Adsorbent for removing volatile organic compounds and preparation method thereof

Abstract

The invention relates to an adsorbent for removing volatile organic compounds and a preparation method thereof, the adsorbent comprises a molecular sieve, the molecular sieve is doped with a transition metal and a group IA metal, the content of the transition metal is 0.05-2 wt%, the content of the group IA metal is 0.01-1 wt%, the specific surface area of the molecular sieve is 100-1000 cm < 2 > / g, and the hydroxyl content is 1-50 mmol / g. The transition metal source and the IA group metal are introduced into the molecular sieve, the purpose of introducing the transition metal source is to eliminate surface hydroxyl, and the IA group metal is creatively introduced, so that the hydrophobicity of the molecular sieve is economically and efficiently improved, and the molecular sieve is suitable for adsorbing volatile organic compounds under humid conditions.

Description

Technical Field

[0001] The present application relates to an adsorbent for removing volatile organic compounds and a preparation method thereof. Background Art

[0002] Volatile Organic Compounds (VOCs) refer to organic compounds with a boiling point below 250°C and a saturated vapor pressure equal to one atmosphere, or a saturated vapor pressure exceeding 133.32 Pa at room temperature. Volatile organic compounds have the characteristics of low boiling point, high vapor pressure, strong photochemical reactivity, etc. They are easy to volatilize at room temperature, and most of them have pungent odor, toxicity, flammability and explosiveness. Zeolite shows broad application prospects in the field of volatile organic compound adsorption due to its good hydrothermal stability, large adsorption capacity and non-flammability.

[0003] The actual adsorption and removal process of volatile organic compounds (such as toluene, xylene and dichloroethane) is usually carried out in a humid environment, and there is a problem of competitive adsorption between water vapor and volatile organic compounds. Therefore, in order to ensure the selectivity of zeolite in the adsorption process of volatile organic compounds, the zeolite is required to have good hydrophobic properties in addition to the aforementioned excellent properties. Traditional zeolites have hydrophilic defects inside and outside their crystals, which limits the ability of zeolites to adsorb volatile organic compounds under humid conditions. How to eliminate the adverse effects of defects and improve the selectivity of zeolites in adsorbing volatile organic compounds under humid conditions is one of the key issues that need to be urgently addressed in the field of volatile organic compound adsorption applications. Summary of the invention

[0004] In order to solve the above problems, the present application discloses an adsorbent for removing volatile organic compounds, including a molecular sieve, wherein the molecular sieve is doped with a transition metal and a group IA metal, wherein the transition metal content is 0.05-2wt%, the group IA metal content is 0.01-1wt%, and the specific surface area of ​​the molecular sieve is 100-1000cm 2 / g, and the hydroxyl content is 1-50mmol / g. The present application introduces a transition metal source and a Group IA metal into the molecular sieve. The purpose of introducing the transition metal source is to eliminate the surface hydroxyl groups, and the Group IA metal is creatively introduced to improve the hydrophobicity of the molecular sieve economically and efficiently, and is suitable for adsorbing volatile organic compounds under humid conditions.

[0005] Preferably, the transition metal is one or more of iron, cobalt, nickel, copper, zinc, molybdenum and tungsten.

[0006] Preferably, the Group IA metal is one or more of sodium, potassium and cesium.

[0007] Preferably, the molecular sieve comprises one or more of the following pore framework topological structures: MFI, MEL, TON, FAU, BEA, and MOR.

[0008] On the other hand, the present application also discloses a method for preparing an adsorbent for removing volatile organic compounds, comprising the following steps:

[0009] S1. Prepare solution A and solution B, and mix solution A and solution B and stir to obtain a mixed solution;

[0010] S2. placing the molecular sieve in the mixed solution and stirring;

[0011] S3. Filter the mixed solution containing the molecular sieve to obtain a filter residue, and dry and calcine the filter residue to obtain an adsorbent. This application adopts an impregnation process loading method, and the effective components are mainly distributed on the surface of the carrier, with high utilization rate, low cost, and short preparation cycle. It is a very simple, easy and economical method, without waste liquid discharge. It is a green process suitable for industrial production. At the same time, the modification effect is good. Under humid conditions, the molecular sieve adsorbs volatile organic compounds such as toluene, xylene, and dichloroethane, showing great advantages.

