectification.

[0059] The preferred embodiments of the present application are described in detail below to make the advantages and features of the present application more easily understood by those skilled in the art, so as to make the scope of protection of the present application more clear and explicit.

[0060] Examples

[0061] The metal nitrate and ammonium fluoride used in the following examples and comparative examples are commercially available analytical pure products, which are used directly without further purification. The activated carbon is purchased from Shanghai Titan Science and Technology Co., Ltd. The 2-chloro-1,1-difluoroethane (HCFC-142) used is provided by Changshu Sanai Fu Zhonghao New Material Co., Ltd., with a purity of more than 99.5%. The water used is deionized water.

[0062] Synthesis Example 1

[0063] A supported-bi-catalytic component catalyst was synthesized in this synthesis example 1 by the following procedure: aqueous solutions of chromium nitrate and cesium nitrate were prepared separately with a concentration of 0.01 M, these two solutions were mixed in a vessel in the desired ratio, and additionally 100 mL of water was added, activated carbon was added to the aqueous solution in the desired ratio, while it was being stirred thoroughly, an aqueous solution of NH4F with a concentration of 0.05 M was added to it in equivalent amounts, so that the metal cation nitrates were converted to the corresponding fluoride salts. The stirring of the contents of the vessel was continued for 2 hours. Then the water in the vessel was evaporated at a temperature of 110 °C, the solid was dried at 110 °C for 10 hours, and calcined at a temperature of 520 °C for 3 hours, to obtain a chromium fluoride-cesium fluoride / activated carbon catalyst, hereinafter referred to as catalyst 1. The ratios of the components in this catalyst 1 are as shown in Table 1.

[0064] Synthesis Example 2

[0065] A supported-bi-catalytic component catalyst was synthesized in this synthesis example 2 by the following procedure: aqueous solutions of aluminum nitrate and magnesium nitrate were prepared separately with a concentration of 0.01 M, these two solutions were mixed in a vessel in the desired ratio, and additionally 100 mL of water was added, activated carbon was added to the aqueous solution in the desired ratio, while it was being stirred thoroughly, an aqueous solution of NH4F with a concentration of 0.05 M was added to it in equivalent amounts, so that the metal cation nitrates were converted to the corresponding fluoride salts. The stirring of the contents of the vessel was continued for 2 hours. Then the water in the vessel was evaporated at a temperature of 110 °C, the solid was dried at 110 °C for 10 hours, and calcined at a temperature of 520 °C for 3 hours, to obtain an aluminum fluoride-magnesium fluoride / activated carbon catalyst, hereinafter referred to as catalyst 2. The ratios of the components in this catalyst 2 are as shown in Table 1.

[0066] Synthesis Example 3

[0067] A supported-bi-catalytic component catalyst was synthesized in this synthesis example 3 by the following procedure: aqueous solutions of cobalt nitrate and calcium nitrate were prepared separately with a concentration of 0.01 M, these two solutions were mixed in a vessel in the desired ratio, and additionally 100 mL of water was added, activated carbon was added to the aqueous solution in the desired ratio, while it was being stirred thoroughly, an aqueous solution of NH4F with a concentration of 0.05 M was added to it in equivalent amounts, so that the metal cation nitrates were converted to the corresponding fluoride salts. The stirring of the contents of the vessel was continued for 2 hours. Then the water in the vessel was evaporated at a temperature of 110 °C, the solid was dried at 110 °C for 10 hours, and calcined at a temperature of 520 °C for 3 hours, to obtain a cobalt fluoride-calcium fluoride / activated carbon catalyst, hereinafter referred to as catalyst 3. The ratios of the components in this catalyst 3 are as shown in Table 1.

[0068] Synthesis Example 4

[0069] In this synthesis example 1, the supported-bi-catalyst component catalyst was synthesized by the following procedure: an aqueous solution of chromium nitrate was prepared with a concentration of 0.01 M, this solution was mixed with 100 mL of water in a vessel, activated carbon was added to the aqueous solution in the required proportion, while stirring it thoroughly, an aqueous solution of NH4F was added to it in equivalent proportion with a concentration of 0.05 M, so that the metal cation nitrate salt was converted to the corresponding fluoride salt. The stirring of the contents of the vessel was continued for 2 hours. The water in the vessel was then evaporated at a temperature of 110 °C, the solid was dried at 110 °C for 10 hours, and calcined at a temperature of 520 °C for 3 hours to obtain the chromium fluoride / activated carbon catalyst, hereinafter referred to as catalyst 1. The proportions of the components in this catalyst 1 are as shown in Table 1.

