A method for preparing porous microspheres

Abstract

The present application relates to the field of porous ceramic microsphere material, and particularly to a preparation method of porous microspheres, which comprises the following steps: adding an oil phase containing organic zirconium and a phase separation inducer into an aqueous phase containing a composite surfactant to form an emulsion, continuously stirring for more than 12 hours, centrifuging, collecting the powder, and then washing, drying and heat treating, so that the porous microspheres with mesoporous structure, complete and regular morphology, high specific surface area and pore volume are prepared, the organic solvent can be recovered by distillation, the requirement for equipment is not high, and the method is more suitable for industrialized batch application.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of porous ceramic microsphere materials, in particular to a preparation method of porous microspheres. BACKGROUND

[0002] Porous ceramic microsphere materials have high specific surface area, strong adsorption, high assembly, high porosity and other characteristics, and have broad application prospects in the fields of catalysis, sensors, construction, electrochemistry, gas adsorption, chromatographic separation and the like. Among them, oxide ceramic porous microspheres and metal porous microspheres also have good mechanical, thermodynamic and chemical stability, and can adapt to more application scenarios.

[0003] At present, common preparation methods of porous microsphere materials include hydrothermal synthesis method, sol-gel method, electrostatic spraying and breath figure coordination assembly technology, phase transfer method, spray granulation method and the like.

[0004] Wang Jinglin et al. in "Preparation and electromagnetic properties of ZnO / Gd2O3 composite hollow microspheres" discloses that ZnO / Gd2O3 composite porous microspheres are synthesized by hydrothermal synthesis method, and the size of the porous microspheres is <5 μm. However, the hydrothermal synthesis method has high requirements for equipment and harsh process conditions, and only "kilogram" level products can be obtained in the laboratory, which is difficult to realize industrialized mass production.

[0005] Ruslan Kuzmin et al. in "Morphology of alumina granules obtained by spray freeze drying with twin-fluid atomization" discloses that porous alumina microspheres are prepared by spray granulation method, specifically, the atomized droplets are frozen in liquid nitrogen, and the water in the spray droplets is extracted under a vacuum of 10 Pa for 10 h, to obtain solidified porous alumina microspheres. The process is complex, the equipment requirement is high, and it is difficult to realize industrial production.

[0006] Liu Bingqian et al. in "Preparation of porous alumina microspheres by sol-spray drying method and its adsorption performance" discloses that porous alumina microspheres are prepared by spray granulation method, specifically, starch and other pore-forming agents are added to the alumina slurry to obtain alumina microspheres containing starch, and then the starch is ablated to obtain porous alumina microspheres. The preparation method is simple, but the addition of pore-forming agents affects the properties of the alumina slurry, and the morphology of the obtained alumina microspheres is irregular, thereby affecting the morphology of the porous microspheres.

[0007] Lyonnard et al. disclosed in "role of interparticle potential in controlling the morphology of spray dried powders from aqueous nanoparticle sols" that TiO2 microspheres with microporous structure were prepared by spray granulation method, specifically, soluble salt (aluminum nitrate) was added into the nano-TiO2 sol to obtain TiO2 microspheres containing micropores. The aluminum ions in the solution can make the TiO2 nano-powder in the solution pre-aggregated to obtain a pre-aggregated body containing a large amount of TiO2, and after the spray droplets of the pre-aggregated body are dried, TiO2 microspheres with microporous structure are obtained. The method is simple, but the microporous structure in the porous microspheres is composed of stacking pores inside and between the aggregates, which is random and difficult to control, and is difficult to apply in industrial production. SUMMARY

[0008] The technical problem to be solved by the present application is to provide a method for preparing porous microspheres.

[0009] The technical solutions adopted by the present application are as follows.

[0010] A method for preparing porous microspheres comprises the following steps:

[0011] An oil phase containing organic zirconium and a phase separation inducer is added into an aqueous phase containing a composite surfactant to form an emulsion, and the stirring is continued for more than 12 hours. After centrifugation, the powder is collected and washed, dried and heat treated.

[0012] Further, the method for preparing porous microspheres comprises the following steps:

[0013] A composite surfactant is added into water to obtain an aqueous phase, and organic zirconium, ethyl acetoacetate, an emulsifier and a phase separation inducer are added into n-octanol to obtain an oil phase. Under vigorous stirring, the oil phase is added into the aqueous phase to form an emulsion, and the stirring is continued for more than 12 hours. After centrifugation, the powder is collected and washed, dried and heat treated.

[0014] Further, the organic zirconium is any one or more of n-butyl zirconium, ethyl zirconium and n-propyl zirconium.

[0015] Further, the phase separation inducer is a chitosan / N-vinyl pyrrolidone graft copolymer.

[0016] Further, the method for preparing the chitosan / N-vinyl pyrrolidone graft copolymer comprises the following steps:

[0017] The chitosan is dissolved in acetic acid solution under nitrogen protection, an initiator is added, and after stirring for 10-30 min, N-vinyl pyrrolidone is added, and the temperature is increased to 60-80 DEG C for reaction for 8 h or more, and the reaction solution is dialyzed to remove small molecules, and then freeze-dried.

