Method for removing nitrogen oxides and volatile organic pollutants using covalent organic framework materials

Abstract

This invention discloses a method for using covalent organic framework materials to catalytically remove nitrogen oxides and volatile organic pollutants, comprising the following steps: (1) processing the covalent organic framework material to obtain a powdered covalent organic framework material; (2) conducting catalytic reaction tests on the powdered covalent organic framework material to remove NOx and VOCs pollutants. The covalent organic framework material of this invention, due to its large specific surface area, adjustable pore size, functionalizable pore surface, and diverse composition, is beneficial for removing nitrogen oxides (NOx). X The invention relates to the catalytic removal reaction of COFs and volatile organic compounds (VOCs). X This method provides a novel and efficient approach for VOCs treatment. The COFs preparation method and pollutant removal process offer advantages such as mild experimental conditions, simple processes, and low energy consumption.

Description

Technical Field

[0001] This invention belongs to the field of covalent organic framework materials and environmental remediation, specifically relating to a method for treating nitrogen oxides and volatile organic pollutants using covalent organic framework materials. Background Technology

[0002] With the continuous development of modern industry and transportation, the environmental problems caused by excessive emissions of nitrogen oxides (NOx) and volatile organic compounds (VOCs) have increasingly attracted attention both domestically and internationally. Nitrogen oxides mainly include compounds such as NO, N2O, NO2, N2O4, and N2O5. VOCs refer to organic compounds that are volatile at room temperature. Currently, my country's Environmental Protection Administration defines them as organic compounds with high saturated vapor pressure (greater than 133.32 Pa under standard conditions), low boiling point, small molecular weight, and easy volatility at room temperature. Nitrogen oxides and VOCs not only cause environmental problems such as acid rain, photochemical smog, the greenhouse effect, and ozone layer depletion, but also pose a threat to human health by causing respiratory pollution and cardiovascular diseases. Therefore, the treatment of nitrogen oxides and VOCs is urgently needed.

[0003] Over the past few decades, rapid industrial development has resulted in the release of large quantities of volatile organic compounds (VOCs) into the atmosphere through industrial processes. Due to their relatively high vapor pressure at room temperature, VOCs are among the most common indoor air pollutants. VOCs are emitted from a range of products, including solvents, paints and coatings, cleaning products, building materials, furniture, office equipment, glues and adhesives, making them prone to concentration in both residential and industrial environments. In industrial environments, upstream treatment is foreseeable; however, elsewhere, VOC concentrations can only be reduced through air treatment processes such as adsorption, condensation, absorption, membrane permeation, oxidation (thermal or catalytic), or biological processes. The choice of the most suitable treatment method depends on the nature of the VOCs, their concentration, and other factors such as safety or economic considerations.

[0004] Selective catalytic reduction (SCR) of nitrogen oxides is currently the most widely used denitrification technology, and the key to its research lies in designing highly efficient catalysts. In recent years, carbon-based supported transition metal catalysts have become a research direction for efficient NO-SCR due to their advantages such as low cost and availability, low catalytic reaction temperature, and high reactivity. Carbon-based supported transition metal catalysts are transition metals with catalytic denitrification activity supported on carbon-based materials. However, the activity of some transition metals decreases significantly after loading, and the loading process also introduces ash impurities. In addition, the disordered structure and varying pore sizes of traditional carbon-based materials prevent the catalytic process from achieving ideal results. If a synergistic treatment technology is developed that can remove volatile organic compounds (VOCs) while removing nitrogen oxides, it can simultaneously avoid the harm caused by these two pollutants, reduce the formation of secondary aerosols, and thus alleviate environmental problems such as photochemical smog and ozone layer depletion—a win-win situation.

[0005] Catalytic methods are used to remove volatile organic compounds (VOCs) and nitrogen oxides (NOx). X Catalysis is one of the most effective methods for controlling pollutants such as nitrogen oxides and phosphorus oxides (PNOCs), and catalysts are the core of this method. Currently, catalysts are mostly used for controlling single pollutants, making it difficult to achieve synergistic control of multiple pollutants.

