Gas phase dehydrochlorination catalyst and application thereof
By coating the surface of carbon nanotubes with non-precious metal catalysts such as copper, nickel, or cobalt, the problem of high-temperature operation in existing technologies has been solved, enabling efficient and stable production of HFO-1234yf at low temperatures, which is suitable for industrial applications.
Patent Information
- Application Number
- CN202511960110.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-24
- Publication Date
- 2026-02-13
AI Technical Summary
Existing gas-phase dehydrochlorination catalysts operate at high temperatures, resulting in high energy consumption, numerous byproducts, easy catalyst deactivation, and low conversion rates, making it difficult to achieve efficient and stable HFO-1234yf production.
Using carbon nanotubes as a carrier, the surface is coated with non-precious metals such as copper, nickel, or cobalt. Through sensitization, activation, and chemical plating processes, uniformly distributed catalytic active centers are formed, which reduces the reaction temperature and improves the catalyst's resistance to carbon deposition and its stability.
Achieving high conversion and selectivity at lower temperatures significantly reduces energy consumption, extends catalyst life, is suitable for continuous industrial production, reduces costs, and improves product purity and yield.
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the field of catalysts, and particularly relates to a gas-phase dehydrochlorination catalyst and application thereof. BACKGROUND
[0002] 2,3,3,3-tetrafluoropropene (HFO-1234yf) is considered as the most potential substitute for the current mainstream refrigerant 1,1,1,2-tetrafluoroethane (HFC-134a, GWP=1430) due to its extremely low global warming potential (GWP=4) and zero ozone depletion potential. HFO-1234yf has similar physicochemical properties as HFC-134a and has a broad application prospect in the fields of refrigerants, foaming agents and aerosols, etc., and has significant economic benefits. Therefore, the development of technology for converting hydrofluorocarbons and hydrochlorofluorocarbons into high-value-added fluorine-containing olefins and intermediates has important significance for efficient utilization of fluorine resources.
[0003] Currently, metal compound catalysts are commonly used in industry to catalyze the cracking of hydrofluorocarbons and hydrochlorofluorocarbons to remove HF or HCl to prepare fluorine-containing olefins. However, due to the high bond energy of C-X bond, such reactions often need to be carried out at a high temperature of 300℃~800℃, which easily leads to carbon deposition on the surface of the catalyst, thereby affecting the service life of the catalyst. Therefore, the development of a catalyst with excellent anti-coking ability and high stability is the key to the development of this technology.
[0004] 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb) is an important intermediate for synthesizing HFO-1234yf. Among the many synthesis routes, the route of preparing HFO-1234yf from HCFC-244bb by dehydrochlorination reaction is the most valuable for industrialization. This route mainly includes liquid-phase method and gas-phase method. The liquid-phase dehydrochlorination process is mostly operated in batch mode, which needs to use a large amount of solvent and easily produces industrial waste that is difficult to handle, causing serious pollution to the environment. Therefore, gas-phase dehydrochlorination reaction has become the focus of current research and technical development.
[0005] Several existing technologies disclose methods for producing HFO-1234yf via gas-phase dechlorination of HCFC-244bb. For example, some patents use activated carbon treated with hydrochloric acid, nitric acid, or a mixture of both as a catalyst, reacting at 350℃~385℃. While a certain conversion rate can be achieved within a certain time, the conversion rate is low or decreases over time. Other technologies use supported catalysts, such as 25% KF / acid-washed activated carbon reacting at 385℃, or 10% CsCl / MgF2 reacting at 475℃~510℃. Although these methods achieve higher selectivity, the reaction temperature is too high, and long-term stability data is insufficient. Further research has attempted to use chromium-based catalysts, optimizing performance by adjusting potassium content, or catalyzing at high temperatures (e.g., 525℃~575℃) using the inner wall of a specific alloy reactor. However, these methods generally suffer from drawbacks such as excessively high reaction temperatures, high energy consumption, numerous byproducts, or low yields. For example, some methods achieve high conversion rates at 525°C but have extremely low selectivity (only 7%), while others have acceptable selectivity but insufficient conversion rates (e.g., 23%), resulting in poor economic efficiency. Furthermore, although some reports suggest that pretreating the inner surface of the alloy reactor can achieve long-term stability (2000 hours) at 480°C, the initial conversion rate is relatively low (approximately 30%), and the process is complex.
