阅读说明：本技术 一种1,1-二氯-3,3,3-三氟丙烯的制备工艺 (Preparation process of 1, 1-dichloro-3, 3, 3-trifluoropropene ) 是由 刘武灿 王术成 周飞翔 张建君 韩文锋 于 2020-06-09 设计创作，主要内容包括：本发明涉及一种以三氟甲烷和三氯乙烯为原料生产具有高附加值的1,1-二氯-3,3,3-三氟丙烯产品的制备工艺,通过设置特定种类和比例的由主催化剂、催化助剂构成的催化体系：所述主催化剂的活性组分选自Fe、Co、Ni、Ru、Rh、Pd、Pt、Cu、Ag、Au中的一种或几种,采用多级微/介孔Cr<Sub>2</Sub>O<Sub>3</Sub>作为载体,催化助剂采用金属氧化物和/或稀土助剂,有效提高了目标产物1,1-二氯-3,3,3-三氟丙烯的选择性。本发明不仅促进了副产物三氟甲烷的资源化利用,还拓宽了1,1-二氯-3,3,3-三氟丙烯产品的原料种类,产生显著的经济效益和社会效益。(The invention relates to a preparation process for producing 1, 1-dichloro-3, 3, 3-trifluoropropene products with high added value by taking trifluoromethane and trichloroethylene as raw materials, which comprises the following steps of setting a catalytic system consisting of a main catalyst and a catalytic auxiliary agent in specific types and proportions: the active component of the main catalyst is selected from one or more of Fe, Co, Ni, Ru, Rh, Pd, Pt, Cu, Ag and AuAdopts multi-stage micro/mesoporous Cr 2 O 3 As a carrier, the catalytic assistant adopts metal oxide and/or rare earth assistant, thus effectively improving the selectivity of the target product 1, 1-dichloro-3, 3, 3-trifluoropropene. The invention not only promotes the resource utilization of the by-product trifluoromethane, but also widens the raw material variety of the 1, 1-dichloro-3, 3, 3-trifluoropropene product and generates remarkable economic and social benefits.)

1. A preparation process for producing 1, 1-dichloro-3, 3, 3-trifluoropropene products by using trifluoromethane and trichloroethylene as raw materials is characterized in that: the method comprises the following steps:

a) respectively introducing a trifluoromethane feed stream (1) and a trichloroethylene feed stream (2) into a reactor, and carrying out gas-phase reaction to generate a reaction product stream (3) in the presence of a catalytic system consisting of a main catalyst and a catalytic auxiliary agent, wherein the active component of the main catalyst consists of one or more of VIII group metal and IB group metal elements, and the carrier is multi-level micro/mesoporous Cr₂O₃Adding CO in the reaction stage₂A reaction promoting gas of (1);

b) and (3) feeding the reaction product flow (3) into a separation system, separating to obtain a target product 1, 1-dichloro-3, 3, 3-trifluoropropene, purifying and recycling excessive trifluoromethane into an initial reactor through an extraction tower to be used as a reaction raw material, wherein the extract is selected from tetrafluoroborate or tetrafluoroethanesulfonate.

2. The process according to claim 1, characterized in that: the active component of the main catalyst is one or more of Fe, Co, Ni, Ru, Rh, Pd, Pt, Cu, Ag and Au.

3. The process according to claim 1, characterized in that: the multi-stage micro/mesoporous Cr₂O₃The specific surface area of (A) is 56-120 m²(ii)/g; the average pore diameter is 0.2-12 nm.

4. The process according to claim 3, characterized in that: the multi-stage micro/mesoporous Cr₂O₃The pore size distribution of (A) has the following characteristics: 40-70% of the pore diameter is 0.2-2 nm; 10-20% of the pores have a diameter of 15-50 nm.

5. The process according to claim 2, characterized in that: the catalytic promoter is at least one metal oxide of K, Na, Zn or Ti and/or a rare earth promoter.

6. The process according to claim 5, characterized in that: the rare earth auxiliary agent is an oxide of a rare earth element or a chloride, a carbonate, a nitrate, an acetate and a sulfate thereof.

7. The process according to claim 6, characterized in that: the rare earth element is La and/or Sm, and the catalytic assistant is at least one metal oxide of Zn or Ti.

8. The process according to claim 1, characterized in that: the extract is selected from imidazole tetrafluoroborate, imidazole tetrafluoroethanesulfonate, pyridine tetrafluoroborate or pyridine tetrafluoroethanesulfonate.

9. The process according to claim 1, characterized in that: the reaction promoting gas is CO₂And Cl₂、CCl₄、O₂And nitrogen oxides.

