Ultrasonic rotary microreactor for preparing porous polystyrene-based microspheres and preparation method of porous polystyrene-based microspheres

Abstract

The invention belongs to the technical field of preparation of porous polystyrene-based microspheres, and discloses an ultrasonic rotary microreactor for preparing the porous polystyrene-based microspheres and a preparation method of the porous polystyrene-based microspheres. The ultrasonic rotary micro-reactor comprises an ultrasonic probe, a spiral micro-reaction tank, a spiral stirrer and a temperature control part, and the ultrasonic probe inputs ultrasonic waves into the spiral micro-reaction tank so as to strengthen the mixing of all preparation raw materials; the spiral micro reaction tank is used for providing a reaction space; the spiral stirrer is arranged in the spiral micro reaction tank and is used for strengthening mass transfer among the preparation raw materials and avoiding agglomeration and secondary nucleation of the porous polystyrene microspheres; and the temperature control component is in communication connection with the spiral micro reaction tank so as to control the reaction temperature in the spiral micro reaction tank. The ultrasonic rotary microreactor disclosed by the invention can be used for efficiently and controllably preparing the porous polystyrene-based microspheres which are controllable in pore channel number, uniform in size and good in monodispersity.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of porous polystyrene-based microspheres, and particularly to an ultrasonic rotary microreactor for the preparation of porous polystyrene-based microspheres and a preparation method of porous polystyrene-based microspheres. Background Art

[0002] Compared with traditional solid particle materials, porous particle materials have been successively developed and widely used in fields such as catalytic reactions, biomedicine, adsorption separation, and tissue regeneration in the past two decades due to their large specific surface area, adjustable pore structure, and high mass transfer efficiency. Various synthetic porous polymer materials, such as polystyrene-based, polyacrylamide-based, polyacrylate-based, and polyacrylonitrile-based materials, have been developed. Among them, porous polystyrene microspheres have received increasing attention due to their good mechanical strength, chemical stability, and compatibility with polar and non-polar organic solvents. Therefore, how to prepare porous polystyrene microspheres with uniform particle size and good dispersibility, and the exploration of their preparation methods and conditions has become a hot research topic in the polymer field.

[0003] In the prior art, the current preparation methods of porous polystyrene microspheres mainly adopt the traditional preparation methods of porous particle materials, namely, mainly the hard template method, the soft template method, and the self-template method. Among them, the hard template method usually first prepares a hard template with a specific shape by using a hard template preparation device, and then selectively modifies / coats the target material on the hard template; then, through a calcination device, a dissolution device, or a chemical etching device, the template is selectively removed to obtain a porous structure. However, this method requires the use of a variety of devices for a complex template removal process, with cumbersome preparation steps, time-consuming and laborious, and a relatively high preparation cost. The soft template method includes emulsion templates, micelle templates, and electrospray. Although this method does not require a complex template removal process, it requires the use of special equipment for preparation, and also requires an additional calcination device or heat treatment device to remove the template, and the size distribution of the prepared porous particle materials is often relatively wide. Compared with the hard template method and the soft template method, all the materials used in the self-template method for preparing porous materials come from the template, so the self-template method often does not require the use of additional equipment to remove the templating agent, with a relatively simple preparation process, narrow particle size distribution, and low cost. However, the synthesis process of the self-template method usually depends on specific formulations and conditions, with too many limitations and difficult to be popularized for large-scale use.

[0004] To solve the above technical problems, those skilled in the art proposed to use the three-phase emulsion system technology to prepare porous polystyrene microspheres. At present, the main preparation device for the three-phase emulsion system technology is an intermittent stirrer. However, it is difficult for the intermittent stirrer to effectively control the structure of the porous polystyrene microspheres, resulting in problems such as uncontrollable pore channels and uneven particle sizes in the prepared porous polystyrene microspheres. Moreover, the preparation using the intermittent stirrer takes a long time and is difficult to promote the large-scale preparation and use of porous particulate materials. In response to this, those skilled in the art further proposed that ultrasound can be added to strengthen the dispersion and mixing of reaction raw materials, thereby strengthening mass transfer and improving the problems of uncontrollable pore channels and uneven particle sizes in porous polystyrene microspheres. However, currently, ultrasonic mixing is mainly directly carried out through an ultrasonic cleaning instrument and then transferred to a round-bottom flask to start the reaction at a certain rotation speed. Due to the inconsistent energy of the ultrasonic cleaning instrument at different positions, the size distribution of the prepared porous polystyrene microspheres is wide, making it difficult to meet some high-precision applications downstream. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides an ultrasonic rotary microreactor for preparing porous polystyrene-based microspheres and a method for preparing porous polystyrene-based microspheres.

[0006] The ultrasonic rotary microreactor for preparing porous polystyrene-based microspheres and the method for preparing porous polystyrene-based microspheres of the present invention are realized through the following technical solutions:

[0007] Considering that the downstream applications of porous polystyrene microspheres all depend on the pore structure parameters, the control of the pore structure parameters is particularly important during the reaction process. However, it is often difficult to achieve the regulation of pore parameters in traditional preparation processes. Therefore, the present invention provides an ultrasonic rotary microreactor for preparing porous polystyrene-based microspheres, and the ultrasonic rotary microreactor for preparing porous polystyrene-based microspheres of the present invention includes an ultrasonic probe, a spiral microreaction tank, a spiral stirrer, and a temperature control component.

[0008] In the present invention, the ultrasonic probe is used to input ultrasonic energy into the spiral microreaction tank to strengthen the mixing of the respective preparation raw materials corresponding to the aqueous phase, oil phase, and solid phase for the preparation of the porous polystyrene-based microspheres.

[0009] In the present invention, the spiral microreaction tank is used to receive the respective preparation raw materials of the porous polystyrene microspheres and provide a reaction space for the reaction of the respective preparation raw materials of the porous polystyrene microspheres.

