CN107899420B - Plasma catalysis method and device for removing volatile organic compounds - Google Patents
Plasma catalysis method and device for removing volatile organic compounds Download PDFInfo
- Publication number
- CN107899420B CN107899420B CN201711396419.3A CN201711396419A CN107899420B CN 107899420 B CN107899420 B CN 107899420B CN 201711396419 A CN201711396419 A CN 201711396419A CN 107899420 B CN107899420 B CN 107899420B
- Authority
- CN
- China
- Prior art keywords
- catalyst
- stage catalyst
- plasma
- volatile organic
- organic compounds
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/8678—Removing components of undefined structure
- B01D53/8687—Organic components
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/002—Mixed oxides other than spinels, e.g. perovskite
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/56—Platinum group metals
- B01J23/64—Platinum group metals with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
- B01J23/656—Manganese, technetium or rhenium
- B01J23/6562—Manganese
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2257/00—Components to be removed
- B01D2257/70—Organic compounds not provided for in groups B01D2257/00 - B01D2257/602
- B01D2257/708—Volatile organic compounds V.O.C.'s
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2523/00—Constitutive chemical elements of heterogeneous catalysts
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Environmental & Geological Engineering (AREA)
- Health & Medical Sciences (AREA)
- Biomedical Technology (AREA)
- Analytical Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Catalysts (AREA)
Abstract
The invention provides a plasma catalyst for removing volatile organic compoundsA chemical method belongs to the field of volatile organic compound treatment. The method comprises the steps of simultaneously introducing volatile organic compounds to be treated and air into low-temperature plasma to form a polymerization product and an oxidation product, wherein in the low-temperature plasma, the polymerization product and the oxidation product are subjected to a first oxidation reaction under the action of the plasma and a first-stage catalyst to obtain the first oxidation product, the first-stage catalyst is a catalyst with medium strong oxidizability, the first oxidation product and a second-stage catalyst are subjected to a second oxidation reaction, the chemical composition of the second-stage catalyst is M/Mn-Ce-X, M comprises one or more of Pt, Pd, Ag and Ru, and X is La, Pr, Sm, Y or Yb. The invention can not only improve the removal rate of VOCs, but also increase CO through the coupling of the first-stage catalyst and the second-stage catalyst2Selectivity of (2).
Description
Technical Field
The invention relates to the technical field of volatile organic compound treatment, in particular to a plasma catalysis method and a plasma catalysis device for removing volatile organic compounds.
Background
According to incomplete statistics, about 300 million tons of Volatile Organic Compounds (VOCs) are discharged to the atmosphere every year in the paint spraying industry of China, and the atmospheric environment is directly polluted and the human health is damaged. The components of the industrial spraying are mainly aromatic hydrocarbons, including toluene, benzene, xylene, styrene and the like. Paint spraying under the non-protection condition, the VOCs concentration in the air of the operation place is quite high, and the harm to paint spraying workers is great. Chronic poisoning, leukopenia, bone marrow hemopoiesis disorder, etc. can be caused by long-term contact. If the intake of the drug is excessive, aplastic anemia will appear in a mild case, and leukemia will appear in a severe case.
The VOCs treatment method mainly comprises a destruction method and a recovery method. The destruction method mainly comprises thermal incineration, catalytic combustion and low-temperature plasma method. In the prior art, in a low-temperature plasma system, high-energy electrons and various free radical groups are generatedThe VOCs are converted into CO through a series of physical and chemical processes2And H2O, or some low toxicity intermediates. Because the average energy of electrons in the plasma is 1-10 eV, chemical reaction which is difficult to occur under common conditions can be realized by properly controlling reaction conditions, and the reaction rate is greatly accelerated, so that the method is widely concerned by environmental workers, but the problem of low VOCs degradation efficiency exists, and CO is used for preparing the catalyst2The selectivity of (a) is low, and a large amount of by-products including polymers formed from charged particles of VOCs are produced, which can undergo secondary conversion in air, creating the problem of more severely contaminated secondary pollutants.
Disclosure of Invention
In view of the above, the present invention provides a plasma catalysis method and apparatus for removing volatile organic compounds. The plasma catalyzing method for removing the volatile organic compounds has higher VOCs degradation efficiency and CO2Selectivity of (2).
In order to achieve the above object, the present invention provides the following technical solutions:
a plasma catalysis method for removing volatile organic compounds comprises the following steps:
(1) simultaneously introducing volatile organic compounds to be treated and air into low-temperature plasma to generate low-temperature plasma charged particles, excited-state particles and oxygen radical active species, wherein the charged particles, the excited-state particles and the oxygen radical active species can generate polymerization reaction to form a polymerization product, and the volatile organic compounds to be treated can generate oxidation reaction to obtain an oxidation product;
(2) in low-temperature plasma, carrying out a first oxidation reaction on the polymerization product and the oxidation product obtained in the step (1) under the action of the plasma and a first-stage catalyst to obtain a first oxidation product, wherein the first-stage catalyst is a catalyst with medium-strong oxidizability;
(3) and (3) carrying out a second oxidation reaction on the first oxidation product obtained in the step (2) and a second-stage catalyst, wherein the second-stage catalyst has a chemical composition of M/Mn-Ce-X, M comprises one or more of Pt, Pd, Ag and Ru, and X is La, Pr, Sm, Y or Yb.