[0070] Synthesis Comparative Example 1

[0071] In this synthesis comparative example 1, the supported-bi-catalyst component catalyst was synthesized by the following procedure: an aqueous solution of chromium nitrate was prepared with a concentration of 0.01 M, this solution was mixed with 100 mL of water in a vessel, activated carbon was added to the aqueous solution in the required proportion, while stirring it thoroughly, an aqueous solution of NH4F was added to it in equivalent proportion with a concentration of 0.05 M, so that the metal cation nitrate salt was converted to the corresponding fluoride salt. The stirring of the contents of the vessel was continued for 2 hours. The water in the vessel was then evaporated at a temperature of 110 °C, the solid was dried at 110 °C for 10 hours, and calcined at a temperature of 520 °C for 3 hours to obtain the chromium fluoride / activated carbon catalyst, hereinafter referred to as catalyst 1. The proportions of the components in this catalyst 1 are as shown in Table 1.

[0072] Synthesis Comparative Example 2

[0073] In this synthesis comparative example 2, the supported-bi-catalyst component catalyst was synthesized by the following procedure: an aqueous solution of aluminium nitrate was prepared with a concentration of 0.01 M, this solution was mixed with 100 mL of water in a vessel, activated carbon was added to the aqueous solution in the required proportion, while stirring it thoroughly, an aqueous solution of NH4F was added to it in equivalent proportion with a concentration of 0.05 M, so that the metal cation nitrate salt was converted to the corresponding fluoride salt. The stirring of the contents of the vessel was continued for 2 hours. The water in the vessel was then evaporated at a temperature of 110 °C, the solid was dried at 110 °C for 10 hours, and calcined at a temperature of 520 °C for 3 hours to obtain the aluminium fluoride / activated carbon catalyst, hereinafter referred to as comparative catalyst 2. The proportions of the components in this comparative catalyst 2 are as shown in Table 1.

[0074] Table 1: Catalyst design formulation for synthesis examples 1-4

[0075]

[0076] Catalytic reaction example 1

[0077] In this catalytic reaction example 1, a nickel-made tubular reactor with a diameter of 12 mm and a length of 150 mm was used as a catalytic cracking reactor, and 10 g of catalyst 1 was filled therein. First, nitrogen was passed into the reactor at a space velocity of 1000 h"1, and the reactor was heated to 200°C for 2 hours to dry the catalyst. After the drying was completed, 2-chloro-1,1-difluoroethane was mixed with nitrogen at a molar ratio of 1:6 to form a mixed gas, the mixed gas was preheated to 250°C, and then passed into the reactor at a space velocity of 1000 h"1, and the reaction was carried out in the reactor at a temperature of 580°C and a pressure of 0.2 MPa. -1 -1

[0078] The tail gas generated in the reaction was subjected to absorption with a caustic solution to remove acidic substances therefrom, and then the composition thereof was analyzed using a gas chromatograph, and the results are summarized in Table 2.

[0079] Catalytic reaction example 2

[0080] In this catalytic reaction example 2, a nickel-made tubular reactor with a diameter of 12 mm and a length of 150 mm was used as a catalytic cracking reactor, and 10 g of catalyst 1 was filled therein. First, nitrogen was passed into the reactor at a space velocity of 1000 h"1, and the reactor was heated to 200°C for 2 hours to dry the catalyst. After the drying was completed, 2-chloro-1,1-difluoroethane was mixed with nitrogen at a molar ratio of 1:6 to form a mixed gas, the mixed gas was preheated to 250°C, and then passed into the reactor at a space velocity of 1000 h"1, and the reaction was carried out in the reactor at a temperature of 670°C and a pressure of 0.2 MPa. -1 -1

[0081] The tail gas generated in the reaction was subjected to absorption with a caustic solution to remove acidic substances therefrom, and then the composition thereof was analyzed using a gas chromatograph, and the results are summarized in Table 2.

