Molecular sieve supported catalyst for catalytic oxidation of pesticide waste salt as well as preparation and application of molecular sieve supported catalyst

Abstract

The invention belongs to the technical field of pesticide waste salt treatment, and particularly relates to a molecular sieve supported catalyst for catalytic oxidation of pesticide waste salt and a preparation method and application thereof. The catalyst consists of a molecular sieve carrier, an active component and a cocatalyst, wherein the mass percentage ratio of the active component to the cocatalyst to the molecular sieve carrier is (0.1-10.0): (0.5-20.0): (70.0-99.4); the molecular sieve carrier is a mesoporous molecular sieve and / or a microporous molecular sieve. The catalyst disclosed by the invention has good performance of pyrolysis catalytic activity in a low-temperature section and is used for pyrolyzing and catalyzing pesticide waste salt, the waste salt is pyrolyzed and catalyzed in a range of 300-500 DEG C, and industrial salt with TOC (Total Organic Carbon) lower than 10-100 mg / kg is obtained by dissolving, evaporating, cooling and crystallizing.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of pesticide waste salt treatment, and particularly relates to a molecular sieve supported catalyst for catalytic oxidation of pesticide waste salt, a preparation method and application thereof. BACKGROUND

[0002] Agricultural production has a very important position in China. In order to avoid crop disease and pest risks and improve crop yield, pesticides are essential products for ensuring the sustainable development of agricultural production and are related to the national economy and people's livelihood. Pesticide waste salt is derived from the production process of pesticide intermediates and original pesticides. The pesticide industry produces about 0.2-2 tons of waste salt per ton of product. Due to the large number of pesticide varieties, there are large differences in the waste production coefficients of products in different subfields. It is estimated that the annual production of pesticide waste salt is about 1.5x10 6 ~2.5x10 6 tons. Pesticide waste salt is a hazardous waste, the main component of which is inorganic salt, and the main pollutant is organic matter. The composition is complex, highly toxic, accumulative and difficult to biodegrade. Improper treatment will cause great harm to the ecological environment and human health.

[0003] Currently, the main technologies for treating pesticide waste salt include landfill, ocean dumping, salt washing, precipitation, and thermal treatment. Landfill disposal technology is generally used to treat industrial waste residues that cannot be resourcefully utilized and are rich in a large number of different types of pollutants. Due to the high water solubility of pesticide waste salt and the presence of toxic and harmful organic pollutants, a high-strength foundation must be provided to achieve impermeability, waterproofness, and leakproofness, which has a high cost requirement. The cost of safe landfill is as high as 3500-4000 yuan / t. At the same time, waste salt landfill disposal occupies a large area of land and has potential ecological environmental risks.

[0004] Ocean dumping is a method of disposing waste materials by utilizing the self-cleaning capacity and environmental capacity of the ocean and selecting suitable ocean space. This method is more commonly used in foreign countries, such as Japan and the United Kingdom, which directly dump pesticide waste salt into the ocean after harmless treatment. However, this method has great limitations for China. Ocean dumping is limited by geographical location, has high environmental risks, and has a certain impact on the ecology.

[0005] Salt washing is a method of washing the saturated solution of pesticide waste salt to dissolve organic matter, impurity ions, and other substances in the waste salt in the washing solution, thereby achieving the purpose of purifying the waste salt. This method has good practicability for waste salt with low impurity content and simple composition. The disadvantage is that the washing water or organic solvent needs to be treated again, causing secondary pollution.

[0006] Precipitation is a method of removing pollutants that are easy to precipitate from waste salt by chemical precipitation. This method has strong specificity and stable removal of specific substances, but it is highly dependent on the characteristics of waste salt and has poor universality.