[0018] Further, the weight ratio of the chitosan and N-vinyl pyrrolidone is 0.1-1:10.

[0019] Further, the initiator includes hydrogen peroxide and ascorbic acid.

[0020] Further, the complex surfactant includes sodium dodecyl sulfate and OP-10, and the weight ratio of the sodium dodecyl sulfate and OP-10 is 1-5:1-5.

[0021] Further, the emulsifier is any one or more of monoglyceride fatty acid ester, diglyceride fatty acid ester, triglyceride fatty acid ester, Tween-80, Span-80, polyoxyethylene fatty acid ester, and polyethylene glycol alkyl ether.

[0022] Further, the amount of the phase separation inducing agent is 5-15% of the weight of the organic zirconium.

[0023] Further, the heat treatment temperature is 500-700 DEG C, and the time is 1-3 h.

[0024] The present application has the following beneficial effects:

[0025] The present application provides a preparation method of porous microspheres, an oil phase is dispersed in a water phase, and is sheared into spherical small droplets under intense stirring, water molecules diffuse into the oil phase droplets, organic zirconium hydrolyzes and polymerizes in the presence of water, the viscosity of the oil phase gradually increases, at the same time, a phase separation inducing agent is precipitated from the system and becomes a nucleation center, which promotes the phase separation process, ethyl acetoacetate diffuses to the nucleation center, thereby causing the coarsening of the phase separation phase, and finally solidifying into porous microspheres. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The SEM photo of the porous microspheres prepared by the present application. DETAILED DESCRIPTION

[0027] Unless otherwise specified in the examples, the procedures were carried out under conventional conditions or according to the manufacturer's instructions. Unless otherwise specified, the reagents or instruments used were conventional products available on the market. The techniques not mentioned in the present application refer to the prior art, unless otherwise specified. The following examples and comparative examples are parallel tests using the same processing steps and parameters.

[0028] Example 1:

[0029] A method for preparing porous microspheres:

[0030] Add 25 g of sodium dodecyl sulfate and 25 g of OP-10 to 500 ml of water, and stir vigorously for 30 min to obtain an aqueous phase. Add 20 g of zirconium n-propyl alcohol 70 wt.% n-propyl alcohol solution and 5 g of ethyl acetoacetate to 250 ml of n-octanol, and stir vigorously for 30 min. Then, add 10 g of Tween-80 and 1.5 g of chitosan / N-vinyl pyrrolidone graft copolymer, and stir vigorously for 30 min to obtain an oil phase. Under vigorous stirring, add the oil phase to the aqueous phase to form an emulsion. Continue stirring for 24 h, and then centrifuge at high speed. Collect the generated powder, wash with ethanol, and dry. Then, place the powder in a tube furnace under an air atmosphere, and heat treat at a rate of 10 ℃ / min to 600 ℃ for 2 h.

[0031] The method for preparing the chitosan / N-vinyl pyrrolidone graft copolymer is as follows:

[0032] Under nitrogen protection, dissolve 1 g of chitosan in 50 ml of 1% acetic acid aqueous solution. Then, add an initiator composed of 0.2 ml of hydrogen peroxide and 0.35 g of ascorbic acid. Stir for 30 min, and then add 20 g of N-vinyl pyrrolidone. Heat to 80 ℃, and react for 12 h. Use an 8000 kDa dialysis bag to dialyze the reaction solution in distilled water for two days to remove small molecules. Then, freeze-dry to obtain the chitosan / N-vinyl pyrrolidone graft copolymer.

[0033] Example 2:

[0034] A method for preparing porous microspheres:

[0035] Add 25 g of sodium dodecyl sulfate and 25 g of OP-10 to 500 ml of water, and stir vigorously for 30 min to obtain an aqueous phase. First, add 20 g of zirconium n-propyl alcohol 70 wt.% n-propyl alcohol solution and 5 g of ethyl acetoacetate to 250 ml of n-octanol, and stir vigorously for 30 min. Then, add 10 g of Tween-80 and 1.8 g of chitosan / N-vinyl pyrrolidone graft copolymer, and stir vigorously for 30 min to obtain an oil phase. Under vigorous stirring, add the oil phase to the aqueous phase to form an emulsion. Continue stirring for 24 h, and then centrifuge at high speed. Collect the generated powder, wash with ethanol, and dry. Then, place the powder in a tube furnace under an air atmosphere, and heat treat at a rate of 10 ℃ / min to 600 ℃ for 2 h.

[0036] The preparation method of the chitosan / N-vinylpyrrolidone graft copolymer is the same as in Example 1.