[0010] In the present invention, the spiral stirrer is disposed inside the spiral micro-reaction tank, and is used to enhance the mass transfer between the various preparation raw materials corresponding to the aqueous phase, oil phase and solid phase for the preparation of the porous polystyrene microspheres, while avoiding the agglomeration and secondary nucleation of the porous polystyrene microspheres.

[0011] In the present invention, the temperature control component is connected to the spiral micro-reaction tank and is used to regulate the reaction temperature inside the spiral micro-reaction tank.

[0012] In some preferred embodiments of the present invention, the ultrasonic probe is vertically disposed inside the spiral micro-reaction tank, and the spiral stirrer, the ultrasonic probe and the spiral micro-reaction tank are coaxially disposed, so that the ultrasonic action applied by the ultrasonic probe can be fully superimposed with the spiral stirring action applied by the spiral stirrer, jointly promoting the pore-forming efficiency and effect of the oil-phase pore former on the polystyrene microspheres, and enabling the formation of porous polystyrene microspheres with uniform pores.

[0013] In some preferred embodiments of the present invention, the ultrasonic rotary micro-reactor further includes a control unit, and the control unit is respectively communicatively connected to the ultrasonic probe, the spiral stirrer and the temperature control component.

[0014] In some preferred embodiments of the present invention, the temperature control component includes a temperature detection unit and a heating unit; wherein, the temperature detection unit is communicatively connected to the control unit for real-time monitoring of the reaction temperature inside the spiral micro-reaction tank and transmitting the monitored reaction temperature signal to the control unit; the heating unit is communicatively connected to the control unit, so that the control unit can start or stop the heating treatment of the spiral micro-reaction tank by the heating unit according to the magnitude of the reaction temperature inside the spiral micro-reaction tank transmitted by the temperature detection unit, until the reaction temperature inside the spiral micro-reaction tank reaches the target temperature.

[0015] In some preferred embodiments of the present invention, the temperature control component is a constant temperature water bath.

[0016] The present invention also provides a method for preparing the above-mentioned porous polystyrene-based microspheres. The porous polystyrene-based microspheres are prepared by the above-mentioned ultrasonic rotary micro-reactor, and the preparation steps are as follows:

[0017] Step 1, mixing the solid phase and the aqueous phase:

[0018] According to the required ratio, add the polystyrene microsphere seeds and the liquid phase solvent into the spiral micro-reaction tank to obtain a first mixture; perform ultrasonic treatment on the first mixture in the spiral micro-reaction tank through the ultrasonic probe, so that the polystyrene microsphere seeds and the liquid phase solvent are mixed more uniformly by the introduction of active ultrasonic waves, forming a uniform milky white emulsion.

[0019] Step 2, uniformly mix the three-phase system:

[0020] Add an oil-phase porogen to the milky white emulsion to obtain a second mixture; perform ultrasonic treatment on the second mixture through the ultrasonic probe, so that the introduced oil-phase porogen can be more uniformly dispersed by the introduction of active ultrasonic waves, and obtain a third mixture with a uniformly mixed three-phase system, so as to prepare for the subsequent occupation of the position of the liquid-phase solvent by the oil-phase porogen.

[0021] Step 3, form a porous structure:

[0022] Perform ultrasonic treatment on the third mixture through the ultrasonic probe, and at the same time apply spiral stirring treatment to the third mixture through the spiral stirrer. Under the combined action of spiral stirring and ultrasonic waves, the oil-phase porogen makes the polystyrene microspheres form a porous structure, and obtain a fourth mixture.

[0023] Step 4, post-treatment:

[0024] Heat the fourth mixture through the temperature control component to volatilize the liquid-phase solvent and the oil-phase porogen, and obtain a finished product of porous polystyrene microspheres.

[0025] Use the finished product of the porous polystyrene microspheres as the porous polystyrene-based microspheres, or continue with Step 5.

[0026] Step 5, load noble metals:

[0027] Use the finished product of the porous polystyrene microspheres as a carrier, use a noble metal salt as a loading source, mix the noble metal salt, the finished product of the porous polystyrene microspheres and a reducing agent in a solution to obtain a precursor solution; control the spiral stirrer to apply spiral stirring treatment to the precursor solution, and at the same time heat the precursor solution through the temperature control component, so that the noble metal salt is reduced to noble metal single atoms under the action of the reducing agent, and obtain porous polystyrene microspheres loaded with noble metal single atoms, and use the porous polystyrene microspheres loaded with noble metal single atoms as the porous polystyrene-based microspheres.

[0028] In the above Step 1, it should be noted that in some more preferred embodiments of the present invention, the liquid-phase solvent is a mixed solvent of water and ethanol mixed at a volume ratio of 0.6 to 0.8:1, so as to ensure that the liquid-phase solvent used has good dispersibility for the polystyrene microsphere seeds.

[0029] In some more preferred embodiments of the present invention, the mass ratio of the polystyrene microsphere seeds to the liquid-phase solvent is 0.8 to 1.2:100, so as to achieve the effects of uniformly dispersing the polystyrene microspheres, regulating the pore structure and the number of pores.

[0030] In some more preferred embodiments of the present invention, when the first mixture in the spiral microreactor is ultrasonically treated, the power of the ultrasonic treatment is 5 W to 20 W, and the ultrasonic treatment is continued until a uniform milky white emulsion is formed.

