Catalyst and preparation method thereof, catalytic module and gas purification system

Abstract

The present invention discloses a catalyst, a preparation method thereof, a catalytic module, and a gas purification system. The catalyst comprises a composite support and an active ingredient dispersed within the composite support. The composite support comprises a first component and a second component doped with CeO2, the first component comprising Al2O3 and the second component comprising activated carbon and TiO2. The active ingredient comprises Pt and / or Ag. The catalyst provided by the present invention achieves high efficiency in both odor removal and ozone purification.

Description

Technical Field

[0001] The present invention particularly relates to a catalyst and a preparation method thereof, a catalytic module and a gas purification system. Background Art

[0002] In real-life situations at home, there are some odor problems that are a headache. For example, there will be odor in the refrigerator. The main sources of odor in the refrigerator are microbial corruption and volatilization of food itself. This requires the refrigerator to have effective sterilization and odor removal functions, so as to completely solve the problem of efficient purification of odor in the refrigerator.

[0003] In the existing technology, plasma synergistic catalytic purification technology has been widely studied due to its high purification efficiency and long service life. Among them, the honeycomb catalyst is built in the middle of two high-voltage mesh electrodes to achieve a high-intensity corona discharge synergistic catalytic effect, referred to as the honeycomb plasma catalytic method. This method has the advantages of low wind resistance and long life, and is considered to be a high-potential purification technology. However, in the actual use environment of the refrigerator freezer, this type of catalytic method has weak discharge and low purification efficiency due to extremely low humidity. This requires increasing high voltage, but excessive voltage will generate risks such as electromagnetic interference, leakage and ozone escape. How to make this catalytic method have high purification efficiency while maintaining a low voltage in a low humidity environment has become a key application point. Summary of the Invention

[0004] The present invention primarily aims to overcome the difficulty of existing plasma purification modules in maintaining both high odor removal efficiency and high ozone purification capabilities in low-humidity environments. The invention provides a catalyst and its preparation method, a catalytic module, and a gas purification system. The catalyst provided by the present invention maintains high odor removal efficiency and high ozone purification efficiency simultaneously.

[0005] The present invention provides a catalyst comprising a composite carrier and an active ingredient dispersed in the composite carrier, wherein the composite carrier comprises a first component and a second component doped with CeO2, the first component comprises Al2O3, the second component comprises activated carbon and TiO2; the active ingredient comprises Pt and / or Ag.

[0006] In the present invention, the mass ratio of the activated carbon to TiO2 can be (0.05-1):1, for example, 0.05:1, 0.3:1 or 1:1.

[0007] In the present invention, the TiO2 is preferably nano-TiO2.

[0008] In the present invention, the Al2O3 is preferably nano-Al2O3.

[0009] In the present invention, the mass ratio of the CeO2 to the second component may be (0.01-0.1):1, for example, 0.01:1, 0.05:1 or 0.1:1.

[0010] In the present invention, the mass ratio of the first component to the second component may be (0.05-0.5):1, for example, 0.05:1, 0.15:1 or 0.5:1.

[0011] In the present invention, the loading amount of the active ingredient may be 0.05%-3%, such as 0.1%, 1% or 3%, where the loading amount is the percentage of the mass of the active ingredient to the total mass of the composite carrier.

[0012] In the present invention, the active ingredient includes Ag and Pt, and the molar ratio of the Ag to the Pt may be (2-30):1, for example, 2:1, 16:1 or 30:1.

[0013] In the present invention, the catalyst may be in the form of a catalyst coating, which preferably includes a binder, and the binder is preferably Al2O3 and / or TiO2.

[0014] The present invention also provides a method for preparing the catalyst as described above, which comprises the following steps:

[0015] S1. The raw material liquid A is mixed with the raw material B and calcined to obtain a composite support; the raw material liquid A comprises a Ce source, a second component and a solvent; the raw material B comprises a first component;

[0016] S2. Dispersing an active ingredient source in the composite carrier, and obtaining the catalyst by calcination, wherein the active ingredient source comprises a Pt source and / or an Ag source.

