Cracking carbonization waste gas purification method for waste circuit board regeneration

Abstract

The invention discloses a method for purifying pyrolysis and carbonization waste gas for waste circuit board regeneration, belongs to the technical field of waste gas treatment, and aims at solving the technical problem that in the prior art, the concentrations of small-molecular organic matters and acid gases in the waste gas generated after pyrolysis, carbonization and purification for waste circuit board regeneration are too high. A purification system is constructed by sequentially layering a calcium-aluminum-carbon composite purification material, polydentate oxidation gel and activated carbon gel, the purification system is used for deep treatment of waste circuit board regeneration, cracking and carbonization waste gas, the front layer realizes acid gas adsorption and neutralization, and the middle layer performs conversion and fixation on organic components such as phenols and aldehyde ketones; the tail layer completes deep trapping of trace VOCs and carbon dust, through gradient design of the structure and the function, various pollutants are sequentially removed in the same device, and the waste gas purification efficiency and the system operation stability are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of waste gas treatment, in particular to a pyrolysis and carbonization waste gas purification method for waste circuit board regeneration. BACKGROUND

[0002] During the waste circuit board regeneration process, the pyrolysis and carbonization process will produce mixed waste gas containing phenol, aldehyde, benzene series and other small molecular organic compounds, as well as SO2, hydrogen chloride and other acidic gases. For the purification of such gases, physical adsorption, chemical adsorption and catalytic oxidation are mainly used. Physical adsorption is mainly represented by activated carbon and molecular sieve, which relies on the porous structure to intercept volatile organic components.

[0003] Chemical adsorption often neutralizes acidic gases by using basic oxides or hydroxides to form stable salts. Catalytic oxidation technology uses metal oxides or noble metal catalysts to promote the oxidation and decomposition of small molecular organic compounds into CO2 and H2O. In recent years, there has also been a trend of applying heterogeneous composite purification materials and graded bed structures in order to achieve simultaneous treatment and deep purification of multi-component waste gas.

[0004] Currently, in the waste circuit board pyrolysis and carbonization waste gas purification process, different types of pollutants often need to be treated by multiple independent devices respectively, resulting in dispersed system structure, discontinuous reaction path, low treatment efficiency, poor adsorption stability of physical adsorption materials for high-activity phenol and aldehyde small molecules, easy desorption and release after saturation, and easy passivation of the acidic gas neutralization layer under high temperature and high humidity conditions, affecting the effective time.

[0005] At the same time, single pore size or single functional material cannot simultaneously remove acidic components and organic components, and there are still trace amounts of VOCs and fine carbon dust in the tail gas. Due to insufficient mass transfer connection between each purification link, the purification effect is easily unstable when the working condition fluctuates, making it difficult to maintain long-term and efficient operation in a complex mixed gas environment.

[0006] In view of the technical defects in this regard, a solution is proposed. SUMMARY

[0007] The present application aims to provide a pyrolysis and carbonization waste gas purification method for waste circuit board regeneration, which solves the technical problem of high concentration of small molecular organic compounds and acidic gases in the waste gas after pyrolysis and carbonization purification in the prior art.

[0008] The purpose of the present application can be achieved by the following technical solution: a pyrolysis and carbonization waste gas purification method for waste circuit board regeneration, comprising the following steps:

[0009] Step one, after laying 60 mesh stainless steel mesh under the adsorption tower, lay 3-5 mm quartz wool layer, then lay calcium aluminum carbon composite purification material, multi-tooth oxidation gel and activated carbon gel from bottom to top, use 2-3 mm quartz wool to isolate each layer, get purification tower;

[0010] Step two, after pyrolysis and carbonization of waste circuit board using pyrolysis carbonization furnace, the exhaust gas is introduced into the purification pipeline after condensation and de-coke, and the exhaust gas temperature is controlled at 200-220 DEG C, then it is introduced into the purification tower for purification, and the purified gas is obtained.

[0011] The reaction principle for preparing the purified gas is:

[0012] In the purification tower, the calcium aluminum carbon composite purification material first reacts with the acidic and halogenated components in the exhaust gas to form stable salts and oxidation products, thereby removing the acidic impurities in the exhaust gas, and the carbon phase reduction promotes the cracking and fixation of part of the chlorine and bromine-containing compounds; subsequently, the multi-tooth oxidation gel layer distributes the multi-coordination oxidation groups, which react with the incomplete reaction components in the exhaust gas to realize further purification of the intermediate organic cracking materials and residual halogenated components; finally, the activated carbon gel layer has a developed pore structure and surface active sites, which can physically and chemically adsorb trace organic residues and small molecule gases in the exhaust gas, thereby completing the deep purification of the gas.

[0013] Further, in step one, the total volume ratio of calcium aluminum carbon composite purification material, multi-tooth oxidation gel and activated carbon gel is 8:5:7;

[0014] Further, in step two, the GHSV of the exhaust gas is 5000h -1 , the system pressure drop is ≤1.5kpa, wherein the total volume V of the absorption tower is determined by V=Q / GHSV, Q is the working volume flow rate in the tower, and the unit is m 3 ·h -1 .

[0015] Further, the preparation method of the calcium aluminum carbon composite purification material comprises the following steps:

[0016] A1, in the reaction kettle, add calcium nitrate tetrahydrate, aluminum nitrate nonahydrate and deionized water, then add citric acid and ethylene glycol, and use saturated ammonia water to adjust the pH of the reaction system to 6.0-6.4, then increase the temperature of the reaction kettle to 80 DEG C, and keep stirring for 2-3h, then get dry gel after post-treatment;

[0017] A2, after calcination treatment of the dry gel, the calcium aluminum complex oxide precursor is obtained;

[0018] A3, the calcium-aluminum complex oxide precursor is mixed with carbon black, transferred to a muffle furnace with a nitrogen atmosphere and a temperature of 1000℃, and treated for 2h, then the temperature of the muffle furnace is naturally cooled to 660-670℃, the mixed fluxing agent is added, and treated for 1h, and the calcium-aluminum carbon composite purification material is obtained after post-processing.

