Hyperbranched Pickering microsphere adsorbent as well as preparation method and application thereof

Abstract

In order to solve the problems that a traditional adsorption material is low in CO2 efficiency, poor in specificity and the like, the invention provides a hyperbranched Pickering microsphere adsorbent and a preparation method and application thereof, the adsorbent has rich branched chains, molecules are not tangled, and the adsorbent has a large number of amino-terminated groups, so that CO2 can be adsorbed with high adsorption capacity and high selectivity, the purpose of purifying flue gas is achieved, and the adsorbent has a wide application prospect. The adsorbent has the advantages of high adsorption speed, capability of reducing desorption energy consumption and the like, and the problems of low adsorption efficiency and poor selectivity of a traditional material are fundamentally solved.

Description

Technical Field

[0001] The invention belongs to the technical field of adsorption materials, and particularly relates to a hyperbranched Pickering microsphere adsorbent and a preparation method and application thereof. Background Art

[0002] Climate change caused by the greenhouse effect has become one of the core issues of the current global environment. Studies have shown that the main factor for temperature rise is the increase in the content of carbon dioxide (CO2) in greenhouse gases. Therefore, the development of efficient and complete processes and methods for CO2 capture has attracted increasing attention. In theory, the main way to deal with global warming is to reduce carbon dioxide emissions.

[0003] Considering the characteristics of the existing energy structure and the high cost of developing and utilizing new energy, the combustion of fossil fuels will remain the main source of energy for a long time in the future. Therefore, CO2 capture and storage (CCS) will be the most feasible solution to stabilize the CO2 concentration in the atmosphere. CO2 capture and storage technology refers to capturing CO2 at the emission source, transporting it to a storage location, and injecting it into the geology or ocean for storage.

[0004] Among them, the solid adsorption method does not involve solvents, which can avoid the construction cost problem caused by equipment corrosion and the additional energy consumption problem caused by solvent evaporation; moreover, CO2 molecules can directly contact the active groups on the adsorption material, reducing a mass transfer interface, which also reduces the energy required to overcome the interfacial tension. Therefore, adsorption separation has greater energy-saving potential. However, at this stage, whether it is pressure swing physical adsorption or temperature swing chemical adsorption, energy consumption is still high. The core problem is that the comprehensive performance of the adsorption material cannot meet the actual needs. The ideal adsorption material should have the following characteristics: high adsorption capacity and CO2 / N2 selectivity, resistance to impurities, fast adsorption and desorption kinetics, good morphology and chemical stability, good wear resistance in the fluidized bed, low regeneration energy consumption and equipment cost.

[0005] Therefore, how to obtain an ideal adsorption material with the above-mentioned comprehensive properties is a problem that needs to be solved. Summary of the invention

[0006] In view of the problems existing in the prior art, the purpose of the present invention is to provide a hyperbranched Pickering microsphere adsorbent and a preparation method and application thereof. The hyperbranched Pickering microsphere adsorbent is used for the adsorption of carbon dioxide and can achieve efficient and highly selective adsorption of CO2 pollutants in the atmosphere.

[0007] The objective of the present invention is achieved through the following technical solutions:

[0008] The first aspect of the present invention provides a method for preparing a hyperbranched Pickering microsphere adsorbent, comprising the following steps:

[0009] (1) First, 0.4-0.5 g of 1-dodecanol, 20-23 mg of azobisbutyronitrile, 1-2 mL of toluene, 2-3 mmol of 2-(diethylamino)ethyl methacrylate and 7-9 mmol of divinylbenzene are weighed in a test tube, mixed by vortexing, referred to as solution A, and nitrogen is continuously introduced into solution A; then 80-140 mg of silica balls are mixed with 10 mL of pure water in a test tube, and ultrasonically treated for 1-2 min, referred to as solution B; solution A is added to solution B, and the mixture is homogenized to obtain a Pickering emulsion; the Pickering emulsion is placed in a water bath at 60-80° C. for polymerization reaction for 20-24 h; after the reaction, the composite material obtained by filtration is soaked in an acidic solution, then filtered and washed with deionized water until the composite material is neutral; methanol is used as an extraction solvent, and Soxhlet extraction is performed for 10-15 h to remove unreacted impurities in the composite material, thereby obtaining a Pickering microsphere material;

[0010] (2) dispersing a mixture of 10 to 30 g of the Pickering microsphere material obtained in step (1) and 20 to 60 g of an epoxy silane coupling agent in 10 to 100 mL of anhydrous toluene, refluxing at 100 to 140° C. for 4 to 8 h under inert gas protection, filtering, washing the resulting precipitate with anhydrous toluene and ethanol, and drying to obtain epoxy-modified Pickering microspheres;

[0011] (3) dissolving 2-50 g of polyethyleneimine in 50-500 mL of a methanol / water mixture, adding 5-50 g of the epoxy-modified Pickering microspheres obtained in step (2), and then reflux reacting at 60-100° C. for 4-8 h. After evaporating the solvent, amino-modified Pickering microspheres are obtained, which are the hyperbranched Pickering microsphere adsorbent.