[0006] In summary, although existing technologies disclose various gas-phase dechlorination methods, they generally suffer from drawbacks such as high reaction temperatures, high energy consumption, high byproduct content, easy catalyst deactivation, or low yields. Therefore, developing a novel catalyst capable of achieving high conversion rates, high selectivity, and long lifespan under relatively mild conditions is crucial for promoting the green and efficient industrial production of HFO-1234yf. Summary of the Invention
[0007] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a gas-phase dehydrochlorination catalyst with relatively low reaction temperature, high catalytic conversion rate, high catalytic selectivity, good catalytic stability and low catalyst cost, as well as its application.
[0008] The technical solution adopted by the present invention to solve its technical problem is: a gas-phase dehydrochlorination catalyst, characterized in that the catalyst is a carbon nanotube with a non-precious metal coated on its surface.
[0009] This invention utilizes carbon nanotubes as a non-precious metal support. Carbon nanotubes possess extremely high specific surface area and excellent mechanical strength and thermal stability, providing highly dispersed anchoring sites for the metal active centers and effectively preventing metal particle agglomeration and sintering during the reaction. Electron interactions may occur between the non-precious metal coating and the carbon nanotube support, helping to modulate the electronic state of the metal, thereby enhancing its catalytic activity and selectivity. Compared to traditional activated carbon or metal oxide supports, this structure combines the excellent mass transfer properties of carbon materials with the catalytic function of metals. This synergistic effect allows the catalyst to achieve high conversion rates and high selectivity even under relatively mild conditions, and significantly enhances the catalyst's resistance to carbon deposition and long-term operational stability, resulting in a significantly extended catalyst lifetime.
[0010] Preferably, the non-precious metal is one or more of copper, nickel, and cobalt.
[0011] The choice of copper, nickel, and cobalt as coating metals in this invention offers several advantages. First, these metals are significantly cheaper than precious metals such as platinum and palladium, making the catalyst highly economical and conducive to large-scale industrial applications. Second, these non-precious metals possess specific activation capabilities for C-Cl and CH bonds, efficiently promoting the dehydrochlorination reaction. Nickel and cobalt, due to their moderate hydrodehydrogenation activity, typically exhibit high initial activity in the deHCl reaction; while copper, due to its unique electronic properties, may help improve the selectivity of the target olefin and reduce side reactions such as excessive dehydrogenation or cracking. Combining different metals (one or more) may also produce synergistic effects, further optimizing catalytic performance, such as adjusting the ratio of acidic and basic sites, thereby maintaining extremely high product selectivity while ensuring high conversion rates.
[0012] The above-mentioned method for preparing the gas-phase dehydrochlorination catalyst includes the following steps:
[0013] a. Purification: Carbon nanotubes are subjected to acid treatment, cleaning, and drying;
[0014] b. Sensitization and activation: The purified carbon nanotubes were treated sequentially with sensitizer and activator solutions, and then washed and dried;
[0015] c. Plating: The carbon nanotubes treated in step b are placed in a plating solution containing the non-precious metal ions for chemical plating.
[0016] The acid treatment in step a of this preparation process not only removes metallic impurities and amorphous carbon from the carbon nanotubes, improving their purity, but more importantly, it introduces oxygen-containing functional groups such as carboxyl and hydroxyl groups onto their surface. This greatly enhances the hydrophilicity and surface activity of the carbon nanotubes, laying a solid foundation for the subsequent uniform deposition of metals. Step b, sensitization and activation, is a crucial pretreatment. This involves the firm adsorption of reducing Sn onto the surface of the carbon nanotubes. 2+Ions and subsequently reduce Pd 2+ The formation of catalytically active palladium nuclei serves as the starting point for electroless plating, ensuring that subsequent non-precious metals can be uniformly and densely deposited on the carbon nanotube surface at the nanoscale, rather than through simple physical mixing or disordered deposition. This effectively increases the number and utilization of active sites. The electroless plating method in step c operates under mild conditions and requires simple equipment, enabling the formation of a uniform coating on complex-shaped supports. This method is highly suitable for carbon nanotubes, a material with a high specific surface area, ultimately yielding a high-performance catalyst with uniformly distributed and firmly bonded active components.
[0017] Preferably, in step a, the acid treatment is a reflux treatment using concentrated nitric acid; in step b, the sensitizer is a SnCl2 solution and the activator is a PdCl2 solution.
