Method for degrading n-pentane by synergy of Mn-CeO2 doped oxide catalyst and low-temperature plasma

Abstract

The invention belongs to the technical field of purification of waste gas containing n-pentane through cooperation of a catalyst and low-temperature plasma, and discloses a method for degrading n-pentane through cooperation of a Mn-CeO2 doped oxide catalyst and low-temperature plasma. The catalyst is a 10-nanometer to 5-micrometer open or non-open hollow sphere, and a burr structure grows on the surface of a spherical shell. Low-temperature gasification of carbonate on the surface of the catalyst and release of active sites are realized by adopting non-noble metal doping, plasma concerted catalytic oxidation reaction, nano-engineering and interface reaction, 100% conversion of n-pentane is realized under the conditions that the temperature is greater than or equal to 30 DEG C and the plasma energy density is 10-150J / L, COx selectivity reaches up to 97%, and the conversion rate of n-pentane is greatly improved. And the generation of ozone by-products in the reaction process is greatly reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst-assisted low-temperature plasma purification of n-pentane-containing waste gas, and specifically relates to a Mn-CeO 2 A method for degrading n-pentane using doped oxide catalysts in conjunction with low-temperature plasma. Background Art

[0002] With the development of the petrochemical industry, volatile organic compounds (VOCs) have gradually come into the public eye due to their pollution to the atmosphere. VOCs are not only harmful to human health, but are also the main component of summer photochemical smog and urban haze. They are also important precursors to the formation of fine particles (PM2.5) and ozone. They are considered to be the main culprits of photochemical pollution, ozone layer depletion and greenhouse effect. Therefore, they must be controlled and eliminated. VOCs are mainly divided into alkanes, alkenes, alkynes, benzene series, alcohols, aldehydes, ethers, ketones, acids, esters, halogenated hydrocarbons and others, among which alkanes have the greatest impact on air pollution. n-Pentane (C 5 H 12 As a typical alkane VOCs, its emission control has become a research hotspot in the field of environmental science due to its wide application in industrial production, such as paints, solvents and fossil fuels.

[0003] Traditional VOCs purification methods, such as activated carbon adsorption, thermal catalytic combustion and biodegradation, can reduce VOCs emissions to a certain extent, but they often have problems such as high energy consumption, low treatment efficiency or secondary pollution. Therefore, it is particularly important to develop new and efficient VOCs purification technologies. In recent years, plasma catalysis technology has attracted widespread attention due to its unique advantages. Since the plasma-catalytic system has the advantages of high degradation efficiency and good selectivity, many research works have focused on using the plasma-catalytic system to degrade various VOCs. The generation mode and catalyst type of NTP in the plasma-catalytic system are key factors affecting its catalytic oxidation degradation rate, byproducts and energy efficiency. Due to the shortage of precious metal resources and high cost, the development of efficient non-metallic catalysts has become necessary.

[0004] Patent No. CN115704097A relates to an M1M2 type diatomic catalyst and its preparation method and application. The core active site of the catalyst is composed of two metal atoms M1 and M2, and the distance between them is L. M1 and M2 can be the same metal or different metals, and they are selected from Mg, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn, Ru, Rh, Pd, Ir, Pt, Ag, and Au. The carrier of the catalyst can be a carbonaceous carrier or a metal oxide, which is prepared by high-temperature pyrolysis in an inert gas environment.

[0005] Patent number CN2019110111392A "A three-dimensional ordered macroporous oxygen-defective cerium dioxide catalyst and its preparation method and application" uses polymethyl methacrylate (PMMA) colloidal crystal template method to prepare a cerium dioxide catalyst. The prepared catalyst shows excellent activity and stability in photothermal catalytic purification of typical atmospheric pollutants such as styrene, n-hexane and cyclohexane.

