KR100998325B1 - A platinum/titania-based catalyst, a method of preparing the same and a method of removing formaldehyde by using the same - Google Patents

Abstract

The present invention relates to a method for preparing a platinum / titania catalyst and a method for removing formaldehyde by using the catalyst and the catalyst, and more particularly, after loading and drying platinum chloride in titania and reducing to remove chlorine, A method of preparing a platinum / titania catalyst by re-reducing at high temperature in order to control the oxidation value of platinum after firing, platinum / titania catalyst having formaldehyde removal characteristics at room temperature, and such platinum / titania It relates to a method for removing formaldehyde using a catalyst.

According to the present invention, a catalyst capable of completely decomposing formaldehyde at room temperature without a separate energy source is provided, and can be variously applied to a ventilation facility, a purification facility, an indoor space, and the like.

Platinum / Titania catalysts, formaldehyde, reduction, lattice oxygen

Description

Platinum / titania-based catalyst, a method of preparing the same and a method of removing formaldehyde by using the same

The present invention relates to a platinum / titania catalyst, and more particularly, to a method for preparing a platinum / titania catalyst capable of completely oxidizing formaldehyde to carbon dioxide at room temperature, and a method for removing formaldehyde using the catalyst and the catalyst.

Recently, discussion on formaldehyde as a causative agent of indoor air pollution has been actively conducted. Formaldehyde is a gas with a strong irritating odor at room temperature. It is commercially available as a formalin at a concentration of about 40% in aqueous solution, and is mainly used as urea-formaldehyde, phenol-aldehyde resin, melanin, and the like. Formaldehyde is also added to the production of ethylene glycol and is used as an adhesive for wood products such as hexamethylene tetramine, fertilizers, dyes, fungicides, shampoos, conditioners, water-based paints, hardeners, corrosion inhibitors, MDFs, plywood and particle boards. It is a situation that directly or indirectly affects the real life space.

Formaldehyde, which is used for various purposes, is emerging as a very detrimental factor affecting the quality of indoor air, especially in sick house syndrome. The effects of formaldehyde on the human body include irritation to the mucous membranes and skin of the upper airway and eyes, and prolonged exposure to obstructive pulmonary symptoms such as allergic contact dermatitis, eczema and cough, sputum, asthma and chronic bronchitis. It also affects the reproductive system, causing natural miscarriage, low birth weight, and pregnancy addiction.

In general, formaldehyde in air is oxidized to harmless CO ₂ and H ₂ O by the following Scheme 1. In recent years, various formaldehyde removal technologies have been developed in recognition of the harmfulness of formaldehyde as described above.

HCHO + O ₂ → CO ₂ + H ₂ O

For example, Korean Patent Application No. 2006-0022977 discloses a gypsum board that can efficiently absorb formaldehyde, and Korean Patent Application No. 2000-0012783 uses activated clay, stone powder, activated carbon, and acetylacetone aqueous solution. An adsorbent capable of adsorbing formaldehyde is disclosed, and Korean Patent Application No. 2006-0068917 discloses a technique for removing formaldehyde and volatile organic compounds (VOCs) using a visible light sensitive photocatalyst.

However, the conventional formaldehyde removal technology is to remove formaldehyde by simply adsorption or absorption method, rather than the fundamental solution to the causative agent, it is difficult to continuously use when saturated and formaldehyde removal efficiency is reduced, and in the case of photocatalyst There is a problem that a separate light source is required and a long residence time is required.

In addition, most of the formaldehyde removal technology shows the removal efficiency by the batch reaction test rather than the test in the reactor of continuous flow, in this experiment, the oxidation and adsorption reaction with CO ₂ coexists in the removal of formaldehyde, strictly It is difficult to mention the oxidation reaction efficiency in the sense.

The present invention has been proposed to solve the above problems, and an object thereof is to provide a method for preparing a platinum / titania catalyst and a method for removing formaldehyde using the catalyst and the catalyst.