[0017] In step S1, the Ce source can be a conventional Ce-containing compound in the art, preferably a Ce salt, such as cerium nitrate hexahydrate. The Ce source is first mixed with activated carbon and TiO2, where it is distributed within the pores of the activated carbon and TiO2. After calcination, the Ce source forms CeO2 within the pores of the activated carbon and TiO2.

[0018] In step S1, the solvent can be any conventional solvent in the art, preferably water.

[0019] In step S2, the Pt source can be a conventional Pt-containing compound in the art, preferably a Pt salt, such as platinum nitrate.

[0020] In step S2, the Ag source may be a conventional Ag-containing compound in the art, preferably an Ag salt, such as silver nitrate.

[0021] In step S1, before the calcination, a mixture of the raw material liquid A and the raw material B is coated on a substrate.

[0022] Among them, the coating method is preferably vacuum coating;

[0023] Among them, the substrate is preferably a ceramic, and the ceramic is more preferably a porous honeycomb ceramic or a foam ceramic.

[0024] Among them, the mixture further includes a binder source, and the binder source is preferably aluminosilicate sol or titania sol; the mass ratio of the binder source to the "first component and the second component" is preferably (0.05 - 0.3):1, such as 0.05:1, 0.1:1 or 0.3:1.

[0025] The chemical formula of the aluminosilicate sol is a(Al2O3·nH2O)·bH

[0033] ,

[0028] ,

[0027] ,

[0026] , x ,

[0032] ,

[0025] ,

[0031] ,

[0030] ,

[0034] ,

[0029] , , , , x , , , , , , , , ·cH2O, where: Al2O3·nH2O is hydrated alumina, and H x is a peptizing agent, and the coefficients: b < a, c, n, and after calcination, it can exist as a binder in the catalyst in the form of alumina.

[0026] The titania sol is a highly dispersed, homogenized and stabilized transparent liquid formed by dispersing nano-titania powder (particle size 5 - 20 nm) in an aqueous medium, and after calcination, it can exist as a binder in the catalyst in the form of titania.

[0027] In step S1, the calcination temperature can be 300°C - 700°C, such as 300°C, 500°C or 700°C.

[0028] In step S1, the calcination can be carried out in an inert atmosphere, and the inert atmosphere is preferably a nitrogen atmosphere;

[0029] In step S2, the calcination temperature can be 300°C - 700°C, such as 300°C, 450°C or 700°C;

[0030] In step S2, the calcination can be carried out in an inert atmosphere, and the inert atmosphere is preferably a nitrogen atmosphere.

[0031] In step S1, drying is carried out before the calcination, and the drying temperature is preferably 120°C.

[0032] In step S2, the dispersion method is the impregnation method.

[0033] In step S2, drying is carried out before the calcination, and the drying temperature is preferably 120°C.

[0034] The present invention also provides a catalytic module, which includes the catalyst and the substrate as described above, and the catalyst is coated on the substrate in the form of a catalyst coating.

[0035] The present invention also provides a gas purification system, which includes the catalyst or the catalytic module as described above.

[0036] In some embodiments, the gas purification system comprises a catalytic component, a high voltage power supply, and a blower.

[0037] Catalytic components

[0038] The catalytic component includes two porous plate electrodes and a catalyst filter, and the catalyst filter is located between the two porous plate electrodes.

[0039] Wherein, the catalyst filter is preferably the catalyst module as described above or includes the catalyst as described above.

[0040] The catalyst filter is preferably a honeycomb ceramic catalyst filter. The honeycomb ceramic catalyst filter has a certain number of straight pores. Through the pores, a high-voltage discharge region is formed between the first and second porous plate electrodes. In particular, a large number of micro-discharges are generated within the catalyst mesh pores, generating a large amount of plasma, thereby increasing discharge intensity and improving purification efficiency.

[0041] When a certain high voltage is applied between the two mesh electrodes, sufficient discharge will occur between the two electrodes under the action of water molecules in the air and the catalyst; this is mainly manifested in a large number of micro-discharges in the substrate pores and the catalyst micro-pores; the metal sites on the catalyst surface can further enhance the micro-discharge amount, generating a large amount of plasma, including active components such as reactive oxygen, free radicals, high-energy electrons and ozone; at the same time, the presence of the catalyst will decompose ozone into reactive oxygen and free radicals.