[0006] Patent No. CN114206781A introduces a nickel composite hydroxide and its application as a precursor of a positive active material for a non-aqueous electrolyte secondary battery, wherein the composite hydroxide contains nickel (Ni), cobalt (Co) and at least one additional metal element selected from manganese (Mn), aluminum (Al), iron (Fe) and titanium (Ti). The method for preparing the nickel composite hydroxide comprises mixing an aqueous solution containing a nickel salt, a cobalt salt and a selected additional metal element salt with an aqueous solution containing an ammonium ion supply source and a pH regulator, and performing a coprecipitation reaction in a reaction vessel to obtain a crude nickel composite hydroxide.

[0007] Despite these significant advances in plasma-catalyzed degradation of VOCs, challenges remain. Although low-temperature plasma technology is highly efficient and applicable in treating volatile organic compounds, it also has some disadvantages. First, the technology has relatively high energy consumption, especially when treating high-velocity, low-concentration VOCs, where the energy consumption problem is more significant and the economic benefits are low. Second, in some cases, plasma-catalyzed degradation of VOCs can produce secondary pollution, such as ozone and incomplete conversion to CO. 2 The production of harmful byproducts will not only aggravate the damage to the environment, but also endanger people's health. Finally, some plasma catalytic degradation of VOCs has high requirements for reaction environment conditions, requiring high reaction temperature, certain pressure and other environmental factors. Therefore, although plasma technology has broad prospects, it still needs to be improved and optimized in many aspects.

[0008] Therefore, this patent develops a catalyst with simple preparation, mature and reliable technology, and less environmental pollution, which is highly efficient, low energy consumption, less secondary pollution, and high CO 2 A method for selectively purifying n-pentane-containing waste gas at room temperature. Summary of the invention

[0009] The present invention relates to a Mn-CeO 2 A method for degrading n-pentane by using doped oxide catalysts in combination with low-temperature plasma, using Mn-CeO 2 The doped oxide is a catalyst that can achieve C under low temperature (30°C) and plasma energy density (ED) of 10 to 150 J / L.5 H 12 (i.e. 100% conversion of n-pentane), CO x The selectivity is as high as 97% and can significantly reduce ozone generation.

[0010] Specifically, the Mn-CeO 2 The doped oxide catalyst is characterized in that the atomic ratio of manganese Mn to cerium Ce in the catalyst is in the range of 0.25 to 4, more specifically, the ratio is in the range of 0.75 to 4. Preferably, the ratio is in the range of 1-2. This specific atomic ratio helps to improve the activity of the catalyst in synergistic plasma degradation of n-pentane and CO x Selective.

[0011] In addition, the Mn-CeO 2 The doped oxide catalyst has a unique structure, which appears as a sphere or hollow broken sphere. These shells can be open or closed, with an outer diameter ranging from 10 nanometers to 5 microns. And a new type of burr structure was observed on the shell. This burr structure on the spherical shell increases the specific surface area and surface defects of the catalyst, which is a key factor in cooperating with low-temperature plasma to efficiently purify n-pentane.

[0012] The above Mn-CeO 2 The doped oxide catalyst was prepared by aerosol pyrolysis. 2 Doped oxide catalysts can achieve high conversion rates in cooperation with low-temperature plasma at room temperature, and have high efficiency, low energy consumption, less secondary pollution, and high CO x Advantages of selectivity and room temperature purification. By precisely controlling the ratio of manganese and cerium and the nanostructure of the catalyst, the catalyst of the present invention exhibits excellent performance in the synergistic low-temperature plasma catalytic degradation of n-pentane.

[0013] The Mn-CeO 2 The preparation method of the doped oxide catalyst comprises the following steps:

[0014] S1: Atomizing an aqueous solution containing a manganese compound and a cerium compound, the mist is carried into an insulated pipe via an inert gas, and water is vaporized to generate an aerosol containing small solid particles of manganese nitrate and cerium nitrate;

[0015] S2: The aerosol is introduced into a high-temperature decomposition tube along with the inert gas to decompose into manganese and cerium oxide. The manganese is doped into the cerium oxide lattice to form partially or fully doped Mn-CeO 2 doping oxide solid products;

[0016] S3: Mn-CeO 2The oxide-doped solid product enters the water absorption bottle along with the inert gas, is absorbed by water, and is separated by high-speed centrifugation to obtain the Mn-CeO 2 Doped oxide catalysts.

