A carbon-confined BaF 2 catalyst, its preparation method and application

Abstract

The present invention discloses a carbon-confined BaF2 catalyst, a preparation method thereof and an application thereof. The preparation method of the catalyst is as follows: a barium source and an organic acid are stirred in an aqueous solvent at 60-80 °C for 1-4 h, and white precipitates will appear during the stirring process; after the stirring is completed, it is aged at room temperature for 1-3 h, and the obtained solid is washed with deionized water and then dried to obtain barium organic acid for use. Under the action of a fluorine source, the barium organic acid is fluorinated to obtain the carbon-confined BaF2 catalyst. The catalyst prepared by the method of the present invention shows extremely high activity and stability in the reaction of preparing fluorinated olefins (HFOs) and chlorinated olefins by gas-phase dehydrochlorination of hydrochlorofluorocarbons (HCFCs) and chlorinated alkanes. The catalyst provided by the present invention has the characteristics of simple preparation, high conversion rate, high selectivity, strong stability, anti-sintering, strong anti-coking ability, etc., and can be used for industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of multiphase thermal catalysts, and particularly relates to a carbon-confined BaF 2 catalyst and its preparation method and application. Background Art

[0002] At present, the contents of hydrochlorofluorocarbons (HCFCs) and chlorocarbons in the atmosphere have been steadily increasing. They have extremely strong destructive power to the atmospheric ozone layer, and their emissions will also exacerbate the greenhouse effect. Therefore, the resource conversion of hydrochlorofluorocarbons (HCFCs) and chlorocarbons is a safe, efficient, and most economically viable treatment method.

[0003] 1,1-Difluoro-1-chloroethane (HCFC-142b, CH 3 -CClF 2 ) is a widely used hydrochlorofluorocarbon and is also the most important industrial raw material for producing vinylidene fluoride (VDF), the monomer of polyvinylidene fluoride (PVDF).

[0004] At present, the industrial production of VDF mainly uses the method of thermal cracking of HCFC-142b in an empty tube. Its pyrolysis temperature is generally between 600 - 800 °C. Due to easy coking and deposition during the reaction process, it is necessary to stop the machine for coke removal at certain time intervals. Moreover, side reactions are likely to occur at high temperatures. Adding a catalyst can lower the reaction energy barrier for the dehydrochlorination of HCFC-142b, and thus can greatly reduce the reaction temperature required, which is expected to become an effective and environmentally friendly way to produce VDF. Among the catalysts for catalytic cracking of HCFC-142b to remove HCl, there are various disadvantages. For example, activated carbon catalysts are prone to deactivation and difficult to regenerate; nitrogen-doped carbon catalysts are difficult to prepare, difficult to regenerate after deactivation, and nitrogen is easily lost; metal oxides are prone to react with hydrogen chloride to form chlorides and quickly deactivate. Summary of the Invention

[0005] Aiming at the problems existing in the application of existing catalysts, the purpose of the present invention is to provide a carbon-confined BaF 2 catalyst and its preparation method and application. The present invention first proposes to apply the carbon-confined BaF 2 catalyst to the reaction of gas-phase dehydrochlorination of hydrochlorofluorocarbons and chlorocarbons to prepare fluoroolefins and chloroolefins. The catalyst preparation method of the present invention is simple, has a high catalytic yield, and strong anti-sintering and anti-carbon deposition capabilities.

[0006] The described carbon-confined BaF 2Preparation method of catalyst, characterized by comprising the following steps: mixing a barium source and an organic acid in an aqueous solvent, stirring at 60-80 °C for 1-4 h, during which a white precipitate will appear; after stirring, aging at room temperature for 1-3 h, washing the obtained solid with deionized water and then drying to obtain barium organic acid for use; under the action of a fluorine source, fluorinating the barium organic acid to obtain the carbon-confined BaF 2 catalyst.

[0007] Further, the barium source is one or a mixture of several of barium hydroxide octahydrate, barium chloride dihydrate, and barium nitrate; the organic acid is one of fumaric acid, citric acid, and benzoic acid, and the molar ratio of the barium source to the organic acid is 1:1 to 3, preferably 1:1 to 2.5.

[0008] Further, the fluorine source is one of a gaseous fluorine source, a liquid fluorine source, and a solid fluorine source.

