Low-temperature plasma catalyst as well as preparation method and application thereof

Abstract

The invention relates to the field of low-temperature plasma catalyst preparation, and discloses a low-temperature plasma catalyst and a preparation method and application thereof. The low-temperature plasma catalyst comprises a carrier, and an active component and a catalyst auxiliary agent which are loaded on the carrier; the active components comprise a first active component and a second active component; the first active component is manganese oxide, and the second active component is selected from one or more than two of Fe oxide, Cu oxide, Co oxide, Ni oxide and Ce oxide; the catalyst auxiliary agent contains one or more than two of a Pt element, an Ag element, an Au element and a Ru element; the carrier is aluminum oxide. According to the low-temperature plasma catalyst, the loading capacity of the active components in the low-temperature plasma catalyst is large, loading of the active components is more uniform, the degradation efficiency of VOCs is improved, emission of toxic by-products NOx and O3 can be avoided at the same time, and secondary pollution is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of low-temperature plasma catalyst preparation, in particular to a low-temperature plasma catalyst and a preparation method and application thereof. BACKGROUND

[0002] Volatile organic compounds (VOCs) are a class of organic compounds with volatility and capable of participating in photochemical reactions. At present, the total amount of VOCs emissions in China has exceeded that of nitrogen oxides and sulfur dioxide, and VOCs has become the main source of air pollution. VOCs is photochemical smog, a precursor of tropospheric ozone secondary aerosol, which will cause secondary pollution, greenhouse effect and regional climate change after complex physical and chemical reactions, and volatile organic compounds are toxic and carcinogenic, which not only harm the environment but also pose a threat to human life and health. Therefore, effectively reducing the emission of VOCs is of great significance for protecting humans and the environment.

[0003] Common methods for treating VOCs mainly include absorption, biodegradation, photocatalysis and plasma technology. At present, low-temperature plasma technology is a new technology integrating physics, chemistry, biology and environmental science. The main reaction principle of this technology is that, through high voltage applied on positive and negative electrodes, the outer electrons in gas molecules can not only have non-elastic collision with VOCs molecules, but also have non-elastic collision with background gas molecules (such as nitrogen, oxygen and water vapor) under the action of the electric field formed in the electrode gap, generating active groups such as N free radicals, O free radicals and OH free radicals to continue to react with VOCs molecules, and finally mineralize VOCs into CO2 and H2O. However, when low-temperature plasma is used alone to degrade VOCs, many organic intermediate products with certain toxicity, NO x and O3 reaction by-products are generated, which can easily cause secondary pollution to the environment.

[0004] Studies have shown that the combination of catalysts and low-temperature plasma technology can effectively inhibit the generation of organic intermediate products and reaction by-products (NO x and O3, etc.), and improve the efficiency of VOCs degradation. According to the placement area of the catalyst, plasma coupling catalysis technology is divided into two types, namely, plasma built-in catalysis and plasma post-catalysis. Plasma built-in catalysis refers to that the catalyst is located in the discharge area of the plasma, which can effectively inhibit the generation of organic intermediate products by increasing the local electric field strength and prolonging the reaction time of VOCs molecules and active particles, and improve the mineralization efficiency of VOCs, but the emission of by-products NO x and O3 is large; plasma post-catalysis refers to that the catalyst is located outside the plasma electric field area, which can effectively inhibit the generation of NO xThe decomposition can be realized by O3, and the organic intermediate products generated by the degradation of VOCs in the plasma area can be further decomposed to improve the treatment effect of VOCs. However, the degradation efficiency of VOCs needs to be further improved because the active particles generated in the plasma area cannot be used for degradation. Therefore, developing an efficient low-temperature plasma coupled catalyst to effectively control the by-products and VOCs is the key to the current low-temperature plasma coupled catalytic treatment of VOCs. SUMMARY

[0005] The purpose of the present application is to overcome the problems in the prior art, such as low catalytic performance of the low-temperature plasma catalyst, low degradation efficiency of VOCs, and easy secondary pollution in the degradation process, and to provide a low-temperature plasma catalyst, a preparation method and application thereof. The active component in the low-temperature plasma catalyst has a large loading amount and is more uniformly loaded, which improves the degradation efficiency of VOCs and also avoids the emission of toxic by-products NO x and O3, and avoids secondary pollution.

[0006] To achieve the above-mentioned purpose, the present application provides a low-temperature plasma catalyst in one aspect, which comprises a carrier, an active component and a catalyst additive loaded on the carrier.

[0007] The active component comprises a first active component and a second active component.

[0008] The first active component is a manganese oxide, and the second active component is selected from one or two or more of Fe oxide, Cu oxide, Co oxide, Ni oxide and Ce oxide.

[0009] The catalyst additive contains one or two or more of Pt element, Ag element, Au element and Ru element.

[0010] The carrier is alumina.

[0011] Preferably, the total weight of the low-temperature plasma catalyst is 100 wt%, the content of the first active component is 10-30 wt%, the content of the second active component is 7.5-15 wt%, the content of the catalyst additive is 0.1-1 wt%, and the content of the carrier is 54-82.4 wt%.

[0012] The second aspect of the present application provides a preparation method of a low-temperature plasma catalyst, which comprises: pretreating a carrier, then immersing the pretreated carrier in a solution containing a manganese source, a second active component precursor and a catalyst additive precursor, and then calcining the immersed material.