[0012] Preferably, the cation in solution A is one or more of sodium, potassium, and cesium; the anion is one or more of nitrate, ethylenediaminetetraacetate, citrate, oxalate, gluconate, and iminodisuccinate;

[0013] The cations in solution B are one or more of iron, cobalt, nickel, copper, zinc, molybdenum and tungsten; the anions are one or more of nitrate, acetate, ethylenediaminetetraacetate, citrate, oxalate, gluconate and iminodisuccinate.

[0014] Preferably, the molar ratio of the cations in solution A to solution B in S1 is 0.1-5;

[0015] The cation concentration in solution A in S1 is 0.001-0.1 mol / L;

[0016] The cation concentration in B is 0.001-0.1 mol / L.

[0017] Preferably, the drying time for the filter residue in S3 is 2-10 hours at a temperature of 60-100° C.; the calcination temperature in S3 is 350-750° C. for 2-10 hours.

[0018] Preferably, the molecular sieve in S2 is placed in the mixed solution and stirred for 2-10 hours at a temperature of 20-80°C.

[0019] This application can bring the following beneficial effects:

[0020] 1. This application adopts an impregnation process for loading, and the effective components are mainly distributed on the surface of the carrier, with high utilization rate, low cost, and short preparation cycle. It is a very simple, easy and economical method with no waste liquid discharge. It is a green process suitable for industrial production. At the same time, the modification effect is good. Under humid conditions, the molecular sieve shows great advantages in adsorbing volatile organic compounds such as toluene, xylene, and dichloroethane.

[0021] 2. This application adopts the impregnation process for loading, and the effective components are mainly distributed on the surface of the carrier, with high utilization rate, low cost and short preparation cycle. It is a very simple, easy and economical method with no waste liquid discharge. It is a green process suitable for industrial production.

[0022] 3. The molecular sieve adsorbent synthesized in this application has the advantages of few defects and good hydrophobicity. DETAILED DESCRIPTION

[0023] In order to clearly illustrate the technical features of this solution, this application is elaborated in detail below through specific implementation methods.

[0024] In a first embodiment, an adsorbent for removing volatile organic compounds includes a molecular sieve, wherein the molecular sieve is doped with a transition metal and a Group IA metal, wherein the transition metal content is 0.05-2 wt %, the Group IA metal content is 0.01-1 wt %, and the specific surface area of ​​the molecular sieve is 100-1000 cm 2 / g, and the hydroxyl content is 1-50mmol / g.

[0025] The transition metal is one or more of iron, cobalt, nickel, copper, zinc, molybdenum and tungsten.

[0026] The Group IA metal is one or more of sodium, potassium and cesium.

[0027] The molecular sieve includes one or more of the following pore framework topological structures: MFI, MEL, TON, FAU, BEA, and MOR.

[0028] A method for preparing an adsorbent for removing volatile organic compounds comprises the following steps:

[0029] S1. Prepare solution A and solution B, and mix solution A and solution B and stir to obtain a mixed solution;

[0030] S2. placing the molecular sieve in the mixed solution and stirring;

[0031] S3. Filter the mixed solution containing the molecular sieve to obtain a filter residue, and dry and calcine the filter residue to obtain an adsorbent.

[0032] The cation in solution A (i.e., the Group IA metal solution) is one or more of sodium, potassium, and cesium; the anion is one or more of nitrate, acetate, ethylenediaminetetraacetate, citrate, oxalate, gluconate, and iminodisuccinate;

[0033] The cations in solution B (i.e., the transition metal solution) are one or more of iron, cobalt, nickel, copper, zinc, molybdenum and tungsten; the anions are one or more of nitrate, acetate, ethylenediaminetetraacetate, citrate, oxalate, gluconate and iminodisuccinate.