[0009] Further, when the fluorine source is a gaseous fluorine source, the specific process of fluorinating the barium organic acid is as follows: placing the barium organic acid in a tube furnace, heating it to 400-600 °C at a rate of 1-5 °C / min under an N 2 atmosphere, then maintaining the temperature for calcination and carbonization for 1-5 h, and preferably the time for maintaining the temperature for calcination and carbonization is 3 h; after the carbonization is completed, switching N 2 to a gaseous fluorine source for fluorination, roasting at 250 °C - 350 °C for 1-6 h, and preferably the roasting temperature and time are 300 °C and 2-4 h respectively. After the fluorination is completed, switching the gaseous fluorine source to N 2 until it naturally cools down to room temperature, thus obtaining the carbon-confined BaF 2 catalyst; wherein, the gaseous fluorine source is one of chlorodifluoromethane (CHFCl 2 ), dichlorofluoromethane (CHClF 2 ), and trifluoromethane (CHF 3 ).

[0010] Further, when the fluorine source is a solid fluorine source, the specific process of fluorinating the barium organic acid is as follows: placing the barium organic acid and the solid fluorine source in a ball milling tank for ball milling, and the mass ratio of the barium organic acid to the solid fluorine source is 1:3 - 1:8, preferably 1:4 - 1:6; the ball milling speed is 150-300 r / min, and the ball milling time is 2-6 h, and preferably the ball milling speed and time are 200 r / min and 3 h respectively; then placing the ball-milled mixture in a tube furnace for roasting and carbonization under an N 2 atmosphere, heating it to 400-600 °C at a rate of 1-5 °C / min, and then maintaining the temperature for roasting and carbonization for 1-5 h, and preferably the time for maintaining the temperature for roasting and carbonization is 2-4 h, thus obtaining the carbon-confined BaF 2 catalyst; wherein, the solid fluorine source is ammonium fluoride (NH 4 F) or ammonium fluoroborate (NH4 BF 4 )。

[0011] Furthermore, the fluorine source is a liquid-phase fluorine source. The specific process of fluorinating the barium organic acid is as follows: Add barium organic acid to the liquid-phase fluorine source, stir at 20-100 °C for 2-10 h. The stirring temperature and time are preferably 60 °C and 5-7 h respectively. After stirring, wash the mixture 3 times with deionized water and dry at 80 °C for 12 h. After drying, place the mixture in a tube furnace and calcine and carbonize it under N 2 atmosphere. Heat it to 400-500 °C at a rate of 1-5 °C / min, and then keep it at a constant temperature for calcination and carbonization for 1-5 h. The time for constant-temperature calcination and carbonization is preferably 2-4 h, and then the carbon-confined BaF 2 catalyst is obtained; wherein, the liquid-phase fluorine source is a 10-60 wt% hydrofluoric acid solution, preferably a 40 wt% hydrofluoric acid solution.

[0012] An application of the carbon-confined BaF 2 catalyst provided by the present invention in the reaction of catalytically dehydrochlorinating fluorochlorohydrocarbons (HCFCs) or chlorohydrocarbons in the gas phase to prepare fluoroolefins (HFOs) or chloroolefins. The application method is as follows: Load the catalyst into a fixed-bed reactor, and introduce N 2 and a mixed gas of fluorochlorohydrocarbons or chlorohydrocarbons. The feed volume ratio of N 2 to fluorochlorohydrocarbons or chlorohydrocarbons is 1:0.25-1:4, and the total space velocity of the mixed gas of N 2 to fluorochlorohydrocarbons or chlorohydrocarbons is 200-600 h -1 , the reaction temperature is 300-450 °C, and the reaction produces fluoroolefin products or chloroolefin products.

[0013] Furthermore, the fluorochlorohydrocarbon is one of 1,1-difluoro-1-chloroethane and 2-chloro-1,1,1,2-tetrafluoropropane, the chlorohydrocarbon is 1,1,1,3-tetrachloropropane, 1,2,2,3-tetrachloropropane or 1,1,2,3-tetrachloropropane, the corresponding fluoroolefin product is vinylidene fluoride or 2,3,3,3-tetrafluoropropene, and the chloroolefin product is 3,3,3-trichloropropene, 2,2,3-trichloropropene or 2,3,3-trichloropropene, but not limited to the above three reactions.

[0014] By adopting the above technology, compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] The carbon-confined BaF 2 catalyst of the present invention is prepared by fluorination and calcination using barium organic acid as a precursor. The obtained carbon-confined BaF 2The catalyst is used for the catalytic cracking of hydrochlorofluorocarbons and chlorocarbons to remove HCl to prepare fluoroolefins and chloroolefins. It is found that the catalyst has the characteristics of simple preparation, high conversion rate, high selectivity, strong stability, anti-sintering and strong anti-coking ability, and can be used for industrial production. Brief Description of the Drawings

[0016] Figure 1 It is the carbon-confined BaF obtained in Examples 1, 2, and 3 of the present invention 2 Activity diagram of the conversion rate and selectivity of the catalyst for catalytic cracking of HCFC-142b varying with reaction time. Detailed Embodiments

[0017] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0018] Example 1

[0019] Dissolve 0.1 mol of barium hydroxide octahydrate in 200 mL of deionized water at 40 °C, abbreviated as solution A, and dissolve 0.25 mol of fumaric acid in 200 mL of deionized water, abbreviated as solution B.

