KR101537269B1 - Pt/TiO2 CATALYST FOR CONCURRENTLY DOCOMPOSING formaldehyde AND CARBON MONOXIDE AND MANUFACTURING METHOD THEREOF - Google Patents

Abstract

The present invention relates to a platinum/titania catalyst for concurrently decomposing formaldehyde and carbon monoxide and a method of manufacturing the same. The method comprises the steps of: impregnating titania carrier into platinum precursor solution; performing drying and firing processes for the resultant material, and performing heat treatment under reducing atmosphere after the firing process, wherein the titania carrier has the grid size of 175 nm. A platinum/titania catalyst manufactured by the method has the amount of active oxygen of not less than 100 μmol, and can concurrently decompose formaldehyde and carbon monoxide contained in contaminated air at a higher rate even at room temperature. Furthermore, a method of manufacturing a platinum/titania catalyst can also be performed at reduced costs.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a platinum / titania catalyst capable of simultaneously removing formaldehyde and carbon monoxide, and a method for producing the same. BACKGROUND ART < RTI ID = 0.0 >

TECHNICAL FIELD The present invention relates to a platinum / titania catalyst and a method for producing the same, and more particularly, to a catalyst capable of removing harmful substances such as formaldehyde and carbon monoxide at room temperature, and a method for producing the same.

In recent years, interest in indoor pollution has been increasing, and harmful substances, especially formaldehyde and carbon monoxide, are one of the most problematic substances.

Formaldehyde is the major cause of building syndrome, sick house syndrome, and chemical hypersensitivity. It occupies the largest amount of aldehydes in the room. It is well known that exposure to formaldehyde causes eye irritation, tearing, irritation of the upper airway, asthma attack, convulsions, vomiting, diarrhea, and more sensitive effects to vulnerable groups such as pregnant women, children and the elderly have.

The generation of formaldehyde occurs in a large amount in insulation materials, fibers, chests, sinks, flooring materials, heating fuel combustion processes, smoking, household goods, medicines and adhesives. Most of these materials are used indoors. Considering that you live indoors, the risk and impact can be considered serious.

On the other hand, accidents caused by gas poisoning frequently occur in a sauna or a steam room in a bathroom recently, and the gas which is a problem at this time is mainly known as an accident caused by carbon monoxide poisoning. Carbon monoxide causes problems such as vomiting and dizziness at low concentrations, but it also causes death if it is exposed at a high concentration for a certain period of time, which is a serious social problem.

A variety of techniques are known for treating and decomposing pollutants present in the interior, among which the catalytic oxidation method is known to be the best method in that it can directly convert pollutants into harmless substances to humans. However, in the case of the conventional method using a catalyst, additional energy such as heat energy or light energy is required, so that there are many restrictions on its use.

Korean Patent Laid-Open Publication No. 2010-0037499 discloses a method for producing a platinum / titania catalyst and a method for removing formaldehyde using the catalyst and the catalyst. The more the amount of lattice oxygen in the catalyst carrier is, the more the removal ability of formaldehyde . However, it is unreasonable to understand that the lattice oxygen, which exhibits the behavior of oxygen at temperatures above 400 ° C, affects the reaction. In the case of the proposed lattice oxygen and O / Ti molar ratios, quantitative It is insufficient to represent the amount of phosphorus.

Korean Patent Laid-Open Publication No. 2012-0135368 discloses a palladium / titania catalyst, which is not a platinum / titania catalyst, and a production method thereof, and discloses a technique for oxidizing formaldehyde, carbon monoxide and hydrogen alone. However, the above-mentioned Patent Publication No. 2012-0135368 does not mention factors that affect the reaction efficiency.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a platinum / titania catalyst capable of simultaneously removing formaldehyde and carbon monoxide at room temperature .

The recognition of the above-mentioned problems and the gist of the present invention based thereon are as follows.

(1) A process for producing a platinum / titania catalyst comprising a step of carrying a titania carrier in an aqueous solution of a platinum precursor, followed by drying and firing, wherein the titania carrier has a lattice size of 175 nm or less, Further comprising a step of heat treating the platinum / titania catalyst.