[0012] Furthermore, in step (1), the acidic solution includes HCl aqueous solution, HF aqueous solution and HNO3 aqueous solution.

[0013] Furthermore, in step (1), the conditions for the homogenization treatment include: the speed of the homogenizer is 4000-6000 rpm, and the stirring time is 1-3 min.

[0014] Furthermore, the epoxysilane coupling agent is a mixture of any one or more of 2-(3,4-epoxycyclohexane)ethyltriethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, and 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane.

[0015] Furthermore, the inert gas includes nitrogen, argon and helium.

[0016] Furthermore, in step (3), the polyethyleneimine is any one or a mixture of two or more of chain or branched polyethyleneimine with molecular weights of 10,000, 25,000, 70,000 and 700,000.

[0017] Furthermore, in step (3), the volume ratio of methanol to water in the methanol / water mixture is 1:5 to 5:1.

[0018] In a second aspect, the present invention provides a hyperbranched Pickering microsphere adsorbent prepared by the above preparation method.

[0019] The second aspect of the present invention provides the use of the hyperbranched Pickering microsphere adsorbent in the adsorption / capture of CO2 in flue gas or air.

[0020] Furthermore, after 20 to 100 adsorption-desorption cycles, the CO2 adsorption capacity of the hyperbranched Pickering microsphere adsorbent decreases within 5%.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The preparation method of the hyperbranched Pickering microsphere adsorbent described in the present invention is simple, has high yield, low raw material price, and is environmentally friendly, providing a new research idea for solving the bottlenecks of low efficiency and poor specificity of traditional adsorption materials for CO2.

[0023] (2) The hyperbranched Pickering microsphere adsorbent prepared by the present invention has abundant side chains, no entanglement between molecules, and a large number of terminal amino groups, so that it can adsorb CO2 with high adsorption capacity and high selectivity to achieve the purpose of purifying flue gas. It has the advantages of fast adsorption speed and reduced desorption energy consumption, which fundamentally solves the problem of low adsorption efficiency and poor selectivity of traditional materials.

[0024] (3) The present invention explores the performance of hyperbranched Pickering microsphere adsorbent in capturing CO2 in simulated flue gas, which has strong water vapor tolerance and cyclic stability, and its pore size matches the kinetic diameter of CO2 molecules, showing high CO2 adsorption selectivity.

[0025] (4) The hyperbranched Pickering microsphere adsorbent prepared by the present invention also exhibits good reusability and can be applied to large-scale CO2 capture projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0027] Figure 1 This is a schematic diagram of the structure of a device for CO2 adsorption treatment using the hyperbranched Pickering microsphere adsorbent of the present invention in Example 2;

[0028] Figure 2 These are the results of 40 adsorption-desorption cycles of the hyperbranched Pickering microsphere material for CO2 adsorption of the present invention. DETAILED DESCRIPTION

[0029] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, features and effects proposed according to the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0030] Example 1

[0031] This embodiment provides a method for preparing a hyperbranched Pickering microsphere adsorbent, comprising the following steps:

[0032] (1) First, 0.422 g of 1-dodecanol, 22.5 mg of azobisbutyronitrile (AIBN), 1.2 mL of toluene, 2 mmol of 2-(diethylamino)ethyl methacrylate (DEAEMA) and 8 mmol of divinylbenzene (DVB) were weighed in a test tube and mixed by vortexing, which was called solution A. Nitrogen was continuously introduced into solution A. Then 120 mg of silica balls and 10 mL of pure water were mixed in a test tube and placed in an ultrasonic bath for 1 min, which was called solution B. Next, solution A was added to solution B, and the mixture was rapidly stirred at 6000 rpm for 1 min using a homogenizer to obtain a Pickering emulsion. The Pickering emulsion was then placed in a water bath at 60°C for 24 h to undergo polymerization. After the reaction was completed, the composite material obtained by filtration was soaked in hydrofluoric acid for 24 h, then filtered and washed with deionized water until the composite material was neutral.

[0033] Methanol was used as the extraction solvent, and Soxhlet extraction was performed at 60° C. for 12 h to remove unreacted impurities in the composite material, thereby obtaining the Pickering microsphere material.

[0034] (2) A mixture of 5 g of the Pickering microsphere material obtained in step (1) and 10 g of 3-glycidyloxypropyltriethoxysilane was dispersed in 20 mL of anhydrous toluene, heated to 100° C. and refluxed for 6 h under nitrogen protection, filtered and washed with anhydrous toluene and ethanol, and then the solid was dried in a vacuum drying oven at 80° C. for 24 h to obtain epoxy-modified Pickering microspheres.