[0013] the second active component precursor is selected from one or more of Fe salt, Cu salt, Co salt, Ni salt and Ce salt;

[0014] the carrier is alumina, and the catalyst auxiliary precursor is selected from one or more of Pt salt, Ag salt, Au salt and Ru salt;

[0015] Preferably, the pretreatment process comprises heat treating the alumina.

[0016] Preferably, the specific surface area of the alumina is 100-350 m 2 / g;

[0017] Preferably, the pore volume of the alumina is 0.3-0.8 mL / g.

[0018] Preferably, the impregnation time is 6-18 h.

[0019] Preferably, the calcination temperature is 500-800 ℃, and the calcination time is 4-12 h.

[0020] Preferably, the temperature rising rate during the calcination is 1-10 ℃ / min.

[0021] Preferably, the molar ratio of the manganese source, the second active component precursor, the catalyst auxiliary precursor and the alumina is 12-370:10-200:1:57-880, wherein the molar amount of the manganese source, the second active component precursor and the catalyst auxiliary precursor is calculated based on the metal elements.

[0022] Preferably, the heat treatment conditions comprise a temperature of 600-750 ℃ and a time of 2-4 h.

[0023] Preferably, the temperature rising rate of the heat treatment is 1-3 ℃ / min.

[0024] Preferably, the atmosphere of the heat treatment is air.

[0025] The third aspect of the present application provides a low-temperature plasma catalyst prepared by the above method.

[0026] The fourth aspect of the present application provides an application of the low-temperature plasma catalyst in degrading VOCs.

[0027] The fifth aspect of the present application provides a method for degrading VOCs, which comprises loading the low-temperature plasma catalyst into a plasma device, and then introducing VOCs for treatment.

[0028] Preferably, the VOCs are C4-C6 alkanes and / or acetone.

[0029] Preferably, the concentration of the C4-C6 alkane is 50-3000 ppm;

[0030] Preferably, the concentration of the acetone is 500-3000 ppm.

[0031] Preferably, the catalytic temperature of the low-temperature plasma catalyst is 18-100℃.

[0032] The low-temperature plasma catalyst of the present application employs multiple metals as active components, and through the cooperation between the first active component and the second active component and the catalyst adjuvant, the energy required for the generation of hydroxyl radicals is reduced, the amount of hydroxyl radicals is further increased, and the energy required for the generation of water in the reaction is increased, thereby reducing the consumption of hydroxyl radicals, improving the mineralization rate of organic intermediates in the process of degradation of VOCs by virtue of the strong oxidizing property of hydroxyl radicals, improving the degradation rate of VOCs, and effectively reducing the emission of by-products NO x and O3, improving the degradation efficiency of VOCs while avoiding secondary pollution, and realizing clean treatment of VOCs.

[0033] Moreover, the catalytic degradation temperature of the low-temperature plasma catalyst of the present application is low, and low-temperature catalysis can be realized, further saving the energy consumption of degradation of VOCs. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is a morphology diagram of the low-temperature plasma catalyst prepared in Example 1. DETAILED DESCRIPTION

[0035] The specific embodiments of the present application are described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely intended to illustrate and explain the present application, and are not intended to limit the present application.

[0036] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The endpoints of the ranges and any values are understood to be approximate values. The exact values are understood to be within the range of values. For ranges of values, the endpoints of the ranges are included within the range. The endpoints of the ranges and the individual values are not to be construed as limiting the range of values. Ranges can be expressed as from one value and / or to another value. When two values are listed, the range can be expressed from the first value to the second value. When three values are listed, the range can be expressed as from the first value, to the second value, and to the third value, and so forth.

[0037] In the present application, the low-temperature plasma catalyst comprises a carrier and active components and catalyst adjuvants supported on the carrier; the active components contain a first active component and a second active component.

[0038] In the present application, the first active component is manganese oxide, the second active component is selected from one or more than two of Fe oxide, Cu oxide, Co oxide, Ni oxide and Ce oxide; the catalyst aid contains one or more than two of Pt element, Ag element, Au element and Ru element; and the carrier is alumina.

[0039] In the low-temperature plasma catalyst of the present application, the first active component and the second active component synergize with each other to reduce the energy required for the generation of hydroxyl radicals, further generate a large amount of hydroxyl radicals by decomposing ozone, i.e. improve the ozone decomposition rate, and also generate more active hydroxyl radicals. The low-temperature plasma catalyst of the present application can further improve the energy required for the generation of water in the reaction, thereby further reducing the consumption of hydroxyl radicals generated in the reaction, further improving the generation amount of hydroxyl radicals, and improving the mineralization rate of organic intermediates generated in the plasma degradation of VOCs by using the strong oxidizing property of hydroxyl radicals, thereby improving the degradation rate of VOCs. The low-temperature plasma catalyst of the present application can also reduce the emission of NO x , and truly realize the harmless degradation of VOCs. Further, the catalyst aid of the present application can further accelerate the catalytic reaction speed and improve the stability of the catalyst, which is helpful for the long-term stable catalytic degradation of VOCs by the low-temperature plasma catalyst and improves the service life of the catalyst.

[0040] In the present application, the coupling mode of the low-temperature plasma catalyst and the plasma technology is not limited, i.e. the coupling mode of the low-temperature plasma catalyst and the plasma technology of the present application can be built-in catalysis or post-catalysis.