(2) the platinum precursor, platinum chloride (PtCl _4), tetra-amine platinum nitrate (Pt (NH _{3) 4} (NO _{3) 2),} hydroxide, platinum (Pt (OH) ₂₎ hydroxyl platinum, (( NH ₂ -CH ₂ CH ₂ -OH) ₂ Pt (OH) ₆ ). The method for producing a platinum / titania catalyst according to the above (1)

(3) The process for producing a platinum / titania catalyst according to (1), wherein the platinum precursor is adjusted to 0.1 to 1 part by weight based on 100 parts by weight of the titania carrier.

(4) The process for producing a platinum / titania catalyst according to the above (1), wherein the heat treatment in the reducing atmosphere is performed at a temperature of 500 to 700 ° C for 0.5 to 2 hours.

(5) The platinum / titania catalyst according to any one of (1) to (4), wherein the amount of active oxygen is 100 μmol or more and has simultaneous decomposition ability to formaldehyde and carbon monoxide.

According to the present invention, it is possible to provide a platinum / titania catalyst having a high concentration of active oxygen even with a relatively small amount of active metal. When such a catalyst is used, the catalyst production cost is reduced and formaldehyde Carbon monoxide can be simultaneously removed with high resolution.

1 is a graph showing the amount of active oxygen of a catalyst according to Example 1 of the present invention.
2 is a graph showing the relationship between the specific surface area of the titania carrier and the amount of active oxygen in the catalyst according to Example 2 of the present invention.
3 is a graph showing the correlation between the crystal size of the titania carrier and the amount of active oxygen in the catalyst according to Example 2 of the present invention.
4 is a graph showing XPS analysis results of the titania carrier according to Example 3 of the present invention.
FIG. 5 is a graph showing the correlation between the oxygen concentration and the active oxygen amount of the titania carrier according to Example 3 of the present invention. FIG.
FIG. 6 is a graph showing the oxidation ability of formaldehyde at room temperature at the catalyst according to Example 4 of the present invention. FIG.
7 is a graph showing the correlation between the amount of active oxygen and the oxidizing ability of formaldehyde at room temperature in the catalyst according to Example 5 of the present invention.

Hereinafter, technical features of the present invention will be described in detail so that those skilled in the art will readily understand the present invention.

The production of the platinum / titania catalyst according to the present invention basically involves carrying a platinum precursor on a titania carrier, and drying and firing the catalyst.

The supporting process is carried out by mixing a predetermined amount of the platinum precursor aqueous solution with a support to form a slurry.

The type of the platinum precursor is not particularly limited, for example, platinum chloride (PtCl _4), tetra-amine platinum nitrate _{(Pt (NH 3) 4 (} NO 3) 2), hydroxide, platinum (Pt (OH) _2), hydroxy (NH ₂ -CH ₂ CH ₂ -OH) ₂ Pt (OH) ₆ ).

The amount of the platinum precursor may be selected in the range of 0.1 to 1 part by weight based on 100 parts by weight of the titania support. In terms of the overall catalyst cost, the smaller the amount of the active metal is, the more advantageous the catalytic activity required can be derived. The present invention can induce the required catalytic activity even with a relatively small amount of active metal by controlling the active oxygen of the catalyst as described later.

The titania (TiO ₂ ) support is preferably selected to have a lattice size of less than 175 nm to increase the amount of 'active oxygen' of the catalyst prepared as described below.

The titania carrier is a typical reducing carrier. As described later, according to the present invention, a new active site of Pt-Ov-Ti ³⁺ is generated due to interaction with platinum during heat treatment in a reducing atmosphere at a temperature of 500 ° C or higher. Since the interaction between the platinum and the titania carrier becomes stronger as the lattice size of the titania becomes smaller, the activity point of Pt-Ov-Ti ^{3 +} is increased in the case of titania having a small lattice size, do.

The slurry prepared by quantitatively charging a titania carrier into an aqueous solution of platinum precursor is stirred and heated using a vacuum evaporator, and dried by a method of completely removing moisture from the micropores using a dryer. Subsequently, the dried sample is calcined in an air atmosphere to form a catalyst.