[0007] The thermal treatment method is to utilize the characteristics that the organic matters in the waste salt are easy to volatilize or thermally decompose under high temperature, decompose the organic matters in the waste salt under high temperature by thermal treatment of the waste salt, and thus achieve the purpose of removing the organic pollutants. SUMMARY

[0008] In order to overcome and solve the problems of high pyrolysis temperature and high energy consumption in the thermal treatment method, the purpose of the present application is to provide a molecular sieve supported catalyst for catalytic oxidation of pesticide waste salt, a preparation method and application thereof.

[0009] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: A molecular sieve supported catalyst for catalytic oxidation of pesticide waste salt, the catalyst is composed of a molecular sieve carrier, an active component and a cocatalyst; wherein the mass percentage of the active component, the cocatalyst and the molecular sieve carrier is: 0.1-10.0:0.5-20.0:70.0-99.4; the molecular sieve carrier is mesoporous molecular sieve and / or microporous molecular sieve.

[0010] The active component is at least one of the elements of Fe, Co, Ni, Cu, Zn, Ag, Pt and Pd; The cocatalyst is at least one of the elements of Ce, La, Sm and Nd.

[0011] The active component is two types of elements A and B, wherein the molar ratio of the two types of elements is 0.01-0.99; wherein the type A element is Pt or Pd; the type B element is Fe, Co, Ni, Cu or Zn.

[0012] The carrier is at least one of mesoporous molecular sieve with a pore size of 2-50 nm, silicon-aluminum, aluminum phosphate or titanium-silicon microporous molecular sieve with a pore size of less than 2 nm and a topological structure of eight-membered ring, ten-membered ring and twelve-membered ring.

[0013] The microporous molecular sieve is at least one of Beta, Y, LTA, MOR, SAPO-18, SAPO-34, AlPO-5, ETS-4, ETS-10, TS-1, ZSM-5, ZSM-35, ZSM-58, SSZ-13, SSZ-39 and SSZ-53 or a combination of multiple thereof; The mesoporous molecular sieve is at least one of MCM-41, MCM-48, SBA-15, SBA-16 or a combination of multiple thereof.

[0014] The mesoporous molecular sieve is a microporous molecular sieve which is hydrothermally treated and / or acid-etched before use.

[0015] The specific surface area of the molecular sieve carrier is not less than 300 m 2 / g.

[0016] The silicon-aluminum ratio of the molecular sieve is 15-200, preferably 15-30.

[0017] A preparation method of the molecular sieve supported catalyst for catalytic oxidation of agricultural waste salt, the preparation method comprising the following steps: (1) first, configure a 0.01-0.5 mol / L aqueous solution of a salt containing rare earth element ions, ion exchange the molecular sieve carrier dried at 60-120 ℃ for 12-48 h at a temperature of 40-80 ℃ for 1-3 times, the liquid-solid ratio is 5-50 (the liquid is the configured aqueous salt solution, and the solid is the dried molecular sieve carrier), after washing and filtering, dry at 60-120 ℃ for 12-48 h, and then calcine at 200-500 ℃ for 0.5-4 h to obtain a rare earth element exchanged molecular sieve; (2) impregnate a salt solution containing metal elements of a catalyst active component onto the rare earth exchanged molecular sieve obtained in step 1) by using an impregnation method, dry at 60-120 ℃ for 12-48 h, and calcine the dried sample in a muffle furnace at 300-600 ℃ for 0.5-4 h to finally obtain a molecular sieve supported catalyst.

[0018] The precursor salt containing rare earth element ions includes at least one of nitrate, chloride, ammonium nitrate, and acetate; The precursor salt containing active component element ions includes at least one of nitrate, ammonium nitrate, and acetate.

[0019] The application of the molecular sieve supported catalyst for catalytic oxidation of agricultural waste salt, the catalyst is applied in the treatment of agricultural waste salt.

[0020] A method for treating agricultural waste salt, which utilizes the catalyst to catalyze the pyrolysis of agricultural waste salt.