The gist of the method for preparing the platinum / titania catalyst according to the present invention and the method for removing formaldehyde using the catalyst and the catalyst is as follows.

(1) A method of producing a platinum / titania catalyst, which is sequentially supported, dried, reduced and calcined using a platinum precursor and a titania carrier,

And a re-reduction step for controlling the oxidation value of platinum to +2 or +0 after the firing step.

(2) The method for producing a platinum / titania catalyst according to (1), wherein the titania carrier has a lattice oxygen of 3000 to 5000 (atomic number / cm 3) and a molar ratio of oxygen and titanium is 1.7 to 1.95.

(3) The platinum / titania catalyst production method according to the above (1), wherein the platinum precursor is platinum chloride (PtCl ₄ ) or tetra-amine platinum nitrate (Pt (NH ₃ ) ₄ (NO ₃ ) ₂ ). .

(4) The method for producing a platinum / titania catalyst according to the above (1), wherein the re-reduction step maintains the fired sample at a temperature of 500 to 800 ° C. for 0.5 to 5 hours in a furnace in a reducing atmosphere.

(5) The method for producing a platinum / titania catalyst according to (4), wherein the furnace is any one selected from a tube furnace, a convection furnace, or a grate furnace.

(6) The method for producing a platinum / titania catalyst according to (4), wherein the reducing atmosphere is formed of a gas containing hydrogen, ammonia, and methane.

(7) The method for producing a platinum / titania catalyst according to the above (6), wherein the gas has a composition of 1 to 50%.

(8) A method for removing formaldehyde by passing air containing formaldehyde through a platinum / titania catalyst prepared according to any one of the above (1) to (7).

(9) A method for removing formaldehyde as described in (8), wherein the platinum / titania catalyst is extruded into a particle or monolith.

(10) The method of removing formaldehyde as described in (8) above, wherein the platinum / titania catalyst is coated on any one structure selected from a metal plate, a metal fiber, a ceramic filter, or a honeycomb.

(11) A method for removing formaldehyde as described in (8), which is carried out in a reactor maintained at a temperature of 20 to 100 ° C. and a space velocity (GHSV) of 1,000 to 200,000 hr ⁻¹ .

(12) A method for removing formaldehyde as described in the above (9), wherein the particles of the platinum / titania catalyst are 1 to 10 µm.

(13) A method for removing formaldehyde as described in (11) above, wherein the relative humidity in the reactor is 0 to 95%.

(14) A platinum / titania catalyst prepared by supporting a platinum precursor on a titania carrier having a lattice oxygen of 3000 to 5000 atoms / cm 3 and a molar ratio of O / Ti of 1.7 to 1.95.

(15) The platinum / titania catalyst according to the above (14), wherein the platinum precursor is 0.05 to 1% by weight of platinum oxide based on titania weight.

(14) The titania carrier has an anatase and rutile ratio of 0: 100 to 100: 0, a specific surface area of 10 to 350 m ² / g, and a particle size of 1.0 to 2.0 μm. Based platinum / titania catalysts.

(17) A platinum / titania catalyst prepared by the method according to any one of (1) to (7) above.

According to the present invention, formaldehyde in the air can be removed without using a separate light source or energy. In addition, according to the present invention it is possible to continuously maintain the removal characteristics of formaldehyde for a long time. In addition, according to the present invention, even when the amount of platinum acting as an active material is very low, excellent formaldehyde removal effect can be obtained at room temperature.

The platinum / titania catalyst according to the present invention is prepared by carrying out a supporting, drying, reducing, and calcining process using a platinum precursor and a titania carrier to reduce the oxidation value of platinum, the active metal.

That is, the present invention is characterized by improving formaldehyde removal activity at room temperature by artificially changing the physical properties of the platinum / titania catalyst.

In this case, XPS (X-ray photoelectron spectroscopy) is used as a means for analyzing and determining the state change of the reprocessed platinum or the characteristics of the catalyst. XPS analysis is a method of analyzing the chemical bonding state of the catalyst by measuring the photoelectron to determine the energy level.