[0037] Example 3:

[0038] A method for preparing porous microspheres:

[0039] Add 25g sodium dodecyl sulfate and 25g OP-10 to 500ml water and stir vigorously for 30min to obtain an aqueous phase. First, add 20g zirconium n-propoxide 70wt.% n-propanol solution and 5g ethyl acetoacetate to 250ml n-octanol and stir vigorously for 30min. Then add 10g Tween-80 and 2.1g chitosan / N-vinylpyrrolidone graft copolymer and stir vigorously for 30min to obtain an oil phase. Under vigorous stirring, add the oil phase to the aqueous phase to form an emulsion. Continue stirring for 24h, centrifuge at high speed, collect the generated powder, wash with ethanol, dry, and then heat-treat in an air atmosphere at 600℃ for 2h at a rate of 10℃ / min.

[0040] The preparation method of the chitosan / N-vinylpyrrolidone graft copolymer is the same as in Example 1.

[0041] Example 4:

[0042] A method for preparing porous microspheres:

[0043] Add 25g sodium dodecyl sulfate and 25g OP-10 to 500ml water and stir vigorously for 30min to obtain an aqueous phase. First, add 20g zirconium n-propoxide 70wt.% n-propanol solution and 5g ethyl acetoacetate to 250ml n-octanol and stir vigorously for 30min. Then add 10g Tween-80 and 0.7g chitosan / N-vinylpyrrolidone graft copolymer and stir vigorously for 30min to obtain an oil phase. Under vigorous stirring, add the oil phase to the aqueous phase to form an emulsion. Continue stirring for 24h, centrifuge at high speed, collect the resulting powder, wash with ethanol, dry, and then heat-treat in an air atmosphere at 600℃ for 2h at a rate of 10℃ / min.

[0044] The preparation method of the chitosan / N-vinylpyrrolidone graft copolymer is the same as in Example 1.

[0045] Example 5:

[0046] A method for preparing porous microspheres:

[0047] Add 25g sodium dodecyl sulfate and 25g OP-10 to 500ml water and stir vigorously for 30min to obtain an aqueous phase. First, add 20g zirconium n-propoxide 70wt.% n-propanol solution and 5g ethyl acetoacetate to 250ml n-octanol and stir vigorously for 30min. Then add 10g Tween-80 and 1g chitosan / N-vinylpyrrolidone graft copolymer and stir vigorously for 30min to obtain an oil phase. Under vigorous stirring, add the oil phase to the aqueous phase to form an emulsion. Continue stirring for 24h, centrifuge at high speed, collect the generated powder, wash with ethanol, dry, and then heat-treat in an air atmosphere at 600℃ for 2h at a rate of 10℃ / min.

[0048] The preparation method of the chitosan / N-vinylpyrrolidone graft copolymer is the same as in Example 1.

[0049] Comparative Example 1:

[0050] The example is essentially the same as Example 1, except that polyvinylpyrrolidone K30 is used instead of chitosan / N-vinylpyrrolidone graft copolymer.

[0051] Performance testing:

[0052] Scanning electron microscopy was used to test the porous microspheres prepared in Examples 1-5 and Comparative Example 1 to obtain the specific surface area, pore volume, and most probable pore size of the porous microspheres. The results are shown in Table 1.

[0053] Table 1:

[0054]

[0055] As shown in Table 1 above, the porous microspheres prepared by this invention have a mesoporous structure and a high specific surface area and pore volume.

[0056] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing porous microspheres, characterized in that, The composite surfactant is added to water to obtain an aqueous phase. Organic zirconium, ethyl acetoacetate, emulsifier and phase separation inducer are added to n-octanol to obtain an oil phase. Under vigorous stirring, the oil phase is added to the aqueous phase to form an emulsion. The mixture is stirred for more than 12 hours, centrifuged, and the powder is collected, washed, dried and heat-treated at 500-700℃ for 1-3 hours. The amount of the phase separation inducer is 5-15% of the weight of organozirconium; The phase separation inducer is a chitosan / N-vinylpyrrolidone graft copolymer; The composite surfactant comprises sodium dodecyl sulfate and OP-10, wherein the weight ratio of sodium dodecyl sulfate to OP-10 is 1-5:1-5; The emulsifier is any one or more of monoglyceride fatty acid esters, diglyceride fatty acid esters, triglyceride fatty acid esters, Tween-80, Span-80, polyoxyethylene fatty acid esters, and polyethylene glycol alkyl ethers. The preparation method of the chitosan / N-vinylpyrrolidone graft copolymer is as follows: Under nitrogen protection, chitosan was dissolved in acetic acid solution, an initiator was added, and the mixture was stirred for 10-30 minutes before N-vinylpyrrolidone was added. The mixture was heated to 60-80℃ and reacted for more than 8 hours. The reaction solution was then dialyzed to remove small molecules and then freeze-dried.

2. The method for preparing porous microspheres as described in claim 1, characterized in that, The organozirconium is any one or more of zirconium n-butoxide, zirconium ethanol, and zirconium n-propoxide.

3. The method for preparing porous microspheres as described in claim 1, characterized in that, The weight ratio of chitosan to N-vinylpyrrolidone is 0.1-1:

10.

4. The method for preparing porous microspheres as described in claim 1, characterized in that, The initiator includes hydrogen peroxide and ascorbic acid.

Images