[0017] Furthermore, the temperature of the heat-insulating pipe is 60-70°C, and the temperature of the high-temperature decomposition tube is 500-800°C.

[0018] Furthermore, the temperature of the insulation pipe is 70°C, and the temperature of the high-temperature decomposition tube is 600°C.

[0019] Furthermore, the drying temperature is 80° C. and the drying time is 12 hours.

[0020] The Mn-CeO 2 A method for degrading n-pentane by using doped oxide catalysts in combination with low-temperature plasma, using Mn-CeO 2 The doped oxide is used as a catalyst to carry out catalytic oxidation degradation of n-pentane at a plasma energy density of 10-150 J / L and a temperature of ≥30°C.

[0021] Furthermore, the n-pentane concentration is 30-330 mg / m 3 ; Gas volume space velocity is 5000-50000mL / (gh).

[0022] Furthermore, the application of the n-pentane degradation includes purification of n-pentane-containing gas, and degradation of n-pentane produced in petrochemical enterprises and refineries.

[0023] The beneficial effects of the present invention are:

[0024] The present invention adopts non-precious metal doping, high temperature, nano-engineering and interface to realize the catalyst-cooperative low-temperature plasma through the low-temperature gasification of carbonate on the catalyst surface, releases active sites, and achieves 100% conversion of n-pentane at a temperature of ≥30°C and an energy density of 10 to 150 J / L. x The selectivity is as high as 97%, which reduces the generation of by-products of n-pentane degradation while significantly reducing the generation of ozone by-products. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The Mn-CeO 2 Method for preparing doped oxide catalyst;

[0026] Figure 2 The catalyst preparation device provided in Examples 1-10;

[0027] Figure 3 Mn-CeO when Mn / Ce=1.5 provided in Example 62 Electron micrograph of doped oxide catalyst;

[0028] Figure 4 Mn-CeO when Mn / Ce=1.5 provided in Example 6 2 Transmission electron microscopy image of doped oxide catalyst;

[0029] Figure 5 Mn-CeO when Mn / Ce=1.5 provided in Example 6 2 XRD spectrum of doped oxide catalyst;

[0030] Figure 6 Mn-CeO with different Mn / Ce atomic ratios provided in Examples 1-10 2 Plot of the relationship between n-pentane conversion and energy density (ED) over the oxide-doped catalysts;

[0031] Figure 7 Mn-CeO with different Mn / Ce atomic ratios provided in Examples 1-10 2 The relationship between the conversion rate of n-pentane and the atomic ratio of the doped oxide catalyst at 30°C and an energy density of 150 J / L;

[0032] Figure 8 Mn-CeO when Mn / Ce=1.5 provided in Example 6 2 Ozone generation by doped oxide catalysts in synergistic low-temperature plasma technology and pure plasma at 30°C and energy density of 100 J / L;

[0033] Fig. 9 Mn-CeO when Mn / Ce=1.5 provided in Example 6 2 Degradation of n-pentane by doped oxide catalysts in synergistic low-temperature plasma technology and simple plasma at different energy densities at 30°C.

[0034] These drawings together constitute the technical solution of the present invention, which not only shows the 2 The preparation process of doped oxide catalysts also provides an in-depth analysis of their structure and properties, providing a scientific basis for achieving efficient catalysis. DETAILED DESCRIPTION

[0035] In order to make the purpose, features and advantages of the present invention clearer and easier to understand, the specific implementation methods of the present invention will be described in detail below with reference to the accompanying drawings. It should be emphasized that these descriptions do not constitute a limitation on the scope of implementation of the present invention.