[0042] When the pollutant VOC gas passes through the filter, it will first be decomposed by a large number of active components in the gas phase; secondly, the VOC molecules will be fully adsorbed and enriched by the catalyst, and then catalytic ozone oxidation and catalytic oxidation in a discharge environment will produce adsorbed active oxygen and free radicals, which will then be decomposed and removed by the adsorbed free radical active oxygen; by combining these two approaches, the filter can achieve efficient VOC purification and ozone control effects.

[0043] On the basis of conforming to the common sense in this field, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0044] The reagents and raw materials used in the present invention are commercially available.

[0045] The positive progress effect of the present invention is:

[0046] (1) The present invention constructs a catalyst with a special structure, which can have high odor purification ability and ozone purification ability in a low humidity environment.

[0047] (2) The catalyst of the present invention has the advantages of high catalytic activity, high adsorption performance, the ability to significantly improve plasma discharge intensity, simple preparation process and low cost, and is suitable for odor purification in the ultra-low temperature and ultra-low humidity environment of the refrigerator freezer. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 Schematic diagram of the catalytic component structure of the present invention (1 is the first porous plate electrode, 2 is the catalyst filter, 3 is the second porous plate electrode) DETAILED DESCRIPTION

[0049] The present invention is further illustrated by way of examples below, but the present invention is not limited to the scope of the examples. Experimental methods in the following examples where specific conditions are not specified were performed according to conventional methods and conditions, or selected according to the product specifications.

[0050] Example 1

[0051] S1. First, a certain amount of cerium nitrate is dissolved in water and stirred thoroughly. Then, the second component, which is nano-TiO2 and activated carbon powder, is added and dispersed thoroughly with stirring to prepare raw material liquid A. Raw material liquid A, raw material B, and aluminum sol are mixed and stirred thoroughly to form a uniform mixed slurry. Raw material B is the first component, namely nano-Al2O3; wherein the mass ratio of activated carbon to TiO2 is 0.3:1, the mass ratio of the first component to the second component is 0.15:1, and the mass ratio of the aluminum sol to the "first component and the second component" is 0.1:1;

[0052] The mixed slurry is applied to a porous honeycomb ceramic substrate by vacuum coating, dried, and calcined at 500° C. in a nitrogen atmosphere to obtain a ceramic substrate coated with a composite carrier;

[0053] In the prepared composite support, cerium nitrate forms CeO2, which is doped into the second component, with a mass ratio of CeO2 to the second component of 0.05:1; aluminum sol forms Al2O3;

[0054] S2. Dispersing platinum nitrate and silver nitrate in water to form a uniform dispersion, and then impregnating and dispersing the platinum nitrate and silver nitrate on the ceramic substrate coated with the composite support obtained in step S1, drying at 120°C, and calcining under nitrogen at 450°C to obtain a porous honeycomb catalytic module;

[0055] In the prepared porous honeycomb catalytic module, Pt and Ag formed by platinum nitrate and silver nitrate respectively are dispersed in the composite carrier. The total loading amount of Pt and Ag relative to the composite carrier is 1%, and the molar ratio of Ag to Pt is 16:1.

[0056] Example 2

[0057] In this embodiment, the mass ratio of activated carbon to TiO2 is changed to 0.05:1, and the other specific operations and material amounts are the same as those in Example 1.

[0058] Example 3

[0059] In this embodiment, the mass ratio of the first component to the second component is changed to 0.05:1, and the other specific operations and material amounts are the same as those in Example 1.

[0060] Example 4

[0061] In this example, the total loading amount of Pt and Ag relative to the composite carrier is changed to 0.1%, and the other specific operations and material amounts are the same as those in Example 1.

[0062] Example 5

[0063] In this example, the molar ratio of Ag to Pt was changed to 2:1, and the other specific operations and amounts of substances used were the same as those in Example 1.

[0064] Example 6

[0065] In this embodiment, the mass ratio of activated carbon to TiO2 is changed to 1:1, the mass ratio of the first component to the second component is 0.5:1, the mass ratio of aluminum sol to the "first component and the second component" is 0.1:1, the total loading amount of Pt and Ag relative to the composite support is 3%, and the molar ratio of Ag to Pt is 30:1; the remaining specific operations and material amounts are the same as those in Example 1.