Based on the above description, the following describes a method for producing the platinum / titania catalyst according to the present invention.

First, in order to support platinum, which is an active metal, on a titania precursor (methitanic acid), the platinum precursor is dissolved in an aqueous solution in an amount of 0.1 to 10 wt% based on the weight of titania. In this case, the platinum precursor is not particularly limited, but it is preferable to use platinum chloride (PtCl ₄ ) or tetra-amine platinum nitrate (Pt (NH ₃ ) ₄ (NO ₃ ) ₂ ).

Next, quantitative titania is added to the aqueous solution in which the platinum precursor is dissolved as described above, and then sufficiently mixed to prepare a slurry.

Subsequently, the platinum precursor is supported on titania by removing water in the slurry through a predetermined process. In this case, in order to completely remove the moisture contained in the micropores, it is preferable to dry enough for more than one day in a drying facility.

At the end of the drying process, the sample is fired. In this case, the manufacturing process is somewhat different depending on the type of platinum precursor used. Specifically, in the case of using platinum chloride, a reduction process is added before calcination to exclude chlorine which is an inactive element, and platinum-free chlorine is added. If used, a reduction step is unnecessary.

The above process is a conventional method for producing a general catalyst, the present invention is characterized in that it further comprises a re-reduction step for adjusting the oxidation value of platinum to +2 or +0 after the firing step.

The re-reduction process is carried out for 0.5 to 5 hours at a temperature of 500 ~ 800 ℃ in the furnace of a reducing atmosphere. In this case, the reducing atmosphere may be formed by a gas having a composition of 1 to 50% including hydrogen, ammonia and methane, and the furnace in which the re-reduction process is performed is a tube furnace, a convection furnace, or A grate type furnace can be used.

Oxidation performance of platinum / titania catalysts prepared according to the present invention comprising such re-reduction processes can be evaluated under certain conditions. Specifically, the supplied formaldehyde concentration is 10 ~ 500ppm, oxygen concentration is 0.5 ~ 21% by volume, moisture is 0 ~ 95% based on relative humidity, space velocity is possible in the range of 5,000 ~ 200,000hr ^-1 .

Here, the space velocity is an index indicating the amount of pollutant gas that the catalyst can treat, and is expressed as a ratio of the amount of catalyst (volume) to the total gas flow rate (volume). For example, a large space velocity means that the amount of processing gas per unit volume of the catalyst is large.

X-ray photoelectron spectroscopy (XPS) is used as a means for analyzing and determining the characteristics of the catalyst and carrier prepared according to the present invention.

According to XPS analysis, the characteristic peak of each element present on the catalyst surface is separated based on the intrinsic binding energy of the oxide containing the element, and the type and distribution ratio of the oxide present on the catalyst surface. The peaks can be separated by Gaussian-Lorentzian method.

In general, TiO ₂ is expressed in the form of Ti ⁴⁺ by the carrier alone, and the binding energy is 458.8 eV at the Ti 2p _3/2 peak.

In addition, the oxygen appearing at the O 1s peak is expressed as the oxygen compound present on the surface, that is, the sum of oxygen in TiOx, OH, and CO bonds, and the lattice oxygen shown in combination with Ti is O ² -form, peak at 531eV is CO ₃ ^2- and OH ^- are separated by surface adsorption of oxygen or the like. Here, lattice oxygen means the number of oxygen present per unit volume of catalyst.

The number of Ti ⁴⁺ atoms of Ti-O and TiO ₂ obtained by the above method is calculated by calculating the area (number of characteristic photoelectrons obtained per unit time) obtained from XPS analysis in consideration of the atomic sensitivity factor. The number of atoms of the element per unit volume in cm ³ can be obtained. It can be seen that the calculated ratios of Ti-O atoms, Ti-O atoms, and TiO ₂ (Ti ⁴⁺ ) atoms are very relevant when compared to formaldehyde removal activity.