[0035] (3) Dissolve 5 g of branched polyethyleneimine with a molecular weight of 70,000 in 50 mL of a methanol / water mixture (the volume ratio of methanol to water is 1:1), add 5 g of the epoxy-modified Pickering microspheres obtained in step (2), heat to 100° C. and reflux for 6 h under nitrogen protection, dry in a vacuum drying oven at 80° C. for 24 h to evaporate the solvent, and obtain amino-modified Pickering microspheres, i.e., the hyperbranched Pickering microsphere adsorbent.

[0036] Example 2

[0037] This embodiment provides another method for preparing a hyperbranched Pickering microsphere adsorbent, comprising the following steps:

[0038] (1) First, 0.422 g of 1-dodecanol, 22.5 mg of azobisbutyronitrile (AIBN), 1.2 mL of toluene, 2 mmol of 2-(diethylamino)ethyl methacrylate (DEAEMA) and 8 mmol of divinylbenzene (DVB) were weighed in a test tube and mixed by vortexing, which was called solution A. Nitrogen was continuously introduced into solution A. Then 80 mg of silica balls were mixed with 10 mL of pure water in a test tube and placed in an ultrasonic bath for 1 min, which was called solution B. Next, solution A was added to solution B, and the mixture was rapidly stirred at 6000 rpm for 1 min using a homogenizer to obtain a Pickering emulsion. The Pickering emulsion was then placed in a water bath at 60°C for 24 h to undergo polymerization. After the reaction was completed, the composite material obtained by filtration was soaked in hydrofluoric acid for 24 h, then filtered and washed with deionized water until the composite material was neutral.

[0039] Methanol was used as the extraction solvent and Soxhlet extraction was performed at 60° C. for 12 h to remove unreacted impurities in the composite material, thereby obtaining a Pickering microsphere material with a size different from that in Example 1.

[0040] (2) Disperse 5 g of the Pickering microsphere material obtained in step (1) and a mixture of 5 g of 3-glycidyloxypropyltriethoxysilane and 5 g of 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane in 20 mL of anhydrous toluene, heat to 100° C. and reflux for 6 h under nitrogen protection, filter and wash with anhydrous toluene and ethanol, and then dry the solid in a vacuum drying oven at 80° C. for 24 h to obtain epoxy-modified Pickering microspheres.

[0041] (3) Dissolve 5 g of branched polyethyleneimine with a molecular weight of 10,000 in 50 mL of a methanol / water mixture (the volume ratio of methanol to water is 1:1), add 5 g of the epoxy-modified Pickering microspheres obtained in step (2), heat to 100° C. and reflux for 6 h under nitrogen protection, dry in a vacuum drying oven at 80° C. for 24 h to evaporate the solvent, and obtain amino-modified Pickering microspheres, i.e., the hyperbranched Pickering microsphere adsorbent.

[0042] Example 3

[0043] In order to explore the adsorption capacity of the hyperbranched Pickering microsphere adsorbent prepared in Example 1, this example adopts Figure 1 The device shown is used to perform the following tests:

[0044] 500 mg of the hyperbranched Pickering microsphere adsorbent sample prepared in Example 1 was added to a U-shaped tube with an outer diameter of 1 cm and an inner diameter of 0.6 cm, supported by quartz wool, and connected to the injection port of a gas chromatograph. The overall experimental device is as follows: Figure 1 Before the CO2 adsorption analysis, the sample was degassed with 50 mL / min nitrogen at 130°C for 1.5 h, then cooled to the test temperature, and the nitrogen was replaced with a mixed gas of 15 vol.% CO2 / 85 vol.% N2, with the total flow rate controlled at 20 mL / min.

[0045] The loaded adsorbent material was subjected to dynamic adsorption evaluation at different temperatures. The temperature was lowered to 30, 40, 50, 60, 70, 80, 90, and 100°C, the humidity was kept at 50%, and the breakthrough curve of CO2 was measured to calculate the adsorption capacity of the hyperbranched Pickering microsphere adsorbent for CO2 adsorption at different temperatures. The results showed that the optimal adsorption capacity was achieved at 50°C.

[0046] The above-mentioned loaded adsorbent material was subjected to dynamic adsorption evaluation under different relative humidity. Water vapor was introduced into 15% vol. CO2 / 85% vol. N2 carrier gas, and the humidity was set to 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, respectively. The temperature was kept at 50°C, the relative humidity of the gas was adjusted, and the CO2 breakthrough curve was measured to calculate the adsorption capacity of the hyperbranched Pickering microsphere adsorbent for CO2 adsorption under different relative humidity. The results showed that the adsorption capacity was higher and the difference was not large when the humidity was 50%-100%.