Preferably, the low-temperature plasma in the step (1) is generated by a low-pressure discharge method, and the voltage used by the low-pressure discharge method is 1-30 kV.
Preferably, the strongly oxidative catalyst in the step (2) comprises a carrier and an active ingredient loaded on the surface of the carrier, wherein the carrier is SiO2、Al2O3Or ZrO2The active component is Pt, Pd, Ru, Ni or Co.
Preferably, the mass content of the active component in the strong oxidizing catalyst is 0.05-0.1%.
Preferably, the mass content of M in the two-stage catalyst in the step (3) is 0.2-1%.
Preferably, the preparation method of the two-stage catalyst comprises the following steps:
(a) soluble Ce3+Salt, soluble Mn2+Mixing the nitrate of the salt and X with water, and carrying out redox-hydrothermal reaction to obtain a Mn-Ce-X carrier;
(b) mixing the Mn-Ce-X carrier obtained in the step (a) with a solution containing an M element, and then sequentially heating and calcining to obtain a second-stage catalyst; the solution containing the M element is a chloroplatinic acid solution, a palladium chloride solution or a ruthenium trichloride solution.
Preferably, the temperature of the hydrothermal reaction in the step (a) is 120-160 ℃, and the time of the hydrothermal reaction is 10-12 h.
Preferably, the temperature of heating in step (b) is 100 ℃.
Preferably, the temperature of the calcination is 300 ℃ and the time of the calcination is 4 h.
The invention also provides a device for removing the volatile organic compounds by the plasma catalysis method, which comprises a double-medium-barrier coaxial cylindrical reactor and a quartz tube loaded with a two-section catalyst, wherein the hollow position of double media in the double-medium-barrier coaxial cylindrical reactor is loaded with the one-section catalyst, and the double-medium-barrier coaxial cylindrical reactor is communicated with the quartz tube through a connecting tube; the first-stage catalyst is a catalyst with medium-strong oxidizability; the chemical composition of the two-stage catalyst is M/Mn-Ce-X, wherein M comprises one or more of Pt, Pd, Ag and Ru, and X is La, Pr, Sm, Y or Yb.
The invention provides a plasma catalyzing method for removing volatile organic compounds, which comprises the steps of simultaneously introducing volatile organic compounds to be treated and air into low-temperature plasma to generate low-temperature plasma charged particles, excited-state particles and oxygen radical active species, wherein the charged particles, the excited-state particles and the oxygen radical active species can undergo a polymerization reaction to form a polymerization product, and the volatile organic compounds to be treated undergo an oxidation reaction to obtain an oxidation product; in low-temperature plasma, the polymerization product and the oxidation product are subjected to a first oxidation reaction under the action of the plasma and a first-stage catalyst to obtain a first oxidation product, wherein the first-stage catalyst is a catalyst with medium-strong oxidizability; and carrying out a second oxidation reaction on the first oxidation product and a second-stage catalyst, wherein the second-stage catalyst has a chemical composition of M/Mn-Ce-X, M comprises one or more of Pt, Pd, Ag and Ru, and X is La, Pr, Sm, Y or Yb. In the invention, in the process of treating VOCs by low-temperature plasma, volatile organic compounds to be treated and air are simultaneously introduced into the low-temperature plasma to generate VOCs charged particles or excited particles, oxygen free radicals and other active species, and as a plurality of active particles simultaneously initiate polymerization reaction in gas phase, polymerization products are deposited on the wall of the device, thereby reducing the conversion rate of VOCs and CO2The first-stage catalyst is introduced to react with toluene quickly to reduce the generation of coking polymer, and then the second-stage catalyst is introduced, wherein the X element in the second-stage catalyst utilizes ozone O existing in plasma3Introducing O3Can be decomposed into oxygen atoms, free radicals and active particles, has stronger oxidizing ability, X element not only can enhance the ozone decomposing ability but also can strengthen the stability of the two-stage catalyst, and Pt, Pd, Ag or Ru noble metal in the two-stage catalyst can also greatly improve the oxidability to VOCs, and finally improve CO2The Mn element presents 4+, the oxidation reduction capability is strong, the ozone can be decomposed into oxygen atoms, free radicals and active particles, the oxidation capability is stronger, the ozone can be desorbed at lower temperature, and the desorbed active oxygen can moveHas stronger performance, can be contacted with the first oxidation product on the surface of the two-section catalyst, and can improve CO2Selectivity of (2). Under the action of low-temperature plasma, the removal rate of VOCs can be improved and CO can be increased by coupling the first-stage catalyst and the second-stage catalyst2The selectivity of the method reduces the generation of byproducts. The data of the embodiment shows that the removal rate of the toluene by the plasma catalysis method for removing the volatile organic compounds provided by the invention is 90.3 percent, and the CO is removed2The selectivity of (a) was 90.7%.
