Odor-free catalytic coating and preparation method of porous honeycomb-shaped catalytic coating module

Abstract

The invention relates to an odorless catalytic coating, which is characterized in that a composite metal oxide composed of ZnCeWSn is loaded in MIL-125 pore channels to construct a functional composite carrier, and then Cu and Fe elements are dispersed on the functional composite carrier; wherein the mass ratio of the ZnCeWSn to the total mass ratio of the MIL-125 is 0.5%-10%. The invention further discloses a preparation method of the porous honeycomb-shaped catalytic coating module. The coating is formed according to a unique formula, plasma discharge and catalysis synergism can be efficiently achieved, the high purification effect is shown, low-price non-noble metal Fe and Cu are used for improvement, and the cost is low.

Description

Technical Field

[0001] The present invention relates to a coating that can be used in refrigerators for odor removal. The present invention also relates to a method for preparing a catalytic coating module. Background Art

[0002] In real family life, the odor in the refrigerator is a headache problem; the main sources of refrigerator odor 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] Plasma-assisted catalytic purification technology has become a hot topic due to its high purification efficiency and long service life. In this method, a honeycomb catalyst is embedded between two high-voltage mesh electrodes to achieve a high-intensity corona discharge synergistic catalytic effect, referred to as honeycomb plasma catalysis. Due to its low wind resistance and long life, this method is considered a high-potential purification technology. The catalytic module is the core component, carrying both discharge and catalytic functions. In addition, this type of catalytic coating generally uses a supported precious metal catalyst. To meet the requirements of high discharge and high activity, a large amount of precious metal is used. Therefore, the key is to develop a high-performance, low-cost catalytic coating. Summary of the Invention

[0004] The first technical problem to be solved by the present invention is to provide a low-cost and highly active odor-free catalytic coating in response to the above-mentioned technical status quo.

[0005] The second technical problem to be solved by the present invention is to provide a method for preparing a porous honeycomb catalytic coating module with low cost and high activity in response to the above-mentioned technical status quo.

[0006] The technical solution adopted by the present invention to solve the above-mentioned first technical problem is: a odorless catalytic coating, characterized in that a composite metal oxide composed of ZnCeWSn is loaded in the pores of MIL-125 to construct a functional composite carrier, and then Cu and Fe elements are dispersed on the functional composite carrier; wherein, the total mass ratio of ZnCeWSn to MIL-125 is 0.5% to 10%, the molar ratio of Zn, Ce, W, and Sn in ZnCeWSn is 1:0.1 to 5:0.1 to 1:0.01 to 0.5, the loading amount of Cu relative to the functional composite carrier is 0.01% to 1%, and the loading amount of Fe relative to the functional composite carrier is 0.01% to 1%.

[0007] The technical solution adopted by the present invention to solve the second technical problem is: a method for preparing a porous honeycomb catalytic coating module of an odor-free catalytic coating, characterized by comprising the following steps:

[0008] Dissolving a Zn source, a Ce source, a W source, and a Sn source in water, stirring to form a uniform mixed solution, then adding MIL-125 and stirring thoroughly; adding aluminum sol to form a uniform dispersion; applying the dispersion to a porous honeycomb ceramic substrate by vacuum coating, drying once, and calcining once under an inert atmosphere to obtain a primary ceramic substrate;

[0009] The Cu source and the Fe source are dispersed in water to form a uniform dispersion, and then the Cu source and the Fe source are impregnated and dispersed in a primary ceramic substrate by an impregnation method, dried for a second time, and calcined for a second time to obtain a porous honeycomb catalytic coating module loaded with a odor-free catalytic coating.

[0010] Preferably, the Zn source is at least one of Zn(NO3)2, ZnSO4, ZnCl2, and Zn(CH3COO)2.

[0011] Preferably, the Ce source is at least one of Ce(NO3)3·6H2O, CeCl3·7H2O, and Ce(CH3COO)3·4H2O.

[0012] Preferably, the W source is (NH4) 10 H2W 12 O 42 ·4H2O.

[0013] Preferably, the Sn source is SnCl2.

[0014] Preferably, the Cu source is Cu(NO3)2·3H2O, CuSO 4· At least one of 5H2O and CuCl2.

[0015] Preferably, the Fe source is at least one of Fe(NO3)3·9H2O, FeCl3·6H2O, and Fe2(SO4)3.

[0016] Preferably, the primary drying temperature is 50-180°C.

[0017] Preferably, the primary calcination temperature is 400-900° C. and the calcination time is 0.5-10 h.

[0018] Preferably, the secondary drying temperature is 50-180°C.

