Treatment agent for blast furnace ironmaking waste gas and waste gas treatment method

Abstract

The invention relates to the technical field of waste gas treatment, and particularly discloses a treatment agent for blast furnace ironmaking waste gas and a waste gas treatment method. The treatment agent comprises TiO2 and COFs co-coated honeycomb carbon and a p-aminobenzoic acid modified molecular sieve. The ligand of the COFs comprises quinoline-8-formaldehyde and diethylenetriamine, and Fe < 3 + > is loaded on the honeycomb carbon. In the treatment process, the TiO2 / COFs honeycomb carbon is mainly used for reducing CO2 into CO, resource utilization of CO2 is achieved, the p-aminobenzoic acid modified molecular sieve is mainly used for adsorbing and removing dust, the adsorption process and the catalysis process are carried out at the same time in the whole treatment process, the adsorption process and the catalysis process cooperate with each other and have a synergistic effect, the overall treatment efficiency of blast furnace ironmaking waste gas is improved, and the treatment cost is reduced. The problems of complex process and resource waste caused by respective treatment are avoided, the emission of pollutants can be effectively reduced, green production of the iron and steel industry is assisted, and the method has important significance for promoting sustainable development of the iron and steel industry.

Description

Technical Field

[0001] The present invention relates to the technical field of waste gas treatment, and particularly to a treatment agent for blast furnace ironmaking waste gas and a waste gas treatment method. Background Art

[0002] The iron and steel industry occupies a pivotal position in China's heavy chemical industry, and blast furnace ironmaking is an important link in iron and steel production. Inevitably, a large amount of waste gas is generated during blast furnace ironmaking. Among them, carbon dioxide and dust are one of the main pollutants. Carbon dioxide mainly comes from the combustion of fuels in the blast furnace and the reduction reaction of iron ore, etc. The dust mainly comes from the crushing, screening, transportation of raw materials such as iron ore and coke, and the smelting process in the blast furnace. As one of the main greenhouse gases, the large emission of carbon dioxide has an undeniable promoting effect on global warming, triggering a series of ecological crises such as glacier melting and sea level rise. The wanton dispersion of dust will not only reduce the air quality, cause frequent haze weather in the surrounding areas, affect visibility, but also be easily inhaled by the human body, triggering respiratory diseases, cardiovascular diseases, etc., seriously threatening the health of residents.

[0003] The existing treatment means for carbon dioxide and dust in blast furnace ironmaking waste gas have obvious defects. For the treatment of carbon dioxide, currently mainly physical adsorption method is used, but the adsorption capacity of the adsorbent is limited, and the desorption process has high energy consumption and high cost. In terms of dust treatment, common bag dust removal is prone to damage of the bags when facing the blast furnace ironmaking waste gas with high temperature, high humidity and complex composition, and the maintenance cost is high; the electrostatic dust removal has low collection efficiency for dust with small particle size. The existing treatment technologies often treat a single pollutant such as carbon dioxide or dust, lacking effective collaborative treatment means, resulting in complex treatment processes, increased costs, and it is difficult to meet the requirements of carbon dioxide emission reduction and ultra-low dust emission at the same time, which is not conducive to the sustainable development of the blast furnace ironmaking industry. In view of the deficiencies of the existing technology, developing a treatment agent that can efficiently treat carbon dioxide and dust in blast furnace ironmaking has become an urgent need for the iron and steel industry to achieve green and sustainable development. Summary of the Invention

[0004] Aiming at the problems that the existing treatment technologies often treat a single pollutant such as carbon dioxide or dust, lacking effective collaborative treatment means, resulting in complex treatment processes and increased costs, etc., the present invention provides a treatment agent for blast furnace ironmaking waste gas and a waste gas treatment method.

[0005] To solve the above technical problems, the technical solution provided by the present invention is: The first aspect of the present application provides a treatment agent for blast furnace ironmaking waste gas, which includes honeycomb carbon co-coated with TiO2 and COFs and p-aminobenzoic acid modified molecular sieve; wherein, the ligand of the COFs includes quinoline-8-carboxaldehyde and diethylenetriamine, and the honeycomb carbon is loaded with Fe 3+ .

[0006] Compared with the prior art, the treatment agent for blast furnace ironmaking waste gas provided by the present invention uses honeycomb carbon co-coated with TiO2 and COFs as the main treatment agent for CO2 in blast furnace ironmaking waste gas, and p-aminobenzoic acid modified molecular sieve as the main treatment agent for dust in blast furnace ironmaking waste gas.

[0007] Among them, the COFs composed of quinoline-8-carboxaldehyde and diethylenetriamine have rich nitrogen atom active sites. These nitrogen atoms are rich in lone pairs of electrons and can form strong interactions with CO2 molecules, enabling efficient chemical adsorption of carbon dioxide, greatly enhancing the adsorption capacity and selectivity for CO2; TiO2 can generate photo-generated electrons and holes under light illumination, and COFs have good light absorption and charge transport properties. The combination of the two can promote the separation and transport of photo-generated charges, improve the photocatalytic efficiency, and thus efficiently reduce CO2 to valuable chemicals (such as CO), realizing the resource utilization of carbon dioxide; at the same time, Fe 3+ synergistically catalyzes with TiO2, which can further improve the conversion rate of CO2 to CO; honeycomb carbon has a huge specific surface area and a developed pore structure, which can provide a large number of attachment sites for the adsorption of pollutants in the waste gas and increase the contact area between CO2 and the catalysts (TiO2 and Fe 3+ ), which is beneficial to the adsorption and conversion of CO2. In addition, the large specific surface area and unique pore structure of honeycomb carbon can efficiently physically intercept the dust in blast furnace ironmaking waste gas. When the dust passes through the pores of honeycomb carbon, due to inertial collision, diffusion sedimentation and other effects, it is adsorbed on the surface and inside the pores of honeycomb carbon; the presence of Fe 3+ can enhance the charge distribution on the surface of honeycomb carbon and generate an electrostatic attraction effect on charged dust, further improving the capture efficiency of dust.