[0019] The reaction principle for preparing the calcium-aluminum carbon composite purification material is as follows:

[0020] In the early stage of the reaction, calcium nitrate and aluminum nitrate form a stable organic complex sol in the citric acid-ethylene glycol system, and after dehydration by heating, a dry gel containing a Ca-Al complex structure is generated; subsequent calcination decomposes the organic matrix and oxidizes it into a porous calcium-aluminum composite oxide precursor; when the precursor is treated at high temperature with a carbon source under an inert nitrogen atmosphere, carbothermal reduction and lattice carbon insertion reactions occur, forming a composite carbonized phase containing a Ca-Al-O-C bonding structure; the carbon element is distributed in the lattice and the interface, enhancing the adsorption and purification function of the material; the addition of Ca(OH)2-KCl flux further promotes the reconstruction of the crystal phase and the development of the pore structure, enabling the oxide phase and the carbon phase to form a synergistic interface at the microscale, thereby improving the purification capacity of the material for waste gas.

[0021] Further, in step A1, the amount ratio of calcium nitrate tetrahydrate, aluminum nitrate nonahydrate, deionized water, citric acid, and ethylene glycol is 17-18g:16-17g:30mL:5.5g:8mL, and the post-processing includes: continuing to increase the temperature of the reaction kettle to 120℃, and treating until no liquid is produced, to obtain a dry gel;

[0022] Further, in step A2, the calcination operation is as follows: the dry gel is transferred to a muffle furnace with a temperature of 400℃, and treated for 1h;

[0023] Further, in step A3, the amount ratio of the calcium-aluminum complex oxide precursor, carbon black, and mixed fluxing agent is 8-10g:0.3g:0.8g, wherein the mixed fluxing agent is obtained by mixing calcium hydroxide and potassium chloride in an amount ratio of 0.5g:0.3g, and the post-processing includes: after the tube furnace is naturally cooled to room temperature, the material is removed, ground, and sieved to obtain a calcium-aluminum carbon composite purification material with a particle size of 3mm.

[0024] Further, the preparation method of the polydentate oxide gel includes the following steps:

[0025] B1, 1-allyl imidazole, 1,4-dibromobutane, and anhydrous acetonitrile are added to a reaction kettle, the temperature of the reaction kettle is increased to the reflux temperature of the reaction system under the protection of nitrogen, and after being treated at reflux for 6h and cooled to room temperature, 30wt% sodium iodide acetone solution and iodine are added to the reaction kettle, and the mixture is left to stand for 1h to obtain a polyhalogenated ionic liquid;

[0026] B2, add polyhalogenated ionic liquid monomer, divinylbenzene and azobisisobutyronitrile into the reaction kettle, and increase the temperature of the reaction kettle to 70°C under nitrogen protection. After heat preservation reaction for 2-3 h, add mercaptoacetic acid and heat preservation treatment for 1-2 h. After post-treatment, a gel intermediate is obtained;

[0027] B3, add the gel intermediate and 8.5 wt% catechol ethanol solution into the reaction kettle, and stir at room temperature for 20-30 min. After reducing the temperature of the reaction kettle to 3-5°C using an ice water bath, add 30% hydrogen peroxide aqueous solution, and heat preservation stirring for 1 h. After post-treatment, a multi-dentate oxidized gel is obtained.

[0028] The reaction principle for preparing the multi-dentate oxidized gel is as follows:

[0029] First, 1-allyl imidazole undergoes nucleophilic substitution reaction with 1,4-dibromobutane to generate imidazole salt ionic liquid, which further reacts with sodium iodide and iodine to form polyhalogenated ionic liquid monomer, providing multiple reaction centers for subsequent polymerization. Then, under nitrogen protection, the polyhalogenated ionic liquid monomer undergoes free radical polymerization reaction with divinylbenzene initiated by azobisisobutyronitrile, and a three-dimensional network gel structure is formed through carbon chain crosslinking. The addition of mercaptoacetic acid introduces sulfur-containing active groups on the gel skeleton. Finally, through catechol-hydrogen peroxide system treatment, the mercapto group is oxidized to hydroxyl or sulfoxy structure, and the gel skeleton is partially oxidized and crosslinked, thereby forming an oxygen-containing network with multi-dentate structure in the material. This process essentially realizes the multifunctionalization of the organic skeleton through ionic liquid polymerization and subsequent oxidation modification, and a stable multi-dentate oxidized structure is formed in the material, which can be used for the purification treatment of cracked carbonized waste gas.

[0030] Further, in step B1, the amount ratio of 1-allyl imidazole, 1,4-dibromobutane, anhydrous acetonitrile, 30 wt% sodium iodide acetone solution and iodine is 1 g:1.1-1.2 g:4-5 mL:3 mL:0.15 g;

[0031] Further, in step B2, the amount ratio of polyhalogenated ionic liquid, divinylbenzene, azobisisobutyronitrile and mercaptoacetic acid is 10 g:0.45-0.50 g:0.1 g:0.7 g. The post-treatment includes: after the reaction is completed, the temperature of the reaction kettle is reduced to room temperature, the material is taken out and washed with anhydrous ethanol and deionized water for 3-5 times, and then the material is transferred to a drying box with a temperature of 80°C for vacuum drying to constant weight, thereby obtaining a gel intermediate;

[0032] Further, in step B3, the use ratio of the gel intermediate, 8.5wt% catechol ethanol solution and 30% hydrogen peroxide aqueous solution is 10g:7-8mL:0.8mL, and the post-treatment includes: after the reaction is completed, the temperature of the reaction kettle is increased to room temperature, the material is taken out and washed with anhydrous ethanol and deionized water for 3-5 times, then the material is transferred to a drying box with a temperature of 80°C and vacuum dried to a constant weight, and then ground and sieved to obtain a multi-toothed oxidized gel with a particle size of 2mm.

[0033] Further, the preparation method of the activated carbon gel includes the following steps:

[0034] C1, adding resorcinol, 37wt% formaldehyde aqueous solution and sodium carbonate into a reaction kettle, increasing the temperature of the reaction kettle to 60°C, stirring for 6h, then adding manganese nitrate tetrahydrate, cerium nitrate hexahydrate and 2.5wt% tetraammine palladium chloride aqueous solution, standing for 12h, and post-treating to obtain a metal-coordinated phenolic aldehyde gel;

[0035] C2, placing the metal-coordinated phenolic aldehyde gel into a tube furnace, increasing the temperature to 850°C at a rate of 5°C / min in a mixed gas of 5% NH3 / 95% N2, keeping the temperature for 2h, then naturally cooling to 300°C, switching to a mixed gas of 0.5% O2 / 99.5% N2, keeping the temperature for 1h, and post-treating to obtain an activated carbon gel.