[0006] Patent CN108704472A discloses metal-organic framework polymers for treating NO. X Methods related to VOCs. Metal-organic framework polymers consist of a metal center and organic ligands, possessing a highly regular pore structure with controllable pore size, uniform pore size distribution, orderly dispersed active sites, and a large surface area, which is beneficial for NO. X The invention relates to the catalytic removal of VOCs. Patent CN115193405A provides supported mesoporous MOF@COF composite porous particles, their preparation method, and applications. The supported covalent organic framework nanoparticles have adjustable sizes, and the prepared supported composite ions exhibit highly efficient adsorption and catalytic degradation capabilities for volatile organic pollutants. Patent CN115193434A provides a carbon-based catalyst that enables the synergistic removal of nitrogen oxides and volatile organic pollutants. Furthermore, the method provided by this invention allows for alternating VOCs adsorption and redox reactions, ensuring continuous operation.

[0007] In recent years, covalent organic frameworks (COFs) have attracted widespread research attention due to their large specific surface area, tunable pore size, functionalizable pore surfaces, and diverse compositions. Because of their structural characteristics, they are widely used in gas adsorption and separation, organic molecule adsorption and separation, and the adsorption of heavy metals and radioactive metal ions. Therefore, applying covalent organic frameworks to environmental catalysis is an excellent option. Summary of the Invention

[0008] In response to the problems of disordered structure, inconsistent pore size, and poor catalytic effect of carbon-based supported transition metal environmental catalysts studied in recent years, this invention is the first to apply covalent organic framework materials to the field of environmental catalysis for the treatment of nitrogen oxides and volatile organic pollutants.

[0009] To achieve the above technical objectives, the technical solution of the present invention is as follows:

[0010] A method for treating nitrogen oxides and volatile organic pollutants using a covalent organic framework material includes the following steps:

[0011] (1) Processing covalent organic framework materials, including the following steps:

[0012] (a) HFPTP and TAPP-M were packed into a Pyrex tube, and then a mixed solution of o-DCB, n-BuOH and acetic acid was added;

[0013] (b) Quick-freeze the Pyrex tube in a liquid nitrogen bath, drain it, and flame-seal it to reduce its total length;

[0014] (c) After the temperature is raised to room temperature, place the tubes in an oven to bake;

[0015] (d) After cooling to room temperature, the precipitate was separated by centrifugation, washed with acetone, and dried under vacuum to obtain powdered covalent organic framework material for later use;

[0016] (2) Conduct catalytic reaction tests to remove NOx and VOCs pollutants. The method is as follows:

[0017] 1) Take an appropriate amount of the treated covalent organic framework material JUC-640-M and place it in a reaction tube plugged with quartz wool;

[0018] 2) The reaction tube is heated by programmed temperature increase to obtain the treated covalent organic framework material;

[0019] 3) Introduce NOx and VOCs polluting gases and control the reaction space velocity to enable the treated covalent organic framework material to efficiently remove NOx and VOCs polluting gases.

[0020] Further, the covalent organic framework material mentioned in step (1) is: JUC-640-M, where M = H, Co, or Ni.

[0021] Further, the outer diameter × inner diameter of the Pyrex tube mentioned in step (a) is 10 × 8 mm. 2 .

[0022] Further, in step (a), the HFPTP is 18.0 mg, o-DCB is 1 mL, n-BuOH is 1 mL, and acetic acid is 0.2 mL.

[0023] Furthermore, in step (b), the Pyrex tube is rapidly frozen in a liquid nitrogen bath, emptied, and flame-sealed, reducing its total length by 10.0 cm.

[0024] Furthermore, in step (c), after the temperature is raised to room temperature, the tube is placed in an oven at 120°C for 7 days.

[0025] Furthermore, the volume of acetone used for washing in step (d) is 3 × 5.0 mL.

[0026] Further, in step (d), the material is dried overnight under vacuum at 80°C to obtain a powdered covalent organic framework material.

[0027] Further, in step 2), the reaction tube is heated to 150℃~480℃ by programmed temperature increase to obtain the treated covalent organic framework material.