[0008] The p-aminobenzoic acid modified molecular sieve has a rich microporous and mesoporous structure, a large specific surface area, and a strong adsorption capacity for dust particles. The surface of the modified molecular sieve is equipped with specific functional groups, which can form chemical bonds with metal ions in the dust, further enhancing the adsorption effect on the dust, effectively removing the dust in the waste gas, and reducing the dust emission concentration. In addition, after being modified with p-aminobenzoic acid, active groups such as amino groups are introduced, and these groups can react with acidic gases in the waste gas such as carbon dioxide and sulfur dioxide, further improving the removal ability of CO2 in the waste gas. At the same time, after the modified molecular sieve reaches saturation in adsorbing dust, it can be regenerated by simple physical or chemical methods, reducing the use cost of the treatment agent and also reducing the generation of waste, with good environmental friendliness.

[0009] The treatment agent provided by the present invention organically combines the functions of carbon dioxide treatment and dust treatment, realizing the coordinated treatment of carbon dioxide and dust in the blast furnace ironmaking waste gas. In the treatment process, TiO2 / COFs honeycomb carbon is mainly used to reduce CO2 to CO, realizing the resource utilization of CO2, and the p-aminobenzoic acid modified molecular sieve is mainly used for the adsorption and removal of dust. In the whole treatment process, the adsorption and catalytic processes are carried out simultaneously, and the two cooperate with each other and act synergistically, improving the overall treatment efficiency of the blast furnace ironmaking waste gas, reducing the treatment cost, avoiding the problems of complex process and resource waste caused by separate treatment, being able to effectively reduce pollutant emissions, helping the steel industry to achieve green production, and having important significance for promoting the sustainable development of the steel industry.

[0010] As a specific embodiment of the present invention, the preparation method of the honeycomb carbon co-coated with TiO2 and COFs includes the following steps: S1, crushing the honeycomb biomass, adding it to an alcohol solution containing Fe 3+ and impregnating it. After solid-liquid separation and drying, the obtained solid is carbonized under an inert atmosphere to obtain honeycomb carbon; S2, dispersing nano-TiO2 in an organic solvent to obtain a nano-TiO2 dispersion; adding diethylenetriamine to the nano-TiO2 dispersion and stirring for reaction to obtain modified nano-TiO2; S3, adding the modified nano-TiO2 and quinoline-8-carboxaldehyde to an organic solvent, mixing evenly to obtain a mixed solution; then adding the honeycomb carbon to the mixed solution, adjusting the pH of the system to acidic, impregnating it, performing solid-liquid separation and drying to obtain the honeycomb carbon co-coated with TiO2 and COFs.

[0011] The present invention first uses a simple solution impregnation method to load Fe 3+ onto the honeycomb carbon precursor, so that Fe 3+During the subsequent carbonization process, it can stably and uniformly exist in the honeycomb carbon structure, laying a foundation for the subsequent honeycomb carbon to play a catalytic role in waste gas treatment. The COF ligand diethylenetriamine was selected to modify TiO2, and a stable chemical bond connection was formed between the hydroxyl groups on the surface of TiO2 nanoparticles and the amino groups in diethylenetriamine, enabling diethylenetriamine to be stably bound to the surface of TiO2. Finally, diethylenetriamine (from modified TiO2) and quinoline-8-carboxaldehyde in-situ coated COFs on the surface of honeycomb carbon through Schiff base reaction. While in-situ coating COFs, the coating of TiO2 on the surface of honeycomb carbon was also achieved.

[0012] The process of forming and coating COFs by the one-step method provided by the present invention not only reduces the operation process, but also ensures the tight combination between COFs, honeycomb carbon, and TiO2. In the treatment of blast furnace ironmaking waste gas, the photocatalytic performance of TiO2, the high selectivity of COFs for carbon dioxide adsorption, and the physical adsorption of honeycomb carbon and the catalytic performance of Fe 3+ cooperate with each other, and can efficiently remove pollutants such as carbon dioxide and dust at the same time, greatly improving the effect and efficiency of waste gas treatment. At the same time, the coating layers of TiO2 and COFs enhance the structural stability of honeycomb carbon, enabling it to operate stably for a long time in the blast furnace ironmaking waste gas environment with high temperature, high humidity, and corrosive gases, and is not easily damaged.

[0013] It should be noted that the honeycomb biomass used in the present invention can be selected from wasp nests and other biomass materials with honeycomb structures, and the present invention does not make special limitations.

[0014] Using honeycomb biomass as the starting material for preparing honeycomb carbon has a wide source and is renewable. It not only has a low cost, but also can effectively reduce the dependence on non-renewable resources, which conforms to the concepts of green chemistry and sustainable development.

[0015] Further, in S1, the honeycomb biomass is crushed to less than 100 mesh.

[0016] Further, in S1, the concentration of Fe 3+ in the alcoholic solution containing Fe 3+ is 0.1 mol / L to 0.5 mol / L.

[0017] Further, in S1, the impregnation time is 3 h to 6 h.

[0018] In S1, the mass ratio of the honeycomb biomass to the alcoholic solution containing Fe 3+ is 1:(8 - 12).

[0019] Further, in S1, the specific steps of carbonization include: first, pre-carbonize the obtained solid at 300°C to 500°C for 1 h to 3 h, and then heat it up to 1000°C to 1200°C for carbonization for 1 h to 2 h.

[0020] Furthermore, the heating rate during the above pre-carbonization and carbonization processes is 2°C / min to 5°C / min.

[0021] Further, in S2, the organic solvent is N,N-dimethylformamide.

[0022] Further, in S2, the mass ratio of the nano-TiO2 to the organic solvent is 1:(10 to 15).

[0023] Further, in S2, the mass ratio of the nano-TiO2 dispersion to diethylenetriamine is 1:(1.2 to 2).

[0024] Further, in S2, the temperature of the stirring reaction is 20°C to 40°C, and the reaction time is 12 h to 24 h.

[0025] Further, in S3, the mass ratio of the modified nano-TiO2 to quinoline-8-carboxaldehyde is 0.8:2 to 2:0.8.