[0036] The reaction principle for preparing the activated carbon gel is as follows:

[0037] Firstly, resorcinol and formaldehyde undergo a condensation reaction under alkaline conditions to generate a phenolic aldehyde gel with a three-dimensional network structure. The manganese, cerium and palladium ions introduced into the gel system form coordination bonds with the phenolic hydroxyl groups, so that the metal components are uniformly dispersed in the organic network to form a stable metal-coordinated phenolic aldehyde structure. Subsequently, during high-temperature heat treatment in an ammonia and nitrogen mixed atmosphere, the phenolic aldehyde skeleton undergoes a carbonization reaction accompanied by dehydration, decarboxylation and aromatization processes of the organic matter, thereby forming a continuous carbon skeleton structure. At the same time, the presence of ammonia gas activates the carbonization process, promotes the generation of pore structures, and adjusts the chemical composition of the material surface. Finally, through the atmosphere stabilization treatment of trace oxygen, the surface structure is homogenized and residual unstable components are removed, thereby obtaining an activated carbon gel with stable structure. Throughout the process, the coordination of metal ions and the atmosphere regulation of ammonia gas jointly promote the conversion of the organic gel to the carbon gel, and provide a suitable structural basis for the purification of cracked carbonization waste gas.

[0038] Further, in step C1, the use amount ratio of the resorcinol, 37wt% formaldehyde aqueous solution, sodium carbonate, manganese nitrate tetrahydrate, cerium nitrate hexahydrate and 2.5wt% aqueous solution of tetraammine palladium chloride is 3.5-3.6g:4.2mL:0.03g:1.2g:1.4g:2mL, and the post-treatment includes: after standing is completed, the temperature of the reaction kettle is reduced to room temperature, the material is taken out and washed 3-5 times using anhydrous ethanol and deionized water, then the material is transferred to a drying box with a temperature of 80 DEG C and vacuum dried to a constant weight, thereby obtaining a metal coordination phenolic aldehyde gel;

[0039] Further, in step C2, the post-treatment includes: after heat preservation is completed, naturally cooling to 80 DEG C, vacuum drying for 6h, and grinding and sieving to obtain an activated carbon gel with a particle size of 1mm.

[0040] The present application has the following advantages:

[0041] 1. The calcium-aluminum-carbon composite purification material filled in the lower layer of the purification tower has strong surface adsorption and microporous structure, can preliminarily capture and hold the high-temperature carbon micro powder entering the system, and reduces the floating of dust; the porous network structure of the multi-tooth oxidation gel in the middle layer further forms a turbulent diffusion zone, so that the fine particles are effectively retained and electrostatically adsorbed in the mass transfer process; the activated carbon gel in the upper layer has developed pore size distribution and high specific surface area, can implement deep adsorption and physical interception on residual ultrafine carbon micro powder, the three-layer material gradually transitions from macropore to micropore in structure, and gradually strengthens from mechanical capture, electrostatic adsorption to porous filtration in function, forming a synergistic system of multi-stage filtration and adsorption, significantly reducing the carbon black dust concentration in the purified gas, and ensuring that the tail gas particulate matter emission is stable and meets the standard.

[0042] 2. The multi-tooth oxidation gel filled in the middle layer of the purification tower relies on its multi-tooth oxygen-containing structure and surface active groups to show strong oxidation conversion and complexation effect on phenolic and aldehyde molecules, can convert high-activity or refractory organic cracking products into low-toxicity or stable products; the bottom layer calcium-aluminum-carbon composite purification material not only provides preliminary adsorption, but also can fix part of the small-molecule organic matter through the reduction cracking effect of the carbon phase, reducing the load of the subsequent layer; the activated carbon gel at the top has rich micropores and surface active sites, and plays a "polishing" adsorption effect on residual small-molecule organic matter, realizes deep purification, and the three materials gradually progress from chemical reaction to complex conversion to physical adsorption in mechanism, thereby constructing an efficient gradient purification system, significantly reducing the concentration of phenolic, benzene and formaldehyde and other organic matters in the purified gas, and ensuring the cleanliness and standard emission of the tail gas.

[0043] 3、The calcium-aluminum-carbon composite material laid at the bottom of the purification tower is rich in basic active sites, can rapidly undergo acid-base neutralization reaction with acid gases, and at the same time, halogen components are fixed as stable salt products, realizing efficient removal, and is the leading layer for removal of acid pollutants; the multi-dentate oxidized gel in the middle layer has rich oxygen-containing coordination groups, can produce complexing and capturing effect on residual acid intermediates or unreacted gases after neutralization, further reducing the breakthrough concentration; the activated carbon gel in the top layer relies on its high specific surface area and rich microporous structure to perform tail-end adsorption and retention on very low concentration SO2 and hydrogen chloride, ensuring that the acid components in the exhaust gas are thoroughly purified, and the three-layer material forms a synergistic purification chain of "neutralization and fixation-complexing and capturing-deep adsorption" in mechanism, which not only improves the overall acid gas removal efficiency, but also enhances the stability of the system under high concentration impact working conditions, realizing sustained, deep and efficient purification effect. DETAILED DESCRIPTION

[0044] The technical solutions of the present application will be clearly and completely described below in combination with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative labor fall within the protection scope of the present application.

[0045] In the present application, the carbon black used is purchased from Shanghai Maikelin Biochemical Technology Co., Ltd., and the article number is C914875.

[0046] Embodiment 1

[0047] The present embodiment provides a preparation method of a calcium-aluminum-carbon composite purification material, comprising the following steps:

[0048] Step I, preparation of xerogel

[0049] After 17.0 g of calcium nitrate tetrahydrate, 16.0 g of aluminum nitrate nonahydrate and 30.0 mL of deionized water are added to the reaction kettle, 5.5 g of citric acid and 8.0 mL of ethylene glycol are further added, and the pH of the reaction system is adjusted to 6.0 using saturated ammonia water, then the temperature of the reaction kettle is increased to 80℃, and the temperature is kept at 80℃ for 2 h, then the temperature of the reaction kettle is further increased to 120℃, and the temperature is kept at 120℃ until no liquid is produced, to obtain the xerogel.