[0031] In some more preferred embodiments of the present invention, the polystyrene microsphere seeds used in the present invention are polystyrene microsphere seeds prepared by dispersion polymerization, so that the size distribution of the polystyrene microsphere seeds used in the present invention is narrow, the coefficient of variation is less than 5%, and the monodispersity is good. The specific steps for preparing polystyrene microsphere seeds by dispersion polymerization are as follows:

[0032] (1) Ammonium persulfate and polyvinylpyrrolidone are mixed, deionized water and ethanol are added, and the mixture is ultrasonically mixed evenly to obtain a mixed solution. Among them, the mass ratio of ammonium persulfate to polyvinylpyrrolidone is 1:0.08 to 0.12, the dosage ratio of deionized water to polyvinylpyrrolidone is 3 mL:0.08 g to 0.12 g, and the dosage ratio of ethanol to polyvinylpyrrolidone is 25 mL:0.08 g to 0.12 g.

[0033] (2) Styrene monomer is added to the mixed solution, and the mixture is stirred at a stirring rate of 300 r / min to 500 r / min for 5 min to 15 min, and then heated to 65°C to 75°C under stirring, and stirred and reacted at 65°C to 75°C for 4 h to 8 h.

[0034] (3) The reaction solution after the above stirring reaction is treated in an ice bath for 20 min to 40 min to quench the reaction.

[0035] (4) The reaction solution after the quenching reaction is centrifugally washed 4 times with ethanol as the washing solution. The rotation speed of each centrifugation is 5000 r / min to 7000 r / min, and the centrifugation time is 5 min to 10 min.

[0036] (5) After the centrifugation product in the above step (4) is spread flat in a petri dish, it is placed in an oven at 40°C to 50°C and dried for 8 h to 16 h to obtain white powder polystyrene seeds.

[0037] In step 2 above, it should be noted that in some more preferred embodiments of the present invention, the oil-phase pore-forming agent is any one of mesitylene, toluene, n-hexane, and cyclohexane, so that the oil-phase pore-forming agent used in the present invention has the advantages of rapid mass transfer and easy volatilization, and can effectively achieve the function of adsorption pore formation.

[0038] In some more preferred embodiments of the present invention, when preparing the second mixture, 70 mL to 80 mL of the oil-phase pore-forming agent is added to each 1 L of the milky white emulsion.

[0039] In some more preferred embodiments of the present invention, when ultrasonic treatment is performed on the second mixture, the power of the ultrasonic treatment is 5 W to 20 W, and the ultrasonic time is 2 min to 5 min.

[0040] In step 3 above, it should be noted that in the present invention, by simultaneously performing ultrasonic treatment and spiral stirring treatment, under the combined action of spiral stirring and ultrasonic treatment, the mass transfer effect of the three-phase system is further improved, so that the oil-phase pore former gradually occupies the position of the liquid-phase solvent and continuously adsorbs on the surface of the polystyrene microspheres. Subsequently, the oil-phase pore former continuously penetrates through the surface of the polystyrene microspheres, causing the polystyrene microspheres to form a porous structure, that is, transforming the polystyrene microspheres into porous polystyrene microspheres, thereby realizing the stable, batch, and controllable and efficient preparation of high-quality, size-uniform, and well-monodisperse porous polystyrene microspheres.

[0041] In some more preferred embodiments of the present invention, when ultrasonic treatment and spiral stirring treatment are simultaneously performed on the third mixture, the power of the ultrasonic treatment is 5 W to 20 W, the stirring rate of the spiral stirring treatment is 300 rpm to 500 rpm, and the treatment time is 2 min to 10 min.

[0042] In some more preferred embodiments of the present invention, the heating temperature is room temperature to 35 °C.

[0043] In step 5 above, the porous polystyrene microspheres loaded with noble metals are specifically prepared through the following steps:

[0044] S1, preparing a porous polystyrene microsphere dispersion:

[0045] Disperse the finished porous polystyrene microspheres into a dispersion solvent to obtain a porous polystyrene microsphere dispersion.

[0046] S2, adding a reducing agent and a noble metal salt:

[0047] Add a reducing agent and a noble metal salt to the porous polystyrene microsphere dispersion in sequence to obtain a precursor solution.

[0048] S3, heating and spiral stirring treatment:

[0049] Control the spiral stirrer to apply spiral stirring treatment to the precursor solution, and at the same time heat the precursor solution through the temperature control component. After heating, perform an ice bath quenching reaction, centrifuge, wash, and dry to obtain the porous polystyrene microspheres loaded with noble metals.

[0050] Among them, the dispersion solvent is a mixed solvent of water and ethanol mixed in a volume ratio of 1:4 to 6 to achieve the effects of uniform dispersion of polystyrene microspheres, regulation of pore structure and number.

[0051] In some more preferred embodiments of the present invention, 20 mg to 60 mg of the finished porous polystyrene microspheres are added to every 6 mL of the dispersion solvent to ensure that the added polystyrene microspheres can be evenly dispersed in the dispersion solvent while avoiding the critical micelle value being reached due to excessive addition of the finished porous polystyrene microspheres, thereby generating excess micelles.

[0052] In some more preferred embodiments of the present invention, the reducing agent is polyvinyl pyrrolidone; and the molar ratio of the reducing agent to the noble metal salt is 1 to 2:1, so that polyvinyl pyrrolidone can not only reduce the noble metal salt to a noble metal element, but also ensure the stability of the microspheres.

[0053] In some more preferred embodiments of the present invention, the added amount of the precious metal salt is 20wt% to 30wt% of the mass of the porous polystyrene microsphere finished product, so that the precious metal components provided by the added precious metal salt can be evenly loaded on the surface of the porous polystyrene microsphere finished product, while not affecting the performance of the porous polystyrene microsphere finished product itself due to excessive addition, and avoiding cost increases.