[0026] Further, in S3, the organic solvent is N,N-dimethylformamide.

[0027] Further, in S3, in order to make the mixture of quinoline-8-carboxaldehyde and diethylenetriamine-modified TiO2 uniform, quinoline-8-carboxaldehyde and diethylenetriamine-modified TiO2 can be dissolved in the organic solvent respectively, and then the solutions are mixed. Specifically, the mass ratio of quinoline-8-carboxaldehyde, diethylenetriamine-modified TiO2 to the organic solvent is 1:(10 to 15).

[0028] Further, in S3, the mass ratio of the honeycomb carbon to the mixed solution is 1:(5 to 10).

[0029] Further, in S3, the acidity refers to pH = 3 to 5.

[0030] Exemplarily, a 0.1 mol / L hydrochloric acid solution is used to adjust the pH of the system to 3 to 5.

[0031] Further, in S3, the temperature of the impregnation is 20°C to 40°C, and the impregnation time is 2 h to 3 h.

[0032] As a specific embodiment of the present invention, the preparation method of the p-aminobenzoic acid-modified molecular sieve includes the following steps: Step a, calcine the molecular sieve at 550°C to 650°C to obtain a pretreated molecular sieve; Step b: Mix the pretreated molecular sieve and the silane coupling agent solution, add water, react, perform solid-liquid separation, dry, then keep warm at 80°C to 120°C for 30 min to 60 min, and then react at 200°C to 300°C for 1 h to 2 h to obtain the silane coupling agent-modified molecular sieve. Step c: Add the silane coupling agent-modified molecular sieve into the p-aminobenzoic acid solution, stir and react to obtain the p-aminobenzoic acid-modified molecular sieve.

[0033] In the present invention, first, the molecular sieve is calcined at 550°C to 650°C to activate the internal structure of the molecular sieve, expand its specific surface area, increase the active sites, and provide a better basis for subsequent modification reactions. Then, the silane coupling agent is grafted onto the surface of the molecular sieve, and by controlling the heat preservation method, the binding strength of the silane coupling agent on the surface of the molecular sieve is improved. Then, taking the molecular sieve as a medium, p-aminobenzoic acid is grafted onto the surface of the molecular sieve. The modified molecular sieve has a high capture ability for particles containing metal particles in blast furnace waste gas, and the amino groups introduced on the surface of the molecular sieve can also improve the adsorption ability of the molecular sieve for acidic gases, and the acidic gases can be fixed on the surface of the molecular sieve through chemical reactions, realizing the efficient treatment of blast furnace waste gas.

[0034] Exemplarily, the molecular sieve is ZSM-5 molecular sieve, which has a uniform one-dimensional straight pore structure (with a diameter of about 0.56 nm) and a two-dimensional inclined pore structure (with a diameter of about 0.53 nm). Therefore, it can selectively adsorb small molecules and shows good selectivity for certain organic substances and inorganic ions. Moreover, the ZSM-5 molecular sieve has high thermal stability and mechanical strength, and is suitable for complex blast furnace ironmaking waste gas such as high temperature and high humidity.

[0035] Further, in step a, the calcination time is 2 h to 4 h.

[0036] Further, in step b, the silane coupling agent solution is an ethanol solution of 3-aminopropyltriethoxysilane, and its mass concentration is 1 wt% to 3 wt%.

[0037] Further, in step b, the mass ratio of the pretreated molecular sieve to the silane coupling agent solution is 1:(0.03 to 0.2).

[0038] Further, in step b, the volume ratio of water to the silane coupling agent solution is (10 to 15):1.

[0039] Further, in step b, the temperature is raised to 200°C to 300°C at a rate of 4°C / min to 6°C / min.

[0040] Further, in step b, the reaction temperature is 20°C to 40°C, and the reaction time is 1 h to 2 h.

[0041] Further, in step c, the p-aminobenzoic acid solution is an ethanol solution of p-aminobenzoic acid with a mass concentration of 1% to 3%.

[0042] Further, in step c, the mass ratio of the silane coupling agent-modified molecular sieve to the p-aminobenzoic acid solution is 1:(0.03 - 0.2).

[0043] Further, in step c, the temperature of the stirring reaction is 20°C to 40°C, and the reaction time is 1 h to 2 h.

[0044] The second aspect of the present application provides a method for treating blast furnace ironmaking waste gas, using the above treatment agent to treat the blast furnace ironmaking waste gas.

[0045] Specifically, the method for treating blast furnace ironmaking waste gas specifically includes the following steps: Fill the p-aminobenzoic acid-modified molecular sieve into an adsorption device to obtain a first adsorption module; Fill the honeycomb carbon co-coated with TiO2 and COFs into an adsorption device to obtain a second adsorption module; Fill the p-aminobenzoic acid-modified molecular sieve, the honeycomb carbon co-coated with TiO2 and COFs together into an adsorption device to obtain a third adsorption module; Pass the blast furnace ironmaking waste gas continuously through the first adsorption module, the second adsorption module and the third adsorption module of the adsorption device in sequence to obtain the treated tail gas.

[0046] The method for treating blast furnace ironmaking waste gas provided by the present invention first uses the p-aminobenzoic acid-modified molecular sieve in the first adsorption module to mainly adsorb dust efficiently, and then uses the honeycomb carbon co-coated with TiO2 and COFs in the second adsorption module to adsorb CO2 in the waste gas and reduce it to CO; the removal of dust in the first adsorption module creates more favorable conditions for the photocatalytic reduction of CO2 and avoids the shielding and interference of dust on the photocatalytic reaction; finally, through the third adsorption module filled with the p-aminobenzoic acid-modified molecular sieve, the honeycomb carbon co-coated with TiO2 and COFs together, the remaining dust and CO2 are further treated, thereby realizing the deep purification of dust and CO2 in the waste gas.