[0019] Preferably, the temperature of the primary calcination is 300-900° C., and the calcination time is 0.5-10 h.

[0020] Preferably, the amount of aluminum sol added is 3% to 20% by weight of MIL-125.

[0021] Compared with the prior art, the advantages of the present invention are:

[0022] (1) Coating formula characteristics: A multifunctional catalytic coating suitable for honeycomb plasma catalytic modules was constructed. The coating, with its unique formula, can efficiently achieve the synergy of plasma discharge and catalysis, showing a high purification effect. It is improved by using low-priced non-precious metals Fe and Cu, and has a low cost.

[0023] Formula composition: MIL-125 is a metal organic framework material (MOF) with titanium (Ti) as the metal center, coordinated with terephthalic acid ligands to form a three-dimensional porous structure with a regular octahedral morphology. The particle diameter is between 0.2-0.3 microns and the specific surface area can reach 1300m 2 / g, with a pore size of approximately 0.6nm×0.8nm. First, the high specific surface area of ​​MIL-125 serves as a support. The mesoporous structure of MIL-125 can highly disperse the composite metal oxide composed of ZnCeWSn. The composite metal oxide composed of Zn, Ce, W, and Sn, however, produces more oxygen vacancies due to interactions between the elements and charge balance. Furthermore, under a special preparation process, the organic framework of the MIL-125 (MOF) material undergoes high temperature and carbonization, and the central metal Ti itself forms highly dispersed TiO2 rich in oxygen vacancies. This process also captures some of the active lattice oxygen in the ZnCeWSn composite oxide, greatly enhancing the oxygen vacancy content in the oxide. Finally, the presence of a large number of oxygen vacancies allows Cu and Fe to be highly dispersed on the oxygen-vacancies-rich, high-specific surface area mixed support, achieving highly dispersed, dual-active components and efficient synergistic catalytic purification between the functional support.

[0024] (2) Good discharge performance: Due to the high specific surface area and rich oxygen vacancies in the coating, Cu and Fe are highly dispersed, forming highly dispersed metal sites at the atomic level. Under the action of a high-voltage electric field, the oxygen vacancy sites and highly dispersed metal sites can effectively serve as stable points for electron transfer, ensuring that the honeycomb catalyst pores are filled with a large number of micro-discharges, generating high-intensity plasma.

[0025] (3) Strong ozone catalytic performance: Under the coordination of highly dispersed Cu sites and Fe sites as well as oxygen vacancy sites, Zn sites and Ce sites, ozone produced by catalysis can be efficiently adsorbed.

[0026] (4) High purification efficiency: First, the high discharge efficiency in the catalyst pores can effectively decompose VOC and other pollutant molecules; second, the high specific surface area carrier can effectively adsorb VOC and other pollutant molecules, especially the special pore structure of MIL-125; in addition, the special catalytic structure of CuFe / ZnCeWSn can efficiently activate oxygen and ozone to produce a large number of free radicals and reactive oxygen species under the synergy of plasma discharge, thereby efficiently oxidizing and decomposing VOC and other pollutants, achieving a high-efficiency purification effect.

[0027] Working principle of porous honeycomb catalytic coating module:

[0028] 1. When a certain high voltage is applied between the two mesh electrodes, sufficient discharge occurs between the two electrodes under the action of water molecules in the air and the ceramic catalyst. This is mainly manifested in a large number of micro-discharges in the porous ceramic channels and the catalyst micro-channels. 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 species, free radicals, high-energy electrons and ozone. At the same time, the presence of the catalyst will decompose ozone into reactive oxygen species and free radicals.

[0029] 2. 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; combining these two approaches, the filter can achieve efficient VOC purification and ozone control effects. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below with reference to Examples and Comparative Examples.

[0031] Example 1

[0032] The catalyst coating described in this embodiment is a multi-loaded metal catalyst, which mainly loads a composite metal oxide composed of ZnCeWSn in the pores of MIL-125 to construct a functional composite carrier, and then a certain amount of Fe and Cu are highly dispersed on the composite carrier, recorded as CuFe / ZnCeWSn / MIL-125; wherein, the total mass ratio of ZnCeWSn to MIL-125 is 8%, the molar ratio of ZnCeWSn is 1:1:0.4:0.1, the Cu loading relative to ZnCeWSn / MIL-125 is 0.6%, and the Fe loading relative to ZnCeWSn / MIL-125 is 0.3%.