[0054] In some more preferred embodiments of the present invention, the noble metal salt is one or more of a soluble Ag salt, a soluble Pt salt, a soluble Pd salt and a soluble Au salt.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] The ultrasonic rotary microreactor for preparing porous polystyrene-based microspheres of the present invention comprises an ultrasonic probe, a spiral microreactor, a spiral agitator and a temperature control component. The ultrasonic probe is used to input ultrasonic energy into the spiral microreactor to strengthen the mixing of the various preparation raw materials of the water phase, oil phase and solid phase for preparing the porous polystyrene-based microspheres. The spiral microreactor is used to receive the various preparation raw materials of the porous polystyrene microspheres and provide a reaction space for the reaction of the various preparation raw materials of the porous polystyrene microspheres. The spiral agitator is arranged in the spiral microreactor to strengthen the mass transfer between the various preparation raw materials of the water phase, oil phase and solid phase for preparing the porous polystyrene-based microspheres, while avoiding the agglomeration and secondary nucleation of the porous polystyrene microspheres. The temperature control component is connected to the spiral microreactor in communication to control the reaction temperature in the spiral microreactor.

[0057] Porous polystyrene microspheres were successfully prepared by the ultrasonic rotary microreactor of the present invention, and the pore structure of the porous polystyrene microspheres can be controllably adjusted by regulating the ultrasonic power, which shows that the ultrasonic rotary microreactor of the present invention can achieve efficient and controllable preparation of porous polystyrene microspheres with controllable pore number, uniform size and good monodispersity.

[0058] The ultrasonic rotary microreactor of the present invention has also successfully prepared porous polystyrene microspheres loaded with noble metals, and the prepared porous polystyrene microspheres loaded with noble metals have a micron or even nanoscale. They can not only be used as a confinement reactor for catalytic reactions, but also can be used as a catalyst to catalyze the nitroamination reduction reaction and the electrocatalytic reaction of methanol oxidation. Brief Description of the Drawings

[0059] Figure 1 It is a schematic structural diagram of the ultrasonic rotary microreactor of the present invention.

[0060] Figure 2 It is a scanning electron microscope image of the porous polystyrene microsphere finished product obtained in Example 2.

[0061] Figure 3 It is a scanning electron microscope image of the porous polystyrene microsphere finished product obtained in Example 3.

[0062] Figure 4 It is the test result of the microscopic morphology of the Ag-loaded porous polystyrene microspheres in Example 4. Figure 4 Among them, Figure (a) is a scanning electron microscope image of the Ag-loaded porous polystyrene microspheres in Example 4, Figure (b) is a transmission electron microscope image of the Ag-loaded porous polystyrene microspheres in Example 4 at a scale of 2 μm, Figure (c) is a transmission electron microscope image of the Ag-loaded porous polystyrene microspheres in Example 4 at a scale of 1 μm, Figure (d) is a transmission electron microscope image of another area of the Ag-loaded porous polystyrene microspheres in Example 4 at a scale of 2 μm, Figure (e) is a transmission electron microscope image of another area of the Ag-loaded porous polystyrene microspheres in Example 4 at a scale of 1 μm, and Figure (f) is a transmission electron microscope image of the Ag-loaded porous polystyrene microspheres in Example 4 at a scale of 500 nm.

[0063] Figure 5 It is a reaction schematic diagram of the catalytic reduction reaction of 4-nitrophenol.

[0064] Figure 6 It is a color change diagram of the reaction solution during the catalytic reduction reaction of 4-nitrophenol.

[0065] Figure 7 It is a full-spectrum ultraviolet absorption spectrum diagram showing the change with time during the catalytic reduction reaction of 4-nitrophenol by the Ag-loaded porous polystyrene microspheres in Example 4.

[0066] Figure 8 It is a diagram showing the change of the reaction rate with time during the catalytic reduction reaction of 4-nitrophenol by the Ag-loaded porous polystyrene microspheres in Example 4.

[0067] Figure 9 Conversion rate change graph of the Ag-loaded porous polystyrene microspheres in Example 4 after 7 cycles of catalytic reduction of 4-nitrophenol. Detailed implementation manners

[0068] The technical solutions in the embodiments of the present invention will be clearly and completely described below. It should be noted that in the following various embodiments of the present invention, the polystyrene microsphere seeds used are the polystyrene microsphere seeds prepared by dispersion polymerization, so that the size distribution of the polystyrene microsphere seeds used in the present invention is narrow, the coefficient of variation is less than 5%, and the monodispersity is good. The specific steps for preparing polystyrene microsphere seeds by dispersion polymerization are as follows:

[0069] (1) Ammonium persulfate and polyvinylpyrrolidone are mixed, deionized water and ethanol are added, and ultrasonic mixing is carried out to obtain a uniform mixed solution. Among them, the mass ratio of ammonium persulfate to polyvinylpyrrolidone is 1:0.1, the dosage ratio of the deionized water to polyvinylpyrrolidone is 3 mL:0.01 g, and the dosage ratio of ethanol to polyvinylpyrrolidone is 25 mL:0.01 g.

[0070] (2) Styrene monomer is added to the mixed solution, and the mixture is stirred at a stirring rate of 400 r / min for 10 min, and then heated to 70 °C under stirring and stirred at 70 °C for 6 h.

[0071] (3) The reaction solution after the above stirring reaction is treated in an ice bath for 0.5 h to quench the reaction.

[0072] (4) The reaction solution after the quenching reaction is centrifugally washed 4 times with ethanol as the washing solution, and the rotation speed of each centrifugation is 6000 r / min, and the centrifugation time is 5 min to 10 min.

[0073] (5) After the centrifugation product in the above step (4) is spread flat in a petri dish, it is placed in an oven at 45 °C and dried for 12 h to obtain white powder polystyrene seeds.

[0074] Example 1

[0075] Please refer to Figure 1 , this embodiment provides an ultrasonic rotary microreactor, including an ultrasonic probe 1, a spiral microreaction tank 2, a spiral stirrer 3 and a temperature control component 4.