The production of the platinum / titania catalyst according to the present invention is characterized by further comprising a step of controlling the oxygen transfer capability of the active metal after firing. This process is performed by heat treatment of the calcined catalyst in a reducing atmosphere, and the interaction of Pt, which is an active metal, with titania, which is a carrier, enhances oxygen transfer ability through the generation of a new active site of Pt-Ov-Ti ^{3 +} .

The heat treatment in the reducing atmosphere is preferably performed at a temperature of 500 ° C to 700 ° C for 0.5 to 2 hours. If the heat treatment temperature is less than 500 ° C, it is not sufficient to induce interaction between platinum and titania for generating a new active site. If the heat treatment temperature is higher than 700 ° C, agglomeration of the active metal may occur. Similarly, if the heat treatment time is less than 0.2, it is not sufficient to induce the interaction between platinum and titania, and if it exceeds 2 hours, the active metal may agglomerate.

In this case, the reducing atmosphere may be a 1 to 50% composition gas containing hydrogen, ammonia, methane, or the like.

The platinum / titania catalyst according to the present invention produced as described above is characterized in that the amount of 'active oxygen' as a factor that can substantially contribute to the decomposition reaction of the pollutant by the catalyst at a room temperature condition of about 25 ° C is in a predetermined range or more do.

As used herein, the term 'active oxygen' refers to oxygen that can be easily adsorbed to and desorbed from a catalyst at room temperature, thereby substantially participating in the decomposition of contaminants. The amount of 'active oxygen' ) Analysis.

In this case, in order to have effective simultaneous decomposing ability at room temperature on formaldehyde and carbon monoxide as pollutants, the amount of 'active oxygen' is preferably 100 μmol or more.

The platinum / titania catalyst prepared according to the present invention can be processed into a bulk form such as powder, honeycomb, slate, pellet or the like, and can be coated on the surface of a metal or ceramic plate, fiber, filter or honeycomb structure .

Hereinafter, the present invention will be described in more detail based on Preparation Examples and Examples of the catalyst according to the present invention. However, these preparation examples and examples are provided for the purpose of illustrating the present invention and should not be construed as limiting the scope of the present invention.

Manufacturing example  1: Preparation of catalyst

Platinum chloride (PtCl ₄ : a trade name of Aldrich Chemical Co.), tetra-amine platinum nitrate (Pt (NH ₃ ) ₄ (NO ₃ ) ₂ : Aldrich Chemical Co. in the trade name) or hydroxyl platinum _{((NH 2 -CH 2 CH 2} -OH) 2 Pt (OH) 6), the platinum precursor is selected from any one of a platinum hydroxide (Pt (OH) ₂₎ 0.1 to 1 part by weight based on 100 parts by weight of the titania carrier is dissolved in distilled water at room temperature. In this case, when platinum chloride (PtCl ₄ ) is used as the platinum precursor, the temperature of the distilled water is raised to 60 ° C to dissolve it.

Subsequently, each of the titania carriers according to the following Table 1 was added in a predetermined amount to an aqueous solution in which the platinum precursor was dissolved to prepare slurry form.

Titania Anatase: rutile (%:%) Specific surface area (m ² / g) Grid Size (nm) TiO ₂ (A) 100: 0 276.04 85.33 TiO ₂ (B) 100: 0 249.26 80.67 TiO ₂ (C) 100: 0 76.65 419 TiO ₂ (D) 100: 0 11.01 155.5 TiO ₂ (E) 100: 0 288.72 189 TiO ₂ (F) 100: 0 344.72 201 TiO ₂ (G) 0: 100 65.24 221.5 TiO ₂ (H) 0: 100 4.4 122.67

Next, the prepared slurry was stirred and heated at 70 ° C using a vacuum evaporator, and dried at 80-120 ° C for 24 hours or longer to completely remove moisture contained in the micropores.

Next, if platinum chloride was used as a precursor of platinum, the catalyst was removed from the catalyst by using 30% hydrogen / nitrogen gas at 300 ° C. for 3 hours, and the calcination process was performed at 400 ° C. for 4 hours in an air atmosphere. On the other hand, when tetra-amine platinum nitrate or hydroxyl platinum not containing chlorine was used as a precursor of platinum, only the calcination process was performed at 400 ° C for 4 hours in an air atmosphere.