[0034] The molar ratio of cations of solution A to solution B in S1 is 0.1-5;

[0035] The cation concentration in solution A in S1 is 0.001-0.1 mol / L;

[0036] The cation concentration in B is 0.001-0.1 mol / L.

[0037] The mass ratio of the molecular sieve added to S2 to the transition metal ions is 40-1000.

[0038] In S3, the drying time for the filter residue is 2-10 hours at a temperature of 60-100° C.; the roasting temperature is 350-750° C. for 2-10 hours.

[0039] The molecular sieve in S2 is placed in the mixed solution and stirred for 2-10 hours at a temperature of 20-80°C.

[0040] In order to characterize the technical effects of the present application, the following examples and comparative examples are made:

[0041] Embodiment 1:

[0042] Liquid A is prepared as 0.005 mol / L tetrasodium iminosuccinate solution, and liquid B is prepared as 0.001 mol / L ferric oxalate solution. Take 83 ml of liquid A and liquid B respectively and add them to a beaker and mix them evenly. Add 4.6 g silicalite-1 molecular sieve (pore skeleton topology is MFI) to the mixed solution and stir for 6 hours at 50 ° C. Then, take out the mixed solution and dry it at 65 ° C for 5 hours. Take out the dried sample and place it in a muffle furnace, calcine it at 550 ° C for 8 hours to obtain the target product.

[0043] Embodiment 2:

[0044] Liquid A is prepared as a 0.01 mol / L potassium nitrate solution, and liquid B is prepared as a 0.02 mol / L cobalt oxalate solution. Take 15 ml of liquid A and 10 ml of liquid B respectively and add them to a beaker and mix them evenly. Add 4.4 g of Y-type molecular sieve (pore skeleton topology is FAU) to the mixed solution and stir it at 80 ° C for 2 hours. Then, take out the mixed solution and dry it at 65 ° C for 5 hours. Take out the dried sample and place it in a muffle furnace, calcine it at 550 ° C for 8 hours to obtain the target product.

[0045] Embodiment 3:

[0046] Liquid A is prepared as a 0.004 mol / L sodium citrate solution, and liquid B is prepared as a 0.05 mol / L copper nitrate solution. Take 50 ml of liquid A and 10 ml of liquid B respectively and add them to a beaker and mix them evenly. Add 2 g of mordenite (pore skeleton topology is MOR) to the mixture and stir for 10 hours at 20 ° C. Then, take out the mixture and dry it at 75 ° C for 4 hours. Take out the dried sample and place it in a muffle furnace, calcine it at 750 ° C for 2 hours to obtain the target product.

[0047] Embodiment 4:

[0048] Liquid A is prepared as a 0.01 mol / L cesium nitrate solution, and liquid B is prepared as a 0.02 mol / L nickel nitrate solution. 10 ml of liquid A and 20 ml of liquid B are added to a beaker and mixed evenly. 2 g of X molecular sieve (pore framework topology is FAU) is added to the mixture and stirred for 10 hours at 20 ° C. Then, the mixture is taken out and dried at 60 ° C for 10 hours. The dried sample is taken out and placed in a muffle furnace, and calcined at 550 ° C for 4 hours to obtain the target product.

[0049] Embodiment 5:

[0050] Liquid A is prepared as a 0.001 mol / L sodium acetate solution, and liquid B is prepared as a 0.05 mol / L zinc nitrate solution. Take 50 ml of liquid A and 5 ml of liquid B respectively, add them to a beaker and mix them evenly. Add 1 g of ZSM-5 molecular sieve (pore skeleton topology is MFI) to the mixed solution and stir for 10 hours at 30 ° C. Then, take out the mixed solution and dry it at 80 ° C for 2 hours. Take out the dried sample and place it in a muffle furnace, calcine it at 350 ° C for 10 hours to obtain the target product.