10. The process according to claim 1, characterized in that: the mass ratio of the carrier to the active components is 100: (0.5 to 25).

Technical Field

The invention relates to a preparation process of 1, 1-dichloro-3, 3, 3-trifluoropropene, in particular to a preparation process for producing a1, 1-dichloro-3, 3, 3-trifluoropropene product with high additional value by taking trifluoromethane and trichloroethylene as raw materials to react in the presence of a catalyst.

Background

With the increasing trend toward global climate change, the technology of replacement of products with high Ozone Depletion Potential (ODP) and high Global Warming Potential (GWP) is increasing. 1, 1-dichloro-3, 3, 3-trifluoropropene is widely used in detergents, aerosols, refrigerants, blowing agents and other solvents as an effective substitute for 3, 3-dichloro-1, 1,1,2, 2-pentafluoropropane and 1, 3-dichloro-1, 1,2,2, 3-pentafluoropropane. In the preparation process of the 1, 1-dichloro-3, 3, 3-trifluoropropene, the raw material cost is reduced, and the optimization process is particularly important.

Trifluoromethane (CHF)₃) Also called fluoroform, which is a byproduct of industrial preparation of chlorodifluoromethane (HCFC-22), the content of the fluoroform in the generated HCFC-22 is about 1.5 to 3 weight percent, and the annual output in China is about 1.3 to 1.5 ten thousand tons.

CHCl₃+2HF→CHClF₂+2HCl

CHClF in the course of the reaction₂Continued fluorination produces CHF as a by-product₃。

Trifluoromethane is a very high potential greenhouse effect (equivalent to CO)₂14800 times of the standard value) and long-life greenhouse gases, with the increase of the accumulation amount in the atmosphere, the ecological hidden trouble is being formed, and the treatment and the conversion and the utilization of the trifluoromethane are not slow.

Currently, trifluoromethane has been regulated to be emitted internationally and is targeted for carbon trading. The traditional treatment methods for trifluoromethane are mainly thermal incineration, plasma treatment and strong base decomposition. The methods can not obtain economic benefits, can consume a large amount of energy, and have the defects of high cost, high energy consumption, environmental pollution and the like, so that the exploration of an environment-friendly and sustainable method for utilizing the trifluoromethane as a raw material is very important and critical.

Currently, the preparation method of 1, 1-dichloro-3, 3, 3-trifluoropropene mainly comprises chloro-trifluoropropane dehydrochlorination and pentachloropropene fluorination, and the research on trifluoromethane as a raw material is less. Therefore, the trifluoromethane is reasonably utilized as a raw material for preparing the 1, 1-dichloro-3, 3, 3-trifluoropropene, and the method has remarkable economic and social benefits.

Patent application JP2017001990A discloses a process for producing high purity 1, 2-dichloro-3, 3, 3-trifluoropropene by dehydrochlorinating 1,2, 2-trichloro-3, 3, 3-trifluoropropane as a raw material in the presence of a halogenating agent such as dichloromethane or dichloromethane in a liquid phase at a temperature of 100 to 350 ℃ in the state of a solution of activated carbon or a base. Wherein the base is at least one selected from the group consisting of metal hydroxides, metal oxides and metal carbonates.

Patent application JP2016079101A discloses a process for the dehydrochlorination of a solution of 1,1, 1-trichloro-3, 3, 3-trifluoropropane in a base dissolved in a solvent in the presence of a phase transfer catalyst, said phase transfer catalyst being a quaternary ammonium salt, to produce 1, 1-dichloro-3, 3, 3-trifluoropropene. Although this process gives 1, 1-dichloro-3, 3, 3-trifluoropropene in high yield and high selectivity, a large amount of alkaline waste water or organic base is discharged in the workup.

Patent application JP2017014160A discloses a process for preparing 1, 2-dichloro-3, 3, 3-trifluoropropene by dehydrochlorination of 1,2, 2-trichloro-3, 3, 3-trifluoropropane under an inert gas atmosphere in the presence of a metal catalyst, wherein the reaction temperature of the process is 200 to 500 ℃, and the metal catalyst comprises at least one metal selected from the group consisting of simple metals of titanium, zirconium, chromium and aluminum, oxides of metals, fluorides of metals and acid fluorides of metals.

Patent application JPWO2018193884A1 discloses a process for the coproduction of 1, 1-dichloro-3, 3, 3-trifluoropropene and 1, 1-dichloro-1, 3,3, 3-tetrafluoropropane by fluorination of 1,1,3, 3-pentachloropropene 1220za using hydrogen fluoride as fluorinating agent, the reaction being carried out in the gas phase or in the liquid phase, the reaction temperature being from 100 ℃ to 500 ℃ in the gas phase and the fluorination temperature being from 0 ℃ to 200 ℃ in the liquid phase.