[0041] In the present application, alumina is used as the carrier of the low-temperature plasma catalyst, which benefits from the large specific surface area and high pore volume of the alumina to improve the loading amount and uniformity of the active components in the low-temperature plasma catalyst, thereby improving the catalytic performance of the low-temperature plasma catalyst.

[0042] In the low-temperature plasma catalyst of the present application, the mutual synergistic cooperation between the first active component, the second active component, the catalyst aid and the carrier can greatly improve the generation amount of hydroxyl radicals with strong oxidizing activity in the degradation process, further improve the degradation rate of VOCs, and also significantly reduce the emission of by-products ozone and NO x , reduce the risk of secondary pollution, and truly realize the treatment of VOCs by low-temperature plasma technology while controlling the emission of toxic by-products.

[0043] In the low-temperature plasma catalyst described in the present application, the second active component is selected from one or more than two of Fe oxide, Cu oxide, Co oxide, Ni oxide and Ce oxide. Specifically, the second active component can be one or two of iron oxide, copper oxide, cobalt oxide, nickel oxide and cerium oxide, and can also be one of a double metal or multi-metal oxide, for example, can be a copper-cobalt double metal oxide, a copper-cobalt-nickel triple metal oxide or a iron-cobalt double metal oxide.

[0044] In a preferred embodiment, the second active component is selected from one or more than two of Cu oxide, Co oxide and Ce oxide. In this preferred embodiment, the low-temperature plasma catalyst can further increase the amount of hydroxyl radicals generated, thereby further improving the degradation efficiency of VOCs.

[0045] In a preferred embodiment, the catalyst adjuvant contains Ag element.

[0046] In the present application, the catalyst adjuvant can exist in the catalyst in the form of an element or an oxide, and its specific form of existence is not limited.

[0047] In the present application, the manganese oxide contains a-MnO2 and optionally one or more of MnO, Mn3O4 and Mn2O3. It can be understood that the a-MnO2 is a necessary component of the manganese oxide, and the manganese oxide can also contain one or more of MnO, Mn3O4 and Mn2O3, for example, the composition of the manganese oxide can be a-MnO2, a-MnO2 and MnO, or a-MnO2, MnO and Mn3O4. In the present application, the a-MnO2 contained in the manganese oxide has excellent activity, further improving the decomposition efficiency of ozone, thereby generating more active hydroxyl radicals in the reaction. In this preferred embodiment, by further limiting the crystal form and composition of the manganese oxide in the active component, the catalytic performance of the low-temperature plasma catalyst can be further improved, and the harmless degradation of VOCs can be further achieved.

[0048] In a preferred embodiment, in order to further improve the catalytic activity of the low-temperature plasma catalyst, the content of the first active component is 10-30wt% based on 100wt% of the total weight of the low-temperature plasma catalyst, the content of the second active component is 7.5-15wt%, the content of the catalyst adjuvant is 0.1-1wt%, and the content of the carrier is 54-82.4wt%.

[0049] In a further preferred embodiment, the content of the first active component is 15-30 wt%, the content of the second active component is 7.5-15 wt%, the content of the catalyst aid is 0.5-1 wt%, and the content of the carrier is 56.5-75 wt%, based on the total weight of the low-temperature plasma catalyst being 100 wt%.

[0050] The present application further provides a preparation method of the low-temperature plasma catalyst, which comprises: pretreating a carrier, then immersing the pretreated carrier in a solution containing a manganese source, a second active component precursor and a catalyst aid precursor, and then calcining the immersed material.

[0051] In a specific embodiment, the second active component precursor is selected from one or more than two of Fe salt, Cu salt, Co salt, Ni salt and Ce salt, and preferably is a combination of one or more than two of Cu salt, Co salt and Ce salt. Specifically, the Fe salt, Cu salt, Co salt, Ni salt and Ce salt are water-soluble salts. For example, the Fe salt can be Fe(NO3)3 or FeCl3; the Cu salt can be Cu(NO3)2 or CuCl2; the Co salt can be Co(NO3)2 or CoCl2; the Ni salt can be Ni(NO3)2 or NiCl2; and the Ce salt can be Ce(NO3)3.

[0052] In a specific embodiment, the catalyst aid precursor is selected from one or more than two of Pt salt, Ag salt, Au salt and Ru salt, and preferably is Ag salt. Specifically, the Pt salt, Ag salt, Au salt and Ru salt are all water-soluble salts. For example, the Pt salt can be platinum acetylacetone, chloroplatinic acid or platinum chloride; the Ag salt can be AgNO3; the Au salt can be potassium chloroaurate; and the Ru salt can be RuCl3.

[0053] In a specific embodiment, when AgNO3 is selected as the catalyst aid precursor, AgNO3 will generate a reducing gas during calcination, so as to reduce the Ag element in the catalyst aid into elemental form. At this time, the Ag element contained in the catalyst aid is in the form of elemental Ag.

[0054] In a specific embodiment, the carrier is alumina, and the present application does not limit the crystal form of the alumina.

[0055] In a preferred embodiment, in order to further increase the loading amount of the active component in the prepared low-temperature plasma catalyst and improve the catalytic activity of the low-temperature plasma catalyst, the specific surface area of the alumina is limited to 100-350 m 2 / g, and preferably is 150-250 m 2The pore volume of the alumina is 0.3-0.8 mL / g, preferably 0.4-0.7 mL / g.

