TW201417875A - Catalyst for decomposing volatile organic compounds and preparation method thereof - Google Patents

Abstract

The present invention provides a catalyst for decomposing volatile organic compounds comprising a support having a porous structure; a plurality of active units attached to the support are composed of at least one noble metal, at least one transition metal oxide or a mixture thereof Forming and catalyzing the decomposition of the volatile organic compounds; and a plurality of capture units bonded to the support and each capture unit containing at least one functional group capable of generating an attractive or bonded bond with the volatile organic material. The present invention also provides a process for preparing a catalyst for decomposing volatile organic compounds as described above. The catalyst continuously and quickly removes volatile organic compounds and can be regenerated on-site without the need for additional regeneration systems.

Description

Catalyst for decomposing volatile organic compounds and preparation method thereof

The present invention relates to a catalyst, and more particularly to a catalyst for decomposing volatile organic compounds.

In the current lifestyle, people spend more and more time indoors, and are slowly dispersed from interior materials such as interior building materials, surface coating materials, adhesives, caulks, floor mats and wallpapers. Volatile organic compounds (VOCs), such as formaldehyde, can have a great adverse effect on indoor air quality and cause harm to the human body. Therefore, improving indoor air quality by removing volatile organic compounds has become an important factor that modern people cannot ignore. issue.

Traditional materials for removing volatile organic compounds can be classified into two types: adsorption type and decomposition type. The adsorbed material utilizes the adsorption capacity of the material to adsorb volatile organic compounds to reduce the content of volatile organic compounds in air or solution. Referring to FIG. 1, a material for adsorbing volatile organic compounds has a carrier 10 and a plurality of trapping units 12 bonded to the carrier 10. The volatile organic compounds 14 are adsorbed by diffusion or forced convection. And so on the capture unit 12. For example, Saeung et al., Journal of Environmental Sciences 20 (2008) 379 and Afkhami et al., Desalination 281 (2011) 151, disclose the use of a compound having an amine group at the end to modify a porous tantalum or alumina to adsorb air. Or formaldehyde in water. However, the above materials will reach saturation after being adsorbed for a period of time, and then need to be combined with other regeneration systems to continue adsorption, resulting in inconvenience in use.

The decomposed material is a catalyst that will contact the volatilization of the material. Oxidation of organic matter causes decomposition of volatile organic compounds. Referring to Fig. 2, a conventional catalyst for decomposing volatile organic compounds has a carrier 20 and a plurality of active units 21 attached to the carrier 20, and the volatile organic compounds 24 are diffused or forced to convect and The active unit 21 is contacted, and the volatile organic substance 24 is catalyzed by the active unit 21 to undergo an oxidation reaction, and the volatile organic substance 24 is decomposed and removed. For example, as disclosed in U.S. Patent No. 5,882,416, U.S. Patent No. 6,458,741 B1, and the Republic of China Patent Publication No. I293036, the volatile organic compounds are decomposed and decomposed by metal or metal oxide catalyst. However, if the concentration of volatile organic compounds in the environment is not high (such as indoor environment), in the objective environment where high temperature and forced convection cannot be provided, the catalyst catalyzes the decomposition of volatile organic compounds due to the low concentration of volatile organic compounds around the catalyst. The rate is very slow and it is difficult to quickly remove volatile organic compounds in a short time.

Generally, when a large amount of volatile organic compounds are processed in the industry, they can be adsorbed and decomposed through the adsorption system and the decomposition system, for example, the Republic of China Patent Publication No. M355751, which rapidly captures volatile organic compounds by adsorbing materials, and then desorbs and concentrates them. Catalyzed by catalyst. However, this system is both complex and bulky and is not suitable for indoor environments or for handling small amounts of volatile organic compounds.

Accordingly, it is an object of the present invention to provide a catalyst for decomposing volatile organic compounds that overcomes the above-described problem of unsustainable or rapid removal of volatile organic compounds, and which does not require subsequent use of other regeneration systems.

Thus, the catalyst for decomposing volatile organic compounds of the present invention comprises a support having a porous structure; a plurality of active units attached to the support, Formed by at least one noble metal, at least one transition metal oxide or a mixture thereof, and capable of catalyzing the decomposition of the volatile organic compound; and a plurality of capture units bonded to the support and each capture unit containing at least one capable of Volatile organic compounds produce attractive or bonded functional groups.