In addition, in the catalyst prepared according to the present invention, the oxidation state of platinum is changed by a re-reduction process, and the effect of the oxidation of platinum on the formaldehyde removal activity can be confirmed indirectly through the crystal phase analysis of the catalyst.

Based on the above analysis, certain titania is used as a carrier in the present invention. Specifically, the present invention is a catalyst having a lattice oxygen of 3000 ~ 5000 (atomic number / cm 3), by using a titania carrier having a molar ratio of oxygen and titanium of 1.7 to 1.95 to control the oxidation value of platinum to exhibit excellent oxidation at room temperature Can be prepared.

The catalyst prepared according to the present invention shows excellent oxidizing power at room temperature by the following action.

First, reduced platinum converts formaldehyde into a formate species, which is converted to carbon monoxide while losing one hydrogen atom, and carbon monoxide is oxidized to carbon dioxide by gaseous oxygen and oxygen of the catalyst.

When the catalyst prepared according to the present invention is actually applied, it is used by coating on a structure such as a metal plate, a metal fiber, a ceramic filter, or a honeycomb, or by coating on an air purifier, an interior decoration, an interior or exterior material, and a wallpaper. Can be used.

It is also possible to add a small amount of binder to the catalyst and to use it by extrusion processing into a granular or monolith type. In this case, the catalyst is preferably pulverized uniformly to a particle size of about 1 ~ 10㎛ coating or extrusion. This is because, when the particle size is less than 1 μm, it is not preferable in view of economics due to the fine grinding step, and when the particle size is larger than 10 μm, uniformity and adhesion of the coating or the extrudate are lowered. The coating or extrusion process is well known herein and the description thereof will be omitted.

In the present invention, the form of the catalyst is not limited, and various forms such as honeycomb, slate, plate, pellet, and the like may be used.

Hereinafter, the production examples and examples of the present invention will be described.

The present invention may be more clearly understood by the following preparation examples and examples, but the following preparation examples and examples are merely for the purpose of illustration of the invention and are not intended to limit the scope of the invention.

Production Example

Platinum chloride (PtCl ₄ : trade name of Aldrich Chemical Co.) or tetra-amine platinum nitrate (Pt (NH ₃ ) ₄ (NO ₃ ) ₂ : trade name of Aldrich Chemical Co.) was 0.1 to 5 based on the weight of the carrier. It was quantified to% and dissolved in heated distilled water of 60 ℃ or more. Subsequently, titania (TiO ₂ ) was added to the aqueous solution to prepare a slurry, and the slurry was heated using a vacuum evaporator under 70 ° C. and stirring conditions, and then heated at a temperature of 80 ° C. to 120 ° C. for 5-30 hours. Drying was completely removed from the water contained in the micropores.

In this case, if platinum chloride was used as a precursor of platinum, it was prepared by excluding chlorine of the catalyst using 30% hydrogen / air gas at 300 ° C. for 3 hours, and calcining at 400 ° C. for 4 hours in an air atmosphere. On the other hand, when tetra-amine platinum nitrate containing no chlorine is used as a precursor of platinum, it is prepared by applying only a calcination process under an air atmosphere at 400 ° C. for 4 hours.

Table 1 below shows the physical properties of the titania carrier used in the present invention.

TABLE 1

Titania Anatase: Rutile (%:%) Specific surface area (m ² / g) Average particle size (μm) TiO ₂ (A) 100: 0 85.84 1.255 TiO ₂ (B) 100: 0 344.72 1.365 TiO ₂ (C) 100: 0 76.65 1.195 TiO ₂ (D) 100: 0 84.31 1.180 TiO ₂ (E) 100: 0 96.05 1.42 TiO ₂ (F) 100: 0 249.26 1.285 TiO ₂ (G) 100: 0 258.88 1.195 TiO ₂ (H) 100: 0 11.02 1.76

Example of manufacture

In the present invention, the heat treatment of the catalyst was further applied in the presence of a reducing gas in order to prepare a highly active formaldehyde removal catalyst at room temperature. Details are as follows.