[0020] Slowly drip solution B into solution A at a dropping rate of 20 drops / min, stir vigorously at 60 °C for 4 h to obtain a white emulsion, then age at room temperature for 1 h. The white emulsion is centrifuged and washed three times with 1000 mL of deionized water, and finally the obtained product is dried at 80 °C for 12 h to obtain barium fumarate.

[0021] Place barium fumarate in a tubular furnace and heat it to 400 °C at a rate of 3 °C / min under N 2 atmosphere, then keep it at a constant temperature for carbonization roasting for 5 h. After the carbonization is completed, switch N 2 to the gaseous fluorine source CHF 3 for fluorination, with a flow rate of 30 mL / min, roast at 250 °C for 6 h. After the fluorination is completed, switch the gaseous fluorine source CHF 3 to N 2 until it cools down to room temperature naturally, then the carbon-confined BaF 2 catalyst is obtained.

[0022] Use the carbon-confined BaF 2 catalyst prepared above to catalyze the cracking of 1,1-difluoro-1-chloroethane (HCFC-142b) to prepare 1,1-difluoroethylene (VDF). The reaction formula is as follows:

[0023] CF 2 ClCH 3 →CF 2 =CH 2 +HCl

[0024] The reaction conditions were as follows: The catalyst was loaded into a fixed-bed reactor with a catalyst loading of 2 mL, and a mixed gas of N 2 and HCFC-142b was introduced. The flow rate of N 2 was 15 mL / min, and the flow rate of HCFC-142b was 5 mL / min. The total space velocity of the mixed gas of N 2 and HCFC-142b was 600 h -1 . The reaction temperature was 350 °C. After reacting for 30 h, the results were as follows: The conversion rate of the reactant 1,1-difluoro-1-chloroethane was 82%, and the selectivity of the product 1,1-difluoroethylene was 92%.

[0025] Example 2

[0026] 0.1 mol of barium nitrate was dissolved in 200 mL of deionized water at 40 °C, abbreviated as solution A, and 0.1 mol of citric acid was dissolved in 200 mL of deionized water, abbreviated as solution B.

[0027] Solution B was slowly dropped into solution A at a dropping rate of 20 drops / min, and it was vigorously stirred at 80 °C for 2 h to obtain a white emulsion. Subsequently, it was aged at room temperature for 1 h. The white emulsion was centrifugally washed three times with 1000 mL of deionized water, and finally the obtained product was dried at 80 °C for 12 h to obtain barium citrate.

[0028] 2 g of barium citrate and 16 g of ammonium fluoride were placed in a ball milling jar made of agate and ball milled at a rotation speed of 150 r / min for 2 h to obtain fluorinated barium citrate. The fluorinated barium citrate was placed in a tube furnace and calcined and carbonized under a N 2 atmosphere. It was heated to 600 °C at a rate of 3 °C / min and then calcined and carbonized at a constant temperature for 2 h to obtain the carbon-confined BaF 2 catalyst.

[0029] The carbon-confined BaF 2 catalyst obtained in Example 2 was used to catalyze the cracking of 1,1-difluoro-1-chloroethane (HCFC-142b) to prepare 1,1-difluoroethylene (VDF). The specific application conditions were repeated in Example 1. After reacting for 30 h, the results were as follows: The conversion rate of the reactant 1,1-difluoro-1-chloroethane was 90%, and the selectivity of the product 1,1-difluoroethylene was 88%.

[0030] Example 3

[0031] 0.1 mol of barium hydroxide octahydrate was dissolved in 200 mL of deionized water at 40 °C, abbreviated as solution A, and 0.25 mol of fumaric acid was dissolved in 200 mL of deionized water, abbreviated as solution B.

[0032] Slowly drop solution B into solution A at a dropping rate of 20 drops / min, stir vigorously at 80 °C for 4 h to obtain a white emulsion, then age it at room temperature for 1 h. Wash the white emulsion three times by centrifugation with 1000 mL of deionized water. Finally, dry the obtained product at 80 °C for 12 h to obtain barium fumarate.

[0033] Place barium fumarate in a tube furnace and heat it from room temperature to 500 °C at a rate of 3 °C / min under N 2 atmosphere, then keep it at a constant temperature for calcination and carbonization for 5 h. After the carbonization is completed, switch N 2 to the gaseous fluorine source CHFCl 2 for fluorination at a flow rate of 30 mL / min, and calcine it at 300 °C for 4 h. After the fluorination is completed, switch the gaseous fluorine source CHFCl 2 to N 2 until it cools down to room temperature naturally, then the carbon-confined BaF 2 catalyst is obtained.