Another object of the present invention is to provide a process for preparing a catalyst for decomposing volatile organic compounds as described above, comprising providing a support having a porous structure; forming a plurality of active units on the support, The active unit is formed from at least one noble metal, at least one transition metal oxide or a mixture thereof, and is capable of catalyzing the decomposition of the volatile organic compound; and bonding a plurality of capture units on the support on which the active units are formed, each A capture unit contains at least one functional group capable of generating an attractive or bonded bond with the volatile organic material.

The effect of the catalyst for decomposing volatile organic compounds in the invention is that the volatile organic compounds are captured by the capturing units, and at the same time, the volatile organic compounds are rapidly decomposed by the active units, thereby effectively improving the long-term use of the catalyst of the present invention. Ability.

Referring to Fig. 3, a preferred embodiment of the catalyst for decomposing volatile organic compounds of the present invention comprises a support 30 having a porous structure; a plurality of active units 31 attached to the support 30 are made of at least one precious metal. Forming at least one transition metal oxide or a mixture thereof, and catalyzing the decomposition of the volatile organic substance 34; and a plurality of capture units 32 bonded to the support 30 and each capture unit 32 containing at least one capable of volatilizing The organic organic matter 34 produces an attractive or bonded functional group.

Preferably, the noble metal is selected from platinum, gold, rhodium or palladium. In this hair In a specific embodiment, the noble metal is platinum.

Preferably, the transition metal oxide is an oxide selected from the group consisting of chromium, cobalt, copper or silver.

Preferably, the support 30 is selected from the group consisting of titanium dioxide, cerium oxide, aluminum oxide, zirconium dioxide, zeolite, cerium oxide, nickel dioxide, ferric oxide, triiron tetroxide, magnesium dioxide. Or a mixture thereof. In a particular embodiment of the invention, the support 30 is titanium dioxide.

Preferably, the functional group is selected from the group consisting of an amine group, a hydroxyl group, a carboxyl group, a sulfate group, a sulfite group or a phosphate group. In a particular embodiment of the invention, the functional group is an amine group.

Preferably, the number of the capturing units 32 bonded to the carrier 30 per unit area is 10 ^-6 to 10 ^-4 mol/m ² .

The present invention provides a method for preparing a catalyst for decomposing volatile organic compounds as described above, comprising: providing a support 30 having a porous structure; forming a plurality of active units 31 on the support 30, the activities Unit 31 is formed from at least one noble metal, at least one transition metal oxide, or a mixture thereof, and is capable of catalyzing the decomposition of the volatile organic compound 34; and a plurality of capture units 32 are bonded to the support 30, each capture unit 32 Containing at least one functional group capable of generating an attractive or bonded bond with the volatile organic compound 34.

Preferably, the active units 31 are formed on the support 30 by an impregnation method, a coprecipitation method, a deposition precipitation method, an ion exchange method, or a chemical vapor deposition method. In a specific embodiment of the invention, the active units 31 are formed on the support 30 by an impregnation method.

Preferably, the active unit is 100 wt% of the weight of the catalyst. The amount of 31 is 0.01 to 10 wt%.

The invention is further described in the following examples, but it should be understood that these examples are for illustrative purposes only and are not to be construed as limiting.

[Example 1]

3 g of titanium dioxide (as a support, purchased from Degussa, model P-25) was placed in a flask, followed by 67.9 μL of an 8 wt% aqueous solution of chloroplatinic acid (H ₂ PtCl ₆ ) was added to the flask, and Drying at 80 ° C to obtain pretreated titanium dioxide. The pretreated titanium dioxide was mixed with 11 mg of sodium borohydride (NaBH ₄ ) and 3.9 mL of water to carry out a reduction reaction for about 4 to 5 hours to obtain a crude product. Finally, centrifugal washing was carried out with deionized water to remove unreacted sodium borohydride, and the crude product was dried at 80 ° C to obtain a titanium oxide support (hereinafter referred to as Pt/TiO ₂ ) containing a platinum metal active unit.