[0018] This invention utilizes concentrated nitric acid reflux treatment, a highly efficient and thorough purification and oxidation method. The reflux conditions ensure sufficient interaction between the acid and carbon nanotubes, deeply removing impurities and maximizing surface functionalization, superior to simple room temperature immersion. The selection of SnCl2 as the sensitizer and PdCl2 as the activator represents an optimized and classic combination. 2+ Ions can be effectively adsorbed on the surface of acid-treated carbon nanotubes, and then act as a reducing agent in the activation step to remove Pd. 2+ The catalyst is reduced to small, uniformly distributed Pd particles, providing a large number of high-quality catalytic centers for subsequent electroless plating. This specific reagent combination has been shown to form high-density, highly active activation centers, which is key to achieving uniform and continuous non-precious metal coatings and ensuring batch-to-batch consistency and high performance of the catalyst.
[0019] Preferably, in step c, the plating solution comprises a non-precious metal salt, a reducing agent, and a complexing agent; wherein the non-precious metal salt is nickel sulfate, cobalt chloride, or copper sulfate; the reducing agent is sodium hypophosphite or formaldehyde; and the complexing agent is sodium citrate, sodium acetate, or disodium EDTA. Beneficial effects: Providing specific plating solution formulations and concentration ranges is crucial for achieving a controllable and efficient electroless plating process. These optimized formulations ensure good stability and a moderate deposition rate in the plating solution. For nickel and cobalt plating solutions, sodium hypophosphite, as a reducing agent, combined with complexing agents and buffers such as sodium citrate and sodium acetate, can stabilize the metal ion concentration, control the smooth progress of the reduction reaction, and prevent spontaneous decomposition of the solution, thereby obtaining a dense and bright coating. The complexing effect of sodium citrate is particularly important, as it avoids the precipitation of hydroxides or basic salts. For copper plating solutions, formaldehyde is an effective reducing agent under strongly alkaline conditions, while disodium EDTA reacts with Cu... 2+The formation of stable complexes also plays a role in controlling the deposition process. The given concentration range has been experimentally verified to ensure a sufficient supply of metal ions to form a continuous coating. At the same time, the amounts of reducing agent and complexing agent are matched to avoid loose, rough coatings or "missing coatings," ultimately resulting in a catalyst with high catalytic activity and stability.
[0020] The specific composition of the plating solution is selected from one of the following three:
[0021] (1) Nickel plating solution: containing 20 g / L to 40 g / L of nickel sulfate, 15 g / L to 35 g / L of sodium hypophosphite, 50 g / L to 100 g / L of sodium citrate, and 10 g / L to 30 g / L of sodium acetate;
[0022] (2) Cobalt plating solution: containing 20 g / L~40 g / L of cobalt chloride, 15 g / L~35 g / L of sodium hypophosphite, 50 g / L~100 g / L of sodium citrate, and 10 g / L~30 g / L of sodium acetate;
[0023] (3) Copper plating solution: contains 10g / L~20g / L copper sulfate, 10mL / L~30mL / L formaldehyde, and 10g / L~20g / L disodium ethylenediaminetetraacetate.
[0024] Application of the above-mentioned gas-phase dehydrochlorination catalyst in the catalytic gas-phase dehydrochlorination reaction of fluorochloroalkanes to prepare fluoroolefins.
[0025] Applying the catalyst with the special structure prepared in this invention to the gas-phase dehydrochlorination reaction of chlorofluorocarbons can fully leverage its comprehensive advantages. The uniformly distributed non-noble metal active sites on the catalyst surface effectively activate C-Cl bonds, promoting the intramolecular elimination of HCl to form fluorinated olefins. The excellent thermal conductivity of the carbon nanotube support helps dissipate reaction heat promptly, reducing catalyst deactivation or side reactions caused by localized overheating. Its high specific surface area and porous structure facilitate the diffusion of reactants and products. Compared with traditional catalysts, this catalyst achieves high activity at relatively lower temperatures, significantly reducing energy consumption. Simultaneously, high selectivity reduces the burden of downstream product separation and waste generation. Excellent resistance to carbon deposition ensures stable performance of the catalyst during long-term operation, making it particularly suitable for continuous industrial production.
[0026] Preferably, the chlorofluoroalkane is 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb), and the fluoroolefin is 2,3,3,3-tetrafluoropropene (HFO-1234yf).
[0027] Synthesis route:
[0028] .
