CN103204695B - Method for preparing porous ceramic microballs by low-temperature coaxial electrostatic spraying - Google Patents

Abstract

The invention discloses a method for preparing porous ceramic microspheres by low-temperature coaxial electrostatic spraying. Firstly, the electrospray liquid is subjected to low-temperature coaxial electrostatic spraying to obtain spherical composite materials, and then the spherical composite materials are freeze-dried and then sintered to obtain porous ceramics. Microspheres. The ceramic microspheres prepared by the method for preparing porous ceramic microspheres by low-temperature coaxial electrostatic spraying of the present invention have a porous structure, a high specific surface area, and the pore structure is easy to control, which helps to improve the adsorption, catalysis, separation and transmission of the ceramic microspheres. Sensitive properties have broad application prospects in the fields of biomedicine, filter materials, catalyst carriers, fuel cells and electronic components.

Description

Method for preparing porous ceramic microspheres by low temperature coaxial electrostatic spraying

technical field

The invention belongs to the technical field of material preparation, and relates to a method for preparing porous ceramic microspheres by low-temperature coaxial electrostatic spraying.

Background technique

Ceramic microspheres refer to spherical inorganic non-metallic materials with diameters in the micron or nanometer scale. Because of their small size and large surface energy, they will produce small size effects, surface effects or interface effects when used. It exhibits special performance in terms of physical and chemical properties.

When ceramic microspheres are used in the fields of controlled drug release, bone repair fillers, catalytic carriers and piezoelectric materials, their porosity and specific surface area are the key factors affecting their performance. Since the surface of porous ceramic microspheres has a mesoporous or macroporous structure Compared with ordinary ceramic microspheres, it can obtain higher porosity and specific surface area, especially when used as a carrier for catalytic reactions and drug sustained release, it has higher adsorption capacity and loading capacity, thus showing excellent performance, so the development of high Porosity and specific surface area of porous ceramic microspheres are critical.

Chinese patent "Nano Titanium Dioxide Porous Microspheres" (Application No.: 02112734.4, Publication No.: 1443601, Publication Date: 2003-09-24) discloses a nano-TiO2 porous microsphere and its manufacturing method. Mix and grind with nano-titanium dioxide colloid to obtain a mixed slurry of nano-titanium dioxide, and then use spray granulation and heat treatment to obtain nano-titanium dioxide porous microspheres. The porous structure is mainly left by the rapid volatilization of the solvent in the titanium dioxide colloid . Chinese patent "A Preparation Method of Diatomite-Based Porous Ceramic Microspheres" (Application No.: 201110228418.4, Publication No.: 102391011A, Publication Date: 2012-03-28), discloses a diatomite-based porous ceramic microspheres The preparation method uses diatomite as the main raw material to prepare porous ceramic microspheres by spray drying, and its porous structure is mainly formed by the gaps of diatomite during sintering. The specific surface area of the porous ceramic microspheres prepared by the above two methods is small, mostly below 300m ² /g, and it is difficult to control the pore structure (porosity and pore size) of the porous ceramic microspheres, which cannot meet the actual needs.

Contents of the invention

The purpose of the present invention is to provide a method for preparing porous ceramic microspheres by low-temperature coaxial electrostatic spraying, which solves the problems of small specific surface area and difficult control of pore structure of porous ceramic microspheres prepared by the existing method.

The technical scheme adopted in the present invention is a method for preparing porous ceramic microspheres by low-temperature coaxial electrostatic spraying. First, the electrospray liquid is subjected to low-temperature coaxial electrostatic spraying to obtain a spherical composite material, and then the spherical composite material is sintered after freeze-drying, namely Porous ceramic microspheres are obtained.

The present invention is also characterized in that,

The electrospray liquid is composed of a solvent and a solute, and the solute is composed of a ceramic precursor and a polymer. The polymer and the ceramic precursor are sequentially added to the solvent, and the electrospray liquid is obtained after mixing evenly; the mass ratio of the solvent to the solute is 95-70: 5-30, the mass ratio of the ceramic precursor to the polymer is 20-80:80-20.