The invention also provides a device for removing the volatile organic compounds by the plasma catalysis method, which comprises a double-medium-barrier coaxial cylindrical reactor and a quartz tube loaded with a two-section catalyst, wherein the hollow position of the double medium of the double-medium-barrier coaxial cylindrical reactor is loaded with the one-section catalyst, and the double-medium-barrier coaxial cylindrical reactor is connected with the quartz tube through a connecting tube. The device of the plasma catalysis method for removing the volatile organic compounds can improve the removal rate of VOCs and increase CO through the coupling of the first-stage catalyst and the second-stage catalyst under the action of low-temperature plasma2Selectivity of (2). The device of the plasma catalysis method for removing the volatile organic compounds is simple in structure, and can be improved on the existing device for generating the plasma.
Drawings
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
Fig. 1 is a schematic view of a plasma catalysis method for removing volatile organic compounds according to the present invention, wherein 1 is a first-stage catalyst, 2 is a dual-dielectric barrier coaxial cylindrical reactor, and 3 is a quartz tube loaded with a second-stage catalyst.
Detailed Description
The invention provides a plasma catalyzing method for removing volatile organic compounds, which comprises the following steps:
(1) simultaneously introducing volatile organic compounds to be treated and air into low-temperature plasma to generate low-temperature plasma charged particles, excited-state particles and oxygen radical active species, wherein the charged particles, the excited-state particles and the oxygen radical active species can generate polymerization reaction to form a polymerization product, and the volatile organic compounds to be treated can generate oxidation reaction to obtain an oxidation product;
(2) in low-temperature plasma, carrying out a first oxidation reaction on the polymerization product and the oxidation product obtained in the step (1) under the action of the plasma and a first-stage catalyst to obtain a first oxidation product, wherein the first-stage catalyst is a catalyst with medium-strong oxidizability;
(3) and (3) carrying out a second oxidation reaction on the first oxidation product obtained in the step (2) and a second-stage catalyst, wherein the second-stage catalyst has a chemical composition of M/Mn-Ce-X, M comprises one or more of Pt, Pd, Ag and Ru, and X is La, Pr, Sm, Y or Yb.
The method comprises the steps of simultaneously introducing volatile organic compounds to be treated and air into low-temperature plasma to generate low-temperature plasma charged particles, excited-state particles and oxygen radical active species, wherein the charged particles, the excited-state particles and the oxygen radical active species can generate polymerization reaction to form a polymerization product, and the volatile organic compounds to be treated can generate oxidation reaction to obtain an oxidation product. In the present invention, the low temperature plasma may generate VOCs charged particles or excited particles, oxygen radical active species, and the polymerization product may be deposited on the wall of the vessel due to the simultaneous initiation of polymerization reaction of a plurality of active species in the gas phase. In the present invention, the polymerization product is a mixture, and the molecular weight of the polymerization product is 570 and 300. In the present invention, other side reactions may also occur, the side reaction products including benzoic acid, NOx，O3And CO, and the like.
In the present invention, the low temperature plasma is preferably generated by a low pressure discharge method, and the voltage used in the low pressure discharge method is preferably 1 to 30kV, preferably 2 to 15kV, and more preferably 2.3 to 5 kV. In the present invention, the low-temperature plasma includes ozone.
In the invention, the low-pressure discharge method preferably adopts a double-dielectric-barrier coaxial cylindrical reactor, the discharge cavity length of the double-dielectric-barrier coaxial cylindrical reactor is preferably 3cm, the unilateral discharge gap is preferably 0.3cm, and the barrier dielectrics are preferably quartz glass and a ceramic shaft cylinder respectively.
The invention has no special limitation on the source and the composition of the volatile organic compounds, and VOCs discharged by VOCs industrial sources can be adopted, particularly VOCs generated in industries such as oil refining and petrifaction, printing, pharmaceutical and chemical industry, plastic and rubber product production, artificial leather production and the like.
In the invention, the polymerization reaction is preferably carried out at normal temperature, no additional heating or cooling is required, and the polymerization reaction is more preferably carried out at 20-30 ℃; the time of the polymerization reaction is preferably 30min or more, and more preferably 60 to 120 min.
After obtaining a polymerization product and an oxidation product, the invention carries out a first oxidation reaction on the polymerization product and the oxidation product under the action of plasma and a first-stage catalyst in low-temperature plasma to obtain the first oxidation product, wherein the first-stage catalyst is a catalyst with medium strong oxidizability2、Al2O3Or ZrO2The active component is Pt, Pd, Ru, Ni or Co. In the present invention, the mass content of the active ingredient in the strong oxidizing catalyst is preferably 0.05 to 0.1%, and more preferably 0.05 to 0.08%. The source of the first stage catalyst is not particularly limited in the present invention, and the first stage catalyst can be prepared by a preparation method well known to those skilled in the art. In the invention, the first-stage catalyst can rapidly generate oxidation reaction with toluene in volatile organic compounds, so that the removal rate of VOCs is improved.