[0056] In a specific embodiment, the morphology of the carrier alumina is rod-shaped, which can be obtained by extrusion using an extruder. Further, the diameter of the carrier alumina is limited to 1-4 mm, preferably 1.5-3 mm, and the length of the alumina is 4-15 mm, preferably 5-12 mm. Specifically, the diameter of the alumina refers to the diameter of the end shape of the rod-shaped alumina obtained by extrusion using an extruder.

[0057] In the present application, in order to further increase the loading amount of the active component in the prepared low-temperature plasma catalyst, the carrier needs to be pretreated. In a preferred embodiment, the pretreatment process comprises heat treating the alumina. By heat treating the alumina, impurities in the pore channels of the alumina are removed, exposing more loadable sites.

[0058] In a specific embodiment, the pretreatment process further comprises vacuum treatment of the heat-treated alumina to prevent the heat-treated alumina from adsorbing impurities in the air and affecting the subsequent loading of the active component. In the present application, the vacuum treatment refers to placing the heat-treated alumina in a vacuum device for vacuum treatment.

[0059] In a preferred embodiment, the heat treatment conditions include a temperature of 600-750℃, preferably 650-720℃, and a time of 2-4 h, preferably 2.5-3.5 h.

[0060] In a preferred embodiment, the heat treatment has a temperature rise rate of 1-3℃ / min. Specifically, the temperature rise rate of the heat treatment refers to the temperature rise rate when the ambient temperature is raised to the target temperature of the heat treatment.

[0061] In a preferred embodiment, the heat treatment is carried out in an air atmosphere.

[0062] In a preferred embodiment, the impregnation time is 6-18 h, preferably 8-12 h.

[0063] In a specific embodiment, the impregnated material needs to be dried before calcination. The specific drying method can be: placing the impregnated material and the impregnation solution in a rotary evaporator for drying at a rotation speed of 20-180 r / min and a temperature of 60-90℃, and then placing the dried material in an oven for drying at 100-150℃ for 6-24 h. This method can make the drying more uniform and the water removal more complete.

[0064] In the preferred embodiment, the rotation speed of the rotary evaporator is 20-100 r / min, and the evaporation temperature is 60-80℃; the drying temperature of the oven is 110-130℃, and the drying time is 8-12h.

[0065] In the preferred embodiment, the molar ratio of the manganese source, the second active component precursor, the catalyst additive precursor and the alumina is 12-370:10-200:1:57-880, and more preferably 30-100:11-80:1:60-300, wherein the molar amount of the manganese source, the second active component precursor and the catalyst additive precursor is calculated based on the metal elements.

[0066] In the present application, when the calcination temperature is too low, the content of the active component and the catalyst additive in the obtained plasma catalyst will not be in the optimal range, resulting in low active component loading and other problems, thereby reducing the catalytic activity of the obtained low-temperature plasma catalyst; when the calcination temperature is too high, the active components will sinter and bond during the preparation of the catalyst, resulting in a large grain size and a large particle size of the obtained catalyst, and a reduced specific surface area, thereby reducing the activity of the prepared catalyst. In the present application, the calcination temperature is limited to 500-800℃, and preferably 600-750℃, and the calcination time is 4-12h, and preferably 6-10h.

[0067] In the preferred embodiment, the heating rate during calcination is 1-10℃ / min, and preferably 1-5℃ / min. Specifically, the heating rate during calcination refers to the heating rate when the ambient temperature is raised to the target calcination temperature.

[0068] In the specific embodiment, the material after calcination is washed with water for 2-3 times to remove the components on the surface that are not tightly combined with the carrier, and then dried, the drying temperature is 120-200℃, and preferably 150-180℃, the drying time is 6-18h, and preferably 10-12h, and the low-temperature plasma catalyst is obtained after drying.

[0069] The present application further provides a low-temperature plasma catalyst prepared by the above preparation method.

[0070] The present application also provides an application of the low-temperature plasma catalyst in the degradation of VOCs by low-temperature plasma.

[0071] The present application further provides a method for degrading VOCs, which comprises: loading the low-temperature plasma catalyst into a plasma device, and then introducing VOCs for treatment.

[0072] In a preferred embodiment, the low-temperature plasma catalyst is located outside the electric field region in the plasma device, i.e., the VOCs are degraded by using a plasma post-catalysis technology.

[0073] In a preferred embodiment, the VOCs are C4-C6 alkanes and / or acetone.

[0074] In a preferred embodiment, in order to ensure the degradation rate of the final VOCs, the concentration of C4-C6 alkanes suitable for catalytic degradation by the low-temperature plasma catalyst is 50-3000 ppm, and the concentration of acetone is 500-3000 ppm.

[0075] In the present application, the low-temperature plasma catalyst can achieve low-temperature catalytic degradation, and can achieve degradation and removal of VOCs at a lower temperature, further saving degradation energy consumption. Specifically, the catalytic temperature of the low-temperature plasma catalyst is 18-100℃. Specifically, the catalytic temperature of the low-temperature plasma catalyst can be 18℃, 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 60℃, 70℃, 80℃, 90℃ or 100℃. In the present application, the catalytic temperature of the low-temperature plasma catalyst refers to the working temperature when the low-temperature plasma catalyst exerts its catalytic effect.

