CN103721659A - Method for immobilizing ionic liquid by cold plasmas - Google Patents

Abstract

The invention discloses a method for immobilizing ionic liquid in cold plasma. Mix the ionic liquid with the carrier and put it directly into the plasma discharger, then pass in the plasma discharge gas, and use the DC or AC current applied at both ends of the electrode by the high-voltage power supply to discharge the discharge gas, and the formed high-energy electrons will activate the ionic liquid. The components are grafted onto the carrier to achieve the purpose of immobilizing the ionic liquid, and the treatment time is 1 to 30 minutes. The invention has the advantages of simple device, convenient operation, energy saving, uniform dispersion of the prepared sample ionic liquid, less dosage, strong interaction with the carrier, excellent performance, environmental friendliness, and simple equipment requirements; It avoids the harsh conditions of bonded immobilization and the disadvantages of difficulty in large-scale application, reduces production costs and avoids environmental pollution problems caused by the use of organic solvents, and has significant economic and social benefits.

Description

Method for Immobilizing Ionic Liquids in Cold Plasma

technical field

The invention relates to the technical field of material science, in particular to a method for promoting the immobilization of ionic liquids under low-temperature plasma. the

Background technique

Ionic liquids are considered to be another large class of green solvents after water and supercritical carbon dioxide. It is widely used in electrochemistry, gas absorption, liquid- Liquid separation, catalytic reaction and other aspects. But on the other hand, the application of ionic liquids is greatly limited by their own characteristics, such as high price and large dosage; high viscosity so that it is inconvenient to transport and operate; difficult to recycle and so on. Therefore, it is particularly necessary to prepare solid-phase materials by loading ionic liquids. the

Supported Ionic Liquids (Supported Ionic Liquids) refers to the immobilization of ionic liquids on some inorganic or organic solid materials by physical or chemical methods, so as to obtain solid materials loaded with ionic liquids or with ionic liquid structures on the surface, and change the surface of solids. nature. Compared with ionic liquids, immobilized ionic liquids have the following advantages: the ionic liquid is dispersed on the surface of the carrier, which improves the utilization rate of the ionic liquid; it is beneficial to the separation of the catalyst and the product, and has high selectivity, good catalytic activity, and reaction conditions Mild; according to the specific surface area of the carrier, the acidity of the immobilized ionic liquid can be adjusted; the reaction process can be continuous, and the production capacity of the equipment can be improved; it can be applied to gas phase reactions. the

At present, the immobilization of ionic liquids mainly adopts impregnation method, bonding method, sol-gel method and so on. The impregnation method is to immerse the carrier in excess ionic liquid, remove the excess ionic liquid after soaking for a period of time, and finally dry the immobilized ionic liquid. This method often cannot form a specific covalent bond with the carrier, but can only be a simple physical adsorption of the ionic liquid on the carrier. According to common sense, the simple physical adsorption force between the ionic liquid and the carrier should be weak, and the ionic liquid will fall off into the main fluid phase during the reaction process. The bonding method refers to the combination of the carrier and the ionic liquid through a covalent bond. However, most ionic liquids do not have this property and must be modified before bonding. The steps are cumbersome and the coupling agent is expensive, making it difficult to produce on a large scale. The sol-gel method is to mix the ionic liquid, the silicon source and the template agent in a certain proportion to obtain the modified silica gel grafted with the ionic liquid. This method has harsh reaction conditions and low carrier selectivity. the

Plasma is an ionized gas, uncharged ionized matter with ions, electrons and core particles. There are two types of plasmas: high temperature and low temperature plasmas. High-temperature plasma only occurs when the temperature is high enough, and consumes a lot of energy. Low-temperature plasma is a plasma that occurs at room temperature. It has the characteristics of high electron energy and low main body temperature. It is currently widely used in material surface modification and catalyst preparation. It has developed into materials, energy, information, environmental space, space The techniques and crafts of physics, geophysics and other sciences. Due to the low-temperature characteristics of the low-temperature plasma, if it is used to immobilize the ionic liquid, it will not destroy the composition and structure of the ionic liquid and the carrier, so that the ionic liquid is evenly dispersed on the carrier and inhibits agglomeration. Moreover, due to the high electron temperature and low gas temperature characteristics of low-temperature plasma, it can break the thermodynamic and kinetic constraints, promote the immobilization reaction between the ionic liquid and the carrier, and increase the interaction between them. Moreover, the cold plasma method has simple device, convenient operation, energy saving, environmental friendliness, and wide application prospect in the field of material preparation. the