[0047] Through the hierarchical adsorption and synergistic effect of the above three modules, the adsorption efficiency of pollutants such as carbon dioxide and dust in the blast furnace ironmaking waste gas is greatly improved, ensuring the deep purification of the waste gas, significantly reducing the pollutant content in the treated tail gas, and providing strong support for the sustainable development of iron and steel enterprises.

[0048] Specifically, the mixing ratio of the p-aminobenzoic acid modified molecular sieve, TiO2, and the honeycomb carbon co-coated with COFs in the third adsorption module can be routinely adjusted according to the actual waste gas composition. Exemplarily, the mass ratio of the p-aminobenzoic acid modified molecular sieve, TiO2, and the honeycomb carbon co-coated with COFs in the third module is (8-12):1.

[0049] When the molecular sieve is saturated with adsorption, the regeneration and reuse of the molecular sieve can be achieved through the following methods: Add the saturated molecular sieve into a hydrochloric acid solution, stir at room temperature for 2h-3h, perform solid-liquid separation, wash the molecular sieve with deionized water until the washing liquid is neutral, and dry to obtain the regenerated molecular sieve.

[0050] For the molecular sieve deactivated due to high temperature, the regeneration and reuse can be carried out through the following methods: Place the deactivated molecular sieve in a muffle furnace, calcine at 500°C-600°C for 20min-40min, then add the calcined molecular sieve into silica sol, perform hydrothermal treatment at 150°C-170°C for 1h-2h, perform solid-liquid separation, wash, dry, and finally calcine at 500°C-600°C for 3h-5h to obtain the regenerated molecular sieve.

[0051] In the treatment agent provided by the present invention, the honeycomb carbon co-coated with TiO2 and COFs combines the photocatalytic performance of TiO2 with the high specific surface area and chemical stability of COFs, can efficiently photocatalytically reduce carbon dioxide into useful substances to achieve resource utilization. At the same time, the porous structure of the honeycomb carbon is conducive to gas adsorption and transmission, improving the treatment efficiency; the p-aminobenzoic acid modified molecular sieve, in synergy with the coated honeycomb carbon, can efficiently adsorb dust in blast furnace waste gas. In addition, the p-aminobenzoic acid modified molecular sieve can be regenerated after adsorption saturation, reducing costs and waste generation, and the preparation method is simple, which has great application value in the field of blast furnace ironmaking waste gas treatment. Detailed implementation manners

[0052] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0053] To better illustrate the present invention, further examples are given below through embodiments.

[0054] All reagents in the following embodiments are commercially available reagents unless otherwise specified, and all experimental methods are existing experimental methods unless otherwise specified.

[0055] Example 1 This embodiment provides a preparation method of a p-aminobenzoic acid modified molecular sieve, including the following steps: Step a: Calcinate the ZSM-5 molecular sieve at 550 °C for 4 h, then ultrasonically clean the ZSM-5 molecular sieve with deionized water and absolute ethanol for 30 min respectively, and dry it to obtain the pretreated molecular sieve; Step b: Dissolve 3-aminopropyltriethoxysilane (APTES) in absolute ethanol to obtain a silane coupling agent solution with a mass concentration of 2%; add the above pretreated molecular sieve into the silane coupling agent solution, and the mass ratio of the pretreated molecular sieve to the silane coupling agent solution is 1:0.03, and add deionized water. The volume ratio of deionized water to the silane coupling agent solution is 1:12, stir at room temperature for 1 h, carry out solid-liquid separation, dry naturally in the air, then place the dried molecular sieve in a muffle furnace, keep it at 120 °C for 30 min, and then heat it to 200 °C at a rate of 4 °C / min and keep it for 2 h to obtain the APTES-modified molecular sieve; Step c: Add the above APTES-modified molecular sieve into a 1 wt% p-aminobenzoic acid ethanol solution, and the mass ratio of the APTES-modified molecular sieve to the p-aminobenzoic acid ethanol solution is 1:0.2, stir at room temperature for 2 h, carry out solid-liquid separation, wash, dry in the air, and place it in a muffle furnace at 80 °C for 2 h to obtain the p-aminobenzoic acid-modified molecular sieve.

[0056] Example 2 This example provides a preparation method of p-aminobenzoic acid-modified molecular sieve, which includes the following steps: Step a: Calcinate the ZSM-5 molecular sieve at 600 °C for 3 h, then ultrasonically clean the ZSM-5 molecular sieve with deionized water and absolute ethanol for 30 min respectively, and dry it to obtain the pretreated molecular sieve; Step b: Dissolve 3-aminopropyltriethoxysilane (APTES) in absolute ethanol to obtain a silane coupling agent solution with a mass concentration of 1%; add the above pretreated molecular sieve into the silane coupling agent solution, and the mass ratio of the pretreated molecular sieve to the silane coupling agent solution is 1:0.2, and add deionized water. The volume ratio of deionized water to the silane coupling agent solution is 1:10, stir at room temperature for 2 h, carry out solid-liquid separation, dry naturally in the air, then place the dried molecular sieve in a muffle furnace, keep it at 100 °C for 50 min, and then heat it to 250 °C at a rate of 5 °C / min and keep it for 1.5 h to obtain the APTES-modified molecular sieve; Step c: Add the above APTES-modified molecular sieve into a 3 wt% p-aminobenzoic acid ethanol solution, and the mass ratio of the APTES-modified molecular sieve to the p-aminobenzoic acid ethanol solution is 1:0.03, stir at room temperature for 1 h, carry out solid-liquid separation, wash, and place it in a muffle furnace at 80 °C for 2 h to obtain the p-aminobenzoic acid-modified molecular sieve.