[0050] Step II, preparation of calcium-aluminum complex oxide precursor

[0051] Weighing: 30.0 g of xerogel is transferred to a muffle furnace with a temperature of 400℃, and the temperature is kept at 400℃ for 1 h to obtain the calcium-aluminum complex oxide precursor.

[0052] Step III, preparation of calcium-aluminum-carbon composite purification material

[0053] Weighing: 1.0 g of calcium hydroxide and 0.6 g of potassium chloride are mixed to obtain a mixed fluxing agent, which is collected for standby;

[0054] Weighing: 8.0 g of calcium-aluminum complex oxide precursor is uniformly mixed with 0.3 g of carbon black, and then transferred to a muffle furnace with a nitrogen atmosphere and a temperature of 1000°C. After heat preservation treatment for 2 h, the temperature of the muffle furnace is naturally cooled to 660°C, 0.8 g of mixed fluxing agent is added, heat preservation treatment is performed for 1 h, the tube furnace is naturally cooled to room temperature, the material is removed and ground to obtain calcium-aluminum carbon composite purification material with a particle size of 3 mm.

[0055] Example 2

[0056] The present embodiment provides a preparation method of calcium-aluminum carbon composite purification material, which comprises the following steps:

[0057] Step I, preparation of dry gel

[0058] In the reaction kettle, 18.0 g of calcium nitrate tetrahydrate, 17.0 g of aluminum nitrate nonahydrate and 30.0 mL of deionized water are added, then 5.5 g of citric acid and 8.0 mL of ethylene glycol are added, and the pH of the reaction system is adjusted to 6.4 using saturated ammonia water. Then the temperature of the reaction kettle is increased to 80°C, and the temperature is kept at 80°C for 3 h. Then the temperature of the reaction kettle is increased to 120°C, and the reaction is carried out until no liquid is produced. The dry gel is obtained.

[0059] Step II, preparation of calcium-aluminum complex oxide precursor

[0060] Weighing: 30.0 g of dry gel is transferred to a muffle furnace with a temperature of 400°C, and heat preservation treatment is performed for 1 h to obtain calcium-aluminum complex oxide precursor.

[0061] Step III, preparation of calcium-aluminum carbon composite purification material

[0062] Weighing: 1.0 g of calcium hydroxide and 0.6 g of potassium chloride are mixed to obtain a mixed fluxing agent, which is collected for standby;

[0063] Weighing: 10.0 g of calcium-aluminum complex oxide precursor is uniformly mixed with 0.3 g of carbon black, and then transferred to a muffle furnace with a nitrogen atmosphere and a temperature of 1000°C. After heat preservation treatment for 2 h, the temperature of the muffle furnace is naturally cooled to 670°C, 0.8 g of mixed fluxing agent is added, heat preservation treatment is performed for 1 h, the tube furnace is naturally cooled to room temperature, the material is removed and ground to obtain calcium-aluminum carbon composite purification material with a particle size of 3 mm.

[0064] Example 3

[0065] The present embodiment provides a preparation method of calcium-aluminum carbon composite purification material, which comprises the following steps:

[0066] Step I, preparation of dry gel

[0067] In a reaction kettle, 17.0 g of calcium nitrate tetrahydrate, 17.0 g of aluminum nitrate nonahydrate and 30.0 mL of deionized water were added, followed by the addition of 5.5 g of citric acid and 8.0 mL of ethylene glycol, and the pH of the reaction system was adjusted to 6.3 using saturated ammonia water. The temperature of the reaction kettle was then increased to 80°C, and the mixture was stirred for 3 h. The temperature of the reaction kettle was then increased to 120°C, and the mixture was treated until no liquid was produced. A dry gel was obtained.

[0068] Step II, preparation of calcium-aluminum complex oxide precursor

[0069] Weighing: 30.0 g of dry gel was transferred to a muffle furnace at a temperature of 400°C, and the mixture was treated for 1 h to obtain a calcium-aluminum complex oxide precursor.

[0070] Step III, preparation of calcium-aluminum carbon composite purification material

[0071] Weighing: 1.0 g of calcium hydroxide and 0.6 g of potassium chloride were mixed to obtain a mixed flux, which was collected for later use.

[0072] Weighing: 9.0 g of calcium-aluminum complex oxide precursor was mixed with 0.3 g of carbon black and then transferred to a muffle furnace with a nitrogen atmosphere and a temperature of 1000°C. The mixture was treated for 2 h, and then the temperature of the muffle furnace was naturally cooled to 660°C. 0.8 g of mixed flux was added, and the mixture was treated for 1 h. The tube furnace was naturally cooled to room temperature, and the material was removed and ground to obtain a calcium-aluminum carbon composite purification material with a particle size of 3 mm.

[0073] Example 4

[0074] The present embodiment provides a method for preparing a multi-tooth oxide gel, comprising the following steps:

[0075] Step 1, preparation of multi-halogenated ionic liquid

[0076] In a reaction kettle, 10.0 g of 1-allyl imidazole, 11.0 g of 1,4-dibromobutane and 40.0 mL of anhydrous acetonitrile were added. The temperature of the reaction kettle was increased to the reflux temperature of the reaction system under the protection of nitrogen, and the mixture was refluxed for 6 h. The mixture was then cooled to room temperature, and 30.0 mL of 30 wt% sodium iodide acetone solution and 1.5 g of iodine were added to the reaction kettle. After standing for 1 h, a multi-halogenated ionic liquid was obtained.

[0077] Step 2, preparation of gel intermediate

[0078] Into a reaction kettle, 10.0 g of polyhalogenated ionic liquid monomer, 0.45 g of divinylbenzene and 0.1 g of azobisisobutyronitrile were added, under the protection of nitrogen, the temperature of the reaction kettle was raised to 70°C, after holding for 2 h, 0.7 g of mercaptoacetic acid was added, and holding for 1 h, after the reaction was completed, the temperature of the reaction kettle was reduced to room temperature, the material was taken out and washed with anhydrous ethanol and deionized water for 3 times, and then the material was transferred to a drying oven with a temperature of 80°C for vacuum drying to constant weight, to obtain a gel intermediate.