Next, 3 g of Pt/TiO ₂ , 0.3 g of 3-aminopropyltriethoxysilane (hereinafter referred to as APTES as a modifier), 15.6 mL of ethanol and 4.5 mL of nitric acid (0.1) N) was mixed and carried out at a temperature of 70 ° C for 3 hours to obtain a crude product. The crude product was mixed with ethanol and subjected to centrifugal washing to remove unreacted APTES, and then the crude product was taken out and dried at 70 ° C to obtain a catalyst for decomposing volatile organic compounds of Example 1.

[Examples 2 to 6]

The preparation methods of Examples 2 to 6 were substantially the same as those of Example 1, except that the amounts of APTES were adjusted according to the following Table 1, respectively, and finally the catalysts for decomposing volatile organic compounds of Examples 2 to 6 were obtained.

[Comparative Example 1]

The preparation method of Comparative Example 1 was substantially the same as that of Example 1, except that APTES was not modified (i.e., Pt/TiO _{2 was} used as a catalyst for decomposing volatile organic compounds).

[Formaldehyde conversion test]

0.3 g of the catalyst of Example 1 was filled into a catalyst bed reactor, and then formaldehyde gas (concentration of 10 ppm) was introduced into the apparatus, and the gas hourly space was controlled. Velocity, GHSV) is 83000 h ^-1 , and the formaldehyde concentration change before and after the reaction is detected by a direct reading formaldehyde detector (purchased from TRACENOSE, model IAQ-F100), and the formaldehyde conversion rate is calculated by the following formula: The results are shown in Table 1 below. Examples 2 to 6 and Comparative Example 1 were tested in the same manner as above, and the results are also shown in Table 1 below.

[Result analysis]

As can be seen from Table 1, the catalyst of Comparative Example 1 which was not modified by APTES had a methanol conversion rate of about 10.7%. As the amount of the modifier APTES increases (Examples 1 to 3), the formaldehyde conversion rate of the catalyst for decomposing volatile organic compounds also increases until the weight ratio of the amount of APTES to the amount of Pt/TiO ₂ is At 1:1 (Example 3, the amount of amine groups on the surface of the catalyst was 4.5×10 ^-5 mol/m ² as determined by acid-base titration), and the conversion of formaldehyde was 25.6%. The conversion rate was increased, which is presumed to be Due to the synergistic effect of the active unit and the capture unit, the decomposition rate is increased by increasing the local concentration of the active unit around the capture unit. However, when the amount of APTES is further increased to a weight ratio of Pd/TiO ₂ of from 1.1:1 to 2:1 (Examples 4 to 6), the formaldehyde conversion rate is decreased from 20.9% to 13.6%, It is because the excess APTES shields part of the platinum metal, so that the platinum metal portion which can be contacted with formaldehyde is reduced, which leads to a decrease in the formaldehyde conversion rate.

[APTES modified position test]

The sample of Example 7 and the sample of Comparative Example 2 were prepared according to the following procedure: [Example 7] : 0.15 g of the catalyst for decomposing volatile organic compounds prepared in Example 3 was uniformly mixed with 0.15 g of TiO ₂ . .

[Comparative Example 2]: Comparative Example 2 Preparation Example 1 is substantially the same sample, except that the substituents of TiO ₂ Pt / TiO _2, for APTES modified, prepared by the APTES modified TiO _2. Further, 0.15 g of the Pt/TiO ₂ obtained in the above Comparative Example 1 was uniformly mixed with 0.15 g of the above APTES-modified TiO ₂ .

The above sample of Example 7 and the sample of Comparative Example 2 were respectively filled into a catalyst bed reactor, and then formaldehyde gas (concentration: 10 ppm) was introduced into the apparatus, and the gas space velocity per hour was controlled to 83000 h ^{-1 .} Then, the formaldehyde conversion rate was detected by a direct reading type formaldehyde detector, and the result is shown in FIG.

[Result analysis]

As can be seen from Fig. 4, the stable formaldehyde conversion rate of the sample of Example 7 was 13.1% after the introduction of the formaldehyde gas for 120 minutes, and the stable formaldehyde conversion rate of the sample of Comparative Example 2 was 8.8%, which was shown by the long-term formaldehyde exposure. The sample of Example 7 is more stable than the sample of Comparative Example 2 to maintain its formaldehyde conversion rate, indicating that the active unit and the capture unit produced by the reaction of Pt/TiO ₂ and APTES are located on the same carrier particle (TiO ₂ ) to form a synergistic effect. Effect to increase activity (Example 7); however, if the active unit and the capture unit were attached to different support particles, respectively, the synergistic effect was attenuated or even disappeared (Comparative Example 2).