[0034] Use the carbon-confined BaF 2 catalyst obtained in Example 3 to catalyze the cracking of 1,1-difluoro-1-chloroethane (HCFC-142b) to prepare 1,1-difluoroethylene (VDF). The specific application conditions are the same as those in Example 1. After reacting for 30 h, the results are as follows: the conversion rate of the reactant 1,1-difluoro-1-chloroethane is 85%, and the selectivity of the product 1,1-difluoroethylene is 97%.

[0035] The activity diagrams of the conversion rate and selectivity of the carbon-confined BaF 2 catalyst for catalyzing the cracking of HCFC-142b with the change of reaction time are as Figure 1 shown.

[0036] Example 4

[0037] Dissolve 0.1 mol of barium nitrate in 200 mL of deionized water at 40 °C, abbreviated as solution A. Dissolve 0.2 mol of benzoic acid in 200 mL of deionized water, abbreviated as solution B.

[0038] Slowly drop solution B into solution A at a dropping rate of 20 drops / min, stir vigorously at 70 °C for 3 h to obtain a white emulsion, then age it at room temperature for 1 h. Wash the white emulsion three times by centrifugation with 1000 mL of deionized water. Finally, dry the obtained product at 80 °C for 12 h to obtain barium benzoate.

[0039] Put 4 g of barium benzoate into 20 mL of 10 wt% HF solution, bath it at 20 °C for 2 h with stirring, wash it three times by centrifugation with 1000 mL of deionized water, and dry it at 80 °C to obtain the fluorinated barium benzoate catalyst. Place the fluorinated barium benzoate in a tube furnace under N2 Roast and carbonize under an atmosphere, heat up to 500 °C at a rate of 3 °C / min, and then keep roasting and carbonizing at a constant temperature for 3 h to obtain the carbon-confined BaF 2 catalyst.

[0040] Use the carbon-confined BaF 2 catalyst prepared above to catalyze the cracking of 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb) to prepare 2,3,3,3-tetrafluoropropene (HFO-1234yf). The reaction formula is as follows:

[0041] CF 3 CClFCH 3 →CF 3 CF=CH 2 +HCl

[0042] The reaction conditions are as follows: The catalyst is loaded into a fixed-bed reactor, the catalyst loading is 2 mL, and a mixed gas of N 2 and HCFC-244bb is introduced. The flow rate of N 2 is 15 mL / min, the flow rate of HCFC-244bb is 5 mL / min, and the total space velocity of the mixed gas of N 2 and HCFC-244bb is 600 h -1 , and the reaction temperature is 350 °C. After reacting for 30 h, the results are as follows: The conversion rate of the reactant 2-chloro-1,1,1,2-tetrafluoropropane is 79%, and the selectivity of the product 2,3,3,3-tetrafluoropropene is 86%.

[0043] Example 5

[0044] Dissolve 0.1 mol of barium chloride dihydrate in 200 mL of deionized water at 40 °C, abbreviated as solution A. Dissolve 0.25 mol of fumaric acid in 200 mL of deionized water, abbreviated as solution B.

[0045] Slowly drop solution B into solution A at a dropping rate of 20 drops / min, stir vigorously at 60 °C for 3 h to obtain a white emulsion, then age at room temperature for 1 h. The white emulsion is centrifuged and washed three times with 1000 mL of deionized water, and finally the obtained product is dried at 80 °C for 12 h to obtain barium fumarate.

[0046] Take 2 g of barium fumarate and 6 g of ammonium fluoride and place them in a ball milling jar made of agate. Ball mill at a rotation speed of 20 r / min for 4 h to obtain fluorinated barium fumarate. Place the fluorinated barium fumarate in a tube furnace and roast and carbonize under an N 2 atmosphere. Heat up to 500 °C at a rate of 3 °C / min, and then keep roasting and carbonizing at a constant temperature for 3 h to obtain the carbon-confined BaF 2 catalyst.

[0047] The carbon-confined BaF obtained in Example 5 2 The catalyst was used to catalyze the cracking of 1,1-difluoro-1-chloroethane (HCFC-142b) to prepare 1,1-difluoroethylene (VDF). The specific application conditions were repeated in Example 1. After reacting for 30 h, the results were as follows: the conversion rate of the reactant 1,1-difluoro-1-chloroethane was 87%, and the selectivity of the product 1,1-difluoroethylene was 85%.

[0048] Example 6

[0049] 0.1 mol of barium hydroxide octahydrate was dissolved in 200 mL of deionized water at 40 °C, referred to as solution A, and 0.1 mol of citric acid was dissolved in 200 mL of deionized water, referred to as solution B.