The currently disclosed immobilized ionic liquid technology is mainly based on the bonding method, such as CN201010172300.X, CN201310344983.6 and CN200710017755.2, etc., all of which use specific coupling agents to modify ionic liquids or carriers for bonded immobilization. It is quite different from the cold plasma method of this patent that does not use any chemical reagents for immobilizing ionic liquids. the

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art, and provide a method for cold plasma immobilized ionic liquid; the method is easy to operate, friendly to the environment, and the prepared sample ionic liquid is uniformly dispersed, and the dosage is small, and it is compatible with the carrier Interaction force is strong, not easy to fall off. the

The present invention is achieved through the following technical solutions:

A method for immobilizing an ionic liquid by cold plasma, the production method comprising the following steps:

(1). Under the condition of stirring, add the ionic liquid to the carrier until it is completely wet and directly put it into the vacuum chamber of the plasma discharger;

(2). Vacuumize the vacuum chamber, and then pass in the plasma discharge gas, and keep the gas pressure at 100-200Pa;

(3).Using a high-voltage power supply to apply 1000-4000V DC or AC at both ends of the electrodes to discharge the discharge gas. The formed plasma activates the ionic liquid and grafts the active components onto the carrier. The treatment time is 1-30min. This firmly immobilizes the ionic liquid on the carrier. the

The ionic liquid is quaternary ammonium salt or phosphonium salt or imidazole or pyridine or pyrrolidine or morpholine or piperidine ionic liquid. the

The carrier is activated carbon or carbon black or carbon fiber or carbon nanotube or resin or diatomaceous earth or silica gel or molecular sieve or chitosan or montmorillonite. the

The plasma discharger described in step (1) includes a sample chamber, an anode, a cathode, a gas inlet, a gas outlet, a dielectric barrier, a high voltage power supply and a vacuum pump. the

The plasma discharge gas described in step (2) is an inert gas or air or oxygen, or a mixture of the above gases. the

The inert gas is argon or nitrogen or helium. the

The gas discharge is in the form of glow discharge or dielectric barrier discharge or corona discharge. the

The temperature of the cold plasma is 25-150°C. the

Advantage of the present invention and beneficial effect are:

1. The cold plasma method immobilized ionic liquid method that the present invention relates to is to utilize a large amount of high-energy electrons in the plasma that high-voltage direct current or alternating current power discharge produces to activate the ionic liquid, make its functional group graft on the carrier, increase the distance between the carrier and the ionic liquid. Interaction force to achieve the purpose of immobilized ionic liquid. The ionic liquid immobilized by the plasma method has the advantages of uniform dispersion, reduced dosage of the ionic liquid, and the ionic liquid is not easy to fall off. the

2. The cold plasma immobilized ionic liquid method adopted in the present invention can quickly and effectively immobilize the ionic liquid, which can be carried out at room temperature, avoids the adverse thermal effect at high temperature, and is simple to operate, saves energy consumption, and the amount of sample processed Large, does not use chemical reducing agents, and is environmentally friendly. the

3. The cold plasma method used in the present invention to immobilize the ionic liquid method has few restrictions on the types of ionic liquids and carriers, has many types of applications, and is easy to popularize

Description of drawings

Figure 1 is the infrared spectrum of 1-butyl-3-methylimidazolium tetrafluoroborate immobilized on activated carbon after cold plasma treatment. the

Detailed ways

The present invention is further described in detail through the following embodiments in conjunction with the accompanying drawings, but the technical content described in this embodiment is illustrative rather than restrictive, and should not be used to limit the protection scope of the present invention. the

Example 1

Under the condition of stirring, the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate is added dropwise on the activated carbon until the activated carbon is completely wetted, then placed between the two electrode plates of the discharge tube in the vacuum chamber, airtight , the vacuum chamber is evacuated, and then filled with argon gas as the discharge gas to maintain a pressure of 100Pa, and a DC voltage of 1000V is applied to the electrode, and the glow discharge plasma is used for treatment. The treatment time is 20 minutes, and the plasma is detected by an infrared camera. The body temperature was 25°C. The prepared ionic liquid is evenly dispersed on the activated carbon. And the sample was put into water to stand still, and no ionic liquid was found to be lost into the solution. It is proved that there is a strong interaction between ionic liquid and activated carbon. the