The sample fired by the above preparation was reduced at 600 ° C. for 1 hour using 30% hydrogen / air gas. In this case, a tubular calciner is used so that the reducing gas is sufficiently in contact with the catalyst. The sample obtained by this method was used by sieving with 40-50 mesh.

The above preparation examples and preparation examples are summarized in Table 2 below.

TABLE 2

division Manufacture method Production Example Wet evaporation drying method
(Supporting 1 wt% platinum chloride → drying → reduction → firing) Example of manufacture 1% by weight of platinum chloride → dried → reduced → calcined → reduced

Comparative Preparation Example 1

In order to analyze the effect of the re-reduction process parameters when applying the re-reduction process to the production of a high activity formaldehyde removal catalyst at room temperature, in the method of the preparation example the catalyst was prepared by the re-reduction temperature in the range of 400 ~ 700 ℃ It was.

Comparative Production Example 2

In order to analyze the effects of re-reduction process parameters when applying a re-reduction process to the production of a high activity formaldehyde removal catalyst at room temperature, the catalyst was prepared by changing the re-reduction time to 0.5 to 4 hours in the method of Preparation Example It was.

Comparative Production Example 3

The preparation of the catalyst for the removal of formaldehyde with high activity at room temperature was carried out by shortening the reduction, calcining and re-reduction process of the above preparation, after carrying out platinum chloride, followed by drying and reduction.

Hereinafter, embodiments of the present invention will be described in detail.

Example 1

In the preparation of the catalyst according to the invention, the final reduction process, the reduction process, has a great influence on the formaldehyde removal activity. In order to evaluate the ability of the oxidation reaction at room temperature, a catalyst was prepared according to the preparation examples and preparation examples using various titania carriers, and formaldehyde removal experiments were performed. The results of comparing formaldehyde conversion at room temperature are shown. 1 is shown. In this case, the temperature of the reactor was maintained at 25 ℃ using a double jacket, the concentration of the supplied formaldehyde was maintained at 20ppm / air, relative humidity 0%, space velocity 60,000hr ^-1 .

The room temperature oxidation reaction of formaldehyde was carried out using a fixed bed reactor, and the formaldehyde used in the experiment was placed in a double jacket containing paraformaldehyde ((CH ₂ O) n: Aldrich Chemical Co.) at 22 ° C and steamed. Formaldehyde is converted into a reactor using a carrier gas. When formaldehyde is oxidized, CO ₂ is generated by Scheme 1. A non-dispersive infrared gas analyzer (ZKJ-2, Fuji Electric Co.) was used to measure the amount of CO ₂ generated.

Referring to FIG. 1, the catalyst according to the preparation example is a catalyst prepared by the basic manufacturing method of the platinum catalyst, and although there is a slight difference in each carrier, formaldehyde removal rate of about 15% or more cannot be expected. On the other hand, it can be seen that the room temperature formaldehyde removal characteristics of the catalyst prepared according to the present invention preparation are enhanced in most catalysts. In particular, the catalyst prepared by the A, B, H titania carrier has a conversion rate of 75% or more, and the formaldehyde removal activity at room temperature was greatly enhanced by the re-reduction process during the catalyst preparation process.

Subsequently, the catalysts prepared according to Preparation Examples and Preparation Examples for TiO ₂ (A) to TiO ₂ (H) carriers according to Table 1 were tested according to the amount of catalyst and the relative humidity concentration. Space velocity of from to to to 60,000hr ^-1, 120,000hr ^-1, and ^-1 with 180,000hr and a relative humidity of 0% and 50% of the experimental conditions carried out in the same conditions as compared to a formaldehyde conversion of at room temperature Table 3 shows.

As shown in the results, in the catalyst prepared according to the preparation example, in view of the relative humidity in the real life of 30 to 60%, the formaldehyde removal characteristics of the catalyst were different from the catalyst at 50% relative humidity, but the activity increased slightly. Able to know. However, in the catalyst prepared according to the preparation example, it can be seen that formaldehyde removal properties are greatly enhanced in the presence of moisture.