[0028] Furthermore, in step 3), the reaction space velocity is controlled to be 10,000-40,000 h⁻¹. -1 The reaction space velocity enables the treated covalent organic framework material to effectively remove NOx and VOCs pollutants. The flow rate of NOx and VOCs pollutants and the amount of treated covalent organic framework material packing are determined based on this reaction space velocity (reaction space velocity = gas flow rate / packing volume). When the concentration of NOx and VOCs pollutants to be treated is too high, the pollutants can be diluted by reducing the reaction space velocity or using other gases, such as ammonia. As the treatment process progresses, the covalent organic framework material will gradually lose its ability to remove pollutants and needs to be replaced in a timely manner to achieve good treatment results.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] (1) COFs themselves have the characteristics of large specific surface area, adjustable pore size, functionalizable pore surface, and diverse composition. Due to their structural characteristics, they are widely used in gas adsorption and separation, organic molecule adsorption and separation, and adsorption of heavy metal and radioactive metal ions.

[0031] (2) The COFs preparation method and pollutant removal process of the present invention have the advantages of mild experimental conditions, simple process and low energy consumption. Detailed Implementation

[0032] The present invention will be further illustrated below with reference to specific embodiments. These embodiments should be understood as illustrative only and not as limiting the scope of protection of the present invention. After reading the description of the present invention, various modifications or alterations made to the present invention based on the principles of the present invention also fall within the scope defined by the claims of the present invention.

[0033] Example 1

[0034] The application method of covalent organic framework material JUC-640-H for treating nitrogen oxides and volatile organic pollutants includes the following steps:

[0035] (1) Treatment of covalent organic framework material JUC-640-H, specific treatment steps:

[0036] (a) In a diameter of outer diameter × inner diameter = 10 × 8 mm 2 HFPTP (18.0 mg, 0.02 mmol) and TAPP-H (19.8 mg, 0.03 mmol) were packed into a Pyrex tube, and then a mixed solution of o-DCB (1 mL), n-BuOH (1 mL) and 6.0 M acetic acid (0.2 mL) was added.

[0037] (b) The Pyrex tube was rapidly frozen in a liquid nitrogen bath, emptied, and flame-sealed to reduce its total length by 10.0 cm;

[0038] (c) After the temperature is raised to room temperature, place the tubes in an oven at 120°C for 7 days;

[0039] (d) After cooling to room temperature, the precipitate was separated by centrifugation, washed with acetone (3×5.0mL), and dried under vacuum at 80℃ overnight to obtain a brownish-red powder JUC-640-H;

[0040] (2) Conduct catalytic reaction tests to remove NOx and VOCs pollutants. The method is as follows:

[0041] (a) Take an appropriate amount of the treated covalent organic framework material JUC-640-H and place it in a reaction tube plugged with quartz wool;

[0042] (b) The reaction tube is heated to 150°C to 480°C using a programmed temperature rise method;

[0043] (c) Introducing NO and polluting gases such as toluene and benzene. Experimental studies have shown that a relatively stable 99% NOx and VOCs removal rate can be maintained within a temperature range of 150℃ to 480℃.

[0044] Example 2

[0045] The application method of the covalent organic framework material JUC-640-Co for treating nitrogen oxides and volatile organic pollutants includes the following steps:

[0046] (1) Treatment of covalent organic framework material JUC-640-Co, specific treatment steps:

[0047] (a) In a diameter of outer diameter × inner diameter = 10 × 8 mm 2 HFPTP (18.0 mg, 0.02 mmol) and TAPP-Co (21.5 mg, 0.03 mmol) were packed into a Pyrex tube, and then a mixed solution of o-DCB (1 mL), n-BuOH (1 mL) and 6.0 M acetic acid (0.2 mL) was added.

[0048] (b) The Pyrex tube was rapidly frozen in a liquid nitrogen bath, emptied, and flame-sealed to reduce its total length by 10.0 cm;

[0049] (c) After the temperature is raised to room temperature, place the tubes in an oven at 120°C for 7 days;

[0050] (d) After cooling to room temperature, the precipitate was separated by centrifugation, washed with acetone (3 × 5.0 mL), and dried under vacuum at 80 °C overnight to obtain red powder JUC-640-Co;

[0051] (2) Conduct catalytic reaction tests to remove NOx and VOCs pollutants. The method is as follows:

[0052] (a) Take an appropriate amount of the treated covalent organic framework material JUC-640-Co and place it in a reaction tube plugged with quartz wool;

[0053] (b) The reaction tube is heated to 150°C to 480°C using a programmed temperature rise method;

[0054] (c) Introducing NO and polluting gases such as toluene and benzene. Experimental studies have shown that a relatively stable 99% NOx and VOCs removal rate can be maintained within a temperature range of 150℃ to 480℃.