The electrospray liquid enters the low-temperature chamber after coaxial electrostatic spraying in the electrostatic sprayer to form spherical droplets, and then falls on the receiver. The temperature of the low-temperature chamber is -50 to 10°C.

Freeze-drying is carried out in a vacuum environment, the vacuum degree is lower than 6Pa, and the sintering temperature is 300°C to 1200°C.

The solvent is any one of water, tert-butanol, amphene, water-tert-butanol and tert-butanol-amphene.

Ceramic precursors are butyl titanate, tetraisopropyl titanate, ethyl orthosilicate, triisopropoxy vanadium oxide, zinc acetate, zinc nitrate, zirconium nitrate, nickel acetate, barium nitrate, iron nitrate, cerium nitrate , yttrium nitrate, indium nitrate and silver nitrate in any one.

The polymer is any one of polyvinylpyrrolidone, polyacrylonitrile, polyvinyl butyral, polyvinyl acetate, polymethyl methacrylate, polyvinyl alcohol, cellulose, nylon 66, polystyrene and polylactic acid kind.

The beneficial effects of the present invention are that the ceramic microspheres prepared by the method for preparing porous ceramic microspheres by low-temperature coaxial electrostatic spraying of the present invention have a porous structure with a positively high specific surface area, and the pore structure is easy to control, which helps to improve the ceramic microspheres. Adsorption, catalysis, separation and sensing properties have broad application prospects in the fields of biomedicine, filter materials, catalyst supports, fuel cells and electronic components.

Description of drawings

Fig. 1 is a schematic structural diagram of an electrostatic sprayer in the method for preparing porous ceramic microspheres by low-temperature coaxial electrostatic spraying of the present invention.

In the figure, 1. Inner tube micro pump; 2. Outer tube micro pump, 3. Saturated gas delivery tube, 4. Solvent saturated gas, 5. Coaxial nozzle inner tube, 6. Coaxial nozzle outer tube , 7. Receiver, 8. Cryogenic cavity.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

The method for preparing porous ceramic microspheres by low-temperature coaxial electrostatic spraying of the present invention firstly conducts low-temperature coaxial electrostatic spraying on an electrospray liquid to obtain spherical composite materials, and then sinters the spherical composite materials after freeze-drying to obtain porous ceramic microspheres.

Specific steps are as follows:

Step 1, preparation of electrospray liquid

Add polymer and ceramic precursor to the solvent in sequence, and mix well to obtain electrospray solution; the mass ratio of solvent to solute is 95-70:5-30, and the mass ratio of ceramic precursor to polymer is 20-80:80 ~20;

Step 2, low temperature coaxial electrostatic spray

Low-temperature coaxial electrostatic spraying is carried out in the electrostatic sprayer shown in Figure 1. The structure of the electrostatic sprayer is: a coaxial nozzle connected to the positive pole of a high-voltage DC power supply. The coaxial nozzle includes the coaxial nozzle inner layer tube 5 and the coaxial nozzle outer Layer pipe 6, the inner pipe 5 of the coaxial nozzle communicates with the micropump 1 of the inner pipe, the outer pipe 6 of the coaxial nozzle communicates with the micropump 2 of the outer pipe, and the micropump 2 of the outer pipe communicates with the saturated gas delivery pipe 3 The gas container is connected, and a receiver 7 placed in a low-temperature cavity 8 is provided at 10-30 cm directly below the coaxial nozzle. The saturated gas 4 of the solvent is passed into the micropump 2 of the outer tube through the saturated gas delivery pipe 3, and then under the voltage of 10-40kV, the temperature of the low-temperature control box is -50-10°C, and the rate is 0.5-2.5ml/h Push the micropump 1 of the inner tube, and push the micropump 2 of the outer tube at a rate of 1-5ml/h. The electrospray liquid is sprayed from the inner tube 5 of the coaxial nozzle through electrostatic spraying, and forms a spherical shape under the action of the electric field force. The droplets are surrounded by the saturated gas of the solvent sprayed from the outer tube 6 of the coaxial nozzle at the same time. The solvent in the spherical droplets does not volatilize or volatilizes in a very small amount and freezes quickly, and finally enters the low temperature chamber 8 and falls on the receiver 7, obtain the spherical composite material;

Step 3, freeze drying, sintering

The spherical composite material obtained in step 3 is freeze-dried in a vacuum environment, the vacuum degree is lower than 6 Pa, and finally sintered at 300-1200° C. to obtain porous ceramic microspheres.