[0057] Example 3 This example provides a preparation method of p-aminobenzoic acid-modified molecular sieve, which includes the following steps: Step a: Calcinate the ZSM-5 molecular sieve at 650 °C for 2 h, then ultrasonically clean the ZSM-5 molecular sieve with deionized water and absolute ethanol for 30 min respectively, and dry it to obtain the pretreated molecular sieve. Step b: Dissolve 3-aminopropyltriethoxysilane (APTES) in absolute ethanol to obtain a silane coupling agent solution with a mass concentration of 3%; add the above pretreated molecular sieve into the silane coupling agent solution, and the mass ratio of the pretreated molecular sieve to the silane coupling agent solution is 1:0.08, and add deionized water, and the volume ratio of deionized water to the silane coupling agent solution is 1:15. Stir at room temperature for 1 h, perform solid-liquid separation, and naturally dry in air. Then place the dried molecular sieve in a muffle furnace, keep it at 80 °C for 60 min, and then heat it to 300 °C at a rate of 6 °C / min and keep it for 1 h to obtain the APTES-modified molecular sieve. Step c: Add the above APTES-modified molecular sieve into a 2 wt% p-aminobenzoic acid ethanol solution, and the mass ratio of the APTES-modified molecular sieve to the p-aminobenzoic acid ethanol solution is 1:0.1. Stir at room temperature for 2 h, perform solid-liquid separation, wash it, and dry it in a muffle furnace at 80 °C for 2 h to obtain the p-aminobenzoic acid-modified molecular sieve.

[0058] Comparative Example 1 This comparative example provides a preparation method of APTES-modified molecular sieve, including the following steps: Step a: Calcinate the ZSM-5 molecular sieve at 650 °C for 2 h, then ultrasonically clean the ZSM-5 molecular sieve with deionized water and absolute ethanol for 30 min respectively, and dry it to obtain the pretreated molecular sieve. Step b: Dissolve 3-aminopropyltriethoxysilane (APTES) in absolute ethanol to obtain a silane coupling agent solution with a mass concentration of 3%; add the above pretreated molecular sieve into the silane coupling agent solution, and the mass ratio of the pretreated molecular sieve to the silane coupling agent solution is 1:0.08, and add deionized water, and the volume ratio of deionized water to the silane coupling agent solution is 1:15. Stir at room temperature for 1 h, perform solid-liquid separation, and naturally dry in air. Then place the dried molecular sieve in a muffle furnace, keep it at 80 °C for 60 min, and then heat it to 300 °C at a rate of 6 °C / min and keep it for 1 h to obtain the APTES-modified molecular sieve.

[0059] Comparative Example 2 This comparative example provides a preparation method of p-aminobenzoic acid-modified molecular sieve, including the following steps: Step a: Calcinate the ZSM-5 molecular sieve at 650 °C for 2 h, then ultrasonically clean the ZSM-5 molecular sieve with deionized water and absolute ethanol for 30 min respectively, and dry it to obtain the pretreated molecular sieve. Step b: Dissolve p-aminobenzoic acid in deionized water to obtain a 2 wt% p-aminobenzoic acid solution. Add absolute ethanol to the solution to improve the dispersibility and reaction activity, where the addition amount of absolute ethanol is 10% of the mass of the p-aminobenzoic acid solution. Add hydrochloric acid to adjust the pH of the solution to 4 to obtain a reaction solution. Step c: Then add the above pretreated molecular sieve to the reaction solution. The mass ratio of the pretreated molecular sieve to the reaction solution is 1:0.1. Stir at room temperature for 2 h, perform solid-liquid separation, wash, and place in a muffle furnace at 80 °C for drying for 2 h to obtain p-aminobenzoic acid-modified molecular sieve.

[0060] Comparative Example 3 This comparative example provides a preparation method of polyetherimide (PEI)-modified molecular sieve, including the following steps: Step a: Calcinate ZSM-5 molecular sieve at 650 °C for 2 h, and then ultrasonically clean ZSM-5 molecular sieve with deionized water and absolute ethanol for 30 min respectively, and dry to obtain a pretreated molecular sieve. Step b: Dissolve 3-aminopropyltriethoxysilane (APTES) in absolute ethanol to obtain a silane coupling agent solution with a mass concentration of 3%. Add the above pretreated molecular sieve to the silane coupling agent solution. The mass ratio of the pretreated molecular sieve to the silane coupling agent solution is 1:0.08, and add deionized water. The volume ratio of deionized water to the silane coupling agent solution is 1:15. Stir at room temperature for 1 h, perform solid-liquid separation, and dry naturally in the air. Then place the dried molecular sieve in a muffle furnace, keep it at 80 °C for 60 min, and then heat it to 300 °C at a rate of 6 °C / min and keep it for 1 h to obtain APTES-modified molecular sieve. Step c: Dissolve PEI in deionized water to obtain a 2 wt% PEI solution. Add absolute ethanol to the solution to improve the dispersibility and reaction activity, where the addition amount of absolute ethanol is 10% of the mass of the PEI solution. Add the above APTES-modified molecular sieve to the PEI solution. The mass ratio of the APTES-modified molecular sieve to the PEI solution is 1:0.1. Stir at room temperature for 2 h, perform solid-liquid separation, wash, and place in a muffle furnace at 80 °C for drying for 2 h to obtain PEI-modified molecular sieve.

[0061] Adsorption performance test In order to detect the adsorption performance of the modified molecular sieves prepared in Examples 1 to 3 and Comparative Examples 1 to 3, perform an adsorption test of heavy metal ions in wastewater on each modified molecular sieve. The detection method is as follows: 50 mg of each modified molecular sieve was separately placed into 200 mL of simulated heavy metal ion-containing wastewater solution, and then placed in a constant temperature shaking incubator. It was shaken at 25 °C for 1 h with a vibration frequency of 100 rpm. The supernatant was transferred into a centrifuge tube and centrifuged at 500 rpm for 3 min. The concentration of heavy metal ions after adsorption was detected, and the adsorption efficiency k was calculated according to the formula k = [(C0 - C) / C0] × 100%, where C0 is the initial concentration of heavy metal ions in mg / L, and C is the concentration of heavy metal ions after being treated by the modified molecular sieve for 1 h in mg / L. The results are shown in Table 1.

[0062] Among them, the simulated heavy metal ion-containing wastewater solution is a solution containing Fe 3+ , Pb 2+ , Mn 2+ . Among them, the concentration of Fe 3+ is 100 ± 10 mg / mL, the concentration of Pb 2+ is 50 ± 10 mg / mL, and the concentration of Mn 2+ is 50 ± 10 mg / mL. Among them, Fe 3+ is provided by ferric chloride, Pb 2+ is provided by lead nitrate, and Mn 2+ is provided by manganese sulfate.