[0036] The present invention adopts non-precious metal doping, high temperature, nano-engineering and interface to realize the catalyst-cooperative low-temperature plasma to release active sites through low-temperature gasification of carbonate on the catalyst surface, and achieve 100% conversion of n-pentane at 30°C and energy density of 10-150J / L, CO x The selectivity is as high as 97%, and the generation of ozone during the reaction is greatly reduced.

[0037] The present invention provides a Mn-CeO 2 Preparation device for doped oxide catalysts. Preparation of Mn-CeO 2 The device for doping oxide catalyst mainly includes an ultrasonic atomization unit, a carrier gas unit, a heating unit, a water absorption unit and a conveying unit, wherein the ultrasonic atomization unit is composed of a glass container and a built-in ultrasonic atomizer, which is used to atomize the catalyst precursor solution in the glass container; the carrier gas unit is equipped with a rotor flowmeter to convey the carrier gas at a preset flow rate; the heating unit is composed of a tubular furnace and an electric furnace temperature controller to control the reaction temperature of catalyst decomposition; the water absorption unit contains an absorption bottle filled with deionized water, which is used to absorb the catalyst products carried by the carrier gas; the conveying unit includes an insulation tube, an insulation thermostat, a high-temperature decomposition tube and an exhaust pipe, which are responsible for conveying the carrier gas and atomized droplets to the reaction zone, and introducing the products into the water absorption bottle after the reaction; the insulation thermostat is used to maintain the temperature of the insulation tube to ensure temperature stability throughout the process; finally, solid catalyst powder is obtained through high-speed centrifugation and drying. The design of the device aims to achieve Mn-CeO 2 Efficient and precise preparation of doped oxide catalysts.

[0038] Based on the above device, see Figure 1 The present invention provides a Mn-CeO 2 Method for preparing doped oxide catalysts.

[0039] S1: An ultrasonic atomizer is used to atomize an aqueous solution of manganese nitrate and cerium nitrate. The resulting mist is transported to an insulated pipe through an inert gas (such as nitrogen). At a temperature of 60-70°C, the water in the mist evaporates to form a particulate aerosol containing manganese nitrate and cerium nitrate.

[0040] S2: The above aerosol enters into a high temperature decomposition tube at 500-800℃ along with nitrogen gas. The aerosol decomposes at high temperature and converts into manganese and cerium oxide. The manganese element is doped into the lattice structure of cerium oxide to form partially or completely doped Mn-CeO 2 Doped oxide solid product.

[0041] S3: Obtained Mn-CeO 2The solid product of doped oxide enters the water absorption bottle with the nitrogen flow. After being absorbed by water, the solid product is separated by high-speed centrifugation and then dried in a drying oven to finally obtain Mn-CeO 2 Doped oxide catalysts.

[0042] The beneficial effects of the present invention are:

[0043] The present invention adopts doping, high temperature, nano-engineering and interface to realize the catalyst-cooperative low-temperature plasma to release active sites through low-temperature gasification of carbonate on the catalyst surface, and achieve 100% conversion of n-pentane under the conditions of temperature ≥30°C and energy density 10-150J / L, CO x The selectivity is as high as 97%, while reducing the generation of byproducts of n-pentane degradation and significantly reducing the generation of ozone.

[0044] Catalyst preparation: Prepare a precursor solution with an atomic ratio of Mn / Ce = 0, weigh 50% manganese nitrate (Mn(NO 3 ) 2 ) aqueous solution m1g, cerium nitrate (Ce(NO 3 ) 3 ) hexahydrate m2g, add deionized water to 50mL and stir evenly, and put it into an atomizing bottle. The precursor solution of manganese nitrate and cerium nitrate is atomized by an ultrasonic atomizer, and the resulting mist is transported to an insulated pipeline by nitrogen. At a temperature of 60-70°C, the water in the mist evaporates to form a particle aerosol containing manganese nitrate and cerium nitrate. The above aerosol enters a 600°C high-temperature decomposition tube with nitrogen. The aerosol decomposes at high temperature and is converted into manganese and cerium oxide. The manganese element is doped into the lattice structure of cerium oxide to form partially or completely doped Mn-CeO 2 Doped oxide solid product. The obtained Mn-CeO 2 The solid product of doped oxide enters the water absorption bottle with the nitrogen flow. After being absorbed by water, the solid product is separated by high-speed centrifugation and then dried in a drying oven to finally obtain Mn-CeO 2 Doped oxide catalysts.