Non-patent documents: henne et al, J.Chem.Soc., 1941, p.3478-3479 disclose the use of antimony fluoride (SbF)₃) Process for treating 1,1,3,3, 3-pentachloropropene in the liquid phase to produce 1, 1-dichloro-3, 3, 3-trifluoropropene but using stoichiometrically greater amounts of expensive SbF₃And is not suitable for mass production on an industrial scale.

Patent application US9029616 discloses a process for obtaining the product 1-chloro-3, 3, 3-trifluoropropene from 1, 2-dichloroethylene with trifluoromethane at a temperature of 350 ℃ to 400 ℃ over a catalyst such as a Cu/CuI impregnated activated carbon catalyst, comprising the steps of: (i) CHF₃Chlorination to CF₃Cl；(ii)CF₃Reacting the Cl with one or more vinyl chloride compounds to produce one or more chlorofluorocarbon-three-carbon synthetic compounds; and (iii) conversion of three-carbon synthetic compounds to CF₃Conversion of CH ═ CHCl. However, the reaction steps are many, the process control is complex, and side reactions are easy to generate.

Patent application WO2011044447A3 discloses the use of chloromethane, fluoromethane or chlorofluoromethane with vinyl chloride or with CHC1 ═ CX₂A process for the reaction of chlorofluoroethylene of structure (I) in the presence of a catalyst and/or initiator to produce chlorinated and/or fluorinated propenes. The catalyst and/or initiator comprises carbon tetrachloride, chlorine, hexachloroethane, trichloride, hexachloroacetone, or combinations thereof; may also be selected from thionyl chloride, sulfuryl chloride,Trichloromethylbenzene, perchlorinated alkylaryl functional groups, or organic and inorganic hypochlorites. The reaction temperature of the method is 350-550 ℃, the reaction time is 30 seconds, but the conversion rate of reaction raw materials is low and is only about 10%.

Through intensive research, the invention carries out resource utilization on the trifluoromethane and converts the trifluoromethane into a compound with higher value. In particular to a preparation process for producing 1, 1-dichloro-3, 3, 3-trifluoropropene products with high added value by taking trifluoromethane and trichloroethylene as raw materials. The method can solve the problem of treatment of the byproduct trifluoromethane, can broaden the types of raw materials for preparing the 1, 1-dichloro-3, 3, 3-trifluoropropene product, and can generate new economic benefits.

Disclosure of Invention

The invention provides a preparation process for producing a1, 1-dichloro-3, 3, 3-trifluoropropene product by using trifluoromethane and trichloroethylene as raw materials.

The reaction equation for the reaction of trifluoromethane with trichloroethylene to produce 1, 1-dichloro-3, 3, 3-trifluoropropene (HCFO-1223za) is as follows:

CHF₃+CCl₂═CHCl→CF₃CH═CCl₂+HCl(1)

during the reaction process, the performance of the trifluoromethane is very stable, the trifluoromethane is very difficult to activate, and researches show that the conversion rate is lower even under the condition of a catalyst at the temperature of below 500 ℃, the conversion rate above 800 ℃ can meet the industrial requirement, but the product selectivity is poor, and the product separation and purification cost is high. The catalytic activation of the trifluoromethane is a great problem for resource utilization. Therefore, the selection of the catalyst is very important, and the catalytic performance of the catalyst is the key for determining the production efficiency and whether the industrial production can be realized.

CHF₃In the reaction conversion process, side reactions, CHF, inevitably occur₃Under the high temperature condition, HF can be removed to generate difluorocarbene CF₂May be further converted into C₂F₄And C₃F₆. The use of a proper catalyst can control the occurrence of side reactions, thereby reducing byproducts and improving the conversion rate of raw materials and the selectivity of target products.

The catalytic system of the invention contains a main catalyst and a catalytic auxiliary agent.

The active component of the main catalyst is composed of one or more of VIII group metal and IB group metal elements, preferably one or more of Fe, Co, Ni, Ru, Rh, Pd, Pt, Cu, Ag and Au, and further preferably Co, Ni, Ru, Rh, Pd and Pt. Preferably, the active component is Pd. In the preparation process of the catalyst, the raw materials of the active component are preferably chlorides, carbonates, nitrates, acetates and sulfates corresponding to the metals of the active component.