In addition, as a result of experiments with varying the space velocity, the catalyst prepared according to the preparation example showed excellent formaldehyde removal characteristics even with a very small amount of catalyst.

Specifically, after preparing the catalyst by adjusting the weight of platinum chloride to 0.5% concentration in the preparation example for the carriers of Table 1, the experiment was carried out according to the catalyst amount and relative humidity concentration and the results are shown in Table 4. As the result, when the content of platinum chloride 0.5% work space velocity 60,000hr ^-1 in the preparation prepared by the exemplary catalysts were reduced in the active removal of formaldehyde extremely small, space velocity 180,000hr ^-1 Again good formaldehyde removal properties.

The catalyst prepared according to the present invention shows excellent formaldehyde removal properties at room temperature even when the weight of platinum chloride is 0.1%. In FIG. 2, the formaldehyde removal characteristics at the relative humidity of 0% and 50% at the space velocity of 60,000hr ⁻¹ were compared with respect to the catalysts according to Preparation Examples and Preparation Examples. As a result, it can be seen that the catalyst prepared according to the preparation example completely removes formaldehyde when the relative humidity is 50%.

Subsequently, in Table 5, platinum chloride was loaded by 1 to 0.05% by weight to prepare a catalyst by the method of the preparation example, and the formaldehyde removal performance was evaluated at room temperature. As can be seen from the results, according to the present invention, it can be seen that even 50% or more of formaldehyde can be removed with a very small amount of platinum of 0.05%.

Therefore, the catalyst prepared according to the present invention can be said to exhibit excellent formaldehyde removal properties at room temperature even in a very small amount, and particularly, even in the case where there is very little expensive platinum used as an active metal, it can be mass-produced. .

In addition, the catalyst prepared by the present invention exhibits excellent formaldehyde removal properties at room temperature regardless of the composition of the titania phase. Table 6 shows the characteristics of formaldehyde removal at room temperature using titania carriers with different ratios of anatase and rutile under conditions of space velocity 60,000hr ^-1 and relative humidity 50%.

[Table 3]

Catalyst name Formaldehyde Conversion Rate (%) Production Example Example of manufacture Space velocity
60,000hr ^-1 Space velocity
60,000hr ^-1 Space velocity
120,000hr ^-1 Space velocity
180,000hr ^-1 Relative humidity
0% Relative humidity
50% Relative humidity
0% Relative humidity
50% Relative humidity
0% Relative humidity
50% Relative humidity
0% Relative humidity
50% Pt [1] / TiO ₂ (A) 10.13 35.17 91.6 100 75 100 20 100 Pt [1] / TiO ₂ (B) 3.35 5.49 99.09 100 86.96 98.69 47.29 96.55 Pt [1] / TiO ₂ (C) 0 13.36 0 99.49 0 79.59 0 18.42 Pt [1] / TiO ₂ (D) 4.39 8.21 41.41 100 11.16 77.21 0 41.58 Pt [1] / TiO ₂ (E) 5.29 11.34 25.99 96.4 5.65 63.48 0 45.91 Pt [1] / TiO ₂ (F) 3.74 21.96 2.94 100 0 100 0 100 Pt [1] / TiO ₂ (G) 1.91 9.09 33.5 100 10.6 100 4.55 100 Pt [1] / TiO ₂ (H) 12.5 31.02 76.47 100 34.97 90.48 0 100

[Table 4]

Catalyst name Formaldehyde Conversion Rate (%) Example of manufacture Space Speed 60,000hr ^-1 Space Speed 180,000hr ^-1 Relative Humidity 0% Relative Humidity 50% Relative Humidity 0% Relative Humidity 50% Pt [0.5] / TiO ₂ (A) 10.83 100 4.93 39.01 Pt [0.5] / TiO ₂ (B) 60.10 100 28.19 95.59 Pt [0.5] / TiO ₂ (C) 0 100 0 100 Pt [0.5] / TiO ₂ (D) 0 54.11 0 13 Pt [0.5] / TiO ₂ (E) 0 100 0 39.02 Pt [0.5] / TiO ₂ (F) 9.90 100 0 100 Pt [0.5] / TiO ₂ (G) 0 79.79 0 7.41 Pt [0.5] / TiO ₂ (H) 98.64 100 21.39 60.46