[0076] The low-temperature plasma catalyst of the present application can significantly reduce the energy consumption of active hydroxyl radicals, and further reduce the consumption of hydroxyl radicals, thereby increasing the generation amount of hydroxyl radicals, and improving the degradation rate of C4-C6 alkanes and / or acetone without increasing the discharge power. More importantly, the low-temperature plasma catalyst of the present application can also significantly reduce the amount of NOx and ozone emitted during the degradation of C4-C6 alkanes and / or acetone, achieving double effective control of organic intermediate products and reaction by-products generated in the plasma discharge area, and avoiding the generation of secondary pollution. x and ozone, achieving double effective control of organic intermediate products and reaction by-products generated in the plasma discharge area, and avoiding the generation of secondary pollution.

[0077] The present application will be described in detail below by way of examples, but the scope of protection of the present application is not limited thereto.

[0078] The examples are implemented on the premise of the technical solutions of the present application, and detailed implementation modes and specific operation processes are given, but the scope of protection of the present application is not limited to the following examples.

[0079] In the following examples, the experimental methods are conventional methods in the art unless otherwise specified. The experimental materials used in the following examples are commercially available unless otherwise specified.

[0080] Example 1

[0081] (1) Al2O3 (specific surface area 100 m 2

[0082] (2) Mn(NO3)2, Ce(NO3)3, Cu(NO3)2 and AgNO3 were mixed with water, then the pretreated Al2O3 was immersed in the mixed solution for 18 h, then the immersed material and solution were placed in a rotary evaporator and dried at a rotation speed of 20 r / min and a temperature of 60 °C, then the rotary evaporated material was placed in an oven and dried at 150 °C for 6 h; wherein the molar ratio of the amounts of Mn(NO3)2, Ce(NO3)3, Cu(NO3)2, AgNO3 and Al2O3 was 50:8:20:1:138, and the molar amounts of Mn(NO3)2, Ce(NO3)3, Cu(NO3)2 and AgNO3 were calculated based on metal elements;

[0083] (3) The dried material of step (2) was calcined at a temperature of 700 °C and a heating rate of 10 °C / min, and the calcined material was washed with deionized water for 3 times and then dried at 120 °C for 18 h to obtain a Mn-Ce-Cu-Ag low-temperature plasma catalyst;

[0084] XRF test showed that the content of Al2O3 in the low-temperature plasma catalyst was 65.5 wt%, the content of manganese oxide was 20 wt%, the content of cerium oxide was 6.5 wt%, the content of copper oxide was 7.5 wt%, and the content of Ag element was 0.5 wt%;

[0085] (4) The low-temperature plasma catalyst was loaded into the catalyst loading device of the plasma device, then 300 ppm of pentane was introduced for treatment, and the low-temperature plasma catalyst was located outside the electric field range of the plasma device, and the catalytic temperature was 35 °C.

[0086] Example 2

[0087] (1) Al2O3 (specific surface area 120 m 2 / g, pore volume 0.6 ml / g) was placed in a muffle furnace and heat treated under an air atmosphere at a heating rate of 2 °C / min to 700 °C for 3 h, then placed in a vacuum oven for vacuum treatment to obtain pretreated Al2O3;

[0088] ​(2) Mn(NO3)2, Ce(NO3)3, Co(NO3)2 and AgNO3 were mixed with water, and then the pretreated alumina was immersed in the mixed solution for 18 h. The immersed material and solution were placed in a rotary evaporator for drying at a rotation speed of 40 r / min and a temperature of 80°C. The rotary evaporated material was placed in an oven for drying at 120°C for 6 h. The molar ratio of the amounts of Mn(NO3)2, Ce(NO3)3, Ni(NO3)2, AgNO3 and alumina was 114:30:30:1:350, and the amounts of Mn(NO3)2, Ce(NO3)3, Cu(NO3)2 and AgNO3 were calculated based on metal elements;

[0089] (3) The dried material of step (2) was calcined at a temperature of 800°C and a temperature rising rate of 10°C / min for 6 h. The calcined material was washed with deionized water for 3 times and then dried at 120°C for 18 h to obtain a Mn-Ce-Co-Ag low-temperature plasma catalyst;

[0090] XRF test showed that the content of alumina in the low-temperature plasma catalyst was 66.5 wt%, the content of manganese oxide was 18.5 wt%, the content of cerium oxide was 10.0 wt%, the content of cobalt oxide was 4.8 wt%, and the content of Ag element was 0.2 wt%;

[0091] (4) The low-temperature plasma catalyst was loaded into a catalyst loading device of a plasma device, and then 400 ppm of pentane was introduced for treatment. The low-temperature plasma catalyst was located outside the electric field range of the plasma device, and the catalytic temperature was 40°C.

[0092] Example 3

[0093] (1) Alumina (specific surface area 100 m 2 / g, pore volume 0.4 ml / g) was placed in a muffle furnace and heat treated at a temperature rising rate of 2°C / min to 700°C under an air atmosphere for 3 h, and then placed in a vacuum oven for vacuum treatment to obtain pretreated alumina;

[0094] (2) Mn(NO3)2, Ce(NO3)3, Co(NO3)2 and AgNO3 were mixed with water, and then the pretreated alumina was immersed in the mixed solution for 18 h. The immersed material and solution were placed in a rotary evaporator for drying at a rotation speed of 40 r / min and a temperature of 80℃. The rotary evaporated material was placed in an oven for drying at 120℃ for 6 h. The molar ratio of the amounts of Mn(NO3)2, Ce(NO3)3, Co(NO3)2, AgNO3 and alumina was 37:7:24:1:148, and the amounts of Mn(NO3)2, Ce(NO3)3, Co(NO3)2 and AgNO3 were calculated based on metal elements;