[0082] Catalytic reaction example 3

[0083] In this catalytic reaction example 3, a nickel-made tubular reactor with a diameter of 12 mm and a length of 150 mm was used as a catalytic cracking reactor, and 10 g of catalyst 2 was filled therein. First, nitrogen was passed into the reactor at a space velocity of 1000 h"1, and the reactor was heated to 200°C for 2 hours to dry the catalyst. After the drying was completed, 2-chloro-1,1-difluoroethane was mixed with nitrogen at a molar ratio of 1:5 to form a mixed gas, the mixed gas was preheated to 250°C, and then passed into the reactor at a space velocity of 1000 h"1, and the reaction was carried out in the reactor at a temperature of 670°C and a pressure of 0.2 MPa. -1 -1 ​​​​​The reactor was heated to 650°C and 0.2 MPa and the reaction was carried out.

[0084] The tail gas produced in the reaction was absorbed by alkali to remove acidic substances therein, and the composition thereof was analyzed using gas chromatography. The results are summarized in Table 2.

[0085] Catalytic reaction example 4

[0086] In this catalytic reaction example 4, a nickel-made tubular reactor having a diameter of 12 mm and a length of 150 mm was used as a catalytic pyrolysis reactor, and 10 g of the catalyst 3 was filled therein. First, nitrogen was passed into the reactor at a space velocity of 1000 h"1, and the reactor was heated to 200°C for 2 hours to dry the catalyst. After the drying was completed, 2-chloro-l,l-difluoroethane was mixed with nitrogen at a molar ratio of 1:5 to form a mixed gas, the mixed gas was preheated to 250°C, and then passed into the reactor at a space velocity of 1000 h"1, and the reaction was carried out in the reactor at a temperature of 650°C and a pressure of 0.2 MPa. -1 -1 The reactor was heated to 650°C and 0.2 MPa and the reaction was carried out.

[0087] The tail gas produced in the reaction was absorbed by alkali to remove acidic substances therein, and the composition thereof was analyzed using gas chromatography. The results are summarized in Table 2.

[0088] Catalytic reaction example 5

[0089] In this catalytic reaction example 5, a nickel-made tubular reactor having a diameter of 12 mm and a length of 150 mm was used as a catalytic pyrolysis reactor, and 10 g of the catalyst 4 was filled therein. First, nitrogen was passed into the reactor at a space velocity of 1000 h"1, and the reactor was heated to 200°C for 2 hours to dry the catalyst. After the drying was completed, 2-chloro-l,l-difluoroethane was mixed with nitrogen at a molar ratio of 1:5 to form a mixed gas, the mixed gas was preheated to 250°C, and then passed into the reactor at a space velocity of 1000 h"1, and the reaction was carried out in the reactor at a temperature of 650°C and a pressure of 0.2 MPa. -1 -1 The reactor was heated to 650°C and 0.2 MPa and the reaction was carried out.

[0090] The tail gas produced in the reaction was absorbed by alkali to remove acidic substances therein, and the composition thereof was analyzed using gas chromatography. The results are summarized in Table 2.

[0091] Catalytic reaction comparative example 1

[0092] In this catalytic reaction comparative example 1, a nickel-made tubular reactor having a diameter of 12 mm and a length of 150 mm was used as a catalytic pyrolysis reactor, and 10 g of the comparative catalyst 1 was filled therein. First, nitrogen was passed into the reactor at a space velocity of 1000 h"1, and the reactor was heated to 200°C for 2 hours to dry the catalyst. After the drying was completed, 2-chloro-l,l-difluoroethane was mixed with nitrogen at a molar ratio of 1:5 to form a mixed gas, the mixed gas was preheated to 250°C, and then passed into the reactor at a space velocity of 1000 h"1, and the reaction was carried out in the reactor at a temperature of 650°C and a pressure of 0.2 MPa. -1 ​​The reactor was dried by passing nitrogen gas into the reactor at a space velocity of 1000 h"1for 2 hours while heating the reactor to 200°C. After the drying was completed, 2-chloro-1,1-difluoroethane was mixed with nitrogen gas at a molar ratio of 1:6 to form a mixed gas, which was preheated to 250°C, and then passed into the reactor at a space velocity of 1000 h"1. -1 The reactor was dried by passing nitrogen gas into the reactor at a space velocity of 1000 h"1for 2 hours while heating the reactor to 200°C. After the drying was completed, 2-chloro-1,1-difluoroethane was mixed with nitrogen gas at a molar ratio of 1:6 to form a mixed gas, which was preheated to 250°C, and then passed into the reactor at a space velocity of 1000 h"1.