In the present invention, the first oxidation reaction is preferably carried out at normal temperature without additional heating or cooling; the time of the first oxidation reaction is preferably 50-80 min, and more preferably 70 min.
After the first oxidation product is obtained, the first oxidation product and a second-stage catalyst are subjected to a second oxidation reaction, wherein the second-stage catalyst has a chemical composition of M/Mn-Ce-X, M comprises one or more of Pt, Pd, Ag and Ru, and X is La, Pr, Sm, Y or Yb. In the present invention, the first oxidation product includes plasma and oxidation products of polymerization products.
In the present invention, the second oxidation reaction is preferably performed at normal temperature without additional heating or cooling; the time of the second oxidation reaction is preferably 50-80 min, and more preferably 70 min.
In the present invention, the mass content of M in the two-stage catalyst is preferably 0.2 to 1%, and more preferably 0.4 to 0.8%.
In the present invention, the method for preparing the two-stage catalyst preferably comprises the steps of:
(a) soluble Ce3+Salt, soluble Mn2+Mixing the nitrate of the salt and X with water, and carrying out hydrothermal reaction to obtain a Mn-Ce-X carrier;
(b) mixing the Mn-Ce-X carrier obtained in the step (a) with a solution containing an M element, and then sequentially heating and calcining to obtain a second-stage catalyst; the solution containing the M element is a chloroplatinic acid solution, a palladium chloride solution or a ruthenium trichloride solution.
The invention mixes the soluble Ce with the calcium carbonate3+Salt, soluble Mn2+Mixing the nitrate of the salt and X with water, and carrying out hydrothermal reaction to obtain the Mn-Ce-X carrier. In the invention, the temperature of the hydrothermal reaction is preferably 120-160 ℃, and more preferably 130-140 ℃; the time of the hydrothermal reaction is preferably 10-12 h, and more preferably 11 h.
The present invention is directed to the soluble Ce3+Salt and soluble Mn2+The kind of the salt is not particularly limited, and soluble Ce known to those skilled in the art is used3+Salts and soluble M2+Salts, in particular, such as Ce (NO)3)3And Mn (NO)3)2。
In the present invention, the soluble Ce3+Cerium element and soluble Mn in salt2+The molar ratio of the manganese element in the salt is preferably 1:14 to 1: 18. The amount of water used in the present invention is not particularly limited, and the soluble Ce can be converted into3+Salt, soluble M2+By dissolving the nitrate of the salt and X, in particular, soluble Ce3+Solubility in saltMn2+The salt was dissolved in 25mL of water and the nitrate of X was dissolved in 10mL of water.
The present invention is directed to the soluble Ce3+Salt, soluble Mn2+The method of adding the nitrate of salt and X and water is not particularly limited, and the method of adding the nitrate of salt and X and water is well known to those skilled in the art, and specifically, soluble Ce is firstly added3+Mixing salt and water to obtain a mixed solution, mixing nitrate of X with water to obtain an X nitrate solution, and adding the X nitrate solution into the mixed solution.
In the present invention, the hydrothermal reaction is preferably carried out under stirring, and more preferably in a hydrothermal reactor having a polytetrafluoroethylene lining and a stirring head.
After the hydrothermal reaction is finished, the hydrothermal product is preferably washed, filtered and dried in sequence to obtain the Mn-Ce-X carrier. In the present invention, the washing is preferably water washing, and the number of times of water washing and the amount of water used per water washing are not particularly limited in the present invention, and it is sufficient that impurity ions in the hydrothermal product can be removed.
After the water washing is completed, the invention preferably filters the water-washed product to obtain a solid product. The specific filtration method of the present invention is not particularly limited, and filtration methods known to those skilled in the art, such as suction filtration, may be used.
After obtaining the solid product, the invention preferably dries the solid product to obtain the Mn-Ce-X carrier. The present invention does not specifically limit the drying manner, and may adopt a drying manner known to those skilled in the art, specifically, drying, and the present invention does not specifically limit the temperature and time of drying, and may remove moisture from the solid product.
After the Mn-Ce-X carrier is obtained, the Mn-Ce-X carrier and a solution containing an M element are mixed and then are sequentially heated and calcined to obtain a two-stage catalyst; the solution containing the M element is a chloroplatinic acid solution, a palladium chloride solution or a ruthenium trichloride solution. In the present invention, the heating temperature is preferably 100 ℃. In the present invention, it is preferable to heat with an oil bath to the heating temperature. In the present invention, the heating can remove moisture in the mixed system.
The specific mixing method is not particularly limited in the present invention, and the mixing method known to those skilled in the art may be adopted, specifically, for example, stirring, and the present invention is not particularly limited in the rotation speed and time of the stirring, and the Mn — Ce — X carrier can be mixed with the solution containing the M element.