[0095] (3) The dried material of step (2) was calcined at a temperature of 700℃ and a temperature rising rate of 10℃ / min for 4 h. The calcined material was washed with deionized water for 3 times and then dried at 110℃ for 12 h to obtain a Mn-Ce-Co-Ag low-temperature plasma catalyst;

[0096] XRF test showed that the content of alumina in the low-temperature plasma catalyst was 70.0wt%, the content of manganese oxide was 15wt%, the content of cerium oxide was 5.5wt%, the content of cobalt oxide was 9.0wt%, and the content of Ag element was 0.5wt%;

[0097] (4) The low-temperature plasma catalyst was loaded into a catalyst loading device of a plasma device, and then 500ppm of pentane was introduced for treatment. The low-temperature plasma catalyst was located outside the electric field range of the plasma device, and the catalytic temperature was 35℃.

[0098] Example 4

[0099] (1) Alumina (specific surface area 180m 2 / g, pore volume 0.6ml / g) was placed in a muffle furnace and heat treated at a temperature rising rate of 2℃ / min to 700℃ under an air atmosphere for 3 h, and then placed in a vacuum oven for vacuum treatment to obtain pretreated alumina;

[0100] (2) Mn(NO3)2, Ce(NO3)3, Fe(NO3)3and AgNO3were mixed with water, and then the pretreated alumina was immersed in the mixed solution for 12 h. The immersed material and solution were placed in a rotary evaporator and dried at a rotation speed of 40 r / min and a temperature of 85°C. The rotary evaporated material was then placed in an oven and dried at 120°C for 12 h. The molar ratio of the amounts of Mn(NO3)2, Ce(NO3)3, Fe(NO3)3, AgNO3and alumina was 34:7:7:1:86, and the amounts of Mn(NO3)2, Ce(NO3)3, Fe(NO3)3and AgNO3were calculated based on metal elements;

[0101] (3) The dried material of step (2) was calcined at a temperature of 600°C and a temperature rising rate of 10°C / min for 6 h. The calcined material was washed with deionized water for 3 times and then dried at 110°C for 12 h to obtain a Mn-Ce-Fe-Ag low-temperature plasma catalyst;

[0102] XRF test showed that the content of alumina in the low-temperature plasma catalyst was 66 wt%, the content of manganese oxide was 21 wt%, the content of cerium oxide was 9.2 wt%, the content of iron oxide was 3.0 wt%, and the content of Ag element was 0.8 wt%;

[0103] (4) The low-temperature plasma catalyst was loaded into the catalyst loading device of the plasma device, and then 600 ppm of pentane was introduced for treatment. The low-temperature plasma catalyst was located outside the electric field range of the plasma device, and the catalytic temperature was 37°C.

[0104] Example 5

[0105] (1) Alumina (specific surface area 200 m 2 / g, pore volume 0.6 ml / g) was placed in a muffle furnace and heat treated at a temperature rising rate of 2°C / min to 700°C under an air atmosphere for 3 h, and then placed in a vacuum oven for vacuum treatment to obtain pretreated alumina;

[0106] (2) Mn(NO3)2, Ce(NO3)3, Co(NO3)2and RuCl3were mixed with water, and then the pretreated alumina was immersed in the mixed solution for 16 h. The immersed material and solution were placed in a rotary evaporator for drying at a rotation speed of 50 r / min and a temperature of 75℃. The rotary evaporated material was placed in an oven for drying at 130℃ for 12 h. The molar ratio of the amounts of Mn(NO3)2, Ce(NO3)3, Co(NO3)2, RuCl3and alumina was 35:11:12:1:138, and the molar amount of Mn(NO3)2, Ce(NO3)3, Co(NO3)2and RuCl3was calculated based on the metal elements;

[0107] (3) The dried material of step (2) was calcined at a temperature of 650℃ and a temperature rising rate of 5℃ / min for 6 h. The calcined material was washed with deionized water for 3 times and then dried at 110℃ for 12 h to obtain a Mn-Ce-Co-Ru low-temperature plasma catalyst;

[0108] XRF test showed that the content of alumina in the low-temperature plasma catalyst was 70.0wt%, the content of manganese oxide was 15wt%, the content of cerium oxide was 9.5wt%, the content of cobalt oxide was 5wt%, and the content of Ru was 0.5wt%;

[0109] (4) The low-temperature plasma catalyst was loaded into a catalyst loading device of a plasma device, and then 300ppm of pentane was introduced for treatment. The low-temperature plasma catalyst was located outside the electric field range of the plasma device, and the catalytic temperature was 35℃.