[0045] Performance test: Take 0.15g of the catalyst obtained in the example (catalyst particle size is 40-60 mesh) and place it in the discharge space of a flow-through dielectric barrier discharge (DBD) fixed bed reactor; the carrier gas flow rate is maintained at 100mL / min, and the unit catalyst mass gas volume space velocity (WHSV) is 40000mL / (gh); n-pentane liquid is injected into the vaporization chamber through a micro-injector, and nitrogen and oxygen are introduced into the vaporization chamber at a ratio of 8:2 and mixed with n-pentane gas before flowing into the DBD reactor. The micro-injector adjusts the n-pentane liquid injection flow rate to adjust the required n-pentane concentration (30-330mg / m3 ) mixed gas, the concentration of n-pentane in the embodiment is 330 mg / m 3 The temperature of the DBD reactor is controlled by an electric furnace. It is 30°C. The discharge in the DBD discharge space is achieved by applying pulsed high voltage to the DBD reactor. The mixed gas containing n-pentane is oxidized by Mn-CeO in the catalyst bed of the DBD reactor. 2 Doped oxide catalyst and low temperature plasma synergistic catalytic degradation. Continuous detection of n-pentane and CO in the gas at the outlet of DBD reactor 2 The concentrations of , CO and ozone can be calculated by calculating the concentrations of n-pentane before and after degradation. The conversion rate of n-pentane by the catalyst in synergistic low-temperature plasma and the conversion of CO, CO 2 , CO x Selectivity. By applying different pulse voltages to adjust the discharge energy density (discharge energy applied per unit volume of gas), different degradation effects can be obtained, and the graph of n-pentane conversion rate versus energy density as well as CO, CO 2 , CO x Selective graph.

[0046] Example 1

[0047] The method is the same as the above-mentioned "catalyst preparation", wherein a precursor solution with an atomic ratio of Mn / Ce=0 is prepared, 0 g of a 50% manganese nitrate aqueous solution and 10 g of cerium nitrate hexahydrate are weighed, and the remaining steps remain unchanged.

[0048] Example 2

[0049] The process is the same as that in Example 1, wherein a precursor solution with an atomic ratio of Mn / Ce=0.25 is prepared, 1.87 g of a 50% manganese nitrate aqueous solution and 9.07 g of cerium nitrate hexahydrate are weighed, and the remaining steps remain unchanged.

[0050] Example 3

[0051] The process is the same as Example 1, wherein a precursor solution with Mn / Ce=0.5 is prepared, 3.42 g of 50% manganese nitrate aqueous solution and 8.29 g of cerium nitrate hexahydrate are weighed, and the remaining steps remain unchanged.

[0052] Example 4

[0053] The process is the same as that in Example 1, wherein a precursor solution with an atomic ratio of Mn / Ce=0.75 is prepared, 4.74 g of a 50% aqueous solution of manganese nitrate and 7.64 g of cerium nitrate hexahydrate are weighed, and the remaining steps remain unchanged.

[0054] Example 5

[0055] The process is the same as that in Example 1, wherein a precursor solution with an atomic ratio of Mn / Ce=1 is prepared, 5.84 g of a 50% aqueous solution of manganese nitrate and 7.08 g of cerium nitrate hexahydrate are weighed, and the remaining steps remain unchanged.

[0056] Example 6

[0057] The same as Example 1, wherein a precursor solution with an atomic ratio of Mn / Ce=1.5 was prepared, 7.64 g of a 50% manganese nitrate aqueous solution and 6.18 g of cerium nitrate hexahydrate were weighed, and the remaining steps remained unchanged.