[0051] Embodiment 6:

[0052] Liquid A is prepared as a 0.001 mol / L potassium oxalate solution, and liquid B is prepared as a 0.001 mol / L molybdenum nitrate solution. Take 65 ml of liquid A and 13 ml of liquid B respectively and add them to a beaker and mix them evenly. Add 1 g of silicalite-2 molecular sieve (pore skeleton topology is MEL) to the mixed solution and stir it at 50 ° C for 5 hours. Then, take out the mixed solution and dry it at 65 ° C for 5 hours. Take out the dried sample and place it in a muffle furnace, calcine it at 450 ° C for 8 hours to obtain the target product.

[0053] Embodiment 7:

[0054] Liquid A is prepared as a 0.1 mol / L potassium citrate solution, and liquid B is prepared as a 0.01 mol / L zinc gluconate solution. Take 0.4 ml of liquid A and 38 ml of liquid B respectively and add them to a beaker and mix them evenly. Add 1 g of Y-type molecular sieve (pore skeleton topology is FAU) to the mixed solution and stir it at 50 ° C for 9 hours. Then, take out the mixed solution and dry it at 65 ° C for 8 hours. Take out the dried sample and place it in a muffle furnace, calcine it at 650 ° C for 3 hours to obtain the target product.

[0055] Embodiment 8:

[0056] Liquid A is prepared as 0.005 mol / L cesium acetate solution, and liquid B is prepared as 0.1 mol / L tungsten nitrate solution. Take 16 ml of liquid A and 0.7 ml of liquid B respectively and add them to a beaker and mix them evenly. Add 1 g of ZSM-22 (pore skeleton topology is TON) to the mixture and stir for 8 hours at 40 ° C. Then, take out the mixture and dry it at 65 ° C for 7 hours. Take out the dried sample and place it in a muffle furnace, calcine it at 750 ° C for 2 hours to obtain the target product.

[0057] Embodiment 9:

[0058] Liquid A is prepared as a 0.01 mol / L potassium diethylenediaminetetraacetic acid solution, and liquid B is prepared as a 0.02 mol / L ferric citrate solution. Take 18 ml of liquid A and 5 ml of liquid B respectively and add them to a beaker and mix them evenly. Add 1 g of Beta molecular sieve (pore skeleton topology is BEA) to the mixed solution and stir for 10 hours at 20 ° C. Then, take out the mixed solution and dry it at 60 ° C for 10 hours. Take out the dried sample and place it in a muffle furnace, calcine it at 500 ° C for 5 hours to obtain the target product.

[0059] Embodiment 10:

[0060] Liquid A is prepared as 0.005 mol / L disodium ethylenediaminetetraacetic acid solution, and liquid B is prepared as 0.01 mol / L copper nitrate solution. Take 13 ml of liquid A and 3 ml of liquid B respectively and add them to a beaker and mix them evenly. Add 1 g of ZSM-5 molecular sieve (pore skeleton topology is MFI) to the mixed solution and stir for 8 hours at 30 ° C. Then, take out the mixed solution and dry it at 80 ° C for 6 hours. Take out the dried sample and place it in a muffle furnace, calcine it at 450 ° C for 6 hours to obtain the target product.

[0061] Comparative Example 1

[0062] Liquid A is prepared as 0.03 mol / L tetrasodium iminodisuccinate solution, and liquid B is prepared as 0.3 mol / L ferric nitrate solution. Take 20 ml of liquid A and 15 ml of liquid B respectively and add them to a beaker and mix them evenly. Add 1 g of silicalite-1 molecular sieve (pore skeleton topology is MFI) to the mixed solution and stir for 6 hours at 60 ° C. Then, take out the mixed solution and dry it at 75 ° C for 9 hours. Take out the dried sample and place it in a muffle furnace, calcine it at 300 ° C for 1 hour to obtain the target product.