[0079] Step ⑥, preparation of a multi-dentate oxidized gel

[0080] Into a reaction kettle, 10.0 g of the gel intermediate and 7.0 mL of 8.5 wt% catechol ethanol solution were weighed and added, after stirring at room temperature for 20 min, the temperature of the reaction kettle was reduced to 3°C using an ice water bath, 0.8 mL of 30% hydrogen peroxide aqueous solution was added, and stirring was continued for 1 h, after the reaction was completed, the temperature of the reaction kettle was raised to room temperature, the material was taken out and washed with anhydrous ethanol and deionized water for 3 times, and then the material was transferred to a drying oven with a temperature of 80°C for vacuum drying to constant weight, and was ground and sieved to obtain a multi-dentate oxidized gel with a particle size of 2 mm.

[0081] Example 5

[0082] The present example provides a method for preparing a multi-dentate oxidized gel, comprising the following steps:

[0083] Step ⑴, preparation of a polyhalogenated ionic liquid

[0084] Into a reaction kettle, 10.0 g of 1-allyl imidazole, 12.0 g of 1,4-dibromobutane and 50.0 mL of anhydrous acetonitrile were added, under the protection of nitrogen, the temperature of the reaction kettle was raised to the refluxing temperature of the reaction system, after holding for 6 h, the temperature was cooled to room temperature, 30.0 mL of 30 wt% sodium iodide acetone solution and 1.5 g of iodine were further added to the reaction kettle, and standing was continued for 1 h, to obtain a polyhalogenated ionic liquid.

[0085] Step ⑵, preparation of a gel intermediate

[0086] Into a reaction kettle, 10.0 g of polyhalogenated ionic liquid monomer, 0.50 g of divinylbenzene and 0.1 g of azobisisobutyronitrile were added, under the protection of nitrogen, the temperature of the reaction kettle was raised to 70°C, after holding for 3 h, 0.7 g of mercaptoacetic acid was added, and holding for 2 h, after the reaction was completed, the temperature of the reaction kettle was reduced to room temperature, the material was taken out and washed with anhydrous ethanol and deionized water for 3-5 times, and then the material was transferred to a drying oven with a temperature of 80°C for vacuum drying to constant weight, to obtain a gel intermediate.

[0087] Step ⑥, preparation of a multi-dentate oxidized gel

[0088] Weighing: 10.0 g of the gel intermediate and 8.0 mL of 8.5 wt% catechol ethanol solution are added to the reaction kettle, stirred at room temperature for 30 min, then the temperature of the reaction kettle is reduced to 5°C using an ice water bath, 0.8 mL of 30% hydrogen peroxide aqueous solution is added, and the reaction is stirred for 1 h. After the reaction is completed, the temperature of the reaction kettle is raised to room temperature, the material is taken out and washed with anhydrous ethanol and deionized water for 5 times, then the material is transferred to a drying oven with a temperature of 80°C for vacuum drying to constant weight, and the multi-tooth oxidized gel with a particle size of 2 mm is obtained by grinding and sieving.

[0089] Example 6

[0090] The present embodiment provides a method for preparing a multi-tooth oxidized gel, comprising the following steps:

[0091] Step 1, preparation of a polyhalogenated ionic liquid

[0092] In the reaction kettle, 10.0 g of 1-allyl imidazole, 11.0 g of 1,4-dibromobutane and 50.0 mL of anhydrous acetonitrile are added, the temperature of the reaction kettle is raised to the refluxing temperature of the reaction system under the protection of nitrogen, and the reaction is refluxed for 6 h. After cooling to room temperature, 30.0 mL of 30 wt% sodium iodide acetone solution and 1.5 g of iodine are added to the reaction kettle, and the reaction is allowed to stand for 1 h to obtain a polyhalogenated ionic liquid.

[0093] Step 2, preparation of a gel intermediate

[0094] In the reaction kettle, 10.0 g of the polyhalogenated ionic liquid monomer, 0.48 g of divinylbenzene and 0.1 g of azobisisobutyronitrile are added, and the temperature of the reaction kettle is raised to 70°C under the protection of nitrogen. After 3 h of reaction, 0.7 g of mercaptoacetic acid is added, and the reaction is allowed to stand for 2 h. After the reaction is completed, the temperature of the reaction kettle is reduced to room temperature, the material is taken out and washed with anhydrous ethanol and deionized water for 4 times, then the material is transferred to a drying oven with a temperature of 80°C for vacuum drying to constant weight to obtain a gel intermediate.

[0095] Step 3, preparation of a multi-tooth oxidized gel

[0096] Weighing: 10.0 g of the gel intermediate and 7.5 mL of 8.5 wt% catechol ethanol solution are added to the reaction kettle, stirred at room temperature for 25 min, then the temperature of the reaction kettle is reduced to 4°C using an ice water bath, 0.8 mL of 30% hydrogen peroxide aqueous solution is added, and the reaction is stirred for 1 h. After the reaction is completed, the temperature of the reaction kettle is raised to room temperature, the material is taken out and washed with anhydrous ethanol and deionized water for 4 times, then the material is transferred to a drying oven with a temperature of 80°C for vacuum drying to constant weight, and the multi-tooth oxidized gel with a particle size of 2 mm is obtained by grinding and sieving.

[0097] Example 7

[0098] The embodiment provides a preparation method of active carbon gel, including the following steps:

[0099] Step 1, preparation of metal coordination phenolic gel

[0100] Into the reaction kettle, 35.0g of resorcinol, 42.0mL of 37wt% formaldehyde aqueous solution and 0.3g of sodium carbonate are added, the reaction kettle is heated to 60 DEG C, and after 6h of heat preservation and stirring, 12g of manganese nitrate tetrahydrate, 14g of cerium nitrate hexahydrate and 20.0mL of 2.5wt% tetraammine palladium chloride aqueous solution are added, and after 12h of standing, the temperature of the reaction kettle is reduced to room temperature, the material is taken out and washed with anhydrous ethanol and deionized water for 3 times, and then the material is transferred to a drying box with a temperature of 80 DEG C and vacuum dried to constant weight, so that the metal coordination phenolic gel is obtained.