[0066] Example 7

[0067] In this embodiment, the mass ratio of aluminum sol to the "first component and the second component" is changed to 0.3:1, and the mass ratio of CeO2 to the second component is changed to 0.1:1; the calcination temperature in preparation step S1 is 300°C, and preparation step S2 is changed to calcination at 300°C under nitrogen; the remaining specific operations and material amounts are the same as in Example 1.

[0068] Example 8

[0069] In this embodiment, the mass ratio of aluminum sol to the "first component and the second component" is changed to 0.05:1, and the mass ratio of CeO2 to the second component is changed to 0.01:1; the calcination temperature in preparation step S1 is 700°C, and the calcination temperature in preparation step S2 is changed to 700°C; the remaining specific operations and material amounts are the same as those in Example 1.

[0070] Example 9

[0071] The mass ratio of activated carbon to TiO2 selected in this embodiment is 0.3:1, the mass ratio of the first component to the second component is 0.15:1, the mass ratio of aluminum sol to the "first component and the second component" is 0.1:1, the total loading amount of Pt relative to the composite support is 1%, and there is no Ag; the rest of the specific operations and material amounts are the same as in Example 1.

[0072] Example 10

[0073] The mass ratio of activated carbon to TiO2 selected in this embodiment is 0.3:1, the mass ratio of the first component to the second component is 0.15:1, the mass ratio of aluminum sol to the "first component and the second component" is 0.1:1, the total loading amount of Ag relative to the composite carrier is 1%, and there is no Pt; the rest of the specific operations and material amounts are the same as in Example 1.

[0074] Comparative Example 1

[0075] The support selected for this comparative example did not contain activated carbon or Al2O3. The mass ratio of CeO2 to TiO2 was 0.05:1, and the mass ratio of alumina sol to TiO2 was 0.1:1. The total loading of Pt and Ag relative to (TiO2 + alumina sol) was 1%, and the molar ratio of Ag to Pt was 16:1. The remaining specific operations were as described in Example 1.

[0076] Comparative Example 2

[0077] In this comparative example, the support selected did not contain activated carbon. The mass ratio of CeO2 to TiO2 was 0.05:1, the mass ratio of Al2O3 to TiO2 was 0.15:1, and the mass ratio of alumina sol to (Al2O3 + TiO2) was 0.1:1. The total loading of Pt and Ag relative to the total (Al2O3 + TiO2 + alumina sol) was 1%, and the molar ratio of Ag / Pt was 16:1. The remaining specific operations were as described in Example 1.

[0078] Comparative Example 3

[0079] The mass ratio of activated carbon and TiO2 selected in this comparative example is 0.3:1, the mass ratio of CeO2 to (activated carbon + TiO2) is 0.05:1, the mass ratio of Al2O3 to (activated carbon + TiO2) is 0.15:1, the mass ratio of aluminum sol to (Al2O3 + TiO2 + activated carbon) is 0.1:1, and there are no Pt and Ag components; the rest of the specific operations are as shown in Example 1.

[0080] Comparative Example 4

[0081] The carrier selected in this comparative example does not contain Al2O3, and the remaining specific operations are the same as those shown in Example 1.

[0082] Comparative Example 5

[0083] The carrier selected in this comparative example does not load CeO2, and the remaining specific operations are the same as those shown in Example 1.

[0084] The catalytic modules prepared in Examples 1-10 and Comparative Examples 1-5 were assembled as follows Figure 1 The catalytic component shown includes a porous plate electrode 1 and a porous plate electrode 3, with a catalyst filter 2 provided between the porous plate electrode 1 and the porous plate electrode 3. The catalytic components are placed in structural components containing a high-voltage power supply and a blower with the same parameters to form a gas purification system, and are tested in the freezer area of ​​the same refrigerator. A certain concentration of durian odor is generated in the freezer area, and then the purification is turned on for a fixed time to test the odor purification effect; the odor degree is qualitatively judged by the same professional odorist, and the judgment standard is based on the odor intensity grading method, 0-odorless, 1-barely perceptible, 2-very weak odor but its nature can be distinguished, 3-very easy to perceptible, 4-strong odor, unbearable extremely strong odor; the test results are listed in the following table.