[0055] Example 3

[0056] The application method of the covalent organic framework material JUC-640-Ni for treating nitrogen oxides and volatile organic pollutants includes the following steps:

[0057] (1) Treatment of covalent organic framework material JUC-640-Ni, specific treatment steps:

[0058] (a) In a diameter of outer diameter × inner diameter = 10 × 8 mm 2HFPTP (18.0 mg, 0.02 mmol) and TAPP-Ni (21.5 mg, 0.03 mmol) were packed into a Pyrex tube, and then a mixed solution of o-DCB (1 mL), n-BuOH (1 mL) and 6.0 M acetic acid (0.2 mL) was added.

[0059] (b) The Pyrex tube was rapidly frozen in a liquid nitrogen bath, emptied, and flame-sealed to reduce its total length by 10.0 cm;

[0060] (c) After the temperature is raised to room temperature, place the tubes in an oven at 120°C for 7 days;

[0061] (d) After cooling to room temperature, the precipitate was separated by centrifugation, washed with acetone (3×5.0 mL), and dried under vacuum at 80 °C overnight to obtain red powder JUC-640-Ni;

[0062] (2) Conduct catalytic reaction tests to remove NOx and VOCs pollutants. The method is as follows:

[0063] (a) Take an appropriate amount of the treated covalent organic framework material JUC-640-Ni and place it in a reaction tube plugged with quartz wool;

[0064] (b) The reaction tube is heated to 150°C to 480°C using a programmed temperature rise method;

[0065] (c) Introducing NO and polluting gases such as toluene and benzene. Experimental studies have shown that a relatively stable 99% NOx and VOCs removal rate can be maintained within a temperature range of 150℃ to 480℃.

[0066] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made using the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method of treating nitrogen oxides and volatile organic pollutants with a covalent organic framework material, characterized in that, The method comprises the following steps: (1) treating the covalent organic framework material, comprising the following steps: (a) loading HFPTP and TAPP-M into a Pyrex tube, and then adding a mixed solution of o-DCB, n-BuOH and acetic acid; (b) rapidly freezing the Pyrex tube in a liquid nitrogen bath, evacuating and flame sealing, and reducing the total length of the tube; (c) after being warmed to room temperature, baking the tube in an oven; (d) after being cooled to room temperature, separating the precipitate by centrifugation, washing with acetone, and drying under vacuum to obtain a powdered covalent organic framework material, which is JUC-640-M, wherein M is H, Co or Ni, for standby use; (2) performing a catalytic reaction test for removing NOx and VOCs contaminated gas, in the following manner: 1) taking an appropriate amount of the treated covalent organic framework material JUC-640-M and placing it in a reaction tube plugged with quartz wool; 2) performing programmed temperature heating on the reaction tube to obtain the treated covalent organic framework material; 3) introducing NOx and VOCs contaminated gas, and controlling the reaction space velocity to enable the treated covalent organic framework material to efficiently remove the NOx and VOCs contaminated gas; In step (a), the HFPTP is 18.0 mg, the o-DCB is 1 mL, the n-BuOH is 1 mL, and the acetic acid is 0.2 mL. In step 2), the reaction tube is heated to 150-480°C by programmed temperature heating to obtain the treated covalent organic framework material. The reaction space velocity in step 3) is controlled to be 10,000-40,000 h -1 .

2. The method of claim 1, wherein the covalent organic framework material is selected from the group consisting of: wherein R is a C1-C6 alkyl group, and wherein the covalent organic framework material is selected from the group consisting of: wherein R is a C1-C6 alkyl group. In step (b), the Pyrex tube is rapidly frozen in a liquid nitrogen bath, evacuated and flame sealed, and the total length of the tube is reduced by 10.0 cm.

3. The method for treating nitrogen oxides and volatile organic pollutants using the covalent organic framework material according to claim 1, characterized in that, In step (c), after being warmed to room temperature, the tube is placed in an oven at 120°C for 7 days.

4. The method for treating nitrogen oxides and volatile organic pollutants using a covalent organic framework material according to claim 1, characterized in that, In step (d), the tube is dried under vacuum at 80°C overnight to obtain a powdered covalent organic framework material.