[0063] Table 1 Adsorption effect

[0064] Example 4 This example provides a preparation method of TiO2 and COFs co-coated honeycomb carbon, including the following steps: S1. The honeycomb was crushed and passed through a 100-mesh sieve. According to the solid-liquid ratio of 1:10, the obtained honeycomb powder was soaked in a 0.3 M ferric nitrate ethanol solution at room temperature for 5 h, followed by solid-liquid separation, air drying at room temperature, and then drying in a drying oven at 100 °C for 40 min. Under a nitrogen atmosphere, it was heated to 400 °C at a rate of 3 °C / min and held for 2 h, and then continued to be heated to 1100 °C at a rate of 3 °C / min and held for 2 h to obtain honeycomb carbon; S2. According to the mass ratio of 1:12, TiO2 nanoparticles were added to N,N-dimethylformamide and sonicated for 40 min to obtain a TiO2 dispersion. Diethylenetriamine (DETA) was added to the TiO2 dispersion, and the mass ratio of the TiO2 dispersion to DETA was 1:1.5. It was stirred at room temperature for 12 h, centrifuged, and alternately washed with N,N-dimethylformamide and absolute ethanol, and then dried in an oven at 50 °C for 8 h to obtain DETA-modified TiO2; S3. Weigh quinoline-8-carboxaldehyde and the above DETA-modified TiO₂ according to a mass ratio of 1:1, and add them to N,N-dimethylformamide respectively. Among them, the mass ratios of quinoline-8-carboxaldehyde, DETA-modified TiO₂ to N,N-dimethylformamide are all 1:12. Stir and mix evenly to obtain a quinoline-8-carboxaldehyde solution and a DETA-modified TiO₂ dispersion; mix the quinoline-8-carboxaldehyde solution and the DETA-modified TiO₂ dispersion evenly to obtain a reaction solution. S4. Add honeycomb carbon to the above reaction solution according to a mass ratio of 1:8. Dropwise add 0.1M dilute hydrochloric acid at room temperature to adjust the pH to 3.2, impregnate at room temperature for 2 h, perform solid-liquid separation, wash, and dry to obtain honeycomb carbon co-coated with TiO₂ and COFs.

[0065] Example 5 This example provides a preparation method of honeycomb carbon co-coated with TiO₂ and COFs, including the following steps: S1. Crush the wasp nest, pass it through a 100-mesh sieve, soak the obtained wasp nest powder in a 0.1M iron nitrate ethanol solution according to a solid-liquid ratio of 1:8, impregnate at room temperature for 6 h, perform solid-liquid separation, air-dry at room temperature, and then dry in a drying oven at 120 °C for 30 min; under a nitrogen atmosphere, heat up to 300 °C at a rate of 2 °C / min and hold for 3 h, and then continue to heat up to 1000 °C at a rate of 2 °C / min and hold for 2 h to obtain honeycomb carbon. S2. Add TiO₂ nanoparticles to N,N-dimethylformamide according to a mass ratio of 1:10, and ultrasonicate for 60 min to obtain a TiO₂ dispersion; add diethylenetriamine (DETA) to the TiO₂ dispersion, and the mass ratio of the TiO₂ dispersion to DETA is 1:2. Stir at room temperature for 24 h, centrifuge, wash alternately with N,N-dimethylformamide and absolute ethanol, and dry in an oven at 60 °C for 10 h to obtain DETA-modified TiO₂. S3. Weigh quinoline-8-carboxaldehyde and the above DETA-modified TiO₂ according to a mass ratio of 2:0.8, and add them to N,N-dimethylformamide respectively. Among them, the mass ratios of quinoline-8-carboxaldehyde, DETA-modified TiO₂ to N,N-dimethylformamide are all 1:15. Stir and mix evenly to obtain a quinoline-8-carboxaldehyde solution and a DETA-modified TiO₂ dispersion; mix the quinoline-8-carboxaldehyde solution and the DETA-modified TiO₂ dispersion evenly to obtain a reaction solution. S4. Add honeycomb carbon to the above reaction solution according to a mass ratio of 1:5. Dropwise add 0.1M dilute hydrochloric acid at room temperature to adjust the pH to 4.8, impregnate at room temperature for 2 h, perform solid-liquid separation, wash, and dry to obtain honeycomb carbon co-coated with TiO₂ and COFs.

[0066] Example 6 This embodiment provides a preparation method of TiO2 and COFs co-coated honeycomb carbon, which includes the following steps: S1, Crush the honeycomb, sieve it through a 100-mesh sieve, soak the obtained honeycomb powder in a 0.5M iron nitrate ethanol solution according to a solid-liquid ratio of 1:12, impregnate it at room temperature for 3h, separate the solid and liquid, air-dry it at room temperature, and then dry it in an 80°C drying oven for 60min; Under a nitrogen atmosphere, heat it to 500°C at a rate of 5°C / min and hold for 1h, then continue to heat it to 1200°C at a rate of 5°C / min and hold for 1h to obtain honeycomb carbon; S2, Add TiO2 nanoparticles to N,N-dimethylformamide according to a mass ratio of 1:15, ultrasonicate for 30min to obtain a TiO2 dispersion; Add diethylenetriamine (DETA) to the TiO2 dispersion, and the mass ratio of the TiO2 dispersion to DETA is 1:1.2, stir at room temperature for 12h, centrifuge, wash alternately with N,N-dimethylformamide and absolute ethanol, and dry in a 60°C oven for 6h to obtain DETA-modified TiO2; S3, Weigh quinoline-8-carboxaldehyde and the above DETA-modified TiO2 according to a mass ratio of 0.8:2, and add them to N,N-dimethylformamide respectively. Among them, the mass ratio of quinoline-8-carboxaldehyde, DETA-modified TiO2 to N,N-dimethylformamide is 1:10, stir and mix evenly to obtain a quinoline-8-carboxaldehyde solution and a DETA-modified TiO2 dispersion; Mix the quinoline-8-carboxaldehyde solution and the DETA-modified TiO2 dispersion evenly to obtain a reaction solution; S4, Add honeycomb carbon to the above reaction solution according to a mass ratio of 1:10, dropwise add 0.1M dilute hydrochloric acid at room temperature to adjust the pH to 3.3, impregnate at room temperature for 3h, separate the solid and liquid, wash, and dry to obtain TiO2 and COFs co-coated honeycomb carbon.