 TABLE 5

Catalyst name Formaldehyde conversion rate of the preparation example (%)
(Space Speed 60,000hr ^-1 , Relative Humidity 50%) Pt [1] / TiO ₂ (G) 100 Pt [0.5] / TiO ₂ (G) 100 Pt [0.1] / TiO ₂ (G) 100 Pt [0.05] / TiO ₂ (G) 54.11

TABLE 6

Catalyst name Formaldehyde conversion rate of the preparation example (%)
(Space Speed 60,000hr ^-1 , Relative Humidity 50%) Pt [1] / TiO ₂ (anatase 100) 100 Pt [1] / TiO ₂ (rutile 100) 100 Pt [1] / TiO ₂ (anatase 75: rutile 25) 100

Example 2

Formaldehyde removal characteristics experiment at room temperature was performed on the reduction catalyst prepared in Comparative Preparation Example 2 above. The experiment was carried out using a Pt / TiO ₂ (B) catalyst prepared by varying the re-reduction time in the final process, the concentration of formaldehyde supplied was not 20ppm / air, moisture was supplied, the space velocity is 60,000hr ^-1 Was maintained.

Formaldehyde removal performance evaluation results are shown in FIG. As shown in FIG. 3, the reduction rate of formaldehyde is increased up to 1 hour, and as the reduction time is increased, the efficiency decreases and increases again. Therefore, according to the present invention it can be produced an optimal catalyst in a 1 hour re-reduction process.

Example 3

Formaldehyde removal characteristics experiments at room temperature were performed on the reduction catalyst prepared in Comparative Preparation Example 1 above. The experiment was performed using Pt / TiO ₂ (B) catalyst prepared by varying the re-reduction temperature in the final process. The concentration of formaldehyde supplied was 20 ppm / air and no water, and the space velocity was 60,000 ^{hr -1.} Was maintained.

Formaldehyde removal performance evaluation results are shown in FIG. As shown in FIG. 4, when the reduction temperature is 600 ° C., the maximum formaldehyde removal property is shown. Therefore, in the case of the present invention, the reduction temperature is suitably 600 ° C. As shown in FIG.

Example 4

XPS (VG Scientific Co. trade name ESCALAB 201) was used to measure the type and distribution of oxygen compounds and titanium oxide formed on the surface of the catalyst.

Typically, XPS analysis results of O 1s of the TiO ₂ (B) carrier are shown in FIG. 5A and XPS analysis results of Ti 2p in FIG. 5B, respectively. Referring to Figure 5a, the oxygen present on the surface of the carrier is a Ti-O bond of the lattice oxygen and OH bond and CO bond of the surface adsorption oxygen appears. In addition, referring to FIG. 5B, only Ti ⁴⁺ is present in the Ti peak of the titania carrier only.

XPS analysis to count the number of atoms per unit volume of the lattice oxygen (atoms / cm ³⁾ each carrier using the results are shown in Figure 6a the relationship between the formaldehyde conversion. Referring to this, it was confirmed that there are differences in the amount of lattice oxygen, formaldehyde removed from the volume and the space velocity of the lattice oxygen 60,000hr ^-1 and ^-1 120,000hr activity and that the linear relationship according to the type of carrier. That is, it can be seen that the carrier of the catalyst having excellent ability to remove formaldehyde also contains a lot of lattice oxygen in the carrier.

In addition, the atomic molar ratio of O / Ti was determined from the number of atoms of oxygen obtained in FIG. 6A compared with the number of atoms of Ti ⁴⁺ 2p _3/2 of the support. The relationship between these and formaldehyde reaction activity is shown in FIG. 6B. The ratio of formaldehyde conversion and the O / Ti molar ratio of the carrier at the space velocity of 60,000hr ^-1 and 120,000hr ^-1 is different from each other. In other words, in order to have the ability to remove formaldehyde at room temperature, the O / Ti molar ratio of the carrier should be present at about 1.8 or more.