[0076] In this embodiment, the ultrasonic probe 1 is used to input ultrasonic energy into the spiral microreaction tank 2 to strengthen the mixing of the respective preparation raw materials corresponding to the aqueous phase, oil phase and solid phase for the preparation of the porous polystyrene-based microspheres.

[0077] The spiral microreactor 2 is used to receive each preparation raw material of the porous polystyrene microspheres and provide a reaction space for the reaction of each preparation raw material of the porous polystyrene microspheres.

[0078] In this embodiment, the spiral stirrer 3 is arranged in the spiral microreactor 2 and is used to strengthen the mass transfer between the respective preparation raw materials corresponding to the aqueous phase, oil phase and solid phase for the preparation of the porous polystyrene-based microspheres, and at the same time avoid the aggregation and secondary nucleation of the porous polystyrene microspheres.

[0079] The temperature control component 4 is communicatively connected to the spiral microreactor 2 to control the reaction temperature in the spiral microreactor 2.

[0080] The ultrasonic rotary microreactor of this embodiment further includes a control unit, and the control unit is communicatively connected to the ultrasonic probe 1, the spiral microreactor 2, the spiral stirrer 3 and the temperature control component 4 respectively.

[0081] In this embodiment, the temperature control component 4 includes a temperature detection unit and a heating unit; wherein, the temperature detection unit is used to monitor the reaction temperature in the spiral microreactor 2 in real time; the heating unit is used to heat the spiral microreactor 2.

[0082] Example 2

[0083] This embodiment provides a preparation method for preparing porous polystyrene microspheres based on the ultrasonic rotary microreactor of Example 1, including the following steps:

[0084] Step 1, mixing the solid phase and the aqueous phase:

[0085] 1.1) Using polystyrene microspheres as seeds for synthesizing porous polystyrene microspheres, and using a mixed solvent of water and ethanol mixed at a volume ratio of 0.7:1 as the liquid phase solvent.

[0086] 1.2) According to the mass ratio of polystyrene microsphere seeds to water of 1:100, add the polystyrene microsphere seeds and the liquid phase solvent into the spiral microreactor 2 to obtain a first mixture.

[0087] 1.3) Ultrasonically treat the first mixture in the spiral microreactor 2 through the ultrasonic probe 1, and control the ultrasonic power of the ultrasonic treatment to be 10 W, so as to make the polystyrene microsphere seeds and the liquid phase solvent mix more evenly by introducing active ultrasonic waves, and ultrasonically treat until a uniform milky white emulsion is formed.

[0088] Step 2, mixing the three-phase system evenly:

[0089] 2.1) Using mesitylene as the oil-phase pore-forming agent, add the corresponding mass of the oil-phase pore-forming agent to the milky white emulsion according to the oil-phase pore-forming agent being 20 wt% - 30 wt% of the mass of the polystyrene microsphere seeds, to obtain a second mixture.

[0090] 2.2) Ultrasonically treat the second mixture with an ultrasonic probe 1, control the ultrasonic treatment power to be 10 W, so that the introduced oil-phase pore-forming agent can be dispersed more uniformly by the introduction of active ultrasonic waves, to obtain a third mixture with a uniformly mixed three-phase system, in preparation for the subsequent oil-phase pore-forming agent to occupy the position of the liquid-phase solvent.

[0091] Step 3, forming a porous structure:

[0092] Ultrasonically treat the third mixture with an ultrasonic probe 1, control the ultrasonic treatment parameters to be 10 W, and at the same time apply a spiral stirring treatment to the third mixture with a spiral stirrer 3, control the stirring speed of the spiral stirring treatment to be 400 rpm, so that under the combined action of rotation and ultrasonic waves, treat for 2 mins, further improve the mass transfer effect of the three-phase system, strengthen the mass transfer from the mesitylene oil droplets to the polystyrene microspheres, make the oil-phase pore-forming agent gradually occupy the position of the liquid-phase solvent and continuously adsorb on the surface of the polystyrene microspheres, and then the oil-phase pore-forming agent continuously passes through the surface of the polystyrene microspheres, making the polystyrene microspheres form a porous structure, that is, turning the polystyrene microspheres into porous polystyrene microspheres. At the same time, the rotating spiral reactor can prevent the secondary nucleation of the polystyrene microspheres, to obtain a fourth mixture.

[0093] Step 4, post-treatment:

[0094] Using a constant temperature water bath as the temperature control component 4, control the temperature of the constant temperature water bath to be 26 °C, to heat the fourth mixture, so that the liquid-phase solvent and the oil-phase pore-forming agent volatilize, to obtain the finished product of the porous polystyrene microspheres.

[0095] The present invention performs a scanning electron microscope test on the finished product of the porous polystyrene microspheres obtained in this example, and the test results are as Figure 2 shown, and it can be seen from Figure 2 that the porous polystyrene microspheres successfully prepared by the ultrasonic rotary microreactor of the present invention, but the number and diameter of the pores on the surface of the porous polystyrene microspheres obtained in this example are both very small, and there are some micelles with incomplete microreactions on the surface.

[0096] Example 3

[0097] This example provides a preparation method for preparing porous polystyrene microspheres based on the ultrasonic rotary microreactor of Example 1, including the following steps:

[0098] Step 1, mixing the solid phase and the aqueous phase:

[0099] 1.1) Using styrene microspheres as seeds and a mixed solvent of water and ethanol mixed at a volume ratio of 0.625:1 as the liquid-phase solvent.

[0100] 1.2) According to the mass ratio of polystyrene microsphere seeds to water of 1:100, add the polystyrene microsphere seeds and the liquid-phase solvent to the spiral micro-reaction tank 2 to obtain a first mixture.

[0101] 1.3) Use the ultrasonic probe 1 to perform ultrasonic treatment on the first mixture in the spiral micro-reaction tank 2, control the ultrasonic treatment parameters at 10W, so as to make the mixing of the polystyrene microsphere seeds and the liquid-phase solvent more uniform by introducing active ultrasonic waves, and ultrasonic until a uniform milky white emulsion is formed.

