KR20020004131A - Preparation Method of Nanotube-shaped TiO2 Powder - Google Patents

Abstract

PURPOSE: A preparation method of nano tube type TiO2 powder for photo catalysts is provided, which increases specific surface area and activity of TiO2 powder by digesting anatase TiO2 formed by a precipitation method unlike a conventional method using rutile TiO2. CONSTITUTION: The preparation method comprises the steps of: reacting 0.5M of TiOCl2 solution, being obtained by diluting TiCl4 with water, with 5M of NH4OH to get a precipitate, titanium hydroxide; washing, filtering and drying; thermal treating over 400deg.C, preferably 450deg.C, for crystalline TiO2 powder; putting it in 5M of NaOH and digesting at 150deg.C for 12hrs. The resultant anatase TiO2 powder has 100-150nanometer of length and 10-20nanometer of diameter, and 270m¬2/g of surface area.

Description

Preparation method of nanotube-type titania powder {Preparation Method of Nanotube-shaped TiO2 Powder}

▲ Field of invention

-Titania fine powder for photocatalyst that can remove various environmental pollutants such as nitrogen oxides, decomposition of harmful substances in aqueous solution.

▲ Prior art in the field

① Conventional example

-A case of making a tube by controlling the pore size of a mold using a porous material such as alumina has been reported.

② Other conventional example

-In order to increase the specific surface area of TiO ₂ powder and improve its activity as a photocatalyst, a research case has been reported to manufacture nanotube by chemically treating TiO ₂ -SiO ₂ powder.

▲ Describe the problem of existing technology

① In the former example, it is difficult to manufacture a tube with a small diameter because the size of the tube is determined by the pore size of the mold used.

② In the latter example, it is expensive because the alkoxide used as starting material is expensive, and continuous process is impossible because autoclave is used. In addition, there is a need to completely remove SiO _2, which may degrade the properties of the photocatalyst.

① To provide a highly active titanium oxide powder for photocatalyst having a high specific surface area through the microstructure control of the powder itself together with the production of titania powder having anatase crystal structure more reactive than rutile phase.

② To provide titania powder with improved overall characteristics compared to conventional titania powder.

1 is a transmission electron microscope photograph of a nanotube TiO ₂ powder

2 is XRD analysis results according to the heat treatment temperature of titanium hydroxide precipitate

Figure 3 XRD analysis of the dry powder after warming

4 is the result of EDS analysis of dry powder after warming

5 is a specific surface area measurement results according to the temperature of the saliva temperature of TiO ₂ powder

① Composition

-Precipitate the precipitate obtained by reacting 0.5M TiOCl ₂ solution with 5M ammonia water in 5M NaOH solution.

② Manufacturing Method

-Dilute TiCl ₄ solution used as starting material to prepare TiOCl ₂ aqueous solution, and then react this solution with ammonia water to obtain titanium hydroxide precipitate. The resulting precipitate was washed and filtered, then dried and heat treated to produce crystalline dry TiO ₂ powder.

The powders were placed in an aqueous NaOH solution and subjected to digestion at room temperature to 200 ° C., respectively. After removing Na ⁺ ions contained in the powder obtained by warming, complete nanotube TiO ₂ powder.

③ Test result

- 0.5M TiOCl ₂ with 5M ammonia and then reacting the dried titanium hydroxide precipitate was obtained and heat treatment, to prepare an anatase phase TiO ₂ powder by onchim for 12 hours at 150 ℃ in 5M NaOH solution 100~150㎚ length, diameter 10 To prepare a nanotube type powder of ˜20 nm (Fig. 1).

-Anatase phase starts to form from 400 ℃ when the crystallinity changes with the heat treatment temperature of the titanium hydroxide precipitate (Fig. 2). The anatase phase is maintained intact in the dry powder after the powder is heat-treated at 450 ℃ in NaOH aqueous solution (Fig. 3).

No element Na was detected even after soaking in 5M aqueous NaOH solution (FIG. 4).

Anatase-phase TiO ₂ powder was incubated at 150 ° C. for 12 hours, showing the highest specific surface area value of about 270 m ² / g (Table 1).

① Improve the performance of photocatalyst titanium oxide.

② Applicable to environmental purification fields such as nitrogen oxide and harmful decomposition.

Claims (1)

In preparing a nanotube-type TiO ₂ fine powder to improve the specific surface area of the powder, Using TiCl ₄ instead of expensive alkoxide as starting material, Using only TiCl ₄ without mixing other metal oxides or dopants that may degrade the photocatalytic activity, After the above step, instead of using an autoclave, anatase-like TiO ₂ powder was added to a 5 M NaOH aqueous solution using a simple reflux apparatus, followed by a warming treatment at 150 ° C. for 12 hours, thereby obtaining a nanotube-type powder. TiO ₂ powder production method comprising the step of improving the specific surface area of the