[0067] Comparative Example 4 This comparative example provides a kind of honeycomb carbon, and the specific steps are as follows: Crush the honeycomb, sieve it through a 100-mesh sieve, soak the obtained honeycomb powder in a 0.1M iron nitrate ethanol solution according to a solid-liquid ratio of 1:8, impregnate it at room temperature for 6h, separate the solid and liquid, air-dry it at room temperature, and then dry it in a 120°C drying oven for 30min; Under a nitrogen atmosphere, heat it to 300°C at a rate of 2°C / min and hold for 3h, then continue to heat it to 1000°C at a rate of 2°C / min and hold for 2h to obtain honeycomb carbon.

[0068] Comparative Example 5 This comparative example provides a preparation method of COFs-coated honeycomb carbon, and the specific steps are as follows: S1. Crush the wasp nest, sieve it through a 100-mesh sieve, and soak the obtained wasp nest powder in a 0.3 M iron nitrate ethanol solution at a solid-liquid ratio of 1:10. Immerse it at room temperature for 5 h, separate the solid from the liquid, air-dry it at room temperature, and then dry it in a drying oven at 100 °C for 40 min. Under a nitrogen atmosphere, heat it to 400 °C at a rate of 3 °C / min and hold for 2 h, and then continue to heat it to 1100 °C at a rate of 3 °C / min and hold for 2 h to obtain honeycomb carbon; S2. Weigh terephthalaldehyde and 1,3,5-tris(4-aminophenyl)benzene according to a mass ratio of 1:1, and add them to N,N-dimethylformamide respectively. Among them, the mass ratio of terephthalaldehyde, 1,3,5-tris(4-aminophenyl)benzene to N,N-dimethylformamide is all 1:12. Stir and mix evenly to obtain a terephthalaldehyde solution and a 1,3,5-tris(4-aminophenyl)benzene solution; Mix the terephthalaldehyde solution and the 1,3,5-tris(4-aminophenyl)benzene solution evenly to obtain a reaction solution; S3. Add honeycomb carbon to the above reaction solution according to a mass ratio of 1:8, dropwise add 0.1 M dilute hydrochloric acid at room temperature to adjust the pH to 3.2, immerse it at room temperature for 2 h, separate the solid from the liquid, wash, and dry to obtain COFs-coated honeycomb carbon.

[0069] Adsorption performance test In order to detect the adsorption capacity of the modified honeycomb carbon prepared in Examples 4-6 and Comparative Examples 4-5, the CO2 adsorption performance test was carried out on each modified honeycomb carbon. The detection method is as follows: Continuously introduce the CO2 gas source into the square chamber containing the test sample through an air pump (the test sample fills the square chamber through a sealing cover, and the square chamber is completely sealed except for the gas inlet after being placed). Control the temperature in the square chamber to be room temperature 25 ± 1 °C. The CO2 gas source controls the CO2 flow rate to be 100 mL / min through a mass flow controller. Set a gas concentration detector at the outlet of the square chamber to monitor the concentration of CO2 in the outflow gas in real time, record the data at different time points until the adsorption reaches a stable state, that is, the outflow gas concentration fluctuates between ±1% and ±5% within 10 s. According to the formula: k = [(C0 - C avg ) / C0] × 100% to calculate the adsorption efficiency k, where C0 is the initial CO2 concentration, and C avg is the average CO2 concentration of the outflow gas under the stable state.

[0070] The results are shown in Table 2.

[0071] Table 2 CO2 adsorption performance

[0072] Practical application Simulated ironmaking waste gas: a mixed gas containing 40% metal dust, 40% pulverized coal, and 20% carbon dioxide.

[0073] Metal dust was used to simulate iron ore dust, and the metal dust contained iron powder, lead powder and manganese powder. The preparation method of the metal dust was as follows: iron powder, lead powder and manganese powder were mixed according to a mass ratio of 6:1:2 and then ground to obtain metal powder with a particle size of 2.5 - 10 μm.

[0074] The pulverized coal was the pulverized coal with a particle size of 0.1 - 1 μm used in blast furnace ironmaking.

[0075] The p - aminobenzoic acid - modified molecular sieve prepared in Example 1, the TiO₂ and COFs co - coated honeycomb carbon prepared in Example 4, and the mixture of the p - aminobenzoic acid - modified molecular sieve and TiO₂ and COFs co - coated honeycomb carbon prepared in a mass ratio of 10:1 were filled into a ceramic adsorption column (with a diameter of 3 cm and a height of 30 cm) from bottom to top in sequence. The filling height of each material was 10 cm. The pulverized coal and metal dust simulating the ironmaking process were placed in a ceramic storage tank and heated to 600 °C in a nitrogen atmosphere in a muffle furnace, then kept warm for 30 min. After that, it was placed on a shaking table and shaken for 2 min, and then CO₂ was introduced to keep the pulverized coal and metal dust in a suspended and dispersed state (simulated ironmaking waste gas: a mixed gas of 40% metal dust, 40% pulverized coal and 20% CO₂). Subsequently, the gas valve of the storage tank was opened, and the simulated waste gas was allowed to enter the bottom of the adsorption column through a transmission pipeline. The waste gas was introduced for 10 min, and a gas analyzer was connected at the outlet of the adsorption column to monitor the concentration of CO in the outflow gas in real time. The recovery rate of CO was calculated. k = C / C0×100%, where C0 is the initial carbon dioxide content and C is the content of generated CO. The calculated k was 91.2%.