[0050] Solution B was slowly dropped into solution A at a dropping rate of 20 drops / min, and stirred vigorously at 60 °C for 4 h to obtain a white emulsion. Subsequently, it was aged at room temperature for 3 h. The white emulsion was centrifugally washed three times with 1000 mL of deionized water, and finally the obtained product was dried at 80 °C for 12 h to obtain barium citrate.

[0051] 4 g of barium citrate was put into 20 mL of 60 wt% HF solution, bathed in water at 60 °C for 8 h with stirring, washed with clear water after centrifugation, and dried at 80 °C to prepare the catalyst. The fluorinated barium citrate was placed in a tubular furnace and calcined and carbonized under N 2 atmosphere. It was heated to 500 °C at a rate of 3 °C / min, and then calcined and carbonized at a constant temperature for 2 h to obtain the carbon-confined BaF 2 catalyst.

[0052] The carbon-confined BaF obtained in Example 6 2 The catalyst was used to catalyze the cracking of 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb) to prepare 2,3,3,3-tetrafluoropropene (HFO-1234yf). The specific application conditions were repeated in Example 4. After reacting for 30 h, the results were as follows: the conversion rate of the reactant 2-chloro-1,1,1,2-tetrafluoropropane was 83%, and the selectivity of the product 2,3,3,3-tetrafluoropropene was 88%.

[0053] Example 7

[0054] 0.1 mol of barium nitrate was dissolved in 200 mL of deionized water at 40 °C, referred to as solution A, and 0.1 mol of citric acid was dissolved in 200 mL of deionized water, referred to as solution B.

[0055] Slowly drop solution B into solution A at a dropping rate of 20 drops / min, stir vigorously at 70 °C for 3 h to obtain a white emulsion, then age at room temperature for 1 h. Wash the white emulsion three times by centrifugation with 1000 mL of deionized water. Finally, dry the obtained product at 80 °C for 12 h to obtain barium citrate.

[0056] Place barium citrate in a tube furnace and heat it to 300 °C at a rate of 3 °C / min under a N 2 atmosphere, then keep it at a constant temperature for calcination and carbonization for 4 h. After the carbonization is completed, introduce the gaseous fluorine source CHClF 2 , with a flow rate of 30 mL / min, and calcine at 300 °C for 4 h. After the fluorination is completed, switch the gaseous fluorine source CHClF 2 to N 2 until it cools down to room temperature naturally, then the carbon-confined BaF 2 catalyst is obtained.

[0057] Use the carbon-confined BaF 2 catalyst obtained in Example 7 to catalyze the cracking of 1,1-difluoro-1-chloroethane (HCFC-142b) to prepare 1,1-difluoroethylene (VDF). The specific application conditions are repeated in Example 1. After reacting for 30 h, the results are as follows: the conversion rate of the reactant 1,1-difluoro-1-chloroethane is 92%, and the selectivity of the product 1,1-difluoroethylene is 98%.

[0058] Example 8

[0059] Dissolve 0.1 mol of barium nitrate in 200 mL of deionized water at 40 °C, abbreviated as solution A. Dissolve 0.25 mol of fumaric acid in 200 mL of deionized water, abbreviated as solution B.

[0060] Slowly drop solution B into solution A at a dropping rate of 20 drops / min, stir vigorously at 60 °C for 3 h to obtain a white emulsion, then age at room temperature for 2 h. Wash the white emulsion three times by centrifugation with 1000 mL of deionized water. Finally, dry the obtained product at 80 °C for 12 h to obtain barium fumarate.

[0061] Take 2 g of barium fumarate and 10 g of ammonium fluoride and place them in an agate ball milling jar, and ball mill at a rotation speed of 200 r / min for 3 h to obtain fluorinated barium fumarate. Place the fluorinated barium fumarate in a tube furnace and calcine and carbonize it under a N 2 atmosphere, heat it to 400 °C at a rate of 3 °C / min, and then keep it at a constant temperature for calcination and carbonization for 2 h to obtain the carbon-confined BaF 2 catalyst.

[0062] Use the carbon-confined BaF 2The catalyst is used to catalyze the cracking of 1,1-difluoro-1-chloroethane (HCFC-142b) to prepare 1,1-difluoroethylene (VDF). The specific application conditions are the same as those in Example 1. After reacting for 30 h, the results are as follows: the conversion rate of the reactant 1,1-difluoro-1-chloroethane is 89%, and the selectivity of the product 1,1-difluoroethylene is 94%.