The carrier of the main catalyst is multi-stage micro/mesoporous Cr₂O₃. For Cr containing a certain proportion of microporous structure₂O₃Vector, studies showed that: the large and medium pores with the aperture larger than 2nm have diffusion function; the catalyst can adsorb a halohydrocarbon reactant, promotes fluorine-chlorine exchange reaction, is provided with micropores with the pore diameter less than 2nm, and simultaneously avoids the problem that the pore diameter is small to limit the diffusion of reactant molecules to an active center on the surface of the catalyst, the invention adopts multi-stage micro/mesoporous Cr₂O₃Thereby having the advantages of both mesopores and micropores.

And the activity of the catalyst can be greatly influenced by selecting proper micropore and mesopore proportion. The invention uses a specific surface and pore size analyzer to measure BET specific surface area and BJH pore size distribution, and utilizes N at liquid nitrogen temperature (77K)₂And (4) measuring by an adsorption method, and respectively calculating the specific surface area and pore size distribution according to a BET model and a BJH model. Before testing, the samples were treated under vacuum with heat (80 ℃) for 2 hours to remove adsorbed water and other impurities from the surface of the material. More preferably, the specific surface area of the catalyst carrier is 15-120 m²(iv)/g, more preferably 56 to 120m²(ii)/g; the average pore diameter is 0.2-12 nm, wherein 10-70% of the pores have a diameter of 0.2-2 nm, and 10% -50% of the pores have a diameter of 15-50 nm; preferably, 40-70% of the pores have a diameter of 0.2-2 nm; 10 to 20% of the pores have a diameter of 15 to 50 nm.

Preferably, the mass ratio of the carrier to the active component of the main catalyst is 100: (0.5 to 25); preferably, the mass ratio of the carrier to the active component is 100: (0.8 to 20).

Preferably, the catalyst promoter is added into the main catalyst, and the catalyst promoter is a metal oxide and/or a rare earth promoter. The rare earth additive is an oxide of a rare earth element or a chloride, a carbonate, a nitrate, an acetate and a sulfate thereof, preferably the carbonate and the acetate, and further preferably the rare earth element is La and/or Sm. The metal oxide is at least one metal oxide selected from K, Na, Zn or Ti, preferably Zn or Ti.

The catalyst provided by the invention has the advantages that the ratio of the main catalyst to the catalytic auxiliary agent is satisfied, so that the catalyst can be used for resource utilization of trifluoromethane. As a preferred technical scheme, the mass ratio of the main catalyst to the catalytic promoter is 1: 0.02-1: 0.8, and further preferably: the mass ratio of the main catalyst to the cocatalyst is 1: 0.05-1: 0.3.

The requirements of a catalytic system consisting of the main catalyst and the catalytic auxiliary agent are as follows: the catalyst needs to be in sufficient, even excess, to achieve optimal selectivity and conversion. The physical properties are not limited, and may be, for example, round balls, tablets, and granules.

The invention also provides a preparation method of the catalytic system, which comprises the following steps:

the main catalyst is prepared by adopting an impregnation method, and the specific preparation method comprises the following steps: adding deionized water into active component metal salt, stirring and dissolving to obtain metal salt solution, namely dipping solution; and (2) soaking the dried carrier in a soaking solution at room temperature for 3-8 h, then filtering, putting into a drying oven, drying at 110-120 ℃ for 8-13 h to obtain a main catalyst precursor, roasting the obtained precursor in an inert gas atmosphere, and roasting at 500 ℃ for 5h to obtain the main catalyst. Wherein, the inert gas is preferably nitrogen, argon or helium.

The addition method of the catalytic promoter is realized by adopting the conventional method for preparing the existing catalyst, such as: physically grinding the catalyst, or doping the catalyst by a coprecipitation method metal salt solution precursor wet mixing method or an impregnation method and then roasting.

Preferably, the catalyst of the invention is pretreated by fluorination, preferably with HF, before use. The specific pretreatment mode is that a catalyst (containing a main catalyst and a catalytic auxiliary agent) is placed in a catalyst reactor, and HF-inert gas mixed gas with the molar ratio of (3-8): 1 is introduced, preferably the mixed gas with the molar ratio of (5-7): 1. Preferably, an inert gas such as nitrogen, helium, argon is mixed with the HF. The fluorination pretreatment temperature is 180-380 ℃, preferably 240-360 ℃, and the fluorination treatment time is 15-400 minutes, preferably 140-220 minutes.