[0047] The CO2 adsorption and desorption cycle performance of the adsorbent was evaluated by performing 40 cycles of CO2 adsorption and desorption on the loaded adsorbent material. CO2 adsorption was performed at 75°C from a 15 vol.% CO2 / 85 vol.% N2 mixture at 60 mL / min. CO2 desorption was performed at 130°C using 100 mL / min N2. Figure 2 The change of CO2 adsorption during 40 cycles of CO2 adsorption and desorption. The decomposition and volatilization of the active components of the adsorbent and the incomplete desorption of CO2 during the adsorption and desorption process will reduce the adsorption active sites in the adsorbent, thereby slightly reducing the carbon dioxide adsorption. After 40 cycles of CO2 adsorption-desorption, there is still a high CO2 adsorption capacity, indicating that the adsorbent has relatively good stability.

[0048] In summary, the hyperbranched Pickering microsphere adsorbent for CO2 adsorption prepared by the present invention has the advantages of high stability, excellent adsorption performance, fast adsorption rate and the ability to reduce desorption energy consumption, and shows good reusability, and can be applied to large-scale CO2 capture projects.

[0049] Finally, it should be noted that the above is only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred arrangement scheme, a person skilled in the art should understand that the technical solution of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for preparing a hyperbranched Pickering microsphere adsorbent, characterized in that: The preparation method comprises the following steps: (1) First, 1-dodecanol, azobisbutyronitrile, toluene, 2-(diethylamino)ethyl methacrylate and divinylbenzene are weighed in a test tube, mixed by vortex, referred to as solution A, and nitrogen is continuously introduced into solution A; then, silicon balls and pure water are mixed in a test tube, and ultrasonic treatment is performed for 1-2 minutes, referred to as solution B; solution A is added to solution B, and slurry treatment is performed to obtain a Pickering emulsion; the Pickering emulsion is placed in a water bath at 60-80° C. for polymerization reaction for 20-24 hours; after the reaction is completed, the composite material obtained by filtration is soaked in an acidic solution, then filtered and the composite material is washed with deionized water until neutral; methanol is used as an extraction solvent, and Soxhlet extraction is performed for 10-15 hours to remove unreacted impurities in the composite material, thereby obtaining a Pickering microsphere material; (2) dispersing the mixture of the Pickering microsphere material and the epoxy silane coupling agent obtained in step (1) in anhydrous toluene, refluxing at 100 to 140° C. for 4 to 8 hours under inert gas protection, filtering, washing the obtained precipitate with anhydrous toluene and ethanol, and drying to obtain epoxy-modified Pickering microspheres; (3) dissolving polyethyleneimine in a methanol / water mixture, adding the epoxy-modified Pickering microspheres obtained in step (2), and then reflux reacting at 60-100° C. for 4-8 hours. After evaporating the solvent, amino-modified Pickering microspheres are obtained, which are the hyperbranched Pickering microsphere adsorbent.

2. The method for preparing the hyperbranched Pickering microsphere adsorbent according to claim 1, characterized in that: In step (1), the acidic solution includes HCl aqueous solution, HF aqueous solution and HNO3 aqueous solution.

3. The method for preparing the hyperbranched Pickering microsphere adsorbent according to claim 1, characterized in that: In step (1), the conditions for the homogenization treatment include: the speed of the homogenizer is 4000-6000 rpm, and the stirring time is 1-3 min.

4. The method for preparing the hyperbranched Pickering microsphere adsorbent according to claim 1, characterized in that: In step (2), the epoxysilane coupling agent is a mixture of any one or more of 2-(3,4-epoxycyclohexane)ethyltriethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, and 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane.

5. The method for preparing the hyperbranched Pickering microsphere adsorbent according to claim 1, characterized in that: In step (2), the inert gas includes nitrogen, argon and helium.

6. The method for preparing the hyperbranched Pickering microsphere adsorbent according to claim 1, characterized in that: In step (3), the polyethyleneimine is any one of chain or branched polyethyleneimines with molecular weights of 10,000, 25,000, 70,000 and 700,000, or a mixture of two or more thereof.

7. The method for preparing the hyperbranched Pickering microsphere adsorbent according to claim 1, characterized in that: In step (3), the volume ratio of methanol to water in the methanol / water mixture is 1:5 to 5:

1.

8. A hyperbranched Pickering microsphere adsorbent prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the hyperbranched Pickering microsphere adsorbent according to claim 8 in adsorbing / capturing CO2 in flue gas or air.

10. The use according to claim 9, characterized in that: After 20 to 100 adsorption-desorption cycles, the CO2 adsorption capacity of the hyperbranched Pickering microsphere adsorbent decreases within 5%.

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