[0063] Example 9

[0064] Dissolve 0.1 mol of barium chloride dihydrate in 200 mL of deionized water at 40 °C, which is designated as Solution A. Dissolve 0.1 mol of citric acid in 200 mL of deionized water, which is designated as Solution B.

[0065] Slowly drip Solution B into Solution A at a dropping rate of 20 drops / min, stir vigorously at 60 °C for 4 h to obtain a white emulsion, then age at room temperature for 3 h. Wash the white emulsion three times by centrifugation with 1000 mL of deionized water, and finally dry the obtained product at 80 °C for 12 h to obtain barium citrate.

[0066] Put 6 g of barium citrate into 20 mL of 40 wt% HF solution, carry out a water bath at 60 °C for 6 h with stirring, wash with clear water after centrifugation, and dry at 80 °C to prepare the catalyst. Place the fluorinated barium citrate in a tubular furnace and calcine and carbonize it under a N 2 atmosphere. Heat it to 400 °C at a rate of 3 °C / min, and then keep it at a constant temperature for calcination and carbonization for 4 h to obtain the carbon-confined BaF 2 catalyst.

[0067] Use the carbon-confined BaF 2 catalyst obtained in Example 9 to catalyze the cracking of 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb) to prepare 2,3,3,3-tetrafluoropropene (HFO-1234yf). The specific application conditions are the same as those in Example 4. After reacting for 30 h, the results are as follows: the conversion rate of the reactant 2-chloro-1,1,1,2-tetrafluoropropane is 92%, and the selectivity of the product 2,3,3,3-tetrafluoropropene is 96%.

[0068] Example 10

[0069] Dissolve 0.1 mol of barium nitrate in 200 mL of deionized water at 40 °C, which is designated as Solution A. Dissolve 0.2 mol of benzoic acid in 200 mL of deionized water, which is designated as Solution B.

[0070] Slowly drip Solution B into Solution A at a dropping rate of 20 drops / min, stir vigorously at 60 °C for 6 h to obtain a white emulsion, then age at room temperature for 1 h. Wash the white emulsion three times by centrifugation with 1000 mL of deionized water, and finally dry the obtained product at 80 °C for 12 h to obtain barium benzoate.

[0071] Place barium benzoate in a tube furnace and heat it at a rate of 3 °C / min to 600 °C under a nitrogen 2 atmosphere, then keep it at a constant temperature for carbonization roasting for 5 h. After the carbonization is completed, introduce the gaseous fluorine source CHClF 2 , with a flow rate of 30 mL / min, and roast it at 250 °C for 6 h. After the fluorination is completed, switch the gaseous fluorine source CHClF 2 to N 2 until it cools down to room temperature naturally, then the carbon-confined BaF 2 catalyst is obtained.

[0072] Use the carbon-confined BaF 2 catalyst obtained in Example 10 to catalyze the cracking of 1,1-difluoro-1-chloroethane (HCFC-142b) to prepare 1,1-difluoroethylene (VDF). The specific application conditions are repeated in Example 1. After reacting for 30 h, the results are as follows: the conversion rate of the reactant 1,1-difluoro-1-chloroethane is 85%, and the selectivity of the product 1,1-difluoroethylene is 90%.

[0073] Example 11

[0074] Dissolve 0.1 mol of barium hydroxide octahydrate in 200 mL of deionized water at 40 °C, abbreviated as solution A. Dissolve 0.2 mol of ammonium fluoride in 200 mL of deionized water, abbreviated as solution B.

[0075] Slowly drip solution B into solution A at a dropping rate of 20 drops / min, stir vigorously at 60 °C for 4 h to obtain a white emulsion, then age it at room temperature for 1 h. Wash the white emulsion three times by centrifugation with 1000 mL of deionized water, and finally dry the obtained product at 80 °C for 12 h to obtain the BaF 2 catalyst.

[0076] Use the BaF 2 catalyst obtained in Example 11 to catalyze the cracking of 1,1-difluoro-1-chloroethane (HCFC-142b) to prepare 1,1-difluoroethylene (VDF). The specific application conditions are repeated in Example 1. After reacting for 30 h, the results are as follows: the conversion rate of the reactant 1,1-difluoro-1-chloroethane is 57%, and the selectivity of the product 1,1-difluoroethylene is 72%.

[0077] Comparing the experimental effects of Examples 1-10 and Example 11 of the present invention, it can be seen that: the BaF 2 catalyst that is not carbon-confined has relatively poor catalytic activity when applied to the reaction of catalytic gas-phase dehydrochlorination of fluorochloroalkanes to prepare fluoroolefins.

[0078] Example 12

[0079] Dissolve 0.1 mol of barium hydroxide octahydrate in 200 mL of deionized water at 40 °C, abbreviated as solution A, and dissolve 0.25 mol of 2-methylimidazole in 200 mL of deionized water, abbreviated as solution B.