The prepared activated carbon-immobilized ionic liquid is analyzed by infrared spectrum, and the following analysis results can be obtained:

The infrared spectrogram shown in Figure 1 shows that the characteristic band at 3156cm ^-1 is CH stretching vibration on the imidazole ring; the characteristic bands at 2962, 2874 and 1384cm ^-1 belong to the opposition of CH on the methyl group, respectively It is called stretching vibration, symmetrical stretching vibration and bending vibration; the spectra at 2936 and 1463 cm ^-1 belong to the antisymmetric stretching vibration and bending vibration of methylene CH respectively; the spectrum at 1339 cm ^-1 belongs to CN stretching vibration; the spectrum at 1059 cm ^-1 belongs to Stretching vibrations of the anion _BF4 . It shows that the ionic liquid has been completely immobilized on the activated carbon.

Example 2:

Under the condition of stirring, the ionic liquid N-ethylpyridinium bromide is added dropwise on the porous silica gel until the silica gel is completely wet and placed between the two electrode plates of the discharge tube in the vacuum chamber, airtight, and the vacuum chamber is evacuated. Then fill it with oxygen as discharge gas, maintain a pressure of 110Pa, apply an AC voltage of 1500V on the electrode, and use dielectric barrier discharge plasma for treatment. The treatment time is 1 minute, and the plasma temperature is 150°C detected by an infrared camera. The prepared ionic liquid is uniformly dispersed on the silica gel. And the sample was put into water to stand still, and no ionic liquid was found to be lost into the solution. It is proved that there is a strong interaction between ionic liquid and silica gel. the

Example 3:

Under the condition of stirring, add the ionic liquid dodecyltrimethylammonium chloride to the resin dropwise, until the resin is completely wet, place it between the two electrode plates of the discharge tube in the vacuum chamber, seal it, and evacuate the vacuum chamber Vacuum, then filled with oxygen as discharge gas, maintain a pressure of 130Pa, apply a DC voltage of 2000V to the electrodes, and use corona discharge plasma for treatment for 10 minutes. The plasma temperature is 50°C detected by an infrared camera. The prepared ionic liquid is uniformly dispersed on the resin. And the sample was put into water to stand still, and no ionic liquid was found to be lost into the solution. It is proved that there is a strong interaction between the ionic liquid and the resin. the

Example 4:

Under the condition of stirring, the ionic liquid N-butyl, methylpyrrolidine trifluoromethanesulfonate is added dropwise on the molecular sieve until the molecular sieve is completely wetted, then placed between the two electrode plates of the discharge tube in the vacuum chamber, airtight , the vacuum chamber is evacuated, and then filled with a mixed gas of helium and oxygen as a discharge gas, maintaining a pressure of 150Pa, applying an AC voltage of 2500V on the electrode, and using glow discharge plasma for treatment. The treatment time is 25 minutes. The plasma temperature was detected by an infrared camera to be 100 °C. The prepared ionic liquid is uniformly dispersed on the molecular sieve. And the sample was put into water to stand still, and no ionic liquid was found to be lost into the solution. It is proved that there is a strong interaction between ionic liquids and molecular sieves. the

Embodiment 5:

Under the condition of stirring, the ionic liquid N-methyl, ethyl morpholine hexafluorophosphate is added dropwise on the chitosan until the chitosan is completely wet and placed between the two electrode plates of the discharge tube in the vacuum chamber , airtight, vacuumize the vacuum chamber, then fill it with helium as the discharge gas, maintain a pressure of 200Pa, apply an AC voltage of 4000V on the electrode, and use dielectric barrier plasma for treatment. The treatment time is 30 minutes, and it is detected by an infrared camera. The plasma temperature was 120°C. The prepared ionic liquid is uniformly dispersed on the chitosan. And the sample was put into water to stand still, and no ionic liquid was found to be lost into the solution. Demonstration of a strong interaction between ionic liquids and chitosan

Embodiment 6:

Under the condition of stirring, the ionic liquid N-propyl, methyl piperidine bistrifluoromethanesulfonimide salt is added dropwise on the diatomite until the diatomite is completely wet, and then placed in the two sides of the discharge tube in the vacuum chamber. Between two electrode plates, airtight, vacuumize the vacuum chamber, then fill it with oxygen as a discharge gas, maintain a pressure of 180Pa, apply an AC voltage of 3000V on the electrodes, and use corona discharge plasma for treatment, the treatment time is 20 minutes , the plasma temperature was detected as 60 °C by an infrared camera. The prepared ionic liquid is evenly dispersed on diatomaceous earth. And the sample was put into water to stand still, and no ionic liquid was found to be lost into the solution. It is proved that there is a strong interaction between ionic liquid and diatomaceous earth. the

Embodiment 7:

Under the condition of stirring, add the ionic liquid tributylmethylphosphine iodide to the montmorillonite dropwise until the montmorillonite is completely wet, then place it between the two electrode plates of the discharge tube in the vacuum chamber, seal it, and evacuate the vacuum chamber Vacuum, then filled with argon as discharge gas, maintain a pressure of 150Pa, apply an AC voltage of 3500V on the electrode, and use a dielectric barrier discharge plasma for treatment. The treatment time is 30 minutes, and the plasma temperature is 125°C detected by an infrared camera. . The prepared ionic liquid is evenly dispersed on the montmorillonite. And the sample was put into water to stand still, and no ionic liquid was found to be lost into the solution. It is proved that there is a strong interaction between ionic liquid and montmorillonite. the

Embodiment 8:

Under the condition of stirring, the ionic liquid 1-ethyl-3-methylimidazolium methyl sulfate is added dropwise on the carbon fiber until the carbon fiber is completely wet and placed between the two electrode plates of the discharge tube in the vacuum chamber, airtight, Evacuate the vacuum chamber, then fill it with oxygen as the discharge gas, maintain a pressure of 100Pa, apply an AC voltage of 1300V on the electrode, and use glow discharge plasma for treatment. The treatment time is 9 minutes, and the plasma temperature is detected by an infrared camera. is 40°C. The prepared ionic liquid is uniformly dispersed on the carbon fiber. And the sample was put into water to stand still, and no ionic liquid was found to be lost into the solution. It is proved that there is a strong interaction between ionic liquid and carbon fiber. the

The above examples are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art on the basis of the present invention are all within the protection scope of the present invention. The protection scope of the present invention shall be determined by the claims. the

Claims (8)

1. a method for cold plasma immobilized ionic liquid, is characterized in that: comprise the following steps: (1). Under the condition of stirring, add the ionic liquid to the carrier until it is completely wet and directly put it into the vacuum chamber of the plasma discharger; (2). Vacuumize the vacuum chamber, and then pass in the plasma discharge gas, and keep the gas pressure at 100-200Pa; (3).Using a high-voltage power supply to apply 1000-4000V DC or AC at both ends of the electrodes to discharge the discharge gas. The formed plasma activates the ionic liquid and grafts the active components onto the carrier. The treatment time is 1-30min. This firmly immobilizes the ionic liquid on the carrier. the 2. according to the method described in claim 1, it is characterized in that: described ionic liquid is quaternary ammonium salts or quaternary phosphorus salts or imidazoles or pyridines or pyrrolidines or morpholines or piperidines ion liquid. the 3. The method according to claim 1, characterized in that: the carrier is activated carbon or carbon black or carbon fiber or carbon nanotube or resin or diatomaceous earth or silica gel or molecular sieve or chitosan or montmorillonite. the 4. The method according to claim 1, characterized in that: the plasma discharger described in step (1) includes a sample chamber, an anode, a cathode, a gas inlet, a gas outlet, a dielectric barrier, a high voltage power supply and vacuum pump. the 5. The method according to claim 1, characterized in that: the plasma discharge gas described in step (2) is an inert gas or air or oxygen, or a mixture of the above gases. the 6. The method according to claim 5, characterized in that: the inert gas is argon or nitrogen or helium. the 7. The method according to claim 1, characterized in that: said gas discharge is in the form of glow discharge, dielectric barrier discharge or corona discharge. the 8. The method according to claim 1, characterized in that the temperature of the cold plasma is 25-150°C. the

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