Wherein, the solvent is any one of water, tert-butanol, amphene, water-tert-butanol and tert-butanol-amphene.

Ceramic precursors are butyl titanate, tetraisopropyl titanate, ethyl orthosilicate, triisopropoxy vanadium oxide, zinc acetate, zinc nitrate, zirconium nitrate, nickel acetate, barium nitrate, iron nitrate, cerium nitrate , yttrium nitrate, indium nitrate and silver nitrate in any one.

The polymer is any one of polyvinylpyrrolidone, polyacrylonitrile, polyvinyl butyral, polyvinyl acetate, polymethyl methacrylate, polyvinyl alcohol, cellulose, nylon 66, polystyrene and polylactic acid kind.

The ceramic microspheres prepared by the method for preparing porous ceramic microspheres by low-temperature coaxial electrostatic spraying of the present invention have a porous structure, a high specific surface area, and the pore structure is easy to control, which helps to improve the adsorption, catalysis, separation and transmission of the ceramic microspheres. Sensitive properties have broad application prospects in the fields of biomedicine, filter materials, catalyst carriers, fuel cells and electronic components.

Example 1

Step 1, add 4.0g of polyvinyl acetate and 1.0g of butyl phthalate to 95g of tert-butanol in sequence, and mix well to obtain the electrospray liquid;

Step 2, pour the electrospray liquid obtained in step 1 into the inner tube micropump 1, pass the saturated gas of tert-butanol into the outer tube micropump 2 through the saturated gas delivery tube 3, and then under the voltage of 20kV, low temperature The temperature of the control box is 10°C, the distance between the outer layer tube 6 of the coaxial nozzle and the collector 7 is 30cm, the collector is grounded, and the inner layer tube micropump 1 is advanced at a rate of 2.5ml/h, and the inner layer tube micropump 1 is advanced at a rate of 5ml/h. The speed advances the micro pump 2 of the outer tube, and the electrospray liquid is sprayed from the inner tube 5 of the coaxial nozzle through electrostatic spraying, and forms spherical droplets under the action of the electric field force, and is sprayed out from the outer tube 6 of the coaxial nozzle at the same time Surrounded by the saturated gas of tert-butanol, the solvent in the spherical droplets does not volatilize or very little volatilizes and freezes rapidly, and finally enters the low-temperature cavity 8 and falls on the receiver 7 to obtain spherical composite materials;

In step 3, the spherical composite material obtained in step 3 is freeze-dried in a vacuum environment with a vacuum degree of 5.5 Pa, and finally sintered at 550° C. to obtain titanium dioxide porous ceramic microspheres.

Example 2

Step 1, add 6.0g of polyvinyl alcohol and 24.0g of zinc acetate in 70g of water in sequence, and mix well to obtain the electrospray liquid;

Step 2, pour the electrospray liquid obtained in step 1 into the micropump 1 of the inner tube, pass the saturated gas of water into the micropump 2 of the outer tube through the saturated gas delivery tube 3, and then under the voltage of 40kV, the low temperature control box The temperature is -50°C, the distance between the outer tube 6 of the coaxial nozzle and the collector 7 is 10cm, the collector is grounded, and the inner tube micropump 1 is pushed at a rate of 0.5ml/h, and the rate is 1ml/h Push the micropump 2 of the outer tube, the electrospray liquid is sprayed from the inner tube 5 of the coaxial nozzle through electrostatic spraying, and forms spherical droplets under the action of the electric field force, and is sprayed from the outer tube 6 of the coaxial nozzle at the same time Surrounded by saturated gas of water, the solvent in the spherical droplets does not volatilize or very little volatilizes and freezes rapidly, and finally enters the low-temperature cavity 8 and falls on the receiver 7 to obtain spherical composite materials;

In step 3, the spherical composite material obtained in step 3 is freeze-dried in a vacuum environment with a vacuum degree of 5 Pa, and finally sintered at 300° C. to obtain zinc oxide porous ceramic microspheres.