[0085]

[0086]

[0087] The data in Table 1 demonstrate that the catalyst provided by this invention maintains excellent odor removal capabilities while achieving excellent ozone control in low-humidity environments. In preferred embodiments, strong odors can be purified to a state of odorlessness or a barely perceptible odor, with a residual ozone concentration of 0 ppb.

[0088] Comparative Example 1 differs from Example 1 in that no activated carbon and Al2O3 are added. From the data in Table 1, it can be seen that the odor purification ability of Comparative Example 1 is worse than that of Example 1, and it can only purify strong odors to the point where the odor is easily noticeable.

[0089] Compared with Example 1, Comparative Example 2 differs only in that no activated carbon is added. As can be seen from the data in Table 1, the odor purification ability of Comparative Example 2 is worse than that of Example 1. It can only purify strong odors to a very weak odor but its nature can be distinguished, and its O3 content is 5 ppb.

[0090] Compared with Example 1, Comparative Example 4 differs only in that no Al2O3 is added. As can be seen from the data in Table 1, its gas purification effect is worse than that of the example.

[0091] In the present invention, activated carbon, TiO2, and Al2O3 are fully combined as catalyst carriers.

[0092] In combination with active ingredients, high purification efficiency can be achieved by increasing discharge intensity, enhancing VOC adsorption performance, improving the dispersion of active ingredients, and enhancing catalytic activity. The high conductivity and high specific surface area of ​​activated carbon effectively promote the generation of strong micro-discharges on the carrier. Simultaneously, the high water absorption of activated carbon and Al2O3, as well as the highly dispersed Pt and Ag metal sites, can further significantly increase the micro-discharge intensity, enhance the plasma concentration in the catalyst pores, and improve purification efficiency by increasing discharge intensity under low humidity.

[0093] Compared with Example 1, Comparative Example 3 does not add Pt and Ag, and its ozone purification ability is very poor. Under the same treatment time and conditions, its ozone concentration is as high as 93 ppb; it can only purify strong odors to the point where the odor is easily noticeable.

[0094] Compared with Example 1, Comparative Example 5 differs in that it is not doped with CeO2. As can be seen from the data in Table 1, its gas purification effect is worse than that of the example and its ozone purification ability is also not good. Under the same processing time and conditions, its ozone concentration is as high as 24 ppb.

[0095] Due to the high specific surface area and pore structure of the carrier of the catalyst of the present invention, as well as the highly dispersed Pt and Ag sites, the adsorption efficiency of pollutant molecules such as VOCs can be jointly improved. Pt and Ag have a good synergistic catalytic effect, especially the Pt and Ag components dispersed in CeO2 and TiO2, which have higher catalytic activity in the presence of oxygen vacancies, can efficiently activate oxygen and ozone to produce strong oxidizing substances such as active oxygen and free radicals, fully oxidize and decompose the efficiently adsorbed VOCs, etc., and can achieve a high-efficiency purification effect in a freezing and low-temperature environment; under the high specific surface area and high adsorption performance, the efficiently dispersed Pt and Ag components fully catalyze the decomposition of ozone under the action of oxygen vacancies and CeO2 to control ozone escape, thereby achieving the technical effect of the present invention.

[0096] The catalyst of the present invention can be typically used in honeycomb-type plasma catalytic modules and refrigerator purification environments, but the present invention is not limited to this. The catalytic coating can be used in occasions and equipment that require deodorization and purification, such as deodorizers, air purifiers, fresh-keeping warehouses, etc., which all fall within the scope of protection of the present invention.

Claims

1. A catalyst, characterized in that The invention comprises a composite carrier and an active ingredient dispersed in the composite carrier, wherein the composite carrier comprises a first component and a second component doped with CeO2, the first component comprises Al2O3, and the second component comprises activated carbon and TiO2; The active ingredient is Pt or "Ag and Pt". When the active ingredient is Ag and Pt, the molar ratio of Ag to Pt is (2-16):1; the loading amount of the active ingredient is 1%-3%, and the loading amount is the percentage of the mass of the active ingredient to the total mass of the composite carrier; The mass ratio of CeO2 to the second component is (0.01-0.1):1; The mass ratio of the activated carbon to TiO2 is (0.05-1):1; The mass ratio of the first component to the second component is (0.05-0.5):1; The catalyst is used for VOC gas purification.