[0033] The preparation process of honeycomb catalytic coating is as follows:

[0034] (1) Add a certain amount of Zn(NO3)2, Ce(NO3)3·6H2O, (NH4) 10 H2W 12 O 42 4H2O and SnCl2 sources were dissolved in water and stirred to form a uniform mixed solution. A certain amount of MIL-125 was then added and stirred thoroughly. Finally, an aluminum sol (8% by weight of the total weight of the MIL-125) was added to form a uniform dispersion. The solution was then vacuum-coated onto a porous honeycomb ceramic substrate, dried at 120°C, and calcined at 600°C in a nitrogen atmosphere to obtain a composite carrier-coated ceramic substrate.

[0035] (2) The Cu(NO3)2·3H2O source and the Fe(NO3)3·9H2O source were dispersed in water to form a uniform dispersion, and then the Cu source and the Fe source were impregnated and dispersed on the composite carrier substrate by an impregnation method, dried at 120°C, and calcined at 500°C to obtain the final honeycomb catalytic coating module.

[0036] The specific structure of the honeycomb catalytic coating module involved in this embodiment refers to the invention patent application disclosed in China 202210765876.X (application publication number CN115090323A), which includes a porous plate electrode and a porous plate electrode. A ceramic catalytic mesh is provided between the plate electrode and the plate electrode. The ceramic catalytic mesh has a certain number of straight hole channels. Through the straight hole channels, a high-voltage discharge area can be formed between the porous plate electrode and the porous plate electrode, especially a large number of micro-discharges will be generated in the straight hole channels, generating a large amount of plasma.

[0037] In this basic embodiment, the porous plate electrodes are made of stainless steel with a thickness of 3 mm. The porous plate electrodes serve as high-voltage electrodes and the porous plate electrodes serve as ground electrodes. High voltage discharge is performed from one porous plate electrode to the other porous plate electrode.

[0038] In this basic embodiment, the catalyst filter uses a honeycomb ceramic catalyst filter with a 0.8mm*0.8mm square ceramic pore size, a pore density of 300 ppi, and a filter thickness of 20mm. Accordingly, the porous plate electrode pore diameter is preferably 2mm, with a pore spacing of 2.5mm. The spacing between porous plate electrode 1 and catalytic mesh 2 is preferably 2mm, and the spacing between porous plate electrode 3 and catalytic mesh is preferably 1mm. The spacing between porous plate electrode 1 and porous electrode 3 is controlled to be 23mm. This design achieves both high discharge performance and low wind resistance.

[0039] Example 2: In this example, the total mass ratio of ZnCeWSn to MIL-125 is changed to 0.5%. The remaining specific operations are the same as those in Example 1.

[0040] Example 3: In this example, the molar ratio of ZnCeWSn is changed to 1:0.1:0.1:0.01, and the remaining specific operations are the same as those in Example 1.

[0041] Example 4: In this example, the Cu loading relative to ZnCeWSn / MIL-125 is changed to 0.01%. The remaining specific operations are the same as those in Example 1.

[0042] Example 5: In this example, the Fe loading relative to ZnCeWSn / MIL-125 is changed to 0.01%. The rest of the specific operations are the same as those in Example 1.

[0043] Example 6. In this example, the total mass ratio of ZnCeWSn to MIL-125 is 10%, the molar ratio of ZnCeWSn is 1:5:1:0.5, the loading amount of Cu relative to ZnCeWSn / MIL-125 is 1%, and the loading amount of Fe relative to ZnCeWSn / MIL-125 is 1%; the remaining specific operations are as shown in Example 1.

[0044] Example 7: In this example, the calcination temperature in preparation step 1 is changed to 400°C, and the calcination in preparation step (2) is changed to 300°C.

[0045] Example 8: In this example, the calcination temperature in preparation step 1 is changed to 900°C, and the calcination in preparation step (2) is changed to 700°C.

[0046] In Comparative Example 1, no Zn source, Ce source, W source, and Sn source were added to the prepared coating, that is, only CuFe / MIL-125 was used. The remaining specific operations were the same as those in Example 1.

[0047] In Comparative Example 2, no Ce source, W source, Sn source, Cu source, and Fe source were added to the prepared coating, namely, ZnO / MIL-125. The remaining specific operations were the same as those in Example 1.

[0048] In Comparative Example 3, no Ce source, W source, or Sn source was added to the prepared coating, that is, only CuFe / ZnO / MIL-125 was used. The remaining specific operations were the same as those shown in Example 4.

[0049] In Comparative Example 4, no W source or Sn source was added to the prepared coating, that is, only CuFe / ZnCe / MIL-125 was used. The rest of the specific operations were the same as those in Example 4.