[0101] Step 2, preparation of active carbon gel

[0102] Into the reaction kettle, 35.0g of resorcinol, 42.0mL of 37wt% formaldehyde aqueous solution and 0.3g of sodium carbonate are added, the reaction kettle is heated to 60 DEG C, and after 6h of heat preservation and stirring, 12g of manganese nitrate tetrahydrate, 14g of cerium nitrate hexahydrate and 20.0mL of 2.5wt% tetraammine palladium chloride aqueous solution are added, and after 12h of standing, the temperature of the reaction kettle is reduced to room temperature, the material is taken out and washed with anhydrous ethanol and deionized water for 3 times, and then the material is transferred to a drying box with a temperature of 80 DEG C and vacuum dried to constant weight, so that the metal coordination phenolic gel is obtained.

[0103] Embodiment 8

[0104] The embodiment provides a preparation method of active carbon gel, including the following steps:

[0105] Step 1, preparation of metal coordination phenolic gel

[0106] Into the reaction kettle, 35.0g of resorcinol, 42.0mL of 37wt% formaldehyde aqueous solution and 0.3g of sodium carbonate are added, the reaction kettle is heated to 60 DEG C, and after 6h of heat preservation and stirring, 12g of manganese nitrate tetrahydrate, 14g of cerium nitrate hexahydrate and 20.0mL of 2.5wt% tetraammine palladium chloride aqueous solution are added, and after 12h of standing, the temperature of the reaction kettle is reduced to room temperature, the material is taken out and washed with anhydrous ethanol and deionized water for 3 times, and then the material is transferred to a drying box with a temperature of 80 DEG C and vacuum dried to constant weight, so that the metal coordination phenolic gel is obtained.

[0107] Step 2, preparation of active carbon gel

[0108] Weighing: 20.0 g of metal-coordinated phenolic gel is placed in a tube furnace, heated to 850℃ at 5℃ / min in 5% NH3 / 95% N2mixed gas, after 2h, naturally cooled to 300℃, switch to 0.5% O2 / 99.5% N2mixed gas, after 1h, after the completion of the heat preservation, naturally cooled to 80℃, vacuum drying for 6h, and grinding and sieving to get activated carbon gel with particle size of 1mm.

[0109] Example 9

[0110] The present embodiment provides a method for preparing activated carbon gel, comprising the following steps:

[0111] Step ①, preparation of metal-coordinated phenolic gel

[0112] Into the reaction kettle, 36.0 g of resorcinol, 42.0 mL of 37wt% formaldehyde aqueous solution and 0.3 g of sodium carbonate are added, the reaction kettle is heated to 60℃, after 6h of heat preservation and stirring, 12 g of manganese nitrate tetrahydrate, 14 g of cerium nitrate hexahydrate and 20.0 mL of 2.5wt% tetraammine palladium chloride aqueous solution are added, and the material is placed for 12h, after the completion of the standing, the material is taken out and washed with anhydrous ethanol and deionized water for 4 times, and then transferred to a drying box with a temperature of 80℃ for vacuum drying until the weight is constant, to obtain the metal-coordinated phenolic gel.

[0113] Step ②, preparation of activated carbon gel

[0114] Weighing: 20.0 g of metal-coordinated phenolic gel is placed in a tube furnace, heated to 850℃ at 5℃ / min in 5% NH3 / 95% N2mixed gas, after 2h, naturally cooled to 300℃, switch to 0.5% O2 / 99.5% N2mixed gas, after 1h, after the completion of the heat preservation, naturally cooled to 80℃, vacuum drying for 6h, and grinding and sieving to get activated carbon gel with particle size of 1mm.

[0115] Example 10

[0116] The present embodiment provides a method for purifying pyrolysis carbonization waste gas for recycling waste circuit boards, comprising the following steps:

[0117] Step one, loading the purification tower

[0118] After laying a 60 mesh stainless steel mesh under the adsorption tower with a volume of 10L, laying a 3mm quartz wool layer, and then laying the calcium-aluminum-carbon composite purification material prepared in Example 1, the multi-dentate oxidation gel prepared in Example 4 and the activated carbon gel prepared in Example 7 from bottom to top according to the volume ratio of 8:5:7, and using 2mm quartz wool to isolate each layer, a purification tower is obtained.

[0119] Step two, preparation of purified gas

[0120] After the waste circuit board is pyrolyzed and carbonized by using the pyrolysis carbonization furnace, the waste gas is introduced into the purification pipeline after condensation and de-coke, and the waste gas temperature is controlled at 200℃, the GHSV of the waste gas is controlled at 5000h -1 , the system pressure drop is less than or equal to 1.5kpa, and the processing capacity is 50m 3 ·h -1 After purification by the purification tower, purified gas is obtained.

[0121] Example 11

[0122] The embodiment provides a pyrolysis carbonization waste gas purification method for waste circuit board regeneration, which comprises the following steps:

[0123] Step one, loading the purification tower

[0124] After a 60-mesh stainless steel mesh is laid under the adsorption tower with a loading volume of 10L, a 5mm quartz wool layer is laid, and then the calcium-aluminum-carbon composite purification material prepared in Example 2, the multi-dentate oxidation gel prepared in Example 5 and the activated carbon gel prepared in Example 8 are laid in layers from bottom to top according to a volume ratio of 8:5:7, 3mm quartz wool is used for isolation between each layer, and the purification tower is obtained.

[0125] Step two, preparing purified gas

[0126] After the waste circuit board is pyrolyzed and carbonized by using the pyrolysis carbonization furnace, the waste gas is introduced into the purification pipeline after condensation and de-coke, and the waste gas temperature is controlled at 220℃, the GHSV of the waste gas is controlled at 5000h -1 , the system pressure drop is less than or equal to 1.5kpa, and the processing capacity is 50m 3 ·h -1 After purification by the purification tower, purified gas is obtained.