[0093] The tail gas produced by the reaction was absorbed by a caustic solution to remove acidic substances therefrom, and then the composition thereof was analyzed using gas chromatography. The results are summarized in Table 2.

[0094] Catalytic reaction comparative example 2

[0095] In this catalytic reaction comparative example 2, a nickel-made tubular reactor having a diameter of 12 mm and a length of 150 mm was used as the catalytic cracking reactor, and 10 g of comparative catalyst 2 was filled therein. First, nitrogen gas was passed into the reactor at a space velocity of 1000 h"1, and the reactor was heated to 200°C for 2 hours to dry the catalyst. After the drying was completed, 2-chloro-1,1-difluoroethane was mixed with nitrogen gas at a molar ratio of 1:5 to form a mixed gas, which was preheated to 250°C, and then passed into the reactor at a space velocity of 1000 h"1. -1 The reactor was dried by passing nitrogen gas into the reactor at a space velocity of 1000 h"1for 2 hours while heating the reactor to 200°C. After the drying was completed, 2-chloro-1,1-difluoroethane was mixed with nitrogen gas at a molar ratio of 1:6 to form a mixed gas, which was preheated to 250°C, and then passed into the reactor at a space velocity of 1000 h"1. -1 The reactor was dried by passing nitrogen gas into the reactor at a space velocity of 1000 h"1for 2 hours while heating the reactor to 200°C. After the drying was completed, 2-chloro-1,1-difluoroethane was mixed with nitrogen gas at a molar ratio of 1:6 to form a mixed gas, which was preheated to 250°C, and then passed into the reactor at a space velocity of 1000 h"1.

[0096] The tail gas produced by the reaction was absorbed by a caustic solution to remove acidic substances therefrom, and then the composition thereof was analyzed using gas chromatography. The results are summarized in Table 2.

[0097] Table 2: Results of catalytic cracking reactions using catalysts 1-4 and comparative catalysts 1-2

[0098]

Claims

1. A process for the preparation of 1,2-difluoroethene from 2-chloro- 1,1-difluoroethane, the process comprising: In a reactor, 2-chloro-1,1-difluoroethane is subjected to a catalytic cracking reaction in the presence of a catalyst to produce 1,2-difluoroethene, the catalyst being a supported catalyst comprising a first catalytic component and a second catalytic component supported on a carrier, the carrier being selected from at least one of activated carbon, molecular sieve, zeolite, amorphous alumina, and porous ceramic; the first catalytic component being aluminum fluoride and the second catalytic component being magnesium fluoride, or the first catalytic component being cobalt fluoride and the second catalytic component being calcium fluoride, or the first catalytic component being chromium fluoride and the second catalytic component being cesium fluoride and calcium fluoride; the weight ratio of the first catalytic component to the second catalytic component being 1:0.4 to 1:5, and the weight ratio of the weight of the carrier to the total weight of the first catalytic component and the second catalytic component being carrier:(first catalytic component + second catalytic component) = 1:0.01 to 1:0.

6.

2. The method of claim 1, wherein, 2-chloro-1,1-difluoroethane is subjected to a catalytic cracking reaction in the presence of a catalyst to produce 1,2-difluoroethene, the inert carrier gas being selected from at least one of nitrogen, helium, neon, argon; the molar ratio of the 2-chloro-1,1-difluoroethane to the inert carrier gas being 1:0.5 to 1:12; The space velocity of the mixed reaction gas is 200-3000h -1 .

3. The method of claim 2, wherein, the inert carrier gas being nitrogen, and the molar ratio of the 2-chloro-1,1-difluoroethane to the inert carrier gas being 1:3 to 1:

8.

4. The method of claim 1, wherein, The reaction temperature of the catalytic cracking reaction is 360-720°C.

5. The method of claim 1, wherein, The reaction pressure of the catalytic cracking reaction is 0.1-1.0 MPa.

6. The method of claim 1, wherein, The reactor is selected from a pipe reactor, a tube reactor, and a microchannel reactor.

7. The method of claim 1, wherein, The weight ratio of the first catalytic component to the second catalytic component is 1:0.5 to 1:2.

5.

8. The method of claim 1, wherein, The weight ratio of the weight of the carrier to the total weight of the first catalytic component and the second catalytic component is carrier:(first catalytic component + second catalytic component) = 1:0.1 to 1:0.5.

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