The invention provides a preparation process for producing 1, 1-dichloro-3, 3, 3-trifluoropropene products by using trifluoromethane and trichloroethylene as raw materials, which comprises the following specific steps:

a) respectively introducing a trifluoromethane feed stream (1) and a trichloroethylene feed stream (2) into the reactor, and carrying out gas-phase reaction in the presence of a catalytic system formed by the main catalyst and the catalytic auxiliary agent to generate a reaction product stream (3).

The heating temperature of the reactor is 200-500 ℃, preferably 280-400 ℃.

The amount of the raw material trifluoromethane is in excess, and the molar ratio of trifluoromethane to trichloroethylene may be (1.5:1) to (10:1), and (1.5:1) to (5:1) are more preferable.

The catalytic efficiency and stability of the catalyst are preferably improved by adding a reaction-promoting gas at the reaction stage. The reaction-promoting gas may be selected from CO₂Or CO₂And Cl₂、CCl₄、O₂And nitrogen oxides. CO in reaction promoting gas₂The molar ratio of (a) is 30% to 100%, preferably 30% to 70%. The reaction promoting gas can prevent the surface of the catalyst from generating carbon deposition, thereby effectively improving the catalytic efficiency and the conversion rate of the trichloroethylene.

Further preferably, the molar ratio of the reaction promoting gas to the trifluoromethane is 0.01: 1-0.5: 1.

b) And (3) feeding the reaction product stream (3) into a separation system, and separating to obtain the target product 1, 1-dichloro-3, 3, 3-trifluoropropene.

The separation system comprises a plurality of separation towers, a standing tank and an extraction tower. The product stream (3) from the reactor is fed to a separation column at the top of which a stream containing HCl is formed, preferably hydrogen chloride which is recovered as industrial hydrochloric acid by water absorption. The excessive trifluoromethane passes through an extraction tower, is purified and is recycled into the initial reactor to be used as a reaction raw material. The extract is selected from tetrafluoroborate and tetrafluoroethanesulfonate, preferably imidazole tetrafluoroborate, imidazole tetrafluoroethanesulfonate, pyridine tetrafluoroborate or pyridine tetrafluoroethanesulfonate, and more preferably 1-butyl-3-methylimidazole tetrafluoroborate.

The extraction pressure is 0.1MPa to 2.5MPa, the extraction temperature is 5-50 ℃, and the preferred temperature is 15-35 ℃. The extract absorbs more than 80% of the trifluoromethane in the gaseous mixture, and ideally, substantially all of the trifluoromethane is absorbed by the extractant, and the extractant containing the absorbed trifluoromethane can be heated in a stripping column to liberate trifluoromethane and effect regeneration of the extractant.

Compared with the prior art, the invention has the following technical characteristics and beneficial effects:

1. the 1, 1-dichloro-3, 3, 3-trifluoropropene product with high added value is produced by taking trifluoromethane and trichloroethylene as raw materials, so that the resource utilization of the by-product trifluoromethane is promoted, the raw material variety of the 1, 1-dichloro-3, 3, 3-trifluoropropene product is widened, and remarkable economic benefit and social benefit are generated.

2. The CHF is effectively promoted by arranging a catalytic system consisting of a main catalyst and a catalytic auxiliary agent in a specific type and proportion₃Generation of CF₃The free radical reaction intermediate improves the selectivity of the target product 1, 1-dichloro-3, 3, 3-trifluoropropene and reduces the occurrence of side reactions; adopts Cr with multilevel micro/meso pores₂O₃The carrier and the proper proportion of micropores and mesopores are selected, so that the service life and the activity of the catalyst are further prolonged.

3. By adding CO in the reaction stage₂The reaction of (2) promotes gas, so that carbon deposition is not easily generated on the surface of the catalyst, and the stability, the carbon deposition resistance and the conversion rate of trichloroethylene of the catalyst are effectively improved.

4. For the arrangement of reaction raw materials, the excessive amount of the selected trifluoromethane promotes the full conversion of the trichloroethylene, and meanwhile, in a subsequent separation system, proper extract liquid tetrafluoroborate or tetrafluoroethanesulfonate is selected, so that the trifluoromethane is fully extracted and recovered and is used as the reaction raw materials to circularly enter an initial reactor, the full utilization of the raw materials is promoted, and the production cost is effectively reduced.

Drawings

FIG. 1 is a schematic flow chart of a preparation process of example 1, 1-dichloro-3, 3, 3-trifluoropropene of the present invention.

Detailed Description

The technical solution and effects of the present invention will be further described below by way of specific embodiments. The following embodiments are merely illustrative of the present invention, and the present invention is not limited to the following embodiments or examples. Simple modifications of the invention applying the inventive concept are within the scope of the invention as claimed.