[0063] Comparative Example 2

[0064] Prepare liquid A as a 0.018 mol / L nickel sulfate solution, take 20 ml of liquid A and add it to a beaker and mix well. Add 1 g of Beta molecular sieve (pore framework topology is BEA) to the mixture and stir it at 60°C for 6 hours. Then, take out the mixture and dry it at 85°C for 8 hours. Take out the dried sample and place it in a muffle furnace, calcine it at 500°C for 8 hours to obtain the target product.

[0065] Comparative Example 3

[0066] Prepare liquid A as 0.001mol / L cesium nitrate solution, prepare liquid B as 0.01mol / L cobalt acetate solution, take 1ml liquid A and 50ml liquid B respectively, add them into a beaker and mix them evenly. Add 4g silicalite-2 molecular sieve (pore skeleton topology is MEL) into the mixed solution and stir for 6h at 60℃. Then, take out the mixed solution and dry it at 70℃ for 12h. Take out the dried sample and place it in a muffle furnace, calcine it at 900℃ for 18 hours to obtain the target product.

[0067] Comparative Example 4

[0068] Prepare liquid A as 0.001 mol / L sodium citrate solution, take 200 ml of liquid A and add it to a beaker and mix well. Add 4 g of ZSM-22 molecular sieve (pore skeleton topology is TON) to the mixture and stir for 6 hours at 60 ° C. Then, take out the mixture and dry it at 70 ° C for 12 hours. Take out the dried sample and place it in a muffle furnace, calcine it at 750 ° C for 18 hours to obtain the target product.

[0069] Comparative Example 5

[0070] Liquid A is prepared as a 0.001 mol / L potassium acetate solution, and liquid B is prepared as a 0.01 mol / L ferric nitrate solution. Take 1 ml of liquid A and 50 ml of liquid B respectively and add them to a beaker and mix them evenly. Add 2 g of ZSM-5 molecular sieve (pore skeleton topology is MFI) to the mixed solution and stir it in a closed place at 120 ° C for 24 hours. Then, take out the mixed solution and dry it at 70 ° C for 12 hours. Take out the dried sample and place it in a muffle furnace, calcine it at 200 ° C for 18 hours to obtain the target product.

[0071] Comparative Example 6

[0072] Liquid A is prepared as a 0.1 mol / L cesium oxalate solution, and liquid B is prepared as a 0.05 mol / L cobalt citrate solution. Take 30 ml of liquid A and 1 ml of liquid B respectively and add them to a beaker and mix them evenly. Add 2 g of ZSM-5 molecular sieve (pore skeleton topology is MFI) to the mixed solution and stir it in a closed state at 120 ° C for 24 hours. Then, take out the mixed solution and dry it at 70 ° C for 12 hours. Take out the dried sample and place it in a muffle furnace, calcine it at 200 ° C for 18 hours to obtain the target product.

[0073] Comparative Example 7

[0074] Liquid A is prepared as a 0.01 mol / L potassium nitrate solution, and liquid B is prepared as a 0.02 mol / L cobalt oxalate solution. Take 15 ml of liquid A, add 4.4 g of Y-type molecular sieve (pore framework topology is FAU) to form a mixed solution K, and stir at 80 ° C for 2 hours. Then, take out the mixed solution K and dry it at 65 ° C for 5 hours. Take out the dried sample and place it in a muffle furnace, calcine it at 550 ° C for 8 hours to obtain an intermediate sample L. Then add 10 ml of liquid B to the beaker and mix it evenly with sample L to form a mixed solution M, and stir it at 80 ° C for 2 hours. Then take out the mixed solution M, dry it at 65 ° C for 5 hours, and obtain intermediate test N. Take out the dried intermediate test N and place it in a muffle furnace, calcine it at 550 ° C for 8 hours to obtain the target product.

[0075] Dynamic adsorption measurements were performed using a fixed bed reactor of a GC apparatus equipped with a hydrogen flame ionization detector (FID). For each test, 0.6 g of sample was loaded into a quartz tube reactor with a total flow rate feed rate of 100 mL / min. The volume fraction of toluene in the feed gas was 0.1%, water vapor was 2.07%, and nitrogen was 97.83%. The sample was 40-60 mesh and pretreated at 573 K for 1 h to remove impurities and water before measurement. Adsorption tests were performed at a relative humidity of 50% and a temperature of 303 K.