[0127] Example 12

[0128] The embodiment provides a pyrolysis carbonization waste gas purification method for waste circuit board regeneration, which comprises the following steps:

[0129] Step one, loading the purification tower

[0130] After a 60-mesh stainless steel mesh is laid under the adsorption tower with a loading volume of 10L, a 4mm quartz wool layer is laid, and then the calcium-aluminum-carbon composite purification material prepared in Example 3, the multi-dentate oxidation gel prepared in Example 6 and the activated carbon gel prepared in Example 9 are laid in layers from bottom to top according to a volume ratio of 8:5:7, 2mm quartz wool is used for isolation between each layer, and the purification tower is obtained.

[0131] Step two, preparing purified gas

[0132] The waste circuit board is pyrolyzed and carbonized by using a pyrolysis carbonization furnace, and the waste gas is introduced into a purification pipeline after condensation and de-coke at the outlet of the pyrolysis carbonization furnace, and the temperature of the waste gas is controlled at 210 DEG C, the GHSV of the waste gas is controlled at 5000h -1 , the system pressure is reduced by less than 1.5kpa, and the processing capacity is 50m 3 ·h -1 , and the purified gas is obtained after passing through the purification tower.

[0133] Comparative Example 1

[0134] The difference between this comparative example and Example 12 is that the multi-toothed oxidized gel used in step one is prepared without step ⑶.

[0135] Comparative Example 2

[0136] The difference between this comparative example and Example 12 is that the calcium-aluminum-carbon composite purification material used in step one is prepared without using a mixed flux in step III, and is directly naturally cooled to room temperature after the 1000 DEG C heat preservation treatment is completed.

[0137] Comparative Example 3

[0138] The difference between this comparative example and Example 12 is that the activated carbon gel is not used in step one.

[0139] Performance test:

[0140] The carbon black dust, phenolic gas, benzene, formaldehyde, sulfur dioxide and hydrogen chloride concentrations of the purified gas prepared by Examples 10-12 and Comparative Examples 1-3 are tested according to the standard GB 16297-1996 "Integrated Emission Standard of Air Pollutants", and the specific data are shown in Table 1.

[0141] Table 1-Performance test data table of each sample

[0142]

[0143] Data analysis:

[0144] After comparing and analyzing the data in Table 1, it is found that the carbon black dust concentration of the purified gas obtained by purifying the pyrolysis carbonization waste gas of the waste circuit board using the process is 17mg·m -3 , the phenolic gas concentration is 7mg·m -3 , the benzene concentration is 1mg·m -3 , the formaldehyde concentration is 2mg·m -3 , the sulfur dioxide concentration is 35mg·m -3 , and the hydrogen chloride concentration is 11mg·m -3 , which is better than the comparative examples, indicating that:

[0145] Without the oxidation modification step of the multi-dentate oxidation gel, the surface of the multi-dentate oxidation gel lacks multi-dentate oxygen-containing groups formed by oxidation activation, the number of active sites such as hydroxyl groups and carbonyl groups in the gel skeleton is significantly reduced, the polarity is reduced, the chemical adsorption and complexation of small molecular organic matters such as phenols, benzene and formaldehyde in the cracking carbonization waste gas on the surface is inhibited, and the oxidation chain scission or stabilization cannot be effectively realized. Some high-activity intermediates penetrate into the rear-end layer, and because the middle layer cannot bear the main reaction function of organic matter conversion, the overall collaborative chain is interrupted, the adsorption load of the subsequent activated carbon gel layer is too high, the organic matter breakthrough concentration rises, the purification time is shortened, the residues of benzene series and phenols in the tail gas are obvious, and the overall purification efficiency is reduced;

[0146] Without the fluxing and restructuring step of the calcium-aluminum-carbon composite purification material in Comparative Example 2, the crystal phase development is insufficient at high temperature, the Ca-Al-O phase is unevenly distributed, the carbon phase coating leads to disconnected pores, the number and accessibility of surface basic active centers are reduced, the contact reaction of acidic gases SO2 and hydrogen chloride in the cracking carbonization waste gas with the solid phase is limited after entering the bed, the acid-base neutralization rate is reduced, the salt products generated accumulate to increase the diffusion resistance, and the bed pressure drop increases with the running time. Because the front-end neutralization and fixation function is weakened, the system cannot effectively buffer the impact of acidic gases, the passive adsorption load of the rear-end material increases, and finally the acidic gas breakthrough is accelerated, the tail gas acidity increases, and the running stability decreases;

[0147] Without the activated carbon gel layer in Comparative Example 3, the pore size gradient and functional synergy of the original three-layer structure are destroyed. After the waste circuit board cracking carbonization waste gas is treated by the calcium-aluminum-carbon composite material and the multi-dentate oxidation gel, the residual trace amounts of small molecular organic matters such as phenols, benzene and formaldehyde, and part of the ultra-fine carbon powder cannot be further deeply adsorbed. Because of the lack of high specific surface area and microporous structure of the terminal “polishing layer”, the organic matter penetration in the tail gas increases; at the same time, small particle dust and high-boiling organic residues accumulate at the outlet end, which easily causes local blockage and pressure drop fluctuation. The overall system shows that the purification precision is reduced, the emission fluctuation is intensified during long-period operation, and the synergistic purification advantage is obviously weakened;

[0148] Finally, in this process system, various functional materials achieve continuous connection and gradient distribution in spatial structure and reaction path. The front-end calcium-aluminum-carbon composite purification material can quickly capture and fix the acid gas, providing a stable environment for subsequent reactions. The middle-layer multi-toothed oxidized gel further adsorbs, complexes and catalytically converts high-activity organic components, weakening the generation of secondary pollutants. The end active carbon gel relies on the developed microporous system to deeply purify residual trace gases, making the tail gas reach a stable emission level. The three-layer material forms a sequential progressive purification chain in chemical reaction and physical adsorption, enabling the graded removal and efficient conversion of different types of pollutants in the same system. This structure not only improves the purification efficiency and operational stability of the cracking carbonization waste gas, but also exhibits significant overall advantages in the treatment of complex multi-component gases.

[0149] The preferred embodiments of the application disclosed above are only used to help explain the application. The preferred embodiments do not describe all the details and limit the application to the specific embodiments. Obviously, many modifications and variations can be made according to the content of the specification. The specification selects and describes these embodiments in order to better explain the principles and practical applications of the application, so that those skilled in the art can well understand and utilize the application. The application is limited only by the claims and their full scope and equivalents.