[0050] In Comparative Example 5, no W source was added to the prepared coating, that is, only CuFe / ZnCeSn / MIL-125 was used, and the remaining specific operations were the same as those in Example 4.

[0051] In Comparative Example 6, no Ce source, W source, Sn source, or Cu source was added to the prepared coating, namely, Fe / ZnO / MIL-125. The remaining specific operations were the same as those in Example 4.

[0052] In Comparative Example 7, no Ce source, W source, Sn source, or Fe source was added to the prepared coating, namely, Cu / ZnO / MIL-125. The remaining specific operations were the same as those in Example 4.

[0053] In Comparative Example 8, the Zn source in the prepared coating is replaced by the Si source, that is, CuFe / SiCeWSn / MIL-125, and the remaining specific operations are as shown in Example 4.

[0054] In Comparative Example 9, the Ce source in the prepared coating was replaced by a Mg source, namely, CuFe / ZnMgWSn / MIL-125, and the remaining specific operations were the same as those in Example 4.

[0055] The filters from each example and comparative example were placed in a structure containing a high-voltage power supply and a blower with identical parameters, forming a circulating purification module. The modules were then tested in the freezer compartment of a refrigerator. A certain concentration of durian odor was generated in the freezer compartment, and then the purification system was activated for a fixed time to test the odor purification effectiveness. The odor intensity was qualitatively determined by a professional odorist using an odor intensity grading system: 0 - no odor, 1 - barely perceptible odor, 2 - very weak odor but discernible, 3 - easily perceptible odor, and 4 - strong odor, an unbearable, extremely strong odor. The test results are listed in the table below.

[0056]

[0057]

Claims

1. A catalytic coating with a clean taste, characterized in that A composite metal oxide composed of ZnCeWSn is loaded in the pores of MIL-125 to construct a functional composite carrier, and then Cu and Fe elements are dispersed on the functional composite carrier; wherein, the total mass ratio of ZnCeWSn to MIL-125 is 0.5% to 10%, the molar ratio of Zn, Ce, W, and Sn in ZnCeWSn is 1:0.1 to 5:0.1 to 1:0.01 to 0.5, the loading amount of Cu relative to the functional composite carrier is 0.01% to 1%, and the loading amount of Fe relative to the functional composite carrier is 0.01% to 1%.

2. A method for preparing a porous honeycomb catalytic coating module having the odor-free catalytic coating according to claim 1, characterized in that The steps include: Dissolving a Zn source, a Ce source, a W source, and a Sn source in water, stirring to form a uniform mixed solution, then adding MIL-125 and stirring thoroughly; adding aluminum sol to form a uniform dispersion; applying the dispersion to a porous honeycomb ceramic substrate by vacuum coating, drying once, and calcining once under an inert atmosphere to obtain a primary ceramic substrate; The Cu source and the Fe source are dispersed in water to form a uniform dispersion, and then the Cu source and the Fe source are impregnated and dispersed in a primary ceramic substrate by an impregnation method, dried for a second time, and calcined for a second time to obtain a porous honeycomb catalytic coating module loaded with a odor-free catalytic coating.

3. The preparation method according to claim 2, wherein The Zn source is at least one of Zn(NO3)2, ZnSO4, ZnCl2, and Zn(CH3COO)2.

4. The preparation method according to claim 2, characterized in that The Ce source is at least one of Ce(NO3)3·6H2O, CeCl3·7H2O, and Ce(CH3COO)3·4H2O.

5. The preparation method according to claim 2, characterized in that The W source is (NH4) 10 H2W 12 O 42 ·4H2O.

6. The preparation method according to claim 2, characterized in that The Sn source is SnCl2.

7. The preparation method according to claim 2, characterized in that The Cu source is Cu(NO3)2·3H2O, CuSO 4· At least one of 5H2O and CuCl2.

8. The preparation method according to claim 2, characterized in that The Fe source is at least one of Fe(NO3)3·9H2O, FeCl3·6H2O, and Fe2(SO4)3.

9. The preparation method according to claim 2, characterized in that The primary drying temperature is 50-180°C.

10. The preparation method according to claim 2, characterized in that The primary calcination temperature is 400-900° C., and the calcination time is 0.5-10 hours.

11. The preparation method according to claim 2, characterized in that The temperature of the secondary drying is 50-180°C.

12. The preparation method according to claim 2, characterized in that The primary calcination temperature is 300-900° C., and the calcination time is 0.5-10 hours.

13. The preparation method according to claim 2, characterized in that The amount of aluminum sol added is 3% to 20% of the weight of MIL-125.

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