[0029] The application of this catalyst in the specific reaction of HCFC-244bb to prepare HFO-1234yf via HCl removal has significant industrial value. HFO-1234yf is a new generation of environmentally friendly refrigerant with huge market demand. This catalyst exhibits excellent adaptability to this molecular reaction. It can efficiently catalyze the removal of Cl at a specific position in the 244bb molecule while effectively suppressing side reactions such as excessive cracking, isomerization, or intramolecular rearrangement, thereby maintaining the selectivity of HFO-1234yf at an extremely high level (generally higher than 95% or even 98% in the examples). This high selectivity is crucial for improving product purity and yield, and reducing subsequent purification costs, making this route more economically and technically competitive, and providing a reliable technical solution for the industrial production of high-performance, low-GWP fluorinated olefins.
[0030] Preferably, the reaction temperature is 200℃~400℃; the reaction is carried out under normal pressure.
[0031] The reaction temperature range is significantly lower than some existing processes that require temperatures above 500°C, bringing several substantial benefits. First, the lower temperature directly reduces energy consumption, production costs, and the requirements for high-temperature resistance in equipment. Second, the lower temperature helps suppress side reactions such as thermal decomposition and carbon buildup, protecting the catalyst, extending its lifespan, and improving the selectivity of the target product. The reaction is carried out at atmospheric pressure, eliminating the investment and operational risks associated with high-pressure equipment, simplifying the process, and improving operational safety. This makes the technology easier to implement and promote industrially, and it is particularly suitable for large-scale continuous production plants.
[0032] Preferably, the feed space velocity of the raw materials in the reaction is 10 h⁻¹. -1 ~1000h -1 .
[0033] Control the raw material space velocity at 10 h -1 ~1000h -1 This provides a wide range of flexibility for optimizing reactor production intensity and conversion / selectivity. Lower space velocities (e.g., 10 h⁻¹) allow for more flexible adjustments. -1 ~30h -1 This means a longer contact time between the feedstock and the catalyst, which is beneficial for achieving a higher single-pass conversion rate and is suitable for scenarios with extremely high conversion requirements. A higher space velocity (e.g., 300 h⁻¹) is also advantageous. -1 ~1000h -1This method moderately reduces the single-pass conversion rate but significantly increases the processing capacity per unit time and per unit catalyst load, potentially leading to higher space production and reducing byproduct accumulation. It can also sometimes improve selectivity. This flexibility allows operators to optimize the process based on actual production needs (such as whether to pursue high conversion or high throughput) and the catalyst's activity at different stages, achieving economic optimization.
[0034] Preferably, the unreacted 2-chloro-1,1,1,2-tetrafluoropropane after the reaction is separated and recycled as a raw material.
[0035] HCFC-244bb is a valuable fluorochemical intermediate, and its recycling can significantly reduce raw material consumption costs. By separating unreacted 244bb from the product HFO-1234yf and the byproduct HCl using conventional separation methods such as condensation and distillation, and then returning it to the reaction system, the overall utilization rate of raw materials can be effectively improved, approaching atom-economic efficiency. This not only reduces the purchase of fresh raw materials and waste emissions, conforming to green chemistry principles, but also makes the material flow in the entire process more closed and easier to control. From an economic perspective, even if the single-pass conversion rate is not absolutely high, the recycling process can still ensure that the overall yield reaches an ideal level, while avoiding the overreaction and selectivity reduction problems that may accompany high conversion rates. This is a crucial step in achieving efficient, energy-saving, and emission-reducing industrial production.
[0036] Compared with existing technologies, this invention has the following advantages: the developed carbon nanotube surface-coated non-precious metal catalyst can efficiently catalyze the dehydrochlorination of HCFC-244bb to prepare HFO-1234yf at lower temperatures, significantly reducing energy consumption. This catalyst exhibits excellent comprehensive performance, achieving both high feed conversion and extremely high product selectivity over a wide space velocity range. It also demonstrates strong resistance to carbon deposition, excellent stability, and a lifespan of up to 2000 hours. The catalyst raw materials are inexpensive, and the preparation process is simple and reliable. The reaction is carried out at atmospheric pressure, ensuring high process safety. Furthermore, the unreacted feedstock recycling technology further enhances atom economy and environmental friendliness, providing an ideal solution for the green and low-cost industrial production of HFO-1234yf. Detailed Implementation
[0037] The present invention will be further described below with reference to specific embodiments, but the invention is not limited to these embodiments. Those skilled in the art should recognize that the present invention covers all possible alternatives, improvements, and equivalents included within the scope of the claims.
[0038] Catalyst preparation:
[0039] a. Purification: Crude carbon nanotubes are placed in concentrated HNO3 solution and refluxed for purification and oxidation. Then they are repeatedly washed with deionized water, filtered, and dried until the pH is close to 7.