[0102] Step 2, mix the three-phase system evenly:

[0103] 2.1) Using mesitylene as the oil-phase pore-forming agent, according to the oil-phase pore-forming agent being 25wt% of the mass of the polystyrene microsphere seeds, add the corresponding mass of the oil-phase pore-forming agent to the milky white emulsion to obtain a second mixture.

[0104] 2.2) Use the ultrasonic probe 1 to perform ultrasonic treatment on the second mixture, control the ultrasonic treatment power at 10W, so as to make the introduced oil-phase pore-forming agent disperse more uniformly by introducing active ultrasonic waves, and obtain a third mixture with a uniformly mixed three-phase system, in order to prepare for the subsequent oil-phase pore-forming agent to occupy the position of the liquid-phase solvent.

[0105] Step 3, form a porous structure:

[0106] Use the ultrasonic probe 1 to perform ultrasonic treatment on the third mixture, control the ultrasonic treatment power at 10W, and at the same time apply spiral stirring treatment to the third mixture through the spiral stirrer 3, control the stirring speed of the spiral stirring treatment at 400rpm, so as to under the combined action of rotation and ultrasonic waves, treat for 6 minutes, further improve the mass transfer effect of the three-phase system, strengthen the mass transfer from the mesitylene oil droplets to the polystyrene microspheres, make the oil-phase pore-forming agent gradually occupy the position of the liquid-phase solvent and continuously adsorb on the surface of the polystyrene microspheres, and then the oil-phase pore-forming agent continuously passes through the surface of the polystyrene microspheres, making the polystyrene microspheres form a porous structure, that is, turning the polystyrene microspheres into porous polystyrene microspheres. At the same time, the rotating spiral reactor can prevent the secondary nucleation of the polystyrene microspheres to obtain a fourth mixture.

[0107] Step 4, post-treatment:

[0108] Using a constant temperature water bath as the temperature control component 4, control the temperature of the constant temperature water bath at 26°C to heat the fourth mixture to volatilize the liquid-phase solvent and the oil-phase pore-forming agent to obtain the finished product of the porous polystyrene microspheres.

[0109] The present invention conducts a scanning electron microscope test on the finished product of the porous polystyrene microspheres obtained in this embodiment, and the test results are as Figure 3 shown. It can be seen from Figure 3 that the porous polystyrene microspheres are successfully prepared by the ultrasonic rotary microreactor of the present invention. Compared with Example 2, in this embodiment, due to the increase in the combined action time of spiral stirring and ultrasonic waves, the number and diameter of the pores on the surface of the porous polystyrene microspheres obtained in this embodiment are both increasing. This indicates that the present invention can regulate the pore structure of the porous polystyrene microspheres by controlling the combined action time of spiral stirring and ultrasonic waves.

[0110] Example 4

[0111] This embodiment provides a preparation method for preparing porous polystyrene microspheres loaded with noble metals based on the ultrasonic rotary microreactor of Example 1, including the following steps:

[0112] Step 1, mixing the solid phase and the aqueous phase:

[0113] 1.1) Using styrene microspheres as seeds and a mixed solvent of water and ethanol mixed at a volume ratio of 0.625:1 as the liquid phase solvent.

[0114] 1.2) According to the mass ratio of polystyrene microsphere seeds to water of 1:100, adding the polystyrene microsphere seeds and the liquid phase solvent into the spiral microreaction tank 2 to obtain a first mixture.

[0115] 1.3) Ultrasonically treating the first mixture in the spiral microreaction tank 2 through the ultrasonic probe 1, controlling the ultrasonic treatment parameters at 10 W, so that the polystyrene microsphere seeds and the liquid phase solvent are mixed more uniformly by the introduction of active ultrasonic waves, and ultrasonicating until a uniform milky white emulsion is formed.

[0116] Step 2, mixing the three-phase system uniformly:

[0117] 2.1) Using mesitylene as the oil-phase porogen, according to the ratio of adding 75 mL of the oil-phase porogen per 1 L of the milky white emulsion, adding the corresponding mass of the oil-phase porogen to the milky white emulsion to obtain a second mixture.

[0118] 2.2) Ultrasonically treating the second mixture through the ultrasonic probe 1, controlling the ultrasonic treatment power at 10 W, so that the introduced oil-phase porogen can be dispersed more uniformly by the introduction of active ultrasonic waves, obtaining a third mixture with a uniformly mixed three-phase system, in order to prepare for the subsequent occupation of the position of the liquid phase solvent by the oil-phase porogen.

[0119] Step 3, forming a porous structure:

[0120] The third mixture is ultrasonically treated by the ultrasonic probe 1, and the ultrasonic treatment power is controlled to be 10 W. At the same time, the third mixture is subjected to spiral stirring treatment by the spiral stirrer 3, and the stirring speed of the spiral stirring treatment is controlled to be 400 rpm. Under the combined action of rotation and ultrasound, it is treated for 6 min to further improve the mass transfer effect of the three-phase system, which is used to strengthen the mass transfer from the mesitylene oil droplets to the polystyrene microspheres, so that the oil-phase pore-forming agent gradually occupies the position of the liquid-phase solvent and continuously adsorbs on the surface of the polystyrene microspheres. Subsequently, the oil-phase pore-forming agent continuously penetrates through the surface of the polystyrene microspheres, causing the polystyrene microspheres to form a porous structure, that is, the polystyrene microspheres are transformed into porous polystyrene microspheres. At the same time, the rotating spiral reactor can prevent the secondary nucleation of the polystyrene microspheres, and a fourth mixture is obtained.