Example 3

Step 1, add 6.0g polystyrene and 14.0g tetraethyl orthosilicate successively to 80g camphene, after mixing uniformly, obtain electrospray liquid;

Step 2, pour the electrospray liquid obtained in step 1 into the inner tube micropump 1, pass the saturated gas of camphene into the outer tube micropump 2 through the saturated gas delivery tube 3, and then under the voltage of 10kV, low temperature control The temperature of the box is 0°C, the distance between the outer layer tube 6 of the coaxial nozzle and the collector 7 is 20cm, the collector is grounded, and the inner tube micropump 1 is advanced at a rate of 1ml/h, and the rate is 3ml/h. Outer tube micropump 2, the electrospray liquid is sprayed from the inner tube 5 of the coaxial nozzle through electrostatic spraying, and forms spherical droplets under the action of the electric field force, and at the same time is sprayed by the camphor sprayed from the outer tube 6 of the coaxial nozzle Surrounded by the saturated gas of alkene, the solvent in the spherical droplets does not volatilize or very little volatilizes and freezes rapidly, and finally enters the low-temperature cavity 8 and falls on the receiver 7 to obtain a spherical composite material;

In step 3, the spherical composite material obtained in step 3 is freeze-dried in a vacuum environment with a vacuum degree of 5.8 Pa, and finally sintered at 1200° C. to obtain silica porous ceramic microspheres.

Example 4

Step 1: Add 7.0 g of polyvinylpyrrolidone and 3.0 g of triisopropoxyvanadium oxide in sequence to 90 g of water-tert-butanol, and mix well to obtain the electrospray solution;

Step 2, pour the electrospray liquid obtained in step 1 into the micropump 1 of the inner tube, pass the saturated gas of water-tert-butanol into the micropump 2 of the outer tube through the saturated gas delivery tube 3, and then under the voltage of 30kV , the temperature of the low-temperature control box is -30°C, the distance between the outer tube 6 of the coaxial nozzle and the collector 7 is 25cm, the collector is grounded, and the inner tube micropump 1 is pushed at a rate of 2.0ml/h, and the micropump 1 of the inner tube is pumped at a rate of 4ml The speed of /h pushes the micropump 2 of the outer tube, and the electrospray liquid is sprayed from the inner tube 5 of the coaxial nozzle through electrostatic spraying, and forms spherical droplets under the action of the electric field force, and is sprayed from the outer tube of the coaxial nozzle at the same time. 6 Surrounded by the sprayed water-tert-butanol saturated gas, the solvent in the spherical droplets does not volatilize or very little volatilizes and freezes rapidly, and finally enters the low-temperature cavity 8 and falls on the receiver 7 to obtain spherical composite materials;

In step 3, the spherical composite material obtained in step 3 is freeze-dried in a vacuum environment with a vacuum degree of 5 Pa, and finally sintered at 500° C. to obtain vanadium pentoxide porous ceramic microspheres.

In this embodiment, the solvent is water-tert-butanol, and it can also be any one of water, tert-butanol, amphene, and tert-butanol-amphene. In this embodiment, the ceramic precursor is triisopropoxy Vanadium oxide, also butyl titanate, tetraisopropyl titanate, ethyl orthosilicate, zinc acetate, zinc nitrate, zirconium nitrate, nickel acetate, barium nitrate, iron nitrate, cerium nitrate, yttrium nitrate, nitric acid Any one of indium and silver nitrate, the polymer in this embodiment is polyvinylpyrrolidone, it can also be polyacrylonitrile, polyvinyl butyral, polyvinyl acetate, polymethyl methacrylate, polyvinyl alcohol , cellulose, nylon 66, polystyrene and polylactic acid in any one.

Diameter and specific surface area of the porous ceramic microspheres made by table 1 embodiment 1-4

Example Element Diameter (nm) Specific surface area (m ² /g)

1 TiO ₂ 20-100 583.7 2 ZnO 80-300 394.6 3 SiO2 50-150 468.1 4 V ₂ O ₅ 300-600 230.4

Table 1 is the diameter and the specific surface area of the porous ceramic microspheres prepared in Examples 1-4. As can be seen from Table 1, the porous ceramic microspheres prepared in Examples 1-4 have a porous structure, which is higher than that prepared by the prior art. Porous ceramic microspheres have a higher specific surface area.

Claims (6)

1. coaxial low temperature electrostatic spray prepares the method for porous ceramics microballoon, it is characterized in that, first EFI liquid is carried out coaxial low temperature electrostatic spray and obtains spherical matrix material, then sintered after lyophilize by spherical matrix material, namely obtain porous ceramics microballoon;

The detailed process of coaxial electrostatic spraying is: EFI liquid is poured into inner tube micro pump (1), the saturated gas (4) of solvent is passed into outer tube micro pump (2) by saturated gas transfer lime (3), then under the voltage of 10 ~ 40kV, the temperature of low temperature controlling box is-50 ~ 10 DEG C, inner tube micro pump (1) is advanced with the speed of 0.5 ~ 2.5ml/h, outer tube micro pump (2) is advanced with the speed of 1 ~ 5ml/h, EFI liquid is ejected from Coaxial nozzle inner tube (5) by electrostatic spray, and spherical drop is formed under the effect of electrical forces, simultaneously by the encirclement of the saturated gas of solvent sprayed from Coaxial nozzle outer tube (6), the volatilization of solvent in spherical drop non-volatile or minute quantity quick freezing, drop on receptor (7) after finally entering low temperature cavity (8), obtain spherical matrix material.

2. coaxial low temperature electrostatic spray according to claim 1 prepares the method for porous ceramics microballoon, it is characterized in that, described EFI liquid is made up of solvent and solute, described solute is made up of ceramic forerunner and polymkeric substance, add polymkeric substance and ceramic forerunner successively in a solvent, after mixing, obtain EFI liquid; The mass ratio of described solvent and described solute is 95 ~ 70:5 ~ 30, and the mass ratio of described ceramic forerunner and described polymkeric substance is 20 ~ 80:80 ~ 20.

3. coaxial low temperature electrostatic spray according to claim 1 and 2 prepares the method for porous ceramics microballoon, it is characterized in that, described lyophilize is carried out in vacuum environment, and low vacuum is in 6Pa, and the temperature of sintering is 300 DEG C ~ 1200 DEG C.

4. coaxial low temperature electrostatic spray according to claim 3 prepares the method for porous ceramics microballoon, it is characterized in that, described solvent is any one in water, the trimethyl carbinol, amphene, water-trimethyl carbinol and the trimethyl carbinol-amphene.

5. coaxial low temperature electrostatic spray according to claim 4 prepares the method for porous ceramics microballoon, it is characterized in that, described ceramic forerunner is any one in butyl (tetra) titanate, titanium isopropylate, tetraethoxy, three isopropoxy vanadium oxides, zinc acetate, zinc nitrate, zirconium nitrate, nickelous acetate, nitrate of baryta, iron nitrate, cerous nitrate, Yttrium trinitrate, indium nitrate and Silver Nitrate.

6. coaxial low temperature electrostatic spray according to claim 5 prepares the method for porous ceramics microballoon, it is characterized in that, described polymkeric substance is any one in polyvinylpyrrolidone, polyacrylonitrile, polyvinyl butyral acetal, polyvinyl acetate, polymethylmethacrylate, polyvinyl alcohol, Mierocrystalline cellulose, nylon66 fiber, polystyrene and poly(lactic acid).