[0110] Example 6

[0111] (1) Alumina (specific surface area 150m 2 / g, pore volume 0.6ml / g) was placed in a muffle furnace and heat treated at a temperature rising rate of 2℃ / min to 650℃ under an air atmosphere for 4 h, and then placed in a vacuum oven for vacuum treatment to obtain pretreated alumina;

[0112] (2) Mn(NO3)2, Ce(NO3)3, Co(NO3)2and RuCl3were mixed with water, and then the pretreated alumina was immersed in the mixed solution for 16 h. The immersed material and solution were placed in a rotary evaporator for drying at a rotation speed of 50 r / min and a temperature of 75℃. The rotary evaporated material was placed in an oven for drying at 130℃ for 12 h. The molar ratio of the amounts of Mn(NO3)2, Ce(NO3)3, Co(NO3)2, RuCl3and alumina was 35:11:12:1:138, and the amounts of Mn(NO3)2, Ce(NO3)3, Co(NO3)2and RuCl3were calculated based on metal elements;

[0113] (3) The dried material of step (2) was calcined at a temperature of 600℃ and a temperature rising rate of 5℃ / min for 8 h. The calcined material was washed with deionized water for 3 times and then dried at 110℃ for 12 h to obtain a Mn-Ce-Co-Ru low-temperature plasma catalyst;

[0114] XRF test showed that the content of alumina in the low-temperature plasma catalyst was 70.0wt%, the content of manganese oxide was 15wt%, the content of cerium oxide was 9.5wt%, the content of cobalt oxide was 5wt%, and the content of Ru was 0.5wt%;

[0115] (4) The low-temperature plasma catalyst was loaded into a catalyst loading device of a plasma device, and then 500ppm of pentane was introduced for treatment. The low-temperature plasma catalyst was located outside the electric field range of the plasma device, and the catalytic temperature was 35℃.

[0116] Example 7

[0117] (1) Alumina (specific surface area 110m 2 / g, pore volume 0.8ml / g) was placed in a muffle furnace and heat treated at a temperature rising rate of 2℃ / min to 750℃ in an air atmosphere for 3 h, and then placed in a vacuum oven for vacuum treatment to obtain pretreated alumina;

[0118] (2) Mn(NO3)2, Ce(NO3)3, Cu(NO3)2 and AgNO3 were mixed with water, and then the pretreated alumina was immersed in the mixed solution for 18 h. The immersed material and solution were placed in a rotary evaporator for drying at a rotation speed of 60 r / min and a temperature of 70°C. The rotary evaporated material was placed in an oven for drying at 120°C for 18 h. The molar ratio of the amounts of Mn(NO3)2, Ce(NO3)3, Cu(NO3)2, AgNO3 and alumina was 30:5:10:1:63, and the amounts of Mn(NO3)2, Ce(NO3)3, Cu(NO3)2 and AgNO3 were calculated based on metal elements;

[0119] (3) The dried material of step (2) was calcined at a temperature of 650°C and a temperature rising rate of 3°C / min for 8.5 h. The calcined material was washed with deionized water for 3 times and then dried at 110°C for 10 h to obtain a Mn-Ce-Cu-Ag low-temperature plasma catalyst.

[0120] XRF test showed that the content of alumina in the low-temperature plasma catalyst was 60.0 wt%, the content of manganese oxide was 24 wt%, the content of cerium oxide was 7.5 wt%, the content of copper oxide was 7.5 wt%, and the content of Ag element was 1.0 wt%.

[0121] (4) The low-temperature plasma catalyst was loaded into a catalyst loading device of a plasma device, and then 400 ppm of pentane was introduced for treatment. The low-temperature plasma catalyst was located outside the electric field range of the plasma device, and the catalytic temperature was 40°C.

[0122] Example 8

[0123] The method of Example 1 was followed, except that the specific surface area of the selected alumina was 95 m 2 / g, and the pore volume was 0.2 ml / g.

[0124] XRF test showed that the content of alumina in the low-temperature plasma catalyst was 84 wt%, the content of manganese oxide was 7 wt%, the content of cerium oxide was 6.5 wt%, the content of copper oxide was 2.2 wt%, and the content of Ag element was 0.3 wt%.

[0125] Example 9

[0126] The method of Example 1 was followed, except that the molar ratio of the amounts of Mn(NO3)2, Ce(NO3)3, Cu(NO3)2, AgNO3 and alumina was 15:3:5:1:138, and the molar amounts of Mn(NO3)2, Ce(NO3)3, Cu(NO3)2 and AgNO3 were calculated based on the metal elements;

[0127] XRF testing showed that the content of alumina in the low-temperature plasma catalyst was 90.2 wt%, the content of manganese oxide was 5.3 wt%, the content of cerium oxide was 2.2 wt%, the content of copper oxide was 1.6 wt%, and the content of Ag element was 0.7 wt%.

[0128] Example 10

[0129] The method of Example 1 was followed, except that the molar ratio of the amounts of Mn(NO3)2, Ce(NO3)3, Cu(NO3)2, AgNO3 and alumina was 380:8:20:1:138, and the molar amounts of Mn(NO3)2, Ce(NO3)3, Cu(NO3)2 and AgNO3 were calculated based on the metal elements;

[0130] XRF testing showed that the content of alumina in the low-temperature plasma catalyst was 37.8 wt%, the content of manganese oxide was 56.7 wt%, the content of cerium oxide was 2.4 wt%, the content of copper oxide was 2.7 wt%, and the content of Ag element was 0.4 wt%.

[0131] Comparative Example 1

[0132] The method of Example 1 was followed, except that no AgNO3 was added.

[0133] Comparative Example 2

[0134] The method of Example 1 was followed, except that no Mn(NO3)2 was added.

[0135] Comparative Example 3

[0136] The method of Example 1 was followed, except that no Ce(NO3)3 and Cu(NO3)2 were added.

[0137] Test Example

[0138] Test Example 1

[0139] The surface morphology of the low-temperature plasma catalyst prepared in Example 1 was tested by SEM, as shown in FIG. 1. Figure 1 The low-temperature plasma catalyst was rod-shaped and had regular morphology.