[0080] Slowly drop solution B into solution A at a dropping rate of 20 drops / min, stir vigorously at 80 °C for 4 h to obtain a white emulsion, then age at room temperature for 1 h. Wash the white emulsion three times by centrifugation with 1000 mL of deionized water, and finally dry the obtained product at 80 °C for 12 h to obtain the barium salt.

[0081] Place the barium salt in a tube furnace, heat it to 500 °C at a rate of 3 °C / min under N 2 atmosphere, then keep it at a constant temperature and calcine and carbonize for 5 h. After the carbonization is completed, switch N 2 to the gaseous fluorine source CHFCl 2 for fluorination, with a flow rate of 30 mL / min, calcine at 350 °C for 4 h. After the fluorination is completed, switch the gaseous fluorine source CHFCl 2 to N 2 until it cools down to room temperature naturally, then the carbon-confined BaF 2 catalyst is obtained.

[0082] Use the carbon-confined BaF 2 catalyst obtained in Example 12 to catalyze the cracking of 1,1-difluoro-1-chloroethane (HCFC-142b) to prepare 1,1-difluoroethylene (VDF). The specific application conditions are repeated in Example 1. After reacting for 30 h, the results are as follows: the conversion rate of the reactant 1,1-difluoro-1-chloroethane is 63%, and the selectivity of the product 1,1-difluoroethylene is 59%.

[0083] Comparing the experimental effects of Examples 1-10 and Example 12 of the present invention, it can be seen that: the carbon-confined BaF 2 catalyst prepared by compounding different types of organic complexes and barium sources in Example 12 has relatively poor catalytic activity in the reaction of catalyzing the gas-phase dehydrochlorination of fluorochloroalkanes to prepare fluoroolefins. At the same time, it shows that the carbon-confined BaF 2 catalyst prepared by the present invention has achieved good technical effects through experimental verification.

Claims

1. A carbon-confined BaF 2 The application of the catalyst in the reaction of catalytic gas-phase dehydrochlorination of fluorochlorohydrocarbons (HCFCs) or chloroalkanes to prepare fluorinated olefins (HFOs) or chloroolefins It is characterized in that Carbon-confined BaF 2 The preparation method of the catalyst comprises the following steps: stirring a barium source and an organic acid in an aqueous solvent at 60-80 °C for 1-4 h, and white precipitates will appear during the stirring process; aging at room temperature for 1-3 h after the stirring ends, washing the obtained solid with deionized water and then drying to obtain barium organic acid for use; fluorinating the barium organic acid under the action of a fluorine source to obtain the carbon-confined BaF 2 catalyst; The barium source is one or a mixture of several of barium hydroxide octahydrate, barium chloride dihydrate, and barium nitrate; the organic acid is one of fumaric acid, citric acid, and benzoic acid, and the molar ratio of the barium source to the organic acid is 1:1 to 3; The fluorine source described is a gaseous fluorine source. The specific process of fluorinating the barium organic acid is as follows: Place the barium organic acid in a tubular furnace and heat it at a rate of 1-5 °C / min to 400-600 °C under N 2 atmosphere, and then keep it at a constant temperature for calcination and carbonization for 1-5 h; after the carbonization is completed, switch N 2 to the gaseous fluorine source for fluorination, and calcine it at 250 °C - 350 °C for 1-6 h. After the fluorination is completed, switch the gaseous fluorine source to N 2 until it cools down to room temperature naturally, and then the carbon-confined BaF 2 catalyst is obtained; wherein, the gaseous fluorine source is one of chlorodifluoromethane, dichlorofluoromethane, and trifluoromethane.

2. The application according to claim 1, It is characterized in that In the specific process of barium fluoride of the organic acid, under N 2 atmosphere, the constant-temperature roasting carbonization time is 3 h. After the carbonization is completed, N 2 is switched to a gas-phase fluorine source for fluorination, and the roasting temperature and time are 300 °C and 2 - 4 h, respectively.