In summary, the catalyst for decomposing volatile organic compounds captures volatile organic compounds 34 by the capturing units 32, increases the concentration of volatile organic compounds around the active units 31, and enhances the decomposition of volatile organic compounds by the catalyst. At the same time, the volatile organic compounds 34 are rapidly decomposed by the active units 31, so that the capturing units 32 can self-regenerate, improve the ability of the catalyst to be used for long-term use, and are suitable for use in an indoor environment.

The above is only the preferred embodiment and the specific examples of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent change according to the scope of the invention and the description of the invention. And modifications are still within the scope of the invention patent.

10‧‧‧Support

12‧‧‧ Capture unit

14‧‧‧Volatile organic compounds

20‧‧‧Support

21‧‧‧Active unit

24‧‧‧Volatile organic compounds

30‧‧‧Support

31‧‧‧Active unit

32‧‧‧Capture unit

34‧‧‧Volatile organic compounds

1 is a schematic view showing the structure of a material for adsorbing volatile organic compounds; FIG. 2 is a schematic view showing the structure of a conventional catalyst for decomposing volatile organic compounds; and FIG. 3 is a schematic view showing the present invention. Used to decompose volatile organic compounds The structure of the catalyst; and FIG. 4 is a graph of formaldehyde conversion rate illustrating the formaldehyde conversion rate of Example 7 and Comparative Example 2 of the catalyst for decomposing volatile organic compounds in accordance with the present invention.

30‧‧‧Support

31‧‧‧Active unit

32‧‧‧Capture unit

34‧‧‧Volatile organic compounds

Claims (10)

A catalyst for decomposing volatile organic compounds, comprising: a support having a porous structure; and a plurality of active units attached to the support are formed of at least one noble metal, at least one transition metal oxide or a mixture thereof And catalyzing the decomposition of the volatile organic compound; and a plurality of capture units bonded to the support and each capture unit containing at least one functional group capable of generating an attraction or bond with the volatile organic substance. The catalyst for decomposing volatile organic compounds according to claim 1, wherein the noble metal is selected from platinum, gold, rhodium or palladium. The catalyst for decomposing volatile organic compounds according to claim 1, wherein the transition metal oxide is an oxide selected from the group consisting of chromium, cobalt, copper or silver. The catalyst for decomposing volatile organic compounds according to claim 1, wherein the support is selected from the group consisting of titanium dioxide, cerium oxide, aluminum oxide, zirconium dioxide, zeolite, cerium oxide, nickel dioxide. , ferric oxide, triiron tetroxide, magnesium dioxide or a mixture thereof. The catalyst for decomposing volatile organic compounds according to claim 1, wherein the functional group is selected from the group consisting of an amine group, a hydroxyl group, a carboxyl group, a sulfate group, a sulfite group or a phosphate group. The catalyst for decomposing volatile organic compounds according to claim 5, wherein the functional group is an amine group. The catalyst for decomposing volatile organic compounds according to claim 1, wherein the number of the trapping units bonded per unit area of the support is 10 ^-6 to 10 ^-4 mol/m ² . A preparation for decomposing volatility according to any one of claims 1 to 7 A method of organic catalyst comprising: providing a support having a porous structure; forming a plurality of active units on the support, the active units being composed of at least one noble metal, at least one transition metal oxide or a mixture thereof Forming, and catalyzing the decomposition of the volatile organic compounds; and bonding a plurality of capture units on the support on which the active units are formed, each capture unit containing at least one capable of generating attraction or bonding with the volatile organic compounds Functional group. The method for preparing a catalyst for decomposing volatile organic compounds according to claim 8, wherein the active units are formed by an impregnation method, a coprecipitation method, a deposition precipitation method, an ion exchange method, or a chemical vapor deposition method. On the support. The method for preparing a catalyst for decomposing volatile organic compounds according to claim 8, wherein the active unit is used in an amount of from 0.01 to 10% by weight based on 100% by weight of the catalyst.