[0121] Step 4, post-treatment:

[0122] Using a constant-temperature water bath as the temperature control component 4, the temperature of the constant-temperature water bath is controlled to be 26 °C to heat the fourth mixture, so that the liquid-phase solvent and the oil-phase pore-forming agent volatilize, and the porous polystyrene microsphere product is obtained.

[0123] Step 5, loading noble metal:

[0124] 5.1) Preparation of a porous polystyrene microsphere dispersion:

[0125] Water and ethanol are mixed at a volume ratio of 1:5 to obtain a dispersion solvent. 10 mg of the porous polystyrene microsphere product is added to 6 ml of the dispersion solvent and mixed evenly to obtain a porous polystyrene microsphere dispersion.

[0126] 5.2) Adding a reducing agent and a noble metal salt:

[0127] Using AgNO 3 as the noble metal salt, 0.5 wt% of polyvinylpyrrolidone and 0.005 g of AgNO 3 are added to the above-obtained porous polystyrene microsphere dispersion to obtain a precursor solution.

[0128] 5.3) Heating and spiral stirring treatment:

[0129] The spiral stirrer 3 is controlled to apply spiral stirring treatment to the precursor solution, and the stirring rate is 400 rpm. At the same time, the precursor solution is heated by the temperature control component 4, and the heating treatment temperature is 60 °C, and the treatment time is 6 h. After the reaction ends, the reaction is quenched by ice bath, and the obtained reaction solution is centrifuged, washed, and dried to obtain Ag-loaded porous polystyrene microspheres.

[0130] The present invention tested the microscopic morphology of the Ag-loaded porous polystyrene microspheres obtained in this example, and the test results are asFigure 4 as shown Figure 4 In (a), it is the scanning electron microscope image of the Ag-loaded porous polystyrene microspheres of Example 4; in (b), it is the transmission electron microscope image of the Ag-loaded porous polystyrene microspheres of Example 4 at a scale of 2 μm; in (c), it is the transmission electron microscope image of the Ag-loaded porous polystyrene microspheres of Example 4 at a scale of 1 μm; in (d), it is the transmission electron microscope image of another area of the Ag-loaded porous polystyrene microspheres of Example 4 at a scale of 2 μm; in (e), it is the transmission electron microscope image of another area of the Ag-loaded porous polystyrene microspheres of Example 4 at a scale of 1 μm; in (f), it is the transmission electron microscope image of the Ag-loaded porous polystyrene microspheres of Example 4 at a scale of 500 nm.

[0131] and from Figure 4 the test results, it can be seen that the prepared porous polystyrene microspheres have good monodispersity, narrow size distribution, and good pore structure; in addition, after Ag loading, the transmission electron microscope results show that a large number of Ag nanoparticles are loaded onto the inside and surface of the porous polystyrene microspheres.

[0132] Application example:

[0133] In the present invention, the Ag-loaded porous polystyrene microspheres prepared in Example 4 are used as a catalyst for the catalytic reduction reaction of 4-nitrophenol. The reaction principle of the catalytic reduction reaction of 4-nitrophenol is as Figure 5 shown, and the specific method is as follows:

[0134] Mix 4-nitrophenol with deionized water to prepare a 4-nitrophenol aqueous solution with a concentration of 5 mM. Mix NaBH 4 with deionized water to prepare a fresh NaBH 4 solution (4 °C - 5 °C) for standby. Take 0.1 mL of the above-prepared 5 mM 4-nitrophenol solution and dilute it to 3.7 mL with 4 °C - 5 °C deionized water, then add 0.1 mL of the above-prepared 0.1 M fresh NaBH 4 solution, and then add 5 mg of the Ag-loaded porous polystyrene microspheres prepared in Example 4 above. Continuously scan through the ultraviolet absorption spectrometer in the mode of spectral scanning. In addition, the present invention also monitors the color of the reaction solution during the entire reaction process of the catalytic reduction reaction of 4-nitrophenol, and the monitoring process record is as Figure 6 shown.

[0135] When only NaBH 4 is added to 4-nitrophenol, the color of the reaction solution deepens, changing from light yellow to yellowish green, and the reaction takes about 3 days to become colorless. FromFigure 6 From the test results, it can be seen that when Ag-loaded porous polystyrene microspheres are further added on the basis of NaBH 4 The reaction solution gradually changes from yellowish green to colorless. And after 8 minutes of the catalytic reduction reaction, the reaction solution completely changes from yellow to colorless and transparent. This indicates that when the Ag-loaded porous polystyrene microspheres of the present invention are used as a catalyst for the catalytic reduction reaction of 4-nitrophenol, it only takes 8 minutes to complete the catalytic reduction of 4-nitrophenol, which can greatly promote the catalytic reduction reaction of -nitrophenol.

[0136] Figure 7 It is the full ultraviolet absorption spectrum diagram showing the change with time during the catalytic reduction reaction of 4-nitrophenol by the Ag-loaded porous polystyrene microspheres of Example 4. It can be seen that as the reaction time increases, the absorbance intensity of 4-nitrophenol ions gradually decreases and is converted into 4-aminophenol. And after 12 minutes of the reaction, almost no 4-nitrophenol ions can be observed, which indicates that at this time, 4-nitrophenol has been completely converted into 4-aminophenol.

[0137] The present invention also organizes the mathematical equation of the reaction rate change with time during the above catalytic reduction reaction by using a chemical reaction kinetics model as Figure 8 shown, so as to describe its kinetic characteristics through the reaction kinetic rate equation during the above catalytic reduction reaction. And from Figure 8 the results, it can be seen that the above catalytic reduction reaction satisfies the first-order kinetics, and the reaction kinetic rate constant of the catalytic reduction reaction measured by ultraviolet absorption is 1.47×10 -2 s -1 , compared with the single NaBH 4 which requires several days of reaction time, adding Ag-loaded porous polystyrene microspheres on the basis of NaBH 4 can greatly strengthen mass transfer and reaction.