The concentration of the solution containing the M element and the volume of the solution containing the M element are not particularly limited, and the mass content of M in the two-stage catalyst may be set to the above-mentioned mass content, specifically, the concentration of the solution containing the M element is 0.01mol/L, the volume of the solution containing the M element is 15.1mL, and the mass of the Mn — Ce — X support is 1.04 g.
After the heating is finished, the invention calcines the heated product to obtain the two-stage catalyst. In the present invention, the temperature of the calcination is preferably 300 ℃, and the time of the calcination is preferably 4 hours.
In the present invention, the calcination is preferably carried out in a muffle furnace.
The invention also provides a device for removing the volatile organic compounds by the plasma catalysis method, which comprises a double-medium-barrier coaxial cylindrical reactor and a quartz tube loaded with a two-section catalyst, wherein the hollow position of double media in the double-medium-barrier coaxial cylindrical reactor is loaded with the one-section catalyst, and the double-medium-barrier coaxial cylindrical reactor is communicated with the quartz tube through a connecting tube; the first-stage catalyst is a catalyst with medium-strong oxidizability; the chemical composition of the two-stage catalyst is M/Mn-Ce-X, wherein M comprises one or more of Pt, Pd, Ag and Ru, and X is La, Pr, Sm, Y or Yb.
In the invention, the length of the discharge cavity of the double-dielectric barrier coaxial cylinder type reactor is preferably 3cm, the unilateral discharge gap is preferably 0.3cm, and the barrier dielectrics are preferably quartz glass and a ceramic shaft cylinder respectively.
In the plasma catalytic method and apparatus for removing volatile organic compounds according to the present invention, the first oxidation reaction and the second oxidation reaction are simultaneously performed.
Fig. 1 is a schematic view of a plasma catalysis method for removing volatile organic compounds according to the present invention, in which 1 is a first-stage catalyst, 2 is a double-medium-barrier coaxial cylindrical reactor, 3 is a quartz tube loaded with a second-stage catalyst, a first-stage catalyst is loaded in a hollow position of a double medium in the double-medium-barrier coaxial cylindrical reactor, and the double-medium-barrier coaxial cylindrical reactor is communicated with the quartz tube through a connection tube; the first-stage catalyst is a catalyst with medium-strong oxidizability; the chemical composition of the two-stage catalyst is M/Mn-Ce-X, wherein M comprises one or more of Pt, Pd, Ag and Ru, and X is La, Pr, Sm, Y or Yb.
In the present invention, the quartz tube is preferably loaded with the two-stage catalyst in an amount of 0.3g, and the two-medium hollow portion is preferably loaded with the one-stage catalyst in an amount of 0.5 g.
The following will explain the plasma catalysis method and apparatus for removing volatile organic compounds provided by the present invention in detail with reference to the examples, but they should not be construed as limiting the scope of the present invention.
The plasma catalysis method for removing the volatile organic compounds is carried out in the device of the plasma catalysis method for removing the volatile organic compounds.
Example 1
The plasma catalysis method for removing the volatile organic compounds comprises the following steps:
(1) in the low-temperature plasma, volatile organic compounds and air are simultaneously introduced, the plasma is started to generate VOCs charged particles or excited-state particles, oxygen free radicals and other active species at room temperature, and a certain amount of polymerization products and oxidation products are generated after the reaction time is 60 min. Low-temperature plasma: the design of the double-medium-blocking coaxial cylindrical reactor is adopted, and the main design parameters are as follows: length of discharge cavity: 3 cm; single-side discharge gap: 0.3 cm; a blocking medium: quartz glass and ceramic shaft cylinders with a voltage of 2 kV;
(2) in low-temperature plasma, the polymerization product and the oxidation product formed by the VOCs charged particles and other species obtained in the step (1) act on the plasma and a section of catalystThe first oxidation reaction is carried out to obtain a first oxidation product, and the carrier of the first-stage catalyst is SiO2The active ingredient is Pt, and the mass content of the active ingredient is 0.05 percent;
(3) and (3) carrying out a second oxidation reaction on the first oxidation product obtained in the step (2) and a second-stage catalyst at room temperature, wherein the second-stage catalyst comprises the chemical composition of Pd/Mn-Ce-La, and the Pd/Mn-Ce-La catalyst is prepared as follows: adding Ce (NO)3)3And Mn (NO)3)2According to the formula of Ce: the Mn molar ratio is 1:14, putting the mixture into a polytetrafluoroethylene lining to obtain a mixed solution, and adding water and stirring. La2(NO3)3Placed in a beaker, added with water, dissolved by slight shaking and poured into a teflon liner. And (3) placing the polytetrafluoroethylene lining under a stirring paddle, stirring for 1.5h, placing the polytetrafluoroethylene lining in a hydrothermal kettle after stirring is finished, and placing in a drying oven at 160 ℃ for 12 h. Taking out, washing and filtering, and drying the pumped filter cake at 60 ℃ overnight to obtain the Mn-Ce-La carrier. Adding PdCl with the molar concentration of 0.01mol/L2And stirring the solution for 1 hour by 15.1mL, then putting the beaker into an oil bath at the temperature of 100 ℃ and heating until the water of the substances in the beaker is evaporated to dryness, putting the beaker into a 60 ℃ drying oven for drying for 12 hours, and then putting the beaker into a muffle furnace to control the temperature to be 300 ℃ and calcining for 4 hours to obtain the Pd/Mn-Ce-La catalyst.