Finally, after completion of the calcination process, the sample was subjected to reduction treatment at a temperature of 600 ° C in a 30% hydrogen / nitrogen atmosphere for 1 hour to prepare a catalyst.

Example  1: Measurement of active oxygen content

In the present invention, the amount of active oxygen of the catalyst was measured as the property of the catalyst which can substantially contribute to the decomposition reaction at room temperature for the pollutant.

The active oxygen amount of the catalyst can be measured using TPO (Temperature Programmed Oxidation) (hereinafter referred to as " TPO ") analysis. The TPO analysis is based on the difference between the oxygen concentration in the reference gas entering the detector without passing through the catalyst bed and the oxygen concentration in the reaction gas passing through the catalyst bed and reacting with the catalyst and entering the sensor To determine the amount of oxygen consumed. The amount of consumed oxygen means the amount of oxygen adsorbed on the catalyst and means the amount of active oxygen that is easily adsorbed and desorbed at room temperature.

Specifically, 2920 Autochem (Micromeritics) was used, and TPO analysis was performed using a TCD (Thermal Conductivity Detector) as a detector for concentration measurement. The procedure of the analysis is as follows. First, 0.25 g of catalyst pulverized to a particle size of 100 μm or less is charged. First, argon (Ar) at 50 cc / min is flowed. The temperature is raised to 120 ° C. at a rate of 10 ° C./min. Impurities were removed and the catalyst was activated. Thereafter, the temperature was dropped to 30 ° C., and the amount of oxygen consumed by TCD was observed while continuously flowing 1.5 vol.% Oxygen / nitrogen.

According to the above method, the amount of active oxygen for the catalyst according to the titania carrier according to Table 1 was measured and is summarized in Table 2 below.

division TiO ₂ (A) TiO ₂ (B) TiO ₂ (C) TiO ₂ (D) Active oxygen amount / μmol 128.93 77.37 47.81 119.19 division TiO ₂ (E) TiO ₂ (F) TiO ₂ (G) TiO ₂ (H) Active oxygen amount / μmol 72.89 63.57 53.8 115.98

Referring to Table 2, it was confirmed that each platinum / titania catalyst showed different amounts of active oxygen depending on the type of titania carrier used at room temperature. In this case, the larger the amount of active oxygen, the easier the catalyst can deliver and receive oxygen at room temperature conditions.

Meanwhile, the amount of active oxygen of the catalyst prepared using TiO ₂ (A) in Table 1 is shown in FIG. 1. 1, at a room temperature condition, 1.5 vol. It can be confirmed that a decreasing peak is generated simultaneously with the% oxygen / nitrogen injection. In the case of such a decrease peak, it means oxygen adsorbed on the catalyst, and the area of the decrease peak indicates the amount of 'active oxygen' capable of adsorption and desorption at room temperature.

Example  2: Titania Carrier Properties (lattice size) and  Correlation of active oxygen amount

The correlation between the amount of active oxygen of the catalyst according to the present invention and the physical properties of the titania carrier was examined.

BET (Micromeritics Co., trade name ASAP 2010C) was used to measure the specific surface area of titania, and XRD (PANalytical Co. product name X'Pert PRO MRD) was used to measure the crystal size of titania.

The correlation between the specific surface area of titania and the active oxygen amount is shown in FIG. 2, and the correlation between the crystal size of titania and the amount of active oxygen is shown in FIG. 2 and 3, although the amount of active oxygen did not show a correlation with the specific surface area of the titania carrier, it was confirmed that the amount of active oxygen increased with decreasing crystal size of titania.

Example  3: Comparison of active oxygen content and lattice oxygen content

As the property of the catalyst, the amount of active oxygen of the catalyst disclosed by the present invention (i.e., the amount of oxygen consumed in the TPO analysis) was compared with the lattice oxygen amount of a conventionally known catalyst.

XPS (VG Scientific Co. product name ESCALAB 201) was used to measure the type and distribution of oxygen compounds and titanium oxides formed on the surface of the catalyst. Typically, XPS analysis results of O1s of the TiO ₂ (A) carrier are shown in FIG. Referring to FIG. 4, the oxygen present on the surface of the carrier shows a lattice oxygen Ti-O bond and a surface adsorption oxygen OH bond.