[0021] Specifically: (1) mix the waste salt containing organic matter pollutants after drying and crushing to 20-200 mesh particles with the molecular sieve supported catalyst crushed to 20-200 mesh particles after tabletting according to a mass ratio of 1:1-10:1; (2) Put the mixed powder of step (1) into a rotary tube furnace and heat it to 300-500℃ at a heating rate of 2-20℃ / min, and catalytically pyrolyze it in an atmosphere containing 10-20% oxygen for 0.5-2h, and collect the solid powder; (3) Dissolve the solid powder of step (2) in water, filter to obtain a salt solution, recover the catalyst, dry it, and calcine it at 300-600℃ for 0.5-4h to remove surface carbon, and use it for the next catalytic pyrolysis; (4) Heat the salt solution of step (3) at a temperature of 60-90℃ for 0.5-2h. After the volume of the heated salt solution is evaporated to 30-60% of the original volume, stop heating, and filter while hot. The filtered liquid is cooled to crystallize, thereby realizing the treatment of agricultural waste salt.

[0022] The treatment principle of the present application is as follows: The present application successfully introduces the active component and the rare earth element component of the catalyst into the molecular sieve carrier by ion exchange and impregnation methods, and by selecting suitable preparation conditions. The rare earth metal element has excellent oxygen migration ability in catalytic oxidation, and can improve the active oxygen content and electron migration ability on the surface of the catalyst. The obtained molecular sieve supported catalyst can catalytically oxidize the organic pollutants in the pesticide waste salt into non-toxic small molecules such as H2O and CO2 at a low temperature range of 300-500℃, realizes the harmless treatment of the pesticide waste salt, and obtains industrial salt.

[0023] Compared with the prior art, the present application has the following advantages: 1. The catalyst of the present application has good catalytic pyrolysis activity at low temperature.

[0024] 2. Compared with the process of heat treating pesticide waste salt, the catalytic pyrolysis of pesticide waste salt can avoid the problems of high temperature and high energy consumption, and the tail gas discharged only contains harmless small molecules such as H2O and CO2, which will not harm the atmospheric environment.

[0025] 3. The catalyst can be effectively recycled by the solid-liquid separation method after catalytic pyrolysis.

[0026] 4. The catalyst preparation method adopted is simple and mild, and is suitable for industrial production.

[0027] 5. The by-product salt obtained has a TOC content of less than 100mg / kg, and can be used as industrial salt, realizing the harmless treatment of pesticide waste salt. DETAILED DESCRIPTION

[0028] In order to facilitate the understanding of the present application, the present application will be further described below in conjunction with specific examples, but does not limit the present application in any way.

[0029] The application is a molecular sieve supported catalyst for catalytic oxidation of pesticide waste salt, which can oxidize organic pollutants in pesticide waste salt into harmless small molecules such as H2O and CO2 in a temperature range of 300-500°C, and the preparation method of the molecular sieve supported catalyst is simple, the cost is controllable, the prepared catalyst can be reused, and harmless treatment of pesticide waste salt is realized.

[0030] The pesticide waste salt in each of the following examples is imidacloprid or pyridaben with a TOC content of 500-4000 mg / kg.

[0031] Example 1 Catalyst preparation: 0.06 mol / L Ce(NO3)3 aqueous solution was prepared, and ion exchange was carried out at 45°C for 1 time with Beta molecular sieve with a Si / Al ratio of 20 after drying at 90°C for 12 h, and the liquid-solid ratio was 20. After ion exchange, it was washed with deionized water and filtered, and then dried at 120°C for 12 h. The dried powder was calcined at 400°C for 2 h to obtain Ce-type Beta molecular sieve. The above obtained Ce-type Beta molecular sieve was immersed in 0.01 mol / L Pt(NO3)2 aqueous solution and 0.62 mol / L Fe(NO3)3 aqueous solution by impregnation method, and then immersed for 2 h, and then 0.1% Pt and 5% Fe were loaded on the Ce-type Beta molecular sieve, and then dried at 120°C for 12 h after loading, and then the dried sample was calcined at 400°C for 4 h in a muffle furnace to obtain Pt-Fe / Ce-Beta zeolite supported catalyst.