[0040] b. Carbon nanotubes were sensitized with SnCl2 solution and activated with PbCl2 solution. The sensitization process was as follows: purified carbon nanotubes were placed in SnCl2 solution and sonicated at room temperature, then filtered, washed with deionized water until the solution was nearly neutral, and finally dried. The activation process was as follows: sensitized carbon nanotubes were ultrasonically dispersed in PdCl2 aqueous solution, activated at room temperature, filtered, washed with deionized water until the solution was nearly neutral, and then dried.
[0041] c. Plating solution (nickel sulfate, sodium hypophosphite, sodium acetate, sodium citrate): The treated carbon nanotubes are placed in the plating solution, then ultrasonically dispersed, and then placed in a constant temperature bath for plating with stirring. After plating, the solution is washed and filtered until the pH value is close to neutral. The pH value of the plating solution can be adjusted with ammonia and H2SO4.
[0042] Dehydrochlorination experiment:
[0043] A certain mass of dehydrochlorination catalyst was weighed and loaded into a reaction tube. The temperature of the reaction tube was then raised to 200℃~400℃. After the temperature stabilized, the vaporized 2-chloro-1,1,1,2-tetrafluoropropane was introduced into the reactor. The feed space velocity was 10 h⁻¹. -1 ~1000h -1 .
[0044] After passing through a condenser, the product enters a gas-liquid separator. The liquid product is collected and diluted after condensation, and then analyzed by gas chromatography. The gaseous product HCl is absorbed by an alkaline solution. Specific Implementation
[0045] Example Catalyst Reaction temperature / °C Space velocity / h Conversion of 2-chloro-1,1,1,2-tetrafluoropropane % Selectivity to 2,3,3,3-tetrafluoropropene % Example 1 Nickel-coated carbon nanotubes 200 30 52.76 98.42 Example 2 Nickel-coated carbon nanotubes 300 300 49.21 96.74 Example 3 Nickel-coated carbon nanotubes 400 900 36.57 87.62
[0046] Catalyst preparation:
[0047] a. Purification: Crude carbon nanotubes are placed in concentrated HNO3 solution and refluxed for purification and oxidation. Then they are repeatedly washed with deionized water, filtered, and dried until the pH is close to 7.
[0048] b. Carbon nanotubes were sensitized with SnCl2 solution and activated with PbCl2 solution. The sensitization process was as follows: purified carbon nanotubes were placed in SnCl2 solution and sonicated at room temperature, then filtered, washed with deionized water until the solution was nearly neutral, and finally dried. The activation process was as follows: sensitized carbon nanotubes were ultrasonically dispersed in PdCl2 aqueous solution, activated at room temperature, filtered, washed with deionized water until the solution was nearly neutral, and then dried.
[0049] c. Plating solution (cobalt chloride, sodium hypophosphite, sodium acetate, sodium citrate): The treated carbon nanotubes are placed in the plating solution, then ultrasonically dispersed, and then placed in a constant temperature bath for plating with stirring. After plating, the solution is washed and filtered until the pH value is close to neutral. The pH value of the plating solution can be adjusted with ammonia and H2SO4.
[0050] Dehydrochlorination experiment:
[0051] A certain mass of dehydrochlorination catalyst was weighed and loaded into a reaction tube. The temperature of the reaction tube was then raised to 200℃~400℃. After the temperature stabilized, the vaporized 2-chloro-1,1,1,2-tetrafluoropropane was introduced into the reactor. The feed space velocity was 10 h⁻¹. -1 ~1000h -1 .
[0052] After passing through a condenser, the product enters a gas-liquid separator. The liquid product is collected and diluted after condensation, and then analyzed by gas chromatography. The gaseous product HCl is absorbed by an alkaline solution. Specific Implementation
[0053] Example Catalyst Reaction temperature / °C Space velocity / h Conversion of 2-chloro-1,1,1,2-tetrafluoropropane % Selectivity to 2,3,3,3-tetrafluoropropene % Example 4 Cobalt-coated carbon nanotubes 200 30 45.31 95.52 Example 5 Cobalt-coated carbon nanotubes 300 300 39.20 90.84 Example 6 Cobalt-coated carbon nanotubes 400 900 26.57 96.71
[0054] Catalyst preparation:
[0055] a. Purification: Crude carbon nanotubes are placed in concentrated HNO3 solution and refluxed for purification and oxidation. Then they are repeatedly washed with deionized water, filtered, and dried until the pH is close to 7.
[0056] b. Carbon nanotubes were sensitized with SnCl2 solution and activated with PbCl2 solution. The sensitization process was as follows: purified carbon nanotubes were placed in SnCl2 solution and sonicated at room temperature, then filtered, washed with deionized water until the solution was nearly neutral, and finally dried. The activation process was as follows: sensitized carbon nanotubes were ultrasonically dispersed in PdCl2 aqueous solution, activated at room temperature, filtered, washed with deionized water until the solution was nearly neutral, and then dried.
[0057] c. Plating solution (copper sulfate, formaldehyde, disodium EDTA): The treated carbon nanotubes are placed in the plating solution, then ultrasonically dispersed, and then placed in a constant temperature bath for plating with stirring. After plating, the solution is washed and filtered until the pH value is close to neutral. The pH value of the plating solution can be adjusted with ammonia and H2SO4.
[0058] Dehydrochlorination experiment:
[0059] A certain mass of dehydrochlorination catalyst was weighed and loaded into a reaction tube. The temperature of the reaction tube was then raised to 200℃~400℃. After the temperature stabilized, the vaporized 2-chloro-1,1,1,2-tetrafluoropropane was introduced into the reactor. The feed space velocity was 10 h⁻¹. -1 ~1000h-1 .
[0060] After passing through a condenser, the product enters a gas-liquid separator. The liquid product is collected and diluted after condensation, and then analyzed by gas chromatography. The gaseous product HCl is absorbed by an alkaline solution.
[0061] Example Catalyst Reaction temperature / °C Space velocity / h Conversion of 2-chloro-1,1,1,2-tetrafluoropropane % Selectivity to 2,3,3,3-tetrafluoropropene % Example 7 Cobalt-coated carbon nanotubes 200 30 25.31 97.32 Example 8 Cobalt-coated carbon nanotubes 300 300 27.32 95.41 Example 9 Cobalt-coated carbon nanotubes 400 900 35.89 98.24
[0062] The contents described in this specification are merely an enumeration of the implementation forms of the inventive concept, and the scope of protection of this invention should not be regarded as limited to the specific forms described in the embodiments.
[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.
Claims
1. A gas phase dehydrochlorination catalyst characterized by, The catalyst is carbon nanotubes plated with non-noble metal on the surface.
2. The vapor phase dehydrochlorination catalyst according to claim 1, characterized by, The non-noble metal is one or more of copper, nickel and cobalt.
3. A vapour phase dehydrochlorination catalyst according to claim 1 or 2, characterised in that: The preparation method comprises the following steps: a. Purification: acid treatment, washing and drying of carbon nanotubes; b. Sensitization and activation: sequential treatment of purified carbon nanotubes with a sensitization agent and an activation agent solution, followed by washing and drying; c. Plating: placing carbon nanotubes treated in step b in a plating solution containing non-noble metal ions for chemical plating.
4. The gas phase dehydrochlorination catalyst according to claim 3, wherein in step a, the acid treatment is reflux treatment with concentrated nitric acid; in step b, the sensitization agent is SnCl2 solution and the activation agent is PdCl2 solution.
5. A vapor phase dehydrochlorination catalyst according to claim 3, wherein in step c, the plating solution comprises a non-noble metal salt, a reducing agent, and a complexing agent; and wherein, The non-noble metal salt is nickel sulfate, cobalt chloride or copper sulfate; The reducing agent is sodium hypophosphite or formaldehyde; The complexing agent is sodium citrate, sodium acetate or disodium ethylenediaminetetraacetate.
6. Use of the gas phase dehydrochlorination catalyst according to any one of claims 1-5 in a reaction for catalytically preparing fluorine-containing olefin from fluorine-containing chloroalkane by gas phase dehydrochlorination.
7. Use according to claim 6, characterized in that, The fluorine-containing chloroalkane is 2-chloro-1,1,1,2-tetrafluoropropane and the fluorine-containing olefin is 2,3,3,3-tetrafluoropropene.
8. Use according to claim 6, characterized in that, The reaction temperature is 200-400°C; and the reaction is carried out under normal pressure.
9. Use according to claim 6, characterized in that, The feed space velocity of the raw material in the reaction is 10 h -1 ~1000 h -1 .
10. Use according to claim 6, characterized in that, Unreacted 2-chloro-1,1,1,2-tetrafluoropropane after the reaction is separated and recycled as raw material.