FIG. 5 shows the relationship between oxygen consumption and the amount of atoms (cm ³ / cm ³ ) per unit volume of lattice oxygen per carrier using XPS analysis results. Referring to FIG. 5, it was confirmed that there was no particular correlation between the number of atoms (atoms / cm ³ ) per unit volume of lattice oxygen present per carrier and the amount of active oxygen (μmol).

Example  4: formaldehyde room temperature Oxidative ability  evaluation

The platinum / titania catalyst prepared according to Preparation Example 1 was used to evaluate formaldehyde oxidation ability at room temperature and is shown in FIG.

 [Experimental Conditions]

The temperature of the catalytic reactor was maintained at 25 ° C using a double jacket. The injected gas was a mixed gas containing 25 ppm of formaldehyde and 55% relative humidity under an air atmosphere. The space velocity was 240,000 hr ^-1 and 360,000 hr ^-1 hr ^{- 1} . The formaldehyde used in the experiment was placed in a double jacket maintained at 20 ° C, paraformaldehyde ((CH ₂ O) n: trade name of Aldrich Chemical Co.) The formaldehyde was fed into the reactor using a carrier gas. For reference, the space velocity is expressed as a ratio of the amount of catalyst (volume) to the total gas flow rate (volume) as an index quantitatively indicating the amount of gas to be treated by the catalyst. For example, if the space velocity is high, it means that the amount of the process gas per unit volume of the catalyst is large.

[How to measure]

When formaldehyde is oxidized, CO ₂ is produced according to Scheme 1 and a non-dispersive infrared gas analyzer (ZKJ-2, Fuji Electric Co.) was used to measure the amount of CO ₂ produced. In this case, a detection tube (91, Gas Tec. Co.) was used at the rear end of the fixed bed reactor to measure the presence of unreacted formaldehyde.

(Scheme 1)

HCHO + O _{2 -} > CO ₂ + H ₂ O

Referring to Figure 6, the catalyst prepared in accordance with the invention the space velocity ^-1 240,000hr conditions, that has an excellent oxidizing ability of 100% formaldehyde at room temperature with a space velocity ^-1 360,000hr in excellent oxidizing ability formaldehyde at room temperature greater than 80% Respectively.

Subsequently, the catalyst was prepared in the same manner as in Preparation Example 1 except that the amount of platinum relative to 100 parts by weight of the titania carrier was varied in the range of 0.1 to 1 part by weight. Then, formaldehyde was oxidized at room temperature at 60,000 hr -1, Table 3 summarizes the results. As a result, it was confirmed that 0.1 part by weight of a catalyst having a very small amount of active metal (platinum) had a normal oxidizing ability of formaldehyde at room temperature of 50% or more.

Platinum weight _{Pt [1] / TiO 2 (} A) _{Pt [0.5] / TiO 2 (} A) _{Pt [0.1] / TiO 2 (} A) Formaldehyde conversion (%) 100 100 55

Example  5: The amount of active oxygen and the formaldehyde temperature Oxidative  correlation

The correlation between the amount of active oxygen of the platinum / titania catalyst and the oxidation ability of formaldehyde at room temperature, which was confirmed through Example 4, as shown in Example 1, is shown in FIG.

Referring to FIG. 7, as the amount of active oxygen of the catalyst increases, formaldehyde has excellent ability to oxidize at room temperature. In the case of catalysts having an active oxygen amount of 100 μmol or more, 70% or more formaldehyde is oxidized at room temperature. In addition, the highest platinum / titania catalyst with an active oxygen content of 128.93 μmol was found to be the best at 89% for formaldehyde at room temperature.

Example  6: Normal temperature of carbon monoxide Oxidative ability  evaluation

Among the platinum / titania catalysts prepared according to Preparation Example 1, the platinum / titania catalysts having the largest amount of active oxygen in Example 1 and superior in the ability to oxidize formaldehyde at room temperature in Example 4 were selected to evaluate the carbon monoxide oxidizing ability at room temperature. Table 4 shows the results.

 [Experimental Conditions]

The temperature of the catalytic reactor was maintained at 25 ℃ by using a double jacket. The gas was injected under a nitrogen atmosphere with a mixture gas containing 250 ppm carbon monoxide, 21% oxygen and 55% relative humidity. The space velocity was 120,000 hr ^{- 1} to 60,000 hr ^{- 1} .