1 is a diagram showing the conversion rate of formaldehyde at room temperature of the catalyst prepared by the method of Preparation Example and Preparation Example;

2 is a view showing the conversion rate of formaldehyde according to the relative humidity of the catalyst prepared by the method of Preparation Example and Preparation Example,

3 is a view showing the conversion rate of formaldehyde according to the reduction time of the catalyst prepared by the method of Comparative Preparation Example 2,

4 is a view showing the conversion rate of formaldehyde according to the reduction temperature of the catalyst prepared by the method of Comparative Preparation Example 1,

5A and 5B show XPS analysis results of TiO ₂ (B) carriers, respectively.

6A and 6B show formaldehyde conversion rates with respect to molar ratios of lattice oxygen and O / Ti, respectively, using XPS analysis results of TiO ₂ carriers AH.

Claims (17)

In the method of producing a platinum / titania catalyst by sequentially supporting, drying, reducing and calcining using a platinum precursor and a titania carrier, And a re-reduction step for controlling the oxidation value of platinum to +2 or +0 after the firing step. The method of claim 1, The titania carrier has a lattice oxygen of 3000 to 5000 (atomic number / cm 3), and the molar ratio of oxygen to titanium is 1.7 to 1.95. The method of claim 1, The platinum precursor is platinum chloride (PtCl ₄ ) or tetra-amine platinum nitrate (Pt (NH ₃ ) ₄ (NO ₃ ) ₂ ) characterized in that the platinum / titania catalyst production method. The method of claim 1, The re-reduction process is platinum / titania catalyst production method characterized in that the calcined sample is maintained for 0.5 to 5 hours at a temperature of 500 ~ 800 ℃ in a furnace of a reducing atmosphere. The method of claim 4, wherein The furnace is any one selected from a tube (tube) furnace, convection (convection) furnace, grate type furnace, characterized in that the platinum / titania catalyst production method. The method of claim 4, wherein The reducing atmosphere is platinum / titania catalyst production method characterized in that formed by a gas containing hydrogen, ammonia, methane. The method of claim 6, The gas is a platinum / titania catalyst production method, characterized in that 1 to 50% composition. A method for removing formaldehyde by passing air containing formaldehyde through a platinum / titania catalyst prepared according to any one of claims 1 to 7. The method of claim 8, The platinum / titania catalyst is a method for removing formaldehyde, characterized in that the extrusion process as a granular or monolith (monolith). The method of claim 8, The platinum / titania catalyst is a method for removing formaldehyde, characterized in that the coating on any one structure selected from metal plates, metal fibers, ceramic filters, or honeycomb. The method of claim 8, Method for removing formaldehyde, characterized in that carried out in a reactor maintained at a temperature of 20 ~ 100 ℃ and a space velocity (GHSV) of 1,000 ~ 200,000hr ^-1 . The method of claim 9, Particles of the platinum / titania catalyst is a method for removing formaldehyde, characterized in that 1 ~ 10㎛. The method of claim 11, Relative humidity in the reactor is a method for removing formaldehyde, characterized in that 0 to 95%. A platinum / titania catalyst prepared by supporting a platinum precursor on a titania carrier having a lattice oxygen of 3000 to 5000 atoms / cm 3 and a molar ratio of O / Ti of 1.7 to 1.95. The method of claim 14, The platinum precursor is platinum / titania catalyst, characterized in that 0.05 to 1% by weight of platinum oxide based on the weight of titania. The method of claim 14, The titania carrier is a platinum / titania catalyst having an anatase and rutile ratio of 0: 100 to 100: 0, a specific surface area of 10 to 350 m ² / g, and a particle size of 1.0 to 2.0 μm. Platinum / titania catalysts prepared by the process according to claim 1.

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