TWI395714B - Inorganic hollow microspheres and its preparation method - Google Patents

Description

Inorganic hollow microspheres and preparation method thereof

The invention relates to inorganic microspheres, in particular to an inorganic hollow microsphere and a preparation method thereof, which can produce inorganic hollow microspheres with good fluidity and single dispersion and size uniformity without using any surfactant. It has an outer diameter of 0.1-3μm and has many micropores. It has a high specific surface area, light weight, low density and high surface permeability, and has a wide range of applications.

Currently, micron-sized inorganic hollow microspheres can be prepared by a Sol-gel Method or a phase separation method. The former needs to first coat a film (2) on the core substrate (1), as shown in the first figure, to form a composite core-shell structure, and then remove the core substrate (1) by thermal cracking or chemical etching. By obtaining the hollow microspheres (3), the shell precursors (ie, the film (2)) are easily adhered to each other, even if the dispersion effect is achieved by the addition of the surfactant, and the core substrate (1) is removed. After that, it is not easy to obtain a single-dispersed hollow structure microsphere (3) having good fluidity, and the prepared microsphere (3) is difficult to form a pore having a fine pore diameter, and its use range is limited. As for the phase separation method, although the hollow structure microspheres can be synthesized without the addition of the core substrate, the synthesized microspheres have different sizes and are only suitable for the occasions where the dimensional uniformity is not required.

An object of the present invention is to provide an inorganic hollow microsphere having a shell layer It has many micropores, which make the microspheres have high specific surface area, light weight, low density and high surface permeability.

Another object of the present invention is to provide a method for producing inorganic hollow microspheres, which can produce inorganic hollow microspheres having good fluidity and single dispersion and size uniformity without using any surfactant.

For the purpose of achieving the foregoing disclosure, the method for preparing inorganic hollow microspheres provided by the present invention, as shown in the second figure, comprises the following steps:

(a) 0.2 to 0.3 g of poly(divinylbenzene) microspheres (10) having a diameter of about 3 μm, 0.1 to 0.3 g of a metal precursor, and 10 mL of tetrachloroethylene at 25 ° C to 95 ° C (at 25 ° C to 95 ° C). C ₂ Cl ₄ ) is uniformly mixed and reacted for a reaction time of at least 5 hours, so that some of the functional groups on the surface of the microspheres are removed by the attack of tetrachloroethylene, and the space is left for the metal precursor to be implanted to form a core ball (12) and a shell (16) of the shell layer (16), wherein the core (14) is an organic core, and the metal precursor may be selected from anhydrous aluminum chloride (AlCl ₃ ) or anhydrous aluminum chloride and hexachlorochloride. a mixture of hydrogen fluoride (H ₂ PtCl ₆ ), in fact, a composition of a metal chloride as a precursor can be used to synthesize a shell of different materials (16), and if two or more metal chlorides are added as a precursor, It can be made into a double-layered shell (16). Different from the conventional process, the shell precursor (2) is coated on the outer layer of the core substrate (1). In this step, the metal precursor is implanted into the organic core (14) so that the precursor exists only in the organic core. (14) Internal.

(b) repeatedly cleaning the mold ball (12) with 5 wt% hydrochloric acid and acetone and drying at 60 to 100 ° C (preferably 80 ° C) to remove the metal precursor remaining on the surface of the mold ball (12). And tetrachloroethylene.

(c) calcining the mold ball (12) in air at 900 ° C to 1100 ° C to remove the organic core (14) and reacting the shell layer (16) with air to form inorganic hollow microspheres (18) Such as alumina hollow microspheres or platinum-alumina hollow microspheres. Since the mold ball (12) is calcined at a high temperature, the organic core (14) shrinks in size, and the metal precursors of the adjacent shell layers (16) do not stick to each other, so that the degree of aggregation of the hollow microspheres (18) can be greatly reduced. It helps non-agglomerated single-dispersed hollow microspheres (18) to form; with the use of polydivinylbenzene-containing organic microspheres (10) as a sacrificial template, the hollow microspheres (18) produced are excellent. Dimensional uniformity, its outer diameter is within 3μm. In addition, hollow microspheres (18) of different sizes can be synthesized by changing the size of the organic microspheres (10). Structurally, the hollow microsphere (18) has a shell layer (20) having a plurality of micropores, and the pore diameter is 0.13% to 3.33% of the outer diameter of the inorganic hollow microsphere, and the shell is measured. The layer (20) has a thickness of less than 0.1 μm.

The foregoing steps for preparing the platinum-alumina hollow microspheres are as a precursor of a mixture of anhydrous aluminum chloride and hydrogen hexachloroplatinate, and the other method comprises first containing polydivinylbenzene microspheres, anhydrous aluminum chloride and four. The vinyl chloride is uniformly mixed, that is, in step (a), the anhydrous aluminum chloride is first implanted on the surface of the microsphere containing polydivinylbenzene to form a mold ball having a core and a shell layer, and after being washed and dried by the step (b), Further mixing the mold ball, hydrogen hexachloroplatinate and tetrachloroethylene at 25 ° C to 95 ° C and reacting, that is, step (a'), implanting hydrogen hexachloroplatinate into the surface of the mold ball, the mold ball After the step (b') is washed and dried, it is calcined in air at 900 ° C to 1100 ° C, that is, step (c), to remove the organic core, and react the shell layer with air to form platinum-alumina. Hollow microspheres.

The inorganic hollow microspheres (18) produced by the invention have a high specific surface The product has the characteristics of light weight, light weight, low density and high surface permeability, and the outer diameter of the microsphere (18) is within 3 μm. The inner cavity can directly encapsulate the drug, and the shell can be used as a drug carrier. The characteristics of high specific surface area, high surface penetration, and the like having a thickness of less than 0.1 μm and having a large number of micropores are used as a catalyst carrier. The inorganic hollow microspheres (18) synthesized by the invention have the single dispersibility and the dimensional uniformity with good fluidity, and the application fields thereof are widely used, for example, as ion adsorbents, sensors, biomedical materials, gene gun treatment, Lightweight structures and photonic crystals can also be used in everyday products such as paints, paints and cosmetics.

Taking alumina hollow microspheres as an example, it has light weight and excellent thermal and chemical stability, and has good thermal insulation and electrical insulation properties, and can be used commercially as a radiation doser. Platinum-alumina hollow microspheres can be used to detect carbon monoxide emissions from automobiles.

In order to better understand the features of the present invention, the following three preferred embodiments are described as follows:

Embodiment 1

Using 0.25 g of polydivinylbenzene-containing organic microspheres having a diameter of 3 μm or less as a sacrificial template, 0.15 g of anhydrous aluminum chloride was mixed as an alumina precursor (i.e., a metal precursor), and 10 ml of tetrachloroethylene was added as a reaction solvent. Firstly, the magnets were stirred at 25, 75, and 95 ° C for 1 hour, and then placed in a constant temperature water bath for 6 hours at the same temperature, so that tetrachloroethylene eroded some functional groups on the surface of the organic microspheres, so that the metal precursors could be effectively implanted. Organic microspheres The space remaining after the internal functional group is removed forms a mold ball having a core and a shell. Next, the product solid (ie, the mold ball) is taken out and sequentially washed with 5 wt% hydrochloric acid and acetone in order to remove the residual aluminum chloride and the excess tetrachloroethylene attached to the surface of the mold ball, and then oven at 80 ° C. Dry overnight. The dried mold ball powder is placed in a tubular high-temperature furnace, air is introduced, heated at a rate of 10 ° C / min, calcined to 900 ° C, 1000 ° C, 1100 ° C and held for 2 hours to remove the inner core. The powder is an alumina hollow microsphere.

The results of the AES depth analysis of the aforementioned mold ball are shown in the third figure. The initial representative Al content of the precursor is much lower than the O content of the representative organic core, indicating that the Al-containing precursor exists in the organic core environment rich in O elements. It was confirmed that the Al-containing precursor was present in the O-containing organic core by implantation to form a core-shell structure.

There are three kinds of phase transitions in the crystallinity of alumina hollow microspheres with the calcination temperature. From the XRD analysis results of hollow microspheres in the fourth graph, it is known that the crystallinity of alumina hollow microspheres will be calcined as the calcination temperature increases. The amorphous phase at 500 ° C is converted to the γ phase by 900 ° C until it is heated to a high temperature of 1000 ° C and is converted into a stable α-Al ₂ O ₃ structure.

The fifth figure shows the results of DLS particle size distribution of hollow microspheres produced by calcination to different temperatures. It can be found that the hollow microspheres have a single peak distribution at different calcination temperatures, indicating that the alumina synthesized by ours is hollow. The microspheres have a single dispersibility with good fluidity, and the outer diameter of the hollow microspheres is about 0.5 μm to 0.6 μm and both are less than 3 μm, and the average particle diameter of the hollow microspheres changes with the calcination temperature.

In addition, changing the calcination temperature can effectively control the shell micropores of the hollow microspheres. The sixth pattern is the pore size distribution curve of the hollow microsphere shell, and the pore size of the shell layer is between 1 and 200 Å. In terms of percentage, the pore diameter is 0.13% of the outer diameter of the inorganic hollow microsphere. ~3.33%; taking alumina hollow microspheres calcined to 1000 °C as an example, as shown in the TEM photograph of the seventh figure, there are nano-scale micropores in the hollow microsphere shell; in addition, TEM photos can also be found in alumina The shell layer of the hollow microspheres is composed of a plurality of nano-scale crystals having a thickness of between 20 and 50 nm and less than 0.1 μm.

Embodiment 2

0.25 g of organic microspheres containing polydivinylbenzene having a diameter of 3 μm was used as a sacrificial template, and a mixture of 0.15 g of aluminum chloride (AlCl ₃ ) and 0.15 g of hydrogen hexachloroplatinate (H ₂ PtCl ₆ ) was added as a metal. The precursor was added with 10 ml of tetrachloroethylene (C ₂ Cl ₄ ) as the reaction solvent. First, the magnet is stirred at 75 ° C for 1 hour, and then placed in a constant temperature water bath for 6 hours at the same temperature, so that the metal precursor can be effectively implanted into the space remaining after the functional groups of the organic microspheres are removed, forming a core with The ball of the shell. The product solid (ie, the mold ball) is taken out, and washed successively with 5 wt% hydrochloric acid and acetone to remove residual aluminum chloride, hexachloroplatinic acid and excess tetrachloroethylene attached to the surface of the mold ball, and finally at 80 ° C. Dry in the oven overnight. The dried mold ball powder was placed in a tubular high-temperature furnace, air was introduced, and the temperature was increased to 10 ° C / min, respectively, and calcined to 900 ° C, 1000 ° C, 1100 ° C and held for 2 hours to remove the inner core. The powder is a platinum-alumina hollow microsphere.

The eighth figure shows the TEM and SAD photographs of the platinum-alumina hollow microspheres. The shell of the hollow microspheres is mainly composed of α-Al ₂ O ₃ film and many Pt nano particles.

The ninth picture shows the SEM image of the platinum-alumina hollow microspheres, and the ninth figure (a) and (b) show the calcination temperature of 900 ° C. The shell layer can be found to be irregular, and the hollow micrometer is roughly estimated by the scale. The ball size is between 0.9 and 1.0 μm, and it can be seen from the ninth figure (b) that the shell layer is granular and has the presence of micropores. As the calcination temperature is raised to 1000 ° C, as shown in the ninth (c), (d), the shell layer is found to be completely spherical, and the size of the hollow microspheres is roughly estimated by the scale to be between 0.9 and 1.0 μm. (d) The presence of micropores was found, but the pore size was much reduced compared to 900 °C. As the calcination temperature is raised to 1100 ° C, as shown in the first figure (e), (f), it can be found that most of the shell layer is completely spherical, a small part of the shell layer is worm-like, and the size of the hollow microsphere is roughly estimated by the scale. Between 0.8 and 0.9 μm, it can be found from the ninth diagram (f) that there are still micropores present.

Embodiment 3

Using 0.25 g of organic microspheres containing 3 μm diameter of polydivinylbenzene as a sacrificial template, first only 0.15 g of anhydrous aluminum chloride (AlCl ₃ ) was added as a metal precursor, and 10 ml of tetrachloroethylene (C ₂ Cl _{4 ) was added.} ) when the solvent is reacted. First, the magnet was stirred at 75 ° C for 1 hour, and then placed in a constant temperature water bath for 6 hours at the same temperature to allow the metal precursor to be implanted inside the organic microsphere to form a core ball with a core layer and a shell layer. The resultant solid (i.e., the mold ball) was taken out, washed successively with 5 wt% hydrochloric acid and acetone, and dried overnight in an oven at 80 °C. Then replace the organic microspheres with the mold ball, and add tetrachloroethylene (10ml) as the reaction solvent, but replace the anhydrous aluminum chloride (AlCl ₃ ) with metal hexachloroplatinate (H ₂ PtCl ₆ ) as the metal precursor. The above experimental procedure was repeated, and the reaction was carried out at 75 ° C for 1 hour with magnet heating, and then placed in a 75 ° C constant temperature water bath for 6 hours, after centrifugation and drying; the dried mold powder was placed. In the tubular high-temperature furnace, air is introduced into the furnace at a heating rate of 10 ° C / min, respectively, and calcined to 900 ° C, 1000 ° C, 1100 ° C and held for 2 hours to remove the inner core, and the obtained powder is platinum-alumina hollow. Microspheres.

The eleventh figure is an SEM image of the platinum-alumina hollow microspheres prepared in the present embodiment, and the tenth (a) and (b) are the calcination temperature of 900 ° C, and most of the shell layers are found to be intact. Spherical, the hollow microspheres are roughly estimated to be between 1.0 and 1.2 μm by the scale. From the tenth (b), the shell is found to be granular and microporous. As the calcination temperature is raised to 1000 ° C, as shown in the first (c), (d), it can be found that the shell layer is completely spherical, and the size of the hollow microspheres is roughly estimated to be between 0.8 and 1.0 μm by the scale. The pore size has a decreasing tendency compared to 900 °C. As the calcination temperature is raised to 1100 ° C, as shown in the tenth (e), (f), the shell layer is found to be completely spherical, and the size of the hollow microspheres is roughly estimated from 0.7-0.9 μm by the scale. The shell layer has a microporous structure.

1‧‧‧ core substrate

2‧‧‧film

3‧‧‧ hollow microspheres

10‧‧‧microspheres

12‧‧‧Model Ball

14‧‧‧ core

16‧‧‧ shell

18‧‧‧Inorganic hollow microspheres

20‧‧‧ shell

The first drawing is a schematic diagram of a conventional inorganic hollow microsphere manufacturing method; the second drawing is a schematic view of the inorganic hollow microsphere manufacturing method of the present invention; and the third drawing is an AES longitudinal analysis drawing of the molding ball in the first preferred embodiment of the present invention; The fourth drawing is an XRD analysis chart of the alumina hollow microspheres of the first preferred embodiment of the present invention; the fifth figure is a DLS particle size distribution diagram of the alumina hollow microspheres of the first preferred embodiment of the present invention; The microporous pore size distribution map of the alumina hollow microsphere shell layer of the first preferred embodiment of the present invention; the seventh diagram is the TEM photograph of the alumina hollow microsphere of the first preferred embodiment of the present invention; The TEM and SAD photographs of the platinum-alumina hollow microspheres of the second preferred embodiment; the ninth photograph is the SEM photograph of the platinum-alumina hollow microspheres of the second preferred embodiment of the present invention; A SEM photograph of a platinum-alumina hollow microsphere of a preferred embodiment.

10‧‧‧microspheres

12‧‧‧Model Ball

14‧‧‧ core

16‧‧‧ shell

18‧‧‧Inorganic hollow microspheres

20‧‧‧ shell

Claims (10)

An inorganic hollow microsphere having an outer diameter of 0.1-3 μm and having a shell layer having a plurality of micropores having a diameter ranging from 0.13% to 3.33% of an outer diameter of the inorganic hollow microspheres, wherein the inorganic hollow microspheres are Made of alumina (Al ₂ O ₃ ) or platinum-alumina (Pt-Al ₂ O ₃ ). The inorganic hollow microspheres according to claim 1, which have a shell thickness of less than 0.1 μm. The invention relates to a method for preparing inorganic hollow microspheres, comprising the steps of: (a) uniformly mixing and reacting polydivinylbenzene-containing microspheres, metal precursors and tetrachloroethylene at 25 ° C to 95 ° C to make microspheres Some of the functional groups on the surface are removed by the attack of tetrachloroethylene. The vacant space is used to implant the metal precursor to form a mold ball with a core and a shell, wherein the core is an organic core; (b) clean and bake Drying the mold ball to remove the metal precursor and tetrachloroethylene remaining on the surface of the mold ball; and (c) calcining the mold ball in air at 900 ° C to 1100 ° C to remove the organic core, and The shell layer is reacted with air to form inorganic hollow microspheres. The method for preparing inorganic hollow microspheres according to claim 3, wherein in the step (a), the metal precursor is anhydrous aluminum chloride (AlCl ₃ ) or anhydrous aluminum chloride and hydrogen hexachloroplatinate (H ₂ PtCl ₆ ). a mixture. The method for preparing inorganic hollow microspheres according to claim 3, wherein in the step (a), the metal precursor is anhydrous aluminum chloride (AlCl ₃ ), and between step (b) and step (c), there is a step. (a') and a step (b'), the step (a') is carried out at 25 ° C to 95 ° C. The mold sphere, hydrogen hexachloroplatinate (H ₂ PtCl ₆ ) and tetrachloroethylene (C ₂ Cl _{4 )} Uniformly mixing and reacting to implant hydrogen hexachloroplatinate into the surface of the mold sphere, and step (b') is to clean and dry the mold sphere to remove hexachloroplatinate and tetrachloride remaining on the surface of the mold sphere. Ethylene. The method for producing inorganic hollow microspheres according to claim 3, wherein the polydivinylbenzene-containing microspheres have a diameter of about 3 μm in the step (a). The method for preparing inorganic hollow microspheres according to claim 3 or 4, wherein in step (a), each 10 ml of tetrachloroethylene is mixed with 0.2 to 0.3 g of polydivinylbenzene containing microspheres and 0.1 to 0.3 g of metal precursor. . The method for producing inorganic hollow microspheres according to claim 3, wherein the reaction time of the step (a) is at least 5 hours. The method for preparing inorganic hollow microspheres according to claim 3, wherein the step (b) is to dry the mold balls at 60 to 100 ° C. The method for producing inorganic hollow microspheres according to claim 3, wherein the mold ball is washed with hydrochloric acid or acetone in the step (b).