[0032] Treatment of pesticide waste salt with catalyst: 1) The pesticide waste salt containing organic pollutant was dried and crushed to 40-60 mesh particles, and the prepared catalyst was mixed with the Pt-Fe / Ce-Beta zeolite supported catalyst with a particle size of 40-60 mesh after tabletting according to a mass ratio of 5:1.

[0033] 2) The mixed powder of step 1) was placed in a rotary tube furnace and heated, and the temperature was raised to 300-500°C at a heating rate of 5°C / min, and catalytic pyrolysis was carried out for 1 h in an atmosphere containing 20% oxygen, and the solid powder was collected.

[0034] 3) The solid powder of step 2) was dissolved in deionized water to prepare a brine with a liquid-solid ratio of 10, the salt was dissolved by stirring, and the salt solution was obtained after filtration, and the catalyst was recovered, dried and calcined at 550°C for 2 h to remove surface carbon, and the catalyst was retained.

[0035] 4) The salt solution of step (3) is heated at a temperature range of 80°C for 1.5h. After the salt solution is heated and the volume of the solution is evaporated to 40% of the original volume, the heating is stopped and the solution is filtered while hot. The filtered solution is cooled to crystallize and the industrial salt with TOC of 75.6mg / kg is obtained.

[0036] Example 2 The difference between this example and Example 1 is only that: The Beta zeolite carrier with a Si / Al ratio of 20 in the step of Example (1) is replaced by Y zeolite with a Si / Al ratio of 30, and the active components 0.1% Pt and 5% Fe are replaced by 0.2% Pt and 3% Co; Other conditions are the same as Example (1).

[0037] After the catalyst treatment, the TOC of the waste salt is 52.3mg / kg.

[0038] Example 3 The difference between this example and Example 1 is only that: The Beta zeolite carrier with a Si / Al ratio of 20 in the step of Example (1) is replaced by ZSM-5 zeolite with a Si / Al ratio of 25, and the 0.06 mol / L Ce(NO3)3 solution is replaced by 0.1 mol / L Ce(NO3)3, and the active components 0.1% Pt and 5% Fe are replaced by 0.2% Pt and 5% Ni; Other conditions are the same as Example (1).

[0039] After the catalyst treatment, the TOC of the waste salt is 47.5mg / kg.

[0040] Example 4 The difference between this example and Example 1 is only that: The Beta zeolite carrier with a Si / Al ratio of 20 in the step of Example (1) is replaced by MCM-41 mesoporous zeolite with a Si / Al ratio of 45, and the active components 0.1% Pt and 5% Fe are replaced by 0.2% Pt and 10% Cu; Other conditions are the same as Example (1).

[0041] After the catalyst treatment, the TOC of the waste salt is 39.4mg / kg.

[0042] Example 5 The difference between this example and Example 1 is only that: The Beta zeolite carrier with a Si / Al ratio of 20 in the step of Example (1) is replaced by SSZ-13 zeolite with a Si / Al ratio of 30, and the active components 0.1% Pt and 5% Fe are replaced by 0.2% Pt and 10% Zn; Other conditions are the same as in Example (1).

[0043] After treatment with a catalyst, the TOC of the waste salt was 31.7 mg / kg.

[0044] Example 6 The only difference between this embodiment and Embodiment 1 is that: The Beta molecular sieve support with a silicon-to-aluminum ratio of 20 in step (1) of Example 1 was replaced with a microporous Beta molecular sieve with a silicon-to-aluminum ratio of 40 and formed by acid etching to form a mesoporous structure. The active components 0.1% Pt and 5% Fe were replaced with 0.1% Pt and 5% Cu. Other conditions are the same as in Example (1).

[0045] After treatment with a catalyst, the TOC of the waste salt was 83.2 mg / kg.