The implementation adopts toluene steam as a representative of volatile organic compounds for testing, the pure liquid of toluene is placed in a constant temperature water bath at 0 ℃, the steam of toluene is taken out by a bubbler, the air flow of toluene blowing and diluting by a mass flow meter is adjusted to obtain different toluene steam concentrations, then the toluene steam is treated by a device of a plasma catalysis method for removing the volatile organic compounds, the concentration of the toluene steam is determined by a gas chromatography GC-960 gas chromatograph, and CO is determined by a methane converter2Selectivity of (2).
Example 2
The plasma catalysis method for removing the volatile organic compounds comprises the following steps:
(1) in the low-temperature plasma, volatile organic compounds and air are simultaneously introduced, the plasma is started to generate VOCs charged particles or excited-state particles, oxygen free radicals and other active species at room temperature, and a certain amount of polymerization products and oxidation products are generated after the reaction time is 60 min. Low-temperature plasma: the design of the double-medium-blocking coaxial cylindrical reactor is adopted, and the main design parameters are as follows: length of discharge cavity: 3 cm; single-side discharge gap: 0.3 cm; a blocking medium: quartz glass and ceramic shaft cylinders with a voltage of 2 kV;
(2) in low-temperature plasma, carrying out first oxidation reaction on a polymerization product and an oxidation product formed by VOCs charged particles and other species obtained in the step (1) under the action of the plasma and a first-stage catalyst to obtain a first oxidation product, wherein the carrier of the first-stage catalyst is SiO2The active ingredient is Pt, and the mass content of the active ingredient is 0.05 percent;
(3) and (3) carrying out a second oxidation reaction on the first oxidation product obtained in the step (2) and a second-stage catalyst at room temperature, wherein the second-stage catalyst comprises the following chemical composition of Pt/Mn-Ce-La, and the preparation of the Pt/Mn-Ce-La catalyst is as follows: adding Ce (NO)3)3And Mn (NO)3)2According to the formula of Ce: the Mn molar ratio is 1:18 is put into the polytetrafluoroethylene lining to obtain mixed liquid, and water is added for stirring. La2(NO3)3Placed in a beaker, added with water, dissolved by slight shaking and poured into a teflon liner. And (3) placing the polytetrafluoroethylene lining under a stirring paddle, stirring for 1.5h, placing the polytetrafluoroethylene lining in a hydrothermal kettle after stirring is finished, and placing in a drying oven at 160 ℃ for 12 h. Taking out, washing and filtering, and drying the pumped filter cake at 60 ℃ overnight to obtain the Mn-Ce-La carrier. H with a molar concentration of 0.01mol/L is added2PtCI6·6H2And stirring 15.1mL of O solution for 1h, putting the beaker into an oil bath at the temperature of 100 ℃, heating until water of substances in the beaker is evaporated to dryness, putting the beaker into a 60 ℃ drying oven for drying for 12h, and putting the beaker into a muffle furnace to control the temperature to be 300 ℃ for calcining for 4h to obtain the Pt/Mn-Ce-La catalyst.
The implementation adopts toluene vapor as a representative of volatile organic compounds for testing, the pure liquid of toluene is placed in a constant temperature water bath at 0 ℃, the vapor of toluene is taken out by a bubbler, the air flow of toluene blowing and diluting by a mass flow meter is adjusted to obtain different toluene vapor concentrations, and then the volatile organic compounds are removedThe concentration of toluene vapor is measured by a gas chromatography GC-960 gas chromatograph, and CO is measured by a methane converter2Selectivity of (2).
Comparative example 1
The implementation adopts toluene steam as a representative of volatile organic compounds for testing, the pure liquid of toluene is placed in a constant temperature water bath at 0 ℃, the steam of toluene is taken out by a bubbler, the air flow of the toluene blown and diluted by a mass flow meter is adjusted to obtain different toluene steam concentrations, then the toluene steam concentrations are subjected to plasma treatment, active species such as VOCs charged particles or excited particles, oxygen free radicals and the like can be generated at room temperature, the reaction time is 60min, and certain polymerization products can be generated. Low-temperature plasma: the design of the double-medium-blocking coaxial cylindrical reactor is adopted, and the main design parameters are as follows: length of discharge cavity: 3 cm; single-side discharge gap: 0.3 cm; a blocking medium: quartz glass and ceramic shaft cylinder at a voltage of 2 kV.
The concentration of toluene vapor was determined by gas chromatography GC-960 gas chromatograph and CO was determined by methane reformer2Selectivity of (2).