[0138] The present invention also fishes out the Ag-loaded porous polystyrene microspheres after the above catalytic reduction reaction experiment and repeats the above catalytic reduction reaction experiment again. One experiment is regarded as one cycle, and it is carried out for 7 cycles. The conversion rate after each cycle is tested, and the conversion rate after each cycle is organized as Figure 9 shown. From Figure 9 it can be seen that even after 7 cycles of use, the Ag-loaded porous polystyrene microspheres still maintain excellent conversion rates, which indicates that the Ag-loaded porous polystyrene microspheres prepared by the present invention have good catalytic performance.

[0139] Obviously, the above embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

Claims

1. An ultrasonic rotary microreactor for preparing porous polystyrene-based microspheres, characterized in that: It comprises an ultrasonic probe (1), a spiral micro-reaction tank (2), a spiral stirrer (3) and a temperature control component (4); The ultrasonic probe (1) is used to input ultrasonic energy into the spiral micro-reaction tank (2) to strengthen the mixing of the various preparation raw materials of the water phase, the oil phase and the solid phase used for preparing the porous polystyrene-based microspheres; The spiral micro-reaction tank (2) is used to receive various raw materials for preparing the porous polystyrene microspheres and provide a reaction space for the reaction of various raw materials for preparing the porous polystyrene microspheres; The spiral stirrer (3) is arranged in the spiral micro-reactor (2) to strengthen the mass transfer between the aqueous phase, the oil phase and the solid phase for preparing the porous polystyrene-based microspheres, and to avoid the agglomeration and secondary nucleation of the porous polystyrene microspheres. The temperature control component (4) is connected to the spiral micro-reaction tank (2) and is used to control the reaction temperature in the spiral micro-reaction tank (2).

2. The ultrasonic rotary microreactor for preparing porous polystyrene-based microspheres according to claim 1, characterized in that: The ultrasonic probe (1) is vertically arranged in the spiral micro-reaction tank (2).

3. The ultrasonic rotary microreactor for preparing porous polystyrene-based microspheres according to claim 1, characterized in that: The spiral stirrer (3), the ultrasonic probe (1) and the spiral micro-reaction tank (2) are coaxially arranged.

4. The ultrasonic rotary microreactor for preparing porous polystyrene-based microspheres according to claim 1, characterized in that: It also comprises a control unit, which is communicatively connected with the ultrasonic probe (1), the spiral stirrer (3) and the temperature control component (4) respectively.

5. The ultrasonic rotary microreactor for preparing porous polystyrene-based microspheres according to claim 4, characterized in that: The temperature control component (4) comprises a temperature detection unit and a heating unit; The temperature detection unit is in communication connection with the control unit to monitor the reaction temperature in the spiral micro-reaction tank (2) in real time, and transmits the monitored reaction temperature signal to the control unit; The heating unit is communicatively connected to the control unit so as to start or stop the heating unit's heating treatment of the spiral micro-reaction tank (2) through the control unit.

6. A method for preparing porous polystyrene-based microspheres, characterized in that: The porous polystyrene-based microspheres are prepared by the ultrasonic rotary microreactor according to any one of claims 1 to 5, and the preparation steps are as follows: According to a required ratio, polystyrene microsphere seeds and a liquid phase solvent are added to the spiral microreactor (2) to obtain a first mixture; the first mixture in the spiral microreactor (2) is subjected to ultrasonic treatment by means of the ultrasonic probe (1) so that the polystyrene microsphere seeds are fully mixed to form a uniform milky white emulsion; Adding an oil phase porogen to the milky white emulsion to obtain a second mixture; subjecting the second mixture to ultrasonic treatment using the ultrasonic probe (1) to uniformly mix the three-phase system to obtain a third mixture; The third mixture is subjected to ultrasonic treatment by the ultrasonic probe (1), and the third mixture is subjected to spiral stirring by the spiral stirrer (3), and under the combined action of spiral stirring and ultrasound, the oil phase porogen causes the polystyrene microspheres to form a porous structure, thereby obtaining a fourth mixture; The fourth mixture is heated by the temperature control component (4) to volatilize the liquid phase solvent and the oil phase porogen to obtain a finished porous polystyrene microsphere, and the finished porous polystyrene microsphere is used as the porous polystyrene-based microsphere; Alternatively, the porous polystyrene microsphere product is used as a carrier, and the noble metal salt is used as a load source. The noble metal salt, the porous polystyrene microsphere product and a reducing agent are mixed in a solution to obtain a precursor solution; the spiral agitator (3) is controlled to apply spiral stirring treatment to the precursor solution, and the precursor solution is heated by the temperature control component (4) so ​​that the noble metal salt is reduced to a noble metal element under the action of the reducing agent to obtain porous polystyrene microspheres loaded with noble metals, and the porous polystyrene microspheres loaded with noble metals are used as porous polystyrene-based microspheres.

7. The preparation method according to claim 6, characterized in that: The liquid phase solvent is a mixed solvent of water and ethanol in a volume ratio of 0.6 to 0.8:1; The mass ratio of the polystyrene microsphere seeds to the liquid phase solvent is 0.8-1.2:

100.

8. The preparation method according to claim 6, characterized in that: The oil phase porogen is any one of trimethylbenzene, toluene, n-hexane and cyclohexane.

9. The preparation method according to claim 6, characterized in that: The amount of the noble metal salt added is 20wt% to 30wt% of the finished porous polystyrene microspheres; The reducing agent is polyvinyl pyrrolidone; and the molar ratio of the reducing agent to the noble metal salt is 1 to 2:

1.

10. The preparation method according to claim 6, characterized in that: The noble metal salt is one or more of a soluble Ag salt, a soluble Pt salt, a soluble Pd salt and a soluble Au salt.

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