[0058] Example 7

[0059] The process is the same as that in Example 1, wherein a precursor solution with an atomic ratio of Mn / Ce=2 is prepared, 9.04 g of a 50% manganese nitrate aqueous solution and 5.48 g of cerium nitrate hexahydrate are weighed, and the remaining steps remain unchanged.

[0060] Example 8

[0061] The same as Example 1, wherein a precursor solution with an atomic ratio of Mn / Ce=3 was prepared, 11.06 g of a 50% manganese nitrate aqueous solution and 4.47 g of cerium nitrate hexahydrate were weighed, and the remaining steps remained unchanged.

[0062] Example 9

[0063] The process is the same as that in Example 1, wherein a precursor solution with an atomic ratio of Mn / Ce=4 is prepared, 12.45 g of a 50% manganese nitrate aqueous solution and 3.78 g of cerium nitrate hexahydrate are weighed, and the remaining steps remain unchanged.

[0064] Example 10

[0065] The same as Example 1, wherein a precursor solution without cerium nitrate is prepared, 10 g of 50% manganese nitrate aqueous solution and 0 g of cerium nitrate hexahydrate are weighed, and the other steps remain unchanged.

[0066] like Figure 2 As shown, the Mn-CeO 2 The doped oxide catalyst preparation device is composed of an ultrasonic atomization component, a carrier gas component, a heating component, a water absorption bottle and a conveying component. The ultrasonic atomization component includes a glass bottle 11 and an ultrasonic atomizer installed in the bottle, which is used to atomize the liquid. The carrier gas component is equipped with a rotor flowmeter to control the carrier gas flow rate. The heating component is composed of a tubular furnace 21 and an electric furnace temperature controller to maintain a suitable reaction temperature. The water absorption bottle is used to collect the Mn-CeO after the reaction. 2The transport component includes an insulation tube, a quartz tube as a high-temperature decomposition tube, an insulation controller, and a discharge pipe, which work together to transport the atomized liquid and carrier gas to the reaction area and introduce the product into a water absorption bottle after the reaction. The entire device is designed to achieve Mn-CeO 2 Efficient preparation of doped oxide catalysts while ensuring the accuracy of operation and the efficiency of product collection.

[0067] The experimental parameters are: N 2 Flow rate: 0.8L / min; precursor solution: 50mL; pipeline temperature: 70℃; electric furnace temperature: 600℃; centrifugal separation: 100000rpm, 3 minutes; drying temperature: 80℃ for 12 hours.

[0068] The 1.5Mn-CeO prepared in Example 6 2 The morphology and composition of the doped oxide catalysts were characterized.

[0069] 1. Mn-CeO with Mn / Ce=1.5 obtained by scanning electron microscope 2 Doped oxide catalyst pictures Figure 3 .

[0070] Result analysis:

[0071] The catalyst is an open or closed hollow sphere with a particle size of 10 nanometers to 5 microns. The sphere wall is composed of solid spheres of a few nanometers to tens of nanometers, and a burr-like structure grows on the surface of the spherical shell. This burr structure on the spherical shell increases the specific surface area and surface defects of the catalyst, which is a key factor in cooperating with low-temperature plasma to efficiently purify n-pentane.

[0072] 2. Mn-CeO with Mn / Ce=1.5 obtained by transmission electron microscopy 2 Doped oxide catalyst pictures Figure 4 .

[0073] Result analysis:

[0074] from Figure 4 CeO can be clearly displayed 2 The crystal stripes (yellow frame) and Mn 3 O 4 The crystal stripes (blue frame) are blurred in the electron microscope photo, indicating the presence of lattice defects.

[0075] 3. Mn-CeO when Mn / Ce=1.5 2 XRD analysis of the doped oxide catalysts is shown in Figure 5 .

[0076] Result analysis:

[0077] When Mn / Ce=1.5, cerium oxide appeared as the main peak on the catalyst, indicating that manganese, which is smaller than cerium atoms, was doped into the cerium oxide framework.