[0076] After the reduction reaction ended, the p - aminobenzoic acid - modified molecular sieve prepared in the example was taken out, stirred with 1.5 M dilute hydrochloric acid for 2 h, solid - liquid separated, and the molecular sieve was washed with deionized water until the washing liquid was neutral, and then dried at 80 °C to obtain the regenerated molecular sieve.

[0077] The regenerated molecular sieve was subjected to cyclic treatment of simulated ironmaking waste gas according to the above test process to evaluate the regeneration performance and stability of the p - aminobenzoic acid - modified molecular sieve. The CO recovery rate results after multiple adsorption - reduction treatments are shown in Table 3.

[0078] Table 3 Recyclability

[0079] The above - mentioned are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements or improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A treatment agent for blast furnace ironmaking waste gas, characterized in that: Including TiO2 and COFs co-coated honeycomb carbon and p-aminobenzoic acid modified molecular sieve; The ligands of the COFs include quinoline-8-carboxaldehyde and diethylenetriamine, and the honeycomb carbon is loaded with Fe 3+ .

2. The treating agent for blast furnace ironmaking waste gas according to claim 1, characterized in that: The preparation method of the honeycomb carbon co-coated with TiO2 and COFs comprises the following steps: S1, crush the honeycomb biomass and add Fe 3+ The solid is then carbonized in an inert atmosphere to obtain a honeycomb carbon; S2, dispersing nano-TiO2 in an organic solvent to obtain a nano-TiO2 dispersion; adding diethylenetriamine to the nano-TiO2 dispersion, stirring and reacting, to obtain modified nano-TiO2; S3, adding the modified nano-TiO2 and quinoline-8-carboxaldehyde into an organic solvent, mixing evenly to obtain a mixed solution; then adding the honeycomb charcoal into the mixed solution, adjusting the pH of the system to acidic, impregnating, solid-liquid separation, and drying to obtain honeycomb charcoal co-coated with TiO2 and COFs.

3. The treating agent for blast furnace ironmaking waste gas according to claim 2, characterized in that: S1, the Fe 3+ Fe in alcohol solution 3+ The concentration is 0.1mol / L~0.5mol / L; and / or In S1, the immersion time is 3h~6h; and / or In S1, the specific steps of carbonization include: first pre-carbonizing the obtained solid at 300°C~500°C for 1h~3h, and then heating to 1000°C~1200°C for carbonization for 1h~2h.

4. The treating agent for blast furnace ironmaking waste gas according to claim 2, characterized in that: In S2 and S3, the organic solvent is N,N-dimethylformamide; and / or In S2, the mass ratio of the nano-TiO2 to the organic solvent is 1:(10-15); and / or In S2, the mass ratio of the nano-TiO2 dispersion to diethylenetriamine is 1:(1.2-2); and / or In S2, the stirring reaction temperature is 20°C to 40°C, and the reaction time is 12h to 24h.

5. The treating agent for blast furnace ironmaking waste gas according to claim 2, characterized in that: In S3, the mass ratio of the modified nano-TiO2 to quinoline-8-carboxaldehyde is 0.8:2~2:0.8; and / or In S3, the mass ratio of the honeycomb carbon to the mixed liquid is 1:(5-10); and / or In S3, the acidity refers to pH=3-5; and / or In S3, the immersion temperature is 20°C to 40°C, and the immersion time is 2h to 3h.

6. The treating agent for blast furnace ironmaking waste gas according to claim 1, characterized in that: The preparation method of the p-aminobenzoic acid modified molecular sieve comprises the following steps: Step a, calcining the molecular sieve at 550° C. to 650° C. to obtain a pretreated molecular sieve; Step b, mixing the pretreated molecular sieve and the silane coupling agent solution, adding water, reacting, solid-liquid separation, drying, and then keeping at 80° C. to 120° C. for 30 min to 60 min, and then reacting at 200° C. to 300° C. for 1 h to 2 h to obtain a silane coupling agent modified molecular sieve; Step c, adding the silane coupling agent modified molecular sieve into the p-aminobenzoic acid solution, stirring and reacting, to obtain the p-aminobenzoic acid modified molecular sieve.

7. The treating agent for blast furnace ironmaking waste gas according to claim 6, characterized in that: In step a, the calcination time is 2h~4h; and / or In step b, the silane coupling agent solution is an ethanol solution of 3-aminopropyltriethoxysilane, and its mass concentration is 1wt%~3wt%; and / or In step b, the mass ratio of the pretreated molecular sieve to the silane coupling agent solution is 1:(0.03-0.2); and / or In step b, the volume ratio of water to silane coupling agent solution is (10-15):1; and / or In step b, the reaction temperature is 20°C to 40°C, and the reaction time is 1h to 2h.

8. The treating agent for blast furnace ironmaking waste gas according to claim 6, characterized in that: In step c, the p-aminobenzoic acid solution is an ethanol solution of p-aminobenzoic acid with a mass concentration of 1% to 3%; and / or In step c, the mass ratio of the silane coupling agent modified molecular sieve to the p-aminobenzoic acid solution is 1:(0.03-0.2); and / or In step c, the stirring reaction temperature is 20° C. to 40° C., and the reaction time is 1 h to 2 h.

9. A method for treating blast furnace ironmaking waste gas, characterized in that: The blast furnace ironmaking waste gas is treated using the treatment agent described in any one of claims 1 to 8.

10. The method for treating blast furnace ironmaking waste gas according to claim 9, characterized in that: The steps include: Filling the p-aminobenzoic acid modified molecular sieve into the adsorption device to obtain a first adsorption module; Filling the honeycomb carbon co-coated with TiO2 and COFs into an adsorption device to obtain a second adsorption module; The p-aminobenzoic acid modified molecular sieve, TiO2 and COFs co-coated honeycomb carbon are co-filled into the adsorption device to obtain a third adsorption module; The blast furnace ironmaking waste gas is passed through the first adsorption module, the second adsorption module and the third adsorption module of the adsorption device in sequence and continuously to obtain the treated tail gas.

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