Claims

1. A molecular sieve supported catalyst for catalytic oxidation of pesticide waste salt, characterized in that, The catalyst is composed of a molecular sieve carrier, an active component and a cocatalyst; wherein the mass percentage of the active component, the cocatalyst and the molecular sieve carrier is 0.1-10.0:0.5-20.0:70.0-99.4; the molecular sieve carrier is mesoporous molecular sieve and / or microporous molecular sieve.

2. The molecular sieve supported catalyst for catalytic oxidation of pesticide waste salt according to claim 1, characterized in that, The active component is at least one of the following elements: Fe, Co, Ni, Cu, Zn, Ag, Pt and Pd; The cocatalyst is at least one of the following rare earth elements: Ce, La, Sm and Nd.

3. The molecular sieve supported catalyst for catalytic oxidation of pesticide waste salt according to claim 2, characterized in that: The active component is A and B type elements, wherein the molar ratio of the two types of elements is 0.01-0.99; wherein the A type element is Pt or Pd; and the B type element is Fe, Co, Ni, Cu or Zn.

4. The molecular sieve supported catalyst for catalytic oxidation of pesticide waste salt according to claim 1, characterized in that, The carrier is at least one of the following: mesoporous molecular sieve with a pore size of 2-50 nm, microporous molecular sieve with a pore size of less than 2 nm and a topological structure of eight-membered ring, ten-membered ring and twelve-membered ring, silicon-aluminum, aluminum phosphate or titanium-silicon microporous molecular sieve.

5. The molecular sieve supported catalyst for catalytic oxidation of pesticide waste salt according to claim 4, characterized in that, The microporous molecular sieve is at least one of the following or a combination of multiple thereof: Beta, Y, LTA, MOR, SAPO-18, SAPO-34, AlPO-5, ETS-4, ETS-10, TS-1, ZSM-5, ZSM-35, ZSM-58, SSZ-13, SSZ-39 and SSZ-53; The mesoporous molecular sieve is at least one of the following or a combination of multiple thereof: MCM-41, MCM-48, SBA-15 and SBA-16.

6. The molecular sieve supported catalyst for catalytic oxidation of pesticide waste salt according to claim 4, characterized in that, The mesoporous molecular sieve is a microporous molecular sieve treated by hydrothermal treatment and / or acid corrosion treatment before use.

7. A method for preparing the molecular sieve supported catalyst for the catalytic oxidation of pesticide waste salts as described in claim 1, characterized in that, The preparation method comprises the following steps: (1) first, configure a 0.01-0.5 mol / L aqueous solution of a salt of a rare earth element ion, and ion-exchange the molecular sieve carrier dried at a temperature of 60-120 ℃ for 12-48 h at a temperature of 40-80 ℃ for 1-3 times with a liquid-solid ratio of 5-50, wash and filter, and then dry at a temperature of 60-120 ℃ for 12-48 h, and then calcine at a temperature of 200-500 ℃ for 0.5-4 h to obtain a rare earth element-exchanged molecular sieve; (2) impregnate a salt solution containing a metal element of a catalyst active component onto the rare earth-exchanged molecular sieve obtained in step 1) by using an impregnation method, dry at a temperature of 60-120 ℃ for 12-48 h, and then calcine the dried sample in a muffle furnace at a temperature of 300-600 ℃ for 0.5-4 h to finally obtain a molecular sieve supported catalyst.

8. The method for preparing a molecular sieve supported catalyst for catalytic oxidation of pesticide waste salt according to claim 7, characterized in that, The precursor salt containing a rare earth element ion comprises at least one of the following: nitrate, chloride, ammonium nitrate and acetate; The precursor salt containing an active component element ion comprises at least one of the following: nitrate, ammonium nitrate and acetate.

9. Use of a molecular sieve supported catalyst as claimed in claim 1 for catalytic oxidation of pesticide waste salts, characterized in that, The catalyst is used for treating agricultural waste salt.

10. A method of treating agricultural waste salts, characterized by: The catalyst is used for catalyzing pyrolysis of agricultural waste salt.