[0078] The above results show that when Mn / Ce=1.5, Mn-CeO 2 The doped oxide catalyst is Mn 3 O 4 、CeO 2 and Mn-doped CeO 2 The mixture contains lattice defects. These mixtures are composed of hollow spheres with diameters ranging from tens of nanometers to 5 micrometers, and burr-like structures grow on the surface of the spherical shell. This burr structure on the spherical shell increases the specific surface area and surface defects of the catalyst, which is considered to be the key factor in cooperating with low-temperature plasma to efficiently purify n-pentane.

[0079] Effect example

[0080] The performance of the catalysts prepared in Examples 1-10 in synergistic cooperation with low-temperature plasma in purifying n-pentane was evaluated using a flow-through dielectric barrier discharge (DBD) fixed bed reactor. The test results at a temperature of 30°C and a plasma energy density of 100 J / L are shown in Table 1.

[0081] Table 1

[0082]

[0083]

[0084] Mn-CeO with different Mn / Ce atomic ratios 2 The relationship between the conversion rate of n-pentane and the energy density of the oxide-doped catalyst is shown in Figure 6 .

[0085] Results: The energy density is in the range of 100-150 J / L, and the atomic ratio of manganese Mn to cerium Ce is from 0.75 to 4 in Mn-CeO 2 The conversion rate of n-pentane doped with oxides was 100%.

[0086] Mn-CeO prepared in Example 1-10 2 The conversion rate of n-pentane is plotted for the doped oxide catalyst at 30 °C and an energy density of 150 J / L. Figure 7 .

[0087] Results: When the atomic ratio of Mn / Ce is 1.5, the energy density of n-pentane degradation can be significantly reduced, thereby reducing energy input. When the atomic ratio of Mn / Ce is in the range of 0.75-4, n-pentane can be 100% converted at a temperature of 30°C and an energy density of 150 J / L.

[0088] Example 6 Preparation of 1.5Mn-CeO 2 The comparison curve of ozone generation under the conditions of doped oxide catalyst at 30℃ and energy density of 10-100J / L and without catalyst is shown in Figure 8 .

[0089] Results: When the atomic ratio of Mn / CeO is 1.5, the ozone concentration generated by low-temperature plasma can be significantly reduced. Under the conditions of temperature of 30°C and energy density of 100 J / L, it was observed that the degradation of n-pentane by low-temperature plasma alone produced 1860 ppm of ozone. However, when the atomic ratio of Mn / CeO is 1.5, the ozone concentration generated by low-temperature plasma is 1860 ppm. 2 The catalyst and low-temperature plasma produced only 670 ppm of ozone, significantly reducing the generation of ozone by-products.

[0090] Example 6 Preparation of 1.5Mn-CeO 2 The comparison curve of n-pentane conversion rate under the conditions of doped oxide catalyst at 30℃ and energy density of 0-150J / L ​​and without catalyst is shown in Fig. 9 .

[0091] Results analysis: When the atomic ratio of manganese Mn / cerium Ce is 1.5, the degradation of n-pentane by low-temperature plasma is better than that by low-temperature plasma alone. Through testing, it was found that low-temperature plasma alone could not completely degrade n-pentane at 30°C and energy density of 150J / L, and CO x The low selectivity indicates that a large amount of intermediate products are produced, which may cause secondary pollution and is not conducive to environmental protection and life safety. 2 The catalyst can not only achieve 100% degradation of n-pentane at a lower energy density (100 J / L) and temperature (30 °C), but also x The selectivity is as high as 97%, which means that the generation of intermediate products is greatly reduced and the generation of secondary pollution is effectively avoided.

[0092] Since the 1.5Mn-CeO 2 The doped oxide catalyst catalyzes the efficient oxidation of n-pentane to CO in the presence of oxygen with an energy density in the range of 10-150 J / L. 2 Therefore, the present invention provides a Mn-CeO 2Doped oxide catalysts are used in conjunction with low-temperature plasma to purify n-pentane, especially in the following aspects:

[0093] (1) Purify air containing n-pentane by low-temperature plasma at room temperature (30°C) or above. The n-pentane gas volatilized from the refinery storage tank is treated with low-temperature plasma and catalyst to convert the toxic and harmful n-pentane into non-toxic and harmless CO. 2 .