Comparative example 2
The implementation adopts toluene steam as a representative of volatile organic compounds for testing, the pure liquid of toluene is placed in a constant temperature water bath at 0 ℃, the steam of toluene is taken out by a bubbler, the air flow of toluene blowing and diluting by a mass flow meter is adjusted to obtain different toluene steam concentrations, then the volatile organic compounds and air are simultaneously introduced into low-temperature plasma, the plasma is started to generate VOCs charged particles or excited particles, oxygen free radicals and other active species at room temperature, the reaction time is 60min, and a certain polymerization product can be generated. Low-temperature plasma: the design of the double-medium-blocking coaxial cylindrical reactor is adopted, and the main design parameters are as follows: length of discharge cavity: 3 cm; single-side discharge gap: 0.3 cm; a blocking medium: quartz glass and ceramic shaft cylinders with a voltage of 2 kV;
in low-temperature plasma, the polymerization product formed by the VOCs charged particles and other species obtained in the step (1) is generated under the action of the plasma and a section of catalystA first oxidation reaction is carried out to obtain a first oxidation product, and the carrier of the first-stage catalyst is SiO2The active ingredient is Pt, and the mass content of the active ingredient is 0.05 percent;
the concentration of toluene vapor was determined by gas chromatography GC-960 gas chromatograph and CO was determined by methane reformer2Selectivity of (2).
Table 1 shows the results of measurements of different removal methods in examples 1 to 2 and comparative examples 1 to 2
As can be seen from Table 1, the plasma catalysis method for removing volatile organic compounds provided by the invention can improve the removal rate of VOCs and increase CO through the coupling of the first-stage catalyst and the second-stage catalyst under the action of low-temperature plasma2Selectivity of (2). The data of the embodiment shows that the removal rate of the toluene by the plasma catalysis method for removing the volatile organic compounds provided by the invention is 90.3 percent, and the CO is removed2The selectivity of (a) was 90.7%.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (7)
1. A plasma catalysis method for removing volatile organic compounds comprises the following steps:
(1) simultaneously introducing volatile organic compounds to be treated and air into low-temperature plasma to generate low-temperature plasma charged particles, excited-state particles and oxygen radical active species, wherein the charged particles, the excited-state particles and the oxygen radical active species can generate polymerization reaction to form a polymerization product, and the volatile organic compounds to be treated can generate oxidation reaction to obtain an oxidation product;
(2) in low-temperature plasma, subjecting the polymerization product and the oxidation product obtained in the step (1) to plasmaThe first oxidation reaction is carried out between the catalyst body and a first-stage catalyst to obtain a first oxidation product, wherein the first-stage catalyst is a catalyst with medium-strong oxidizability; the strong oxidation catalyst in the step (2) comprises a carrier and an active component loaded on the surface of the carrier, wherein the carrier is SiO2、Al2O3Or ZrO2The active component is Pt, Pd, Ru, Ni or Co, and the mass content of the active component in the strong oxidizing catalyst is 0.05-0.1%;
(3) and (3) carrying out a second oxidation reaction on the first oxidation product obtained in the step (2) and a second-stage catalyst, wherein the second-stage catalyst has a chemical composition of M/Mn-Ce-X, M comprises one or more of Pt, Pd, Ag and Ru, X is La, Pr, Sm, Y or Yb, the molar ratio of cerium to manganese in the second-stage catalyst is 1: 14-1: 18, Mn-Ce-X is a carrier of the second-stage catalyst, and the mass content of M in the second-stage catalyst in the step (3) is 0.2-1%.
2. The plasma catalysis method according to claim 1, wherein the low-temperature plasma in the step (1) is generated by a low-pressure discharge method, and the low-pressure discharge method uses 1-30 KV voltage.
3. A plasma catalytic process according to claim 1, characterised in that the process for the preparation of the two-stage catalyst comprises the following steps:
(a) soluble Ce3+Salt and soluble Mn2+Mixing the nitrate of the salt and the nitrate of the X with water, and carrying out redox-hydrothermal reaction to obtain a Mn-Ce-X carrier;
(b) mixing the Mn-Ce-X carrier obtained in the step (a) with a solution containing an M element, and then sequentially heating and calcining to obtain a second-stage catalyst; the solution containing the M element is a chloroplatinic acid solution, a palladium chloride solution or a ruthenium trichloride solution.
4. The plasma catalysis method according to claim 3, wherein the temperature of the hydrothermal reaction in the step (a) is 120-160 ℃, and the time of the hydrothermal reaction is 10-12 h.
5. A plasma catalytic process according to claim 3, characterised in that the temperature of the heating in step (b) is 100 ℃.
6. A plasma-catalytic process according to claim 3 or 5, characterised in that the calcination temperature is 300 ℃ and the calcination time is 4 h.