Claims

1. A method for purifying waste gas from pyrolysis and carbonization for recycling of waste circuit boards, characterized by, The method comprises the following steps: Step one, after laying a 60-mesh stainless steel mesh at the bottom of the adsorption tower, laying a 3-5mm quartz wool layer, then laying calcium-aluminum-carbon composite purification material, multi-toothed oxidized gel and activated carbon gel from bottom to top, using 2-3mm quartz wool to isolate each layer, to obtain a purification tower; Step two, after pyrolysis and carbonization of waste circuit boards using a pyrolysis carbonization furnace, the exhaust gas is introduced into the purification pipeline after condensation and de-focusing, and the exhaust gas temperature is controlled at 200-220℃, then the exhaust gas is introduced into the purification tower for purification, to obtain purified gas.

2. The method according to claim 1, wherein the method is characterized by, In step one, the total volume ratio of calcium-aluminum-carbon composite purification material, polydentate oxidation gel and activated carbon gel is 8:5:7; in step two, the GHSV of waste gas is 5000h -1 -1.5kpa, wherein the total volume V of the absorption tower is determined according to V=Q / GHSV, Q is the volume flow rate under working conditions in the tower, and the unit is m 3 ·h -1 .

3. The method according to claim 1, wherein the method is characterized by, The preparation method of the calcium-aluminum-carbon composite purification material comprises the following steps: A1, adding calcium nitrate tetrahydrate, aluminum nitrate nonahydrate and deionized water in a reaction kettle, then adding citric acid and ethylene glycol, and adjusting the pH of the reaction system to 6.0-6.4 using saturated ammonia water, then increasing the temperature of the reaction kettle to 80℃, and keeping the temperature and stirring for 2-3h, then post-processing to obtain dry gel; A2, after calcination treatment of the dry gel, a calcium-aluminum complex oxide precursor is obtained; A3, uniformly mixing the calcium-aluminum complex oxide precursor and carbon black, then transferring to a muffle furnace with a nitrogen atmosphere and a temperature of 1000℃, keeping the temperature for 2h, then naturally cooling the temperature of the muffle furnace to 660-670℃, adding mixed fluxing agent, keeping the temperature for 1h, and post-processing to obtain calcium-aluminum-carbon composite purification material.

4. The method according to claim 3, wherein the method is characterized by, In step A1, the amount ratio of calcium nitrate tetrahydrate, aluminum nitrate nonahydrate, deionized water, citric acid and ethylene glycol is 17-18g:16-17g:30mL:5.5g:8mL; in step A2, the calcination operation is: transferring the dry gel to a muffle furnace with a temperature of 400℃, keeping the temperature for 1h; in step A3, the amount ratio of calcium-aluminum complex oxide precursor, carbon black and mixed fluxing agent is 8-10g:0.3g:0.8g, wherein the mixed fluxing agent is obtained by mixing calcium hydroxide and potassium chloride with an amount ratio of 0.5g:0.3g.

5. The method according to claim 1, wherein the method is characterized by, The preparation method of the multi-toothed oxidized gel comprises the following steps: B1, adding 1-allyl imidazole, 1,4-dibromobutane and anhydrous acetonitrile in a reaction kettle, increasing the temperature of the reaction kettle to the refluxing temperature of the reaction system under the protection of nitrogen, keeping the temperature and refluxing for 6h, then cooling to room temperature, then adding 30wt% sodium iodide acetone solution and iodine into the reaction kettle, and standing for 1h to obtain a polyhalogenated ionic liquid; B2, adding the polyhalogenated ionic liquid monomer, divinylbenzene and azobisisobutyronitrile into the reaction kettle, increasing the temperature of the reaction kettle to 70℃ under the protection of nitrogen, keeping the temperature and reacting for 2-3h, then adding mercaptoacetic acid, keeping the temperature and treating for 1-2h, and post-processing to obtain a gel intermediate; B3, adding the gel intermediate and 8.5wt% catechol ethanol solution into the reaction kettle, stirring at room temperature for 20-30min, then reducing the temperature of the reaction kettle to 3-5℃ using an ice water bath, then adding 30% hydrogen peroxide aqueous solution, keeping the temperature and stirring for 1h, and post-processing to obtain a multi-toothed oxidized gel.

6. The method according to claim 5, wherein the method is characterized by, In step B1, the amount ratio of 1-allylimidazole, 1,4-dibromobutane, anhydrous acetonitrile, 30wt% sodium iodide acetone solution and iodine is 1g:1.1-1.2g:4-5mL:3mL:0.15g; in step B2, the amount ratio of polyhalogenated ionic liquid, divinylbenzene, azobisisobutyronitrile and mercaptoacetic acid is 10g:0.45-0.50g:0.1g:0.7g; in step B3, the amount ratio of gel intermediate, 8.5wt% catechol ethanol solution and 30% hydrogen peroxide aqueous solution is 10g:7-8mL:0.8mL.

7. The method according to claim 1, wherein the method is characterized by, The preparation method of the active carbon gel comprises the following steps: C1, adding resorcinol, 37wt% formaldehyde aqueous solution and sodium carbonate into a reaction kettle, heating the reaction kettle to 60℃, and after 6h of heat preservation and stirring, adding manganese nitrate tetrahydrate, cerium nitrate hexahydrate and 2.5wt% aqueous solution of tetraammine palladium chloride, standing for 12h, and then carrying out post-treatment to obtain a metal coordination phenolic aldehyde gel; C2, placing the metal coordination phenolic aldehyde gel into a tube furnace, heating to 850℃ at a rate of 5℃ / min in 5% NH3 / 95% N2mixed gas, naturally cooling to 300℃, switching to 0.5% O2 / 99.5% N2mixed gas, and after 1h of heat preservation, carrying out post-treatment to obtain an active carbon gel.

8. The method for purifying pyrolysis and carbonization waste gas used in the recycling of waste circuit boards according to claim 7, characterized in that, In step C1, the amount ratio of the resorcinol, 37wt% formaldehyde aqueous solution, sodium carbonate, manganese nitrate tetrahydrate, cerium nitrate hexahydrate and 2.5wt% aqueous solution of tetraammine palladium chloride is 3.5-3.6g:4.2mL:0.03g:1.2g:1.4g:2mL.

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