[0076] The target product's transition metal content, IA group metal content, molecular sieve specific surface area, hydroxyl content, and molecular sieve to transition metal ion mass ratio are tested. The transition metal content, IA group metal content, and molecular sieve to transition metal ion mass ratio are analyzed by X-ray fluorescence; the molecular sieve specific surface area is analyzed by low-temperature nitrogen isothermal adsorption test; and the hydroxyl content is tested by in-situ infrared spectroscopy.

[0077]

[0078]

[0079]

[0080] From the above examples, it can be seen that the preparation method provided by the present invention can prepare a molecular sieve with adjustable surface hydroxyl defects and good hydrophobicity by introducing a transition metal source and a group IA metal to hydrophobically modify the molecular sieve. The preparation method has simple preparation steps, has certain universality, has no waste liquid discharge, is economical and environmentally friendly, and has broad application prospects.

[0081] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. An adsorbent for removing volatile organic compounds, characterized in that: The molecular sieve comprises a transition metal and a group IA metal doped therein, wherein the transition metal content is 0.05-2wt%, the group IA metal content is 0.01-1wt%, and the specific surface area of ​​the molecular sieve is 100-1000cm 2 / g, and the hydroxyl content is 1-50mmol / g.

2. The adsorbent for removing volatile organic compounds according to claim 1, characterized in that: The transition metal is one or more of Group VIB, VIIB, VIII, IB, and IIB; the Group IA metal is one or more of sodium, potassium, and cesium.

3. The adsorbent for removing volatile organic compounds according to claim 2, characterized in that: The transition metal is one or more of iron, cobalt, nickel, copper, zinc, molybdenum and tungsten.

4. The adsorbent for removing volatile organic compounds according to claim 1, characterized in that: The molecular sieve includes one or more of the following pore framework topological structures: MFI, MEL, TON, FAU, BEA, and MOR.

5. A method for preparing an adsorbent for removing volatile organic compounds, characterized in that: The steps include: S1. Prepare solution A and solution B, and mix solution A and solution B and stir to obtain a mixed solution; S2. placing the molecular sieve in the mixed solution and stirring; S3. Filter the mixed solution containing the molecular sieve to obtain a filter residue, and dry and calcine the filter residue to obtain an adsorbent.

6. The method for preparing an adsorbent for removing volatile organic compounds according to claim 5, characterized in that: The cation in solution A is one or more of sodium, potassium and cesium; the anion is one or more of nitrate, acetate, ethylenediaminetetraacetate, citrate, oxalate, gluconate and iminodisuccinate; The cations in solution B are one or more of iron, cobalt, nickel, copper, zinc, molybdenum and tungsten; the anions are one or more of nitrate, acetate, ethylenediaminetetraacetate, citrate, oxalate, gluconate and iminodisuccinate.

7. The method for preparing a volatile organic compound adsorbent according to claim 5, characterized in that: The molar ratio of cations in solution A to solution B in S1 is 0.1-5; The cation concentration in solution A in S1 is 0.001-0.5 mol / L; The cation concentration in B is 0.001-0.5 mol / L.

8. The method for preparing a volatile organic compound adsorbent according to claim 5, characterized in that: The mass ratio of the molecular sieve added to S2 to the transition metal ions is 40-1000.

9. The method for preparing a volatile organic compound adsorbent according to claim 5, characterized in that: The drying time for the filter residue in S3 is 2-10 hours at a temperature of 60-100° C.; the roasting temperature in S3 is 350-750° C. for 2-10 hours.

10. The method for preparing a volatile organic compound adsorbent according to claim 5, characterized in that: The molecular sieve in S2 is placed in the mixed solution and stirred for 2-10 hours at a temperature of 20-80°C.

Images