[0140] Test Example 2

[0141] The low-temperature plasma catalysts prepared in Examples 1-10 and Comparative Examples 1-3 were tested for the degradation rate of VOCs, and the O3 and NO in the exhaust gas were also tested. x concentration.

[0142] Test method: Agilent 8890B gas chromatograph was used to measure the VOCs content in the degraded gas, equipped with a double hydrogen flame ionization detector, according to the formula: (M 降解前气体中vocs的浓度 -M 降解后气体中vocs的浓度 )÷M 降解前气体中vocs的浓度 ×100%, calculate the degradation rate of VOCs, and the results are shown in Table 1;

[0143] The NO in the exhaust gas was analyzed online using a gas analyzer (Antaris IGS) x The concentrations are shown in Table 1.

[0144] The 106-M ozone analyzer from the American 2B company was used to detect the changes in the O3 concentration of the treated exhaust gas. The results are shown in Table 1.

[0145] Table 1

[0146] Example number VOCs degradation rate / % <![CDATA[尾气中O3的浓度 / ppm]]> Concentration of NO in exhaust gas / ppm x ​ Example 1 97.1 0.01 0.58 Example 2 99.1 0.03 0.14 Example 3 99.2 0.01 0.41 Example 4 99.5 0.07 0.11 Example 5 97.1 0.05 0.32 Example 6 97.9 0.01 0.41 Example 7 95.5 0.09 0.98 Example 8 90.7 1.13 3.67 Example 9 90.1 1.94 5.3 Example 10 89.5 1.89 5.19 Comparative Example 1 91.5 2.15 7.51 Comparative Example 2 75.1 315 25.74 Comparative Example 3 82.1 2.74 21.87

[0147] The results in Table 1 show that the low-temperature plasma catalyst of the present invention can significantly improve the removal rate of pentane and significantly reduce the ozone and NO in the tail gas. x concentration, reducing the toxic byproducts ozone and NO x emissions, achieving harmless treatment of VOCs.

[0148] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A low-temperature plasma catalyst, characterized in that The low-temperature plasma catalyst includes a carrier and an active component and a catalyst promoter supported on the carrier; The active component comprises a first active component and a second active component; The first active component is manganese oxide, and the second active component is selected from one or more of Fe oxide, Cu oxide, Co oxide, Ni oxide and Ce oxide; The catalyst promoter contains one or more of Pt, Ag, Au and Ru elements; The carrier is alumina.

2. The low-temperature plasma catalyst according to claim 1, characterized in that Taking the total weight of the low-temperature plasma catalyst as 100wt%, the content of the first active component is 10-30wt%, the content of the second active component is 7.5-15wt%, the content of the catalyst auxiliary agent is 0.1-1wt%, and the content of the carrier is 54-82.4wt%.

3. A method for preparing a low-temperature plasma catalyst, characterized in that: The preparation method comprises: pre-treating the carrier, then impregnating the pre-treated carrier in a solution containing a manganese source, a second active component precursor and a catalyst promoter precursor, and then calcining the impregnated material; The second active component precursor is selected from one or more of Fe salt, Cu salt, Co salt, Ni salt and Ce salt; The carrier is aluminum oxide, and the catalyst promoter precursor is selected from one or more of Pt salt, Ag salt, Au salt and Ru salt.

4. The method for preparing a low-temperature plasma catalyst according to claim 3, wherein: The pretreatment process includes: heat treating the aluminum oxide; Preferably, the heat treatment conditions include: temperature of 600-750°C and time of 2-4h; Preferably, the heating rate of the heat treatment is 1-3°C / min; Preferably, the atmosphere of the heat treatment is air.

5. The method for preparing a low-temperature plasma catalyst according to claim 3 or 4, characterized in that: The specific surface area of ​​the alumina is 100-350m 2 / g; Preferably, the pore volume of the alumina is 0.3-0.8 mL / g.

6. The method for preparing a low-temperature plasma catalyst according to claim 3, wherein: The calcination temperature is 500-800°C, and the calcination time is 4-12h; Preferably, the heating rate during the calcination is 1-10°C / min.

7. The method for preparing a low-temperature plasma catalyst according to claim 3, wherein: The molar ratio of the manganese source, the second active component precursor, the catalyst promoter precursor and the aluminum oxide is 12-370:10-200:1:57-880, wherein the molar amounts of the manganese source, the second active component precursor and the catalyst promoter precursor are calculated based on metal elements.

8. A low-temperature plasma catalyst obtained according to the preparation method of a low-temperature plasma catalyst according to any one of claims 3 to 7.

9. Use of the low-temperature plasma catalyst according to any one of claims 1 to 2 or the low-temperature plasma catalyst according to claim 8 in degrading VOCs.

10. A method for degrading VOCs, characterized in that: The method comprises: loading a low-temperature plasma catalyst into a plasma device, and then introducing VOCs for treatment; The low-temperature plasma catalyst is the low-temperature plasma catalyst according to any one of claims 1 to 2 or the low-temperature plasma catalyst according to claim 8.

11. The method for degrading VOCs according to claim 10, characterized in that: The VOCs are C4-C6 alkanes and / or acetone; Preferably, the concentration of the C4-C6 alkane is 50-3000 ppm; Preferably, the concentration of acetone is 500-3000 ppm.

12. The method for degrading VOCs according to claim 10, characterized in that: The catalytic temperature of the low-temperature plasma catalyst is 18-100°C.

Images