[How to measure]

A fixed - bed reactor was used for the oxidation reaction of carbon monoxide at room temperature. When carbon monoxide is oxidized, CO ₂ is produced by the reaction scheme 2. A non-dispersive infrared gas analyzer (ZKJ-2, Fuji Electric Co.) was used to measure the amount of CO ₂ produced and unreacted CO.

(Scheme 2)

2CO + O ₂ ? 2CO ₂

Space velocity (hr ^-1 ) 120,000 90,000 60,000 Carbon monoxide conversion (%) 81 86.6 91.2

As shown in Table 3, it was confirmed that the platinum / titania catalyst having excellent formaldehyde room temperature oxidizing ability also had excellent carbon monoxide oxidizing ability at room temperature of 80% or more.

Example  7: Normal temperature for formaldehyde and carbon monoxide Oxidative ability  evaluation

The platinum / titania catalyst of formaldehyde and carbon monoxide was simultaneously produced at the same time by using platinum / titania catalyst having the largest amount of active oxygen in Example 1 and showing the most excellent formaldehyde room temperature oxidizing ability and carbon monoxide room temperature oxidizing ability in each of Example 4 and Example 6 The oxidative ability in the case of injection was evaluated, and the results are shown in Table 5 below.

[Experimental Conditions]

The temperature of the catalytic reactor was maintained at 25 ° C. by using a double jacket. The gas to be injected was a mixed gas containing 25 ppm of formaldehyde, 250 ppm of carbon monoxide, 21% of oxygen and 55% The speed was maintained at 45,000 and 60,000 hr ^{- 1} .

[How to measure]

A fixed - bed reactor was used for the oxidation reaction of formaldehyde and carbon monoxide at room temperature. When formaldehyde and carbon monoxide are oxidized, CO ₂ is produced according to Reaction 1 and Reaction 2, and a non-dispersive IR gas analyzer (ZKJ-2, Fuji Electric Co.) is used to measure the amount of CO ₂ produced and unreacted CO. Respectively. In this case, a detection tube (91, Gas Tec. Co.) was used at the rear end of the fixed bed reactor to measure the presence of unreacted formaldehyde.

Space velocity (hr ^-1 ) 60,000 45,000 Formaldehyde conversion (%) 100 100 Carbon monoxide conversion (%) 91.2 100

Referring to Table 4, a space velocity of 60,000hr ^- in the condition of ¹ showed 90% or more of formaldehyde and carbon monoxide at room temperature oxidizing ability 45,000hr ^-1 condition was confirmed two target Sikkim complete oxidation of all materials.

From the above, in the case of a catalyst prepared by adding a heat treatment process in a reducing atmosphere using a titania carrier having a small lattice size, since the amount of 'active oxygen' in the catalyst is increased, formaldehyde and carbon monoxide are simultaneously .

Claims (5)

A method for producing a platinum / titania catalyst comprising a step of carrying a titania carrier on an aqueous solution of a platinum precursor, followed by drying and calcining,
Wherein the titania carrier has a lattice size of 175 nm or less and further comprises a heat treatment in a reducing atmosphere after the calcination step.
The method of claim 1 wherein the platinum precursor, platinum chloride (PtCl _4), tetra-amine platinum nitrate _{(Pt (NH 3) 4 (} NO 3) 2), hydroxide, platinum (Pt (OH) _2), hydroxyl Wherein the catalyst is at least one selected from platinum ((NH ₂ -CH ₂ CH ₂ -OH) ₂ Pt (OH) ₆ ).
The method of claim 1, wherein the platinum precursor is adjusted to 0.1 to 1 part by weight based on 100 parts by weight of the titania support.
The method for producing a platinum / titania catalyst according to claim 1, wherein the heat treatment in the reducing atmosphere is performed at a temperature of 500 to 700 ° C for 0.5 to 2 hours.
5. A platinum / titania catalyst according to any one of claims 1 to 4, characterized in that the amount of active oxygen is 100 占 퐉 ol or more and has simultaneous decomposition ability to formaldehyde and carbon monoxide.

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