3. A carbon-confined BaF 2 Application of the catalyst in the reaction of catalytic gas-phase dehydrochlorination of hydrochlorofluorocarbons (HCFCs) or chloroalkanes to prepare hydrofluoroolefins (HFOs) or chloroolefins It is characterized in that Carbon-confined BaF 2 The preparation method of the catalyst comprises the following steps: stirring a barium source and an organic acid in an aqueous solvent at 60-80 °C for 1-4 h, during which a white precipitate will appear; aging at room temperature for 1-3 h after stirring, washing the obtained solid with deionized water and then drying to obtain barium organic acid for use; fluorinating the barium organic acid under the action of a fluorine source to obtain the carbon-confined BaF 2 catalyst; The barium source is one or a mixture of several of barium hydroxide octahydrate, barium chloride dihydrate, and barium nitrate; the organic acid is one of fumaric acid, citric acid, and benzoic acid, and the molar ratio of the barium source to the organic acid is 1:1 to 3; The fluorine source described is a solid-phase fluorine source. The specific process of fluorinating the barium organic acid is as follows: The barium organic acid and the solid-phase fluorine source are placed in a ball-milling tank for ball milling. The mass ratio of the barium organic acid to the solid-phase fluorine source is 1:3 - 1:8; the ball-milling speed is 150 - 300 r / min, and the ball-milling time is 2 - 6 h; subsequently, the ball-milled mixture is placed in a tubular furnace and calcined and carbonized under N 2 atmosphere, heated to 400 - 600 °C at a rate of 1 - 5 °C / min, and then calcined and carbonized at a constant temperature for 1 - 5 h to obtain the carbon-confined BaF 2 catalyst; wherein, the solid-phase fluorine source is ammonium fluoride or ammonium fluoroborate.

4. The application according to claim 3, It is characterized in that In the specific process of barium organic acid fluorination, the mass ratio of barium organic acid to solid-phase fluorine source is 1:4 - 1:6, and the ball-milling rotation speed and time are 200 r / min and 3 h respectively; under N 2 The constant-temperature roasting carbonization time for roasting carbonization in an atmosphere is 2 - 4 h.

5. A carbon-confined BaF 2 Application of the catalyst in the reaction of catalytic gas-phase dehydrochlorination of hydrochlorofluorocarbons (HCFCs) or chloroalkanes to prepare hydrofluoroolefins (HFOs) or chloroolefins It is characterized in that Carbon-confined BaF 2 The preparation method of the catalyst comprises the following steps: stirring a barium source and an organic acid in an aqueous solvent at 60-80 °C for 1-4 h, and white precipitates will appear during the stirring process; after the stirring is completed, aging at room temperature for 1-3 h, washing the obtained solid with deionized water and then drying to obtain barium organic acid for use; under the action of a fluorine source, fluorinating the barium organic acid to obtain the carbon-confined BaF 2 catalyst; The barium source is one or a mixture of several of barium hydroxide octahydrate, barium chloride dihydrate, and barium nitrate; the organic acid is one of fumaric acid, citric acid, and benzoic acid, and the molar ratio of the barium source to the organic acid is 1:1 to 3; The fluorine source described is a liquid-phase fluorine source. The specific process of fluorinating the barium organic acid is as follows: Add barium organic acid to the liquid-phase fluorine source and stir at 20 - 100 °C for 2 - 10 h; after stirring, wash the mixture 3 times with deionized water and dry at 80 °C for 12 h; after drying, place the mixture in a tubular furnace and calcine and carbonize it under N 2 atmosphere. Heat it to 400 - 500 °C at a rate of 1 - 5 °C / min, and then keep it at a constant temperature for calcination and carbonization for 1 - 5 h to obtain the carbon-confined BaF 2 catalyst; wherein, the liquid-phase fluorine source is a 10 - 60 wt% hydrofluoric acid solution.

6. The application according to claim 5, It is characterized in that During the specific process of barium fluorination of the organic acid, the stirring temperature and time are 60°C and 5 - 7 h respectively; under N 2 The constant temperature calcination carbonization time for calcination carbonization in an atmosphere is 2 - 4 h; the liquid-phase fluorine source is a 40 wt% hydrofluoric acid solution.

7. The application according to any one of claims 1-6, It is characterized in that The fluorochloroalkane is one of 1,1-difluoro-1-chloroethane and 2-chloro-1,1,1,2-tetrafluoropropane, the chloroalkane is 1,1,1,3-tetrachloropropane, 1,2,2,3-tetrachloropropane or 1,1,2,3-tetrachloropropane, the corresponding fluoroolefin product is vinylidene fluoride or 2,3,3,3-tetrafluoropropene, and the chloroolefin product is 3,3,3-trichloropropene, 2,2,3-trichloropropene or 2,3,3-trichloropropene.

8. The application according to claim 7, It is characterized in that The application method is as follows: The catalyst is filled into a fixed-bed reactor, and N 2 and a mixed gas of fluorochloroalkane or chloroalkane is introduced. The feed volume ratio of N 2 to fluorochloroalkane or chloroalkane is 1:0.25 - 1:

4. The total space velocity of the mixed gas of N 2 and fluorochloroalkane or chloroalkane is 200 - 600 h -1 . The reaction temperature is 300 - 450 °C, and a fluorinated olefin product or a chlorinated olefin product is produced by the reaction.

Images