7. A device for removing volatile organic compounds by a plasma catalysis method comprises a double-medium-barrier coaxial cylindrical reactor and a quartz tube loaded with a two-section catalyst, wherein the hollow position of double media in the double-medium-barrier coaxial cylindrical reactor is loaded with the one-section catalyst, and the double-medium-barrier coaxial cylindrical reactor is communicated with the quartz tube through a connecting tube; the first-stage catalyst is a catalyst with medium-strong oxidizability; the chemical composition of the two-stage catalyst is M/Mn-Ce-X, wherein M comprises one or more of Pt, Pd, Ag and Ru, X is La, Pr, Sm, Y or Yb, the molar ratio of cerium to manganese in the two-stage catalyst is 1: 14-1: 18, and Mn-Ce-X is a carrier of the two-stage catalyst.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711396419.3A CN107899420B (en) | 2017-12-21 | 2017-12-21 | Plasma catalysis method and device for removing volatile organic compounds |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711396419.3A CN107899420B (en) | 2017-12-21 | 2017-12-21 | Plasma catalysis method and device for removing volatile organic compounds |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN107899420A CN107899420A (en) | 2018-04-13 |
| CN107899420B true CN107899420B (en) | 2020-05-05 |
Family
ID=61870650
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201711396419.3A Active CN107899420B (en) | 2017-12-21 | 2017-12-21 | Plasma catalysis method and device for removing volatile organic compounds |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN107899420B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115650175B (en) * | 2022-09-23 | 2023-12-01 | 北京理工大学 | Method for improving oxygen atom conversion efficiency of plate-type ozone generator |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105597529B (en) * | 2015-12-24 | 2018-07-24 | 浙江大学 | A kind of technique and device of low-temperature plasma synergistic two-stage catalytic degradation industrial organic exhaust gas |
| CN105478136B (en) * | 2015-12-24 | 2018-01-23 | 浙江大学 | A kind of catalyst of cooperating with low-temperature plasma-catalytic degraded industrial organic exhaust gas and preparation method and application |
| CN105772072A (en) * | 2016-03-16 | 2016-07-20 | 南京工业大学 | Catalyst suitable for low-temperature plasma treatment of organic waste gas and preparation method and application of catalyst |
| CN206535426U (en) * | 2017-02-17 | 2017-10-03 | 浙江大学 | A kind of double-dielectric barrier discharge device with catalyst coatings for exhaust-gas treatment |
-
2017
- 2017-12-21 CN CN201711396419.3A patent/CN107899420B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN107899420A (en) | 2018-04-13 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108855199A (en) | A kind of composite catalyst and preparation method thereof for catalytic ozonation processing industrial wastewater | |
| CN104676610A (en) | Method for removing toluene by catalytic oxidation | |
| CN107552067A (en) | A kind of material for water treatment and its application | |
| CN107899420B (en) | Plasma catalysis method and device for removing volatile organic compounds | |
| Zhu et al. | VOCs decomposition via modified ferroelectric packed bed dielectric barrier discharge plasma | |
| CN105921009A (en) | Light-oxygen combined waste gas treatment device and treatment method thereof | |
| KR20090121943A (en) | Treatment method and device of waste gas using combustion catalyst and photocatalyst | |
| JP2006326530A (en) | Nanoporous titanium oxide membrane and method for treating volatile organic compound using the same | |
| CN113385184B (en) | Mn-Co-La composite catalyst for catalyzing and degrading VOCs (volatile organic compounds) by synergistic discharge plasma and preparation method and application thereof | |
| CN105833674B (en) | The apparatus and method of thermoelectricity corona and Pintsch process Combined Treatment spraying exhaust gas | |
| CN111957319A (en) | Preparation method of supported ozone catalyst | |
| KR101928882B1 (en) | Process for preparing manganese-activated carbon catalyst using brewing yeast by-products and apparatus for decomposing organic compounds containing the catalyst | |
| CN108993498B (en) | Method for degrading aromatic VOCs (volatile organic compounds) by low-temperature microwave-enhanced cerium oxide-loaded platinum monatomic catalyst | |
| KR101270509B1 (en) | Catalyst using mesoporous materials and manganese oxide, and method for decomposing volatile organic compounds using the same | |
| KR100506813B1 (en) | Mn oxide catalyst for decomposing ozone and the method therefor | |
| CN106630109A (en) | Ceramic membrane, preparation method thereof, ceramic membrane component and wastewater treatment system | |
| KR20010028216A (en) | Catalyst for removing the volatile organic compounds and it's preparation method | |
| CN107803205A (en) | A kind of manufacture method of material for water treatment | |
| CN114225969A (en) | Cerium-based metal organic framework derivative material with synergistic effect with low-temperature plasma and preparation method and application thereof | |
| CN108636008B (en) | Method for purifying tail gas of coal gangue shale sintered brick | |
| JP7177671B2 (en) | Filter body used for ozone oxidation decomposition treatment and manufacturing method thereof | |
| JPH09155364A (en) | Treatment of waste water | |
| CN112619608A (en) | Preparation and application of glucose-based porous carbon material | |
| CN112642428B (en) | Catalyst, preparation method and application thereof, and exhaust gas treatment method | |
| CN108855067B (en) | The method of loaded catalyst and its preparation method and application and preparing propylene by dehydrogenating propane |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |