TWI386373B - Method for manufacturing regular mesoporous titania - Google Patents

Description

Method for manufacturing porous titanium dioxide in rules

The invention relates to a method for manufacturing a mesoporous material, in particular to a method for producing a regular titanium dioxide in a hole.

The so-called mesoporous means that the pore size is between 2 and 50 nm. Traditionally, the use of phase separation technology to prepare mesoporous materials is a popular method. The phase separation technique uses a surfactant to mix two without each other. The mutually soluble phase is such that one of the phases is dispersed in the other phase in the form of a micelle, and the metal ion-containing raw material is added thereto to cause the metal ion to react on the surface of the two-phase interface, that is, on the surface of the microcell. a metal shell having a microcell morphology is obtained, and finally, the metal shell having the microcell morphology is dried and calcined, and the surface and the inner material of the metal shell having the microcell morphology are removed, thereby obtaining Metal material in the middle hole structure.

Conventional mesoporous materials, such as mesoporous zirconia (YSZ), are mostly made using ionic surfactants such as cetyltrimethylammonium bromide ([CH ₃ (CH ₂ ) ₁₅ N+(CH ₃ ) ₃ Br ^- )], CTAB, cetyltrimethylammonium bromide), which is obtained by synthesis reaction with a metal ion compound. However, since this method does not easily control the pore size of the mesoporous structure, and such an surfactant The metal ion source materials used in combination with them, such as (Zr(i-OPr) ₄ ), are also expensive, so the use of the method for producing the mesoporous material has the problems of high cost and difficulty in controlling the pore size of the mesopores.

In recent years, triblock polyethylene oxide-polyepoxypropylene-polyethylene oxide has been used as a surfactant to synthesize materials with mesoporous structures, such as YSZ and titanium dioxide. The reason for the high-profile research topic is that the cost of the surfactant is low, and the metal ion source used in combination is mostly chloride, and the price is relatively cheap. At the same time, the production method is easier to control the product. The pore size of the mesoporous structure. However, the biggest difficulty of this method is that during aging and calcining, the removal process of organic matter often leads to the collapse of the originally arranged mesoporous structure.

Therefore, triblock polyethylene oxide-polyepoxypropylene-polyepoxyethylene is currently used as a surfactant to synthesize titanium dioxide (TiO ₂ ) with a mesoporous structure, which has a regular mesoporous structure and is easy to remove organic matter. The problem of disintegration in the process.

In view of this, the present invention proposes a method for manufacturing a porous titanium dioxide in a regular manner, which can solve the problem that the pore structure in the rule collapses during the manufacturing process. In the rule, the pore titanium dioxide has the advantages of high surface area, high porosity, low bulk density, high thermal stability and alignment rules, and the invention is produced by using an evaporation-induced self assembly (ESA) synthesis method using a surfactant. Micelle is used as a template, tetrabutyl orthotitanate is an inorganic precursor, which is aged under a specific temperature and humidity and then calcined to produce regular mesoporous titanium dioxide. The method includes the following Step: uniformly stirring the surfactant and the solvent to form a first solution in the first closed container; uniformly stirring the tetrabutyl titanate and hydrochloric acid in the second closed container to form a second solution; Slowly adding to the second solution, stirring at room temperature for a gelation time, forming a titanium dioxide sol to be formed; then placing the titanium dioxide sol to be formed on the substrate, keeping the liquid surface flat, and waiting for a forming time to form The titania sol is to be matured; then the titania sol to be aged is allowed to stand at a curing temperature and a ripening humidity, and is allowed to stand for ripening. Forming the matured titanium dioxide sol; then heating the matured titanium dioxide sol to a first drying temperature at a heating rate, holding the first drying time, then heating to the second drying temperature at the heating rate, and holding the temperature The second drying time is obtained to obtain the dried titanium dioxide sol; finally, the dried titanium oxide sol is heated to the calcining temperature at the heating rate, and then the temperature is calcined to form a sheet-like regular mesoporous titanium dioxide.

Thereafter, the above-mentioned sheet-like regular hole titanium dioxide furnace is cooled to room temperature, and ground to a powder appearance to further obtain a powdery regular mesoporous titanium dioxide.

The invention solves the problem of collapse of the mesoporous structure in the manufacturing process by controlling the ripening temperature and the ripening humidity during the ripening, the two-stage drying procedure, and adjusting the calcining temperature.

Please refer to FIG. 1 , which is a flow chart of a method according to a first embodiment of the present invention. In this embodiment, a tri-block copolymer type surfactant is used, and the general formula is ABA. The A block is polyethylene oxide (PEO), the B block is polypropylene oxide (PPO), and the molecular ratio of the A block and the B block is substantially 0.57. DETAILED DESCRIPTION The present embodiment is as follows: Step S01: Configuring the first solution.

1.4 g of the surfactant and 31.6 g of the solvent were placed in the first closed container, and the magnet was stirred uniformly at room temperature to form a first solution.

The solvent is selected from one of anhydrous ethanol, n-butanol and propylene glycol monomethyl ether (NMP). In this example, propylene glycol monomethyl ether (NMP) was selected as the solvent.

Step S02: Configuring the second solution.

4.08 g of tetrabutyl titanate (TBOT) and 2.91 g of 37 wt% hydrochloric acid were placed in a second closed container and uniformly stirred at room temperature with a magnet. The second solution, wherein the concentration of hydrochloric acid is substantially 37 wt%.

Step S03: Disposing a titanium oxide sol.

The first solution is slowly added to the second solution, and the titanium dioxide sol to be formed is formed by continuously stirring the magnet with a magnet at room temperature and in the second closed container, wherein the gelation time is substantially 6 hours.

The concentration of the surfactant in the titania sol to be formed is at least 2.0 wt%, and at most 5.0 wt%, wherein 3.5 wt% is optimal. In this embodiment, the concentration of the surfactant in the titania sol to be formed is 3.5 wt%.

Further, the concentration of the tetrabutyl titanate in the titania sol to be formed is at least 8.5 wt%, and at most 11.5 wt%, wherein 10.2 wt% is optimal, and in the present embodiment, tetrabutyl titanate is to be treated. The concentration in the formed titania sol was 10.2 wt%.

Step S04: Forming.

Taking 6.5 ml of the titanium dioxide sol to be formed on the substrate, and keeping the liquid surface of the titanium dioxide sol to be formed flat, and then standing for a molding time to form a titanium oxide sol to be matured, wherein the molding time is substantially 5 minutes, and the present embodiment The substrate used in the example was a petri dish having a diameter of 14 cm.

Step S05: ripening.

The matured titanium dioxide sol is formed by standing a ripening time at a curing temperature and a curing humidity.

Wherein, the curing temperature is substantially 30 ° C to 40 ° C, wherein 35 ° C is optimal; the ripening humidity is substantially 30 RH% to 50 RH%, wherein 40 RH% is optimal, and the curing time is substantially 24 hours. . In this embodiment, the titanium oxide sol to be aged is allowed to stand in a constant temperature and humidity apparatus at a temperature of 35 ° C and a humidity of 40 RH % for 24 hours.

Step S06: The first stage is dried.

Since the mature titanium dioxide sol still completes the step S05, it still contains a small amount of water and a solvent. If the drying speed is too fast, the water and the solvent will evaporate rapidly, and the mesoporous structure cannot be regularly arranged or even collapsed. Therefore, the titanium dioxide has been matured. The sol must be divided into two stages of drying. The heating rate of the first stage drying is substantially the slowest at 0.5 ° C per minute, and the fastest is 1.5 ° C per minute, with 1 ° C per minute being optimal. In this step, the matured titania sol was heated to 80 ° C at a heating rate of 1 ° C per minute, and then held at a temperature of 6 hours.

Step S07: The second stage is dried.

The heating rate of the second stage drying is substantially the slowest at 0.5 ° C per minute, and the fastest is 1.5 ° C per minute, with 1 ° C per minute being optimal. In this step, the matured titanium oxide sol which has completed the first stage drying process is further heated to 110 ° C at a heating rate of 1 ° C per minute, and then maintained at a temperature of 6 hours to form a dried titanium oxide sol.

Step S08: Burning.

The purpose of the simmering is to remove the polymer in the dried titanium dioxide sol. If the heating rate of the smoldering process is too fast, the pore structure will be uneven, and if it is too slow, the process time will be prolonged, so the heating rate of the smoldering process is substantially The slowest is 0.5 ° C per minute, the fastest is 1.5 ° C per minute, which is best at 1 ° C per minute. This step is to heat the dried titanium dioxide sol to the calcining temperature at a heating rate of 1 ° C per minute, and then hold The temperature is burned to form a sheet of regular titanium dioxide in the pores.

In addition, the too high temperature of the calcination will cause the structure of the mesopores to collapse. Too low will make the crystallinity of the pores in the regular rule after calcination poor, so the calcination temperature is substantially at least 300 ° C and the highest is 450 ° C. Further, 350 ° C is preferred, and the calcination temperature in this example is 350 ° C, and the calcination time is substantially 1 hour.

Step S09: grinding.

After the sheet-like regular hole titanium dioxide furnace was cooled to room temperature, it was ground to an appearance of powder in an agate mortar to obtain a powdery regular medium-sized titanium dioxide.

In addition, in this embodiment, after step S08, the regular titanium dioxide in the form of a sheet is heated to a decarburization temperature at a heating rate of 1 ° C per minute in an oxygen-containing atmosphere having an oxygen content of 20% to 100%. The temperature is decarburization time, wherein the decarburization temperature is substantially 300 ° C to 450 ° C, and the decarburization time is substantially 1 to 5 hours. This example was carried out in a decarburization procedure in air, in which the decarburization temperature was 350 ° C and the decarburization time was 1 hour.

The second embodiment utilizes the regular mesoporous titanium dioxide produced in the first embodiment. This embodiment was ground and heated at 150 ° C for 6 hours to remove the adsorbed air and moisture, and then subjected to nitrogen physico-sorption measurement at a low temperature of 77 K using a nitrogen adsorption desorber (ASAP 2000 type). The constant temperature nitrogen absorption/desorption curve shown in Fig. 2 can further obtain the BET specific surface area of the present embodiment of 239.2 m ² /g by the constant temperature nitrogen absorption/desorption curve and the BET formula.

For the mesoporous material, since the affinity between the adsorbent and the adsorbate is not large, when the relative pressure value (P/P _o ) becomes large, the internal activation energy is sufficient to provide the molecule to the saturation pressure to cause capillary condensation. (capillary condensation), so that the amount of adsorption is greatly increased, so hysteresis loops can be observed in the constant temperature nitrogen absorption/desorption curve, which is an important characteristic of the mesoporous material.

Please refer to FIG. 3, which is a BJH adsorption pore size distribution map according to a second embodiment of the present invention. From the peak positions in the figure, the main aperture of this embodiment is 63 angstroms (6.3 nm).

Referring to FIG. 4, the X-ray small-angle diffraction pattern according to the second embodiment of the present invention is characterized in that the diffraction peak width in the figure is very narrow, and the microstructure of the present embodiment is regularly arranged.

Please refer to "Fig. 5A" and "Fig. 5B" for a transmission electron microscope photograph of the second embodiment of the present invention. It can be further confirmed from the photograph that the microstructure of the present embodiment is closely and regularly arranged.

Please refer to FIG. 6 for the absorption spectrum of the second embodiment of the present invention. In addition to absorbing ultraviolet light, this embodiment also has good absorption in the visible light range, so that it is in ultraviolet light or visible light. Both of them have good photocatalytic properties under irradiation.

By using the above characteristics, the present embodiment can be applied not only to general photocatalysts and visible light photocatalysts, but also to sterilizing and decomposing organic pollutants, and can also be applied to solar cells using titanium dioxide as photovoltaic elements to improve photoelectric conversion efficiency. .

Although the technical content of the present invention has been disclosed in the above preferred embodiments, it is not intended to limit the present invention, and any modifications and refinements made by those skilled in the art without departing from the spirit of the present invention are encompassed by the present invention. The scope of protection of the present invention is therefore defined by the scope of the appended claims.

Figure 1 is a flow chart of the method of the first embodiment.

Fig. 2 is a graph showing the constant temperature nitrogen gas absorption/desorption curve of the second embodiment.

Fig. 3 is a BJH adsorption pore size distribution map of the second embodiment.

Fig. 4 is a view showing the X-ray small angle diffraction of the second embodiment.

Fig. 5A is a transmission electron microscope (TEM) photograph (1) of the second embodiment.