2. The catalyst according to claim 1, wherein The mass ratio of CeO2 to the second component is 0.01:1, 0.05:1 or 0.1:1; and / or, the mass ratio of the activated carbon to TiO2 is 0.05:1, 0.3:1 or 1:1; And / or, the mass ratio of the first component to the second component is 0.05:1, 0.15:1 or 0.5:

1.

3. The catalyst according to claim 1, characterized in that The TiO2 is nano-TiO2; And / or, the Al2O3 is nano-Al2O3; And / or, the catalyst is in the form of a catalyst coating.

4. The catalyst according to claim 3, characterized in that The catalyst is in the form of a catalyst coating, which includes a binder.

5. The catalyst according to claim 1, wherein The catalyst is in the form of a catalyst coating. The catalyst coating comprises a binder, and the binder is Al2O3 and / or TiO2.

6. A method for preparing the catalyst according to any one of claims 1 to 5, characterized in that: S1. The raw material liquid A is mixed with the raw material B and calcined to obtain a composite support; the raw material liquid A comprises a Ce source, a second component and a solvent; the raw material B comprises a first component; S2. Dispersing an active ingredient source in the composite carrier, and obtaining the catalyst by calcination, wherein the active ingredient source comprises a Pt source and / or an Ag source.

7. The method for preparing the catalyst according to claim 6, wherein In step S1, the calcination temperature is 300°C-700°C; and / or, in step S1, the calcination is performed under an inert atmosphere; And / or, in step S2, the calcination temperature is 300°C-700°C; And / or, in step S2, the calcination is performed under an inert atmosphere.

8. The method for preparing the catalyst according to claim 7, wherein: In step S1, the calcination temperature is 300°C, 500°C or 700°C; And / or, in step S1, the calcination is performed under an inert atmosphere, and the inert atmosphere is a nitrogen atmosphere; and / or, in step S2, the calcination temperature is 300° C., 450° C. or 700° C.; And / or, in step S2, the calcination is performed under an inert atmosphere, and the inert atmosphere is a nitrogen atmosphere.

9. The method for preparing the catalyst according to claim 6, wherein: In step S1, the Ce source is a Ce salt; and / or, in step S1, the solvent is water; And / or, in step S2, the Pt source is a Pt salt; And / or, in step S2, the Ag source is an Ag salt; and / or, in step S1, drying is performed before calcination; And / or, in step S2, the dispersing method is an immersion method; And / or, in step S2, drying is performed before calcination.

10. The method for preparing the catalyst according to claim 9, wherein: In step S1, the Ce source is cerium nitrate; And / or, in step S2, the Pt source is platinum nitrate; And / or, in step S2, the Ag source is silver nitrate; And / or, in step S1, drying is performed before calcination, and the drying temperature is 120°C; And / or, in step S2, drying is performed before calcination, and the drying temperature is 120°C.

11. The method for preparing the catalyst according to claim 6, wherein: In step S1, before the calcination, a mixture of the raw material liquid A and the raw material B is coated on a substrate.

12. The method for preparing the catalyst according to claim 11, wherein: In step S1, the coating method is vacuum coating; And / or, the substrate is ceramic; And / or, the mixture further comprises a binder source.

13. The method for preparing the catalyst according to claim 12, wherein: The substrate is ceramic, and the ceramic is porous honeycomb ceramic or foam ceramic; And / or, the mixture further comprises a binder source, and the binder source is aluminum sol and / or titanium sol.

14. The method for preparing the catalyst according to claim 13, wherein: The mixture further includes a binder source, which is aluminum sol and / or titanium sol; the mass ratio of the binder source to the "first component and the second component" is (0.05-0.3):

1.

15. The method for preparing the catalyst according to claim 14, wherein: The mass ratio of the binder source to the "first component and the second component" is 0.05:1, 0.1:1 or 0.3:

1.

16. A catalytic module, characterized in that: The method comprises the catalyst according to any one of claims 1 to 5 and a substrate, wherein the catalyst is coated on the substrate in the form of a catalyst coating.

17. A gas purification system, characterized in that: It comprises the catalyst according to any one of claims 1 to 5 or the catalytic module according to claim 16.

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