[0094] (2) Degradation of n-pentane in the exhaust gas from the combustion of fossil fuels (such as gasoline engines, diesel engines, etc.).

[0095] Using Mn-CeO 2 The doped oxide catalyst cooperated with low temperature plasma catalysis under different conditions, and the Mn / Ce atomic ratio was 0.75-4, which could achieve 100% conversion of n-pentane. When there was no water in the gas, the energy density was 10-150 J / L, and the conversion rate of n-pentane was 100%, CO x Selectivity up to 97%

[0096] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A method for degrading n-pentane using a Mn-CeO2 doped oxide catalyst in conjunction with low temperature plasma, characterized in that: The method comprises the following steps: placing a Mn-CeO2 doped oxide catalyst into a reactor, introducing a gas containing n-pentane, and catalytically oxidizing and degrading n-pentane at a plasma energy density of 10-150 J / L and a temperature of ≥30°C.

2. The method for degrading n-pentane using a Mn-CeO2 doped oxide catalyst in cooperation with low temperature plasma as claimed in claim 1, characterized in that: The n-pentane concentration is 30-330 mg / m 3 , the gas volume space velocity per unit catalyst mass is 5000-50000mL / (gh).

3. The method for degrading n-pentane using a Mn-CeO2 doped oxide catalyst in cooperation with low temperature plasma as claimed in claim 1, characterized in that: The Mn-CeO2 doped oxide catalyst is an open or non-open hollow sphere composed of a mixture of Mn3O4, CeO2 and Mn-doped CeO2, with a burr-like structure on the surface of the sphere shell, and the mixture is nanoparticles.

4. The method for degrading n-pentane using a Mn-CeO2 doped oxide catalyst in cooperation with low temperature plasma as claimed in claim 1, characterized in that: The Mn / Ce atomic ratio in the Mn-CeO2 doped oxide catalyst is 0.75-4.

5. The method for degrading n-pentane using a Mn-CeO2 doped oxide catalyst in cooperation with low temperature plasma as claimed in claim 1, characterized in that: The Mn / Ce atomic ratio in the Mn-CeO2 doped oxide catalyst is 1-2.

6. The method for degrading n-pentane using a Mn-CeO2 doped oxide catalyst in cooperation with low temperature plasma as claimed in claim 1, characterized in that: The reactor is a flow-through dielectric barrier discharge fixed bed reactor.

7. The method for degrading n-pentane using a Mn-CeO2 doped oxide catalyst in cooperation with low temperature plasma as claimed in claim 1, characterized in that: The preparation method of the Mn-CeO2 doped oxide catalyst comprises the following steps: S1: Dissolve the compound containing manganese source and cerium source in water to form a solution, and then use atomization technology to atomize the solution to form fine droplets. These droplets are then carried by inert gas into the insulated pipe, where the water in the droplets evaporates, leaving solid particles containing manganese and cerium to form an aerosol; S2: The aerosol is then transported to a pyrolysis tube by an inert gas, where the solid particles in the aerosol decompose to form Mn-CeO2-doped oxides; S3: The generated Mn-CeO2 doped oxide flows into the water absorption bottle along with the inert gas, where it is captured by water. The captured solid product is separated by high-speed centrifugation and dried to obtain a Mn-CeO2 doped oxide catalyst.

8. The method for degrading n-pentane using a Mn-CeO2 doped oxide catalyst in conjunction with low temperature plasma as claimed in claim 7, characterized in that: The temperature of the heat-insulated pipe is 60-70°C.

9. The method for degrading n-pentane using a Mn-CeO2 doped oxide catalyst in cooperation with low temperature plasma as claimed in claim 7, characterized in that: The temperature of the high temperature decomposition tube is 500-800°C.

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