Fig. 5B is a transmission electron microscope (TEM) photograph (2) of the second embodiment.

Fig. 6 is an absorption spectrum of the second embodiment.

Claims (20)

A method for producing a porous titanium dioxide in a rule comprises the steps of uniformly stirring an interface active agent and a solvent in a first closed container to form a first solution; and uniformly stirring the tetrabutyl group in a second closed container The titanate and the hydrochloric acid form a second solution; the first solution is slowly added to the second solution, and the gelation time is stirred at room temperature to form a titania sol to be formed; the titania sol to be formed is placed On the substrate, after the liquid surface of the titania sol to be formed is kept flat, a titanate sol to be cured is formed after a forming time; the titan sol to be aged is allowed to stand at a curing temperature and a curing humidity, and the curing time is allowed to stand. Forming a matured titanium dioxide sol; heating the matured titanium dioxide sol to substantially 80 ° C at a heating rate, then holding the temperature for substantially 6 hours, and then heating to substantially 110 ° C at the heating rate, and then holding the temperature substantially 6 hours to form a dried titanium dioxide sol; and heating the dried titanium dioxide sol to a temperature at the heating rate The temperature is burned, and then the temperature is maintained for a while to form a regular titanium dioxide in the form of a sheet. The method for producing a porous titanium dioxide according to the rule of claim 1 further comprises the steps of: cooling the pore-shaped titanium dioxide in the regular form of the sheet to room temperature, and grinding to the appearance of the powder to obtain the powdered regular voided titanium dioxide. A method for producing a porous titanium dioxide according to the rule of claim 1, wherein the surfactant is a triblock copolymer type having a general formula of ABA. The method for producing a porous titanium dioxide according to the rule of claim 3, wherein the A block of the surfactant is polyethylene oxide (PEO), and the B block is polyepoxy Polypropylene oxide (PPO), and the molecular ratio of the A block and the B block is substantially 0.57. The method for producing a porous titanium dioxide according to the rule of claim 4, wherein the concentration of the surfactant in the titanium oxide sol to be formed is substantially 2.0 wt% to 5.0 wt%. The method for producing a porous titanium dioxide according to the rule of claim 1, wherein the concentration of the tetrabutyl titanate in the titanium oxide sol to be formed is substantially 8.5 wt% to 11.5 wt%. The method for producing a porous titanium dioxide according to the rule of claim 1 is to form the first solution and the second solution at room temperature. A method of producing a porous titanium dioxide according to the rule of claim 1, wherein the solvent is selected from the group consisting of anhydrous ethanol, n-butanol, and propylene glycol monomethyl ether (NMP). A method of producing a porous titanium dioxide according to the rule of claim 1, wherein the gel forming time is substantially 6 hours. A method of producing a porous titanium dioxide according to the rule of claim 1, wherein the forming time is substantially 5 minutes. A method of producing a porous titanium dioxide according to the rule of claim 1, wherein the curing temperature is substantially 30 ° C to 40 ° C. A method of producing a porous titanium dioxide according to the rule of claim 1, wherein the ripening humidity is substantially 30 to 50 RH%. A method of producing a porous titanium dioxide according to the rule of claim 1, wherein the ripening time is substantially 24 hours. A method of producing a porous titanium dioxide according to the rule of claim 1, wherein the heating rate is substantially 0.5 ° C to 1.5 ° C per minute. A method of producing a porous titanium dioxide according to the rule of claim 1, wherein the calcining temperature is substantially from 300 ° C to 450 ° C. A method of producing a porous titanium dioxide according to the rule of claim 1, wherein the calcining time is substantially one hour. The method for producing a porous titanium dioxide according to the rule of claim 1 further comprises the step of: heating the pore-shaped titanium dioxide in the ruled state to a temperature at a heating rate in an oxygen-containing atmosphere. Carbon temperature, then temperature-decarburization time A method of producing a porous titanium dioxide according to the rule of claim 17, wherein the oxygen-containing atmosphere has an oxygen content of between 20% and 100%. A method of producing a porous titanium dioxide according to the rule of claim 17, wherein the decarburization temperature is substantially from 300 ° C to 450 ° C. A method of producing a porous titanium dioxide according to the rule of claim 17, wherein the decarburization time is substantially 1 to 5 hours.