Enhanced activated carbon for organic waste gas and method for preparing the same

Abstract

The present application belongs to the technical field of organic waste gas adsorption treatment, and particularly relates to a reinforced activated carbon for organic waste gas and a preparation method thereof. The raw material composition comprises the following components: coconut shell activated carbon, Mn(NO3)2.4H2O, Ce(NO3)3.6H2O, 3-glycidoxypropyltrimethoxysilane, organic affinity silane and hydrophobic agent. The present application generates a Mn-Ce mixed oxide core in situ in the inner hole through equal-volume impregnation and staged heat treatment, which is used for digesting oxygen-containing organic matter and adsorbing intermediates and maintaining the cleanliness of the pore channel; then GPTMS is used to form a silicon-oxygen anchoring layer on the surface of the activated carbon, and is co-condensed with the organic affinity silane to obtain an organic affinity interface matched with aromatic hydrocarbons and non-polar VOCs without blocking the pores; finally, a low-dose hydrophobic silane is used to condense into an ultrathin hydrophobic layer, which reduces the penetration of moisture while retaining the diffusion channel of organic small molecules; and the whole process uses a water / alcohol system and low-temperature curing to effectively protect the pore structure.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of organic waste gas adsorption treatment, and particularly relates to an enhanced activated carbon for organic waste gas and a preparation method thereof. BACKGROUND

[0002] Activated carbon is derived from porous adsorbent obtained by carbonization and activation of carbon-containing raw materials such as coal, wood, and coconut shell, and has a developed microporous structure and a high specific surface area. It can remove volatile organic compounds (VOCs) in air and process tail gas through physical adsorption, and is widely used in solvent recovery, spray and printing exhaust purification, fine chemical and electronic manufacturing, etc. To adapt to complex waste gas and variable working conditions, the existing technology often modifies the surface of activated carbon, such as impregnating metal salts or metal oxides to impart catalytic function, using organic silicon or polymer coating to enhance hydrophobicity, or introducing specific chemical groups to enhance selectivity to certain pollutants. However, the existing modification methods have multiple limitations in actual mixed organic waste gas and high humidity environment: first, water vapor has a strong competitive effect on micropores, and when humidity increases, water clusters and capillary condensation easily occur in micropores, resulting in occupation of effective sites and induction of adsorption-desorption fluctuation; second, there is a competitive adsorption and coverage effect between mixed VOC components, and components with high boiling point, aromatic or large polarity difference preferentially occupy the pores, resulting in decreased selectivity and stability of target pollutants removal; third, mass transfer limitation and external boundary layer problem are more prominent in particle bed or honeycomb packing, and without reasonable interface and pore design, initial rate and long-term breakthrough performance are difficult to balance. Targeted modification also has inherent contradictions: surface catalytic impregnation is easily deactivated and accelerated under high humidity and multi-component conditions, and overall hydrophobic coating can reduce water competition, but often causes pore blockage and pressure drop rise at the same time; amine modification for aldehydes has insufficient universality for mixed VOCs, and is easily migrated and degraded under warm air or light steam regeneration, resulting in odor playback and shortened service life. In terms of regeneration, the recovery method relying on high temperature or vacuum has high energy consumption and high equipment requirements, and is difficult to coordinate with conventional end-of-pipe treatment facilities. In terms of process consistency, co-impregnation of multiple functional components in the same surface layer is easy to be mutually shielded and unevenly distributed, and powdering, coating shedding and performance drift often occur after long-term circulation. Based on the above contradictions and defects, it is extremely necessary to develop an activated carbon that can maintain stability and regeneration friendliness under mixed VOC and fluctuating humidity conditions. SUMMARY

[0003] In view of the defects of the prior art, the purpose of the present application is to provide an enhanced activated carbon for organic waste gas and a preparation method thereof. The conventional hydrophobic modification or catalytic impregnation activated carbon is easily covered by water under mixed organic waste gas and high humidity conditions, the surface catalytic site is deactivated, the polymerized coating is easy to block the hole, the regeneration energy consumption is high and the capacity attenuation is fast; based on this problem, the present scheme constructs a gradient structure of core Mn-Ce self-cleaning, surface organic affinity and outermost hydrophobic control: first, the Mn-Ce mixed oxide core is generated in situ in the inner hole by equal volume impregnation and staged heat treatment, which is used for digesting oxygen-containing organic matter and adsorbing intermediates and maintaining the cleanliness of the pore channel; then, a silicon-oxygen anchor layer is formed on the surface of the activated carbon by using 3-glycidyl oxypropyltrimethoxysilane (GPTMS), and co-condensation is obtained with organic affinity silane, so as to obtain an organic affinity interface matched with aromatic hydrocarbons and non-polar VOC without blocking the hole; finally, a low-dose hydrophobic silane is condensed into an ultrathin hydrophobic layer, which reduces the penetration of water while retaining the diffusion channel of organic small molecules; and the whole process uses water / alcohol system and low-temperature curing to effectively protect the pore structure.

[0004] The technical effect of the present application is realized by the following technical scheme: an enhanced activated carbon for organic waste gas, the raw material composition of which comprises the following components: coconut shell activated carbon, Mn(NO3)2·4H2O, Ce(NO3)3·6H2O, 3-glycidyl oxypropyltrimethoxysilane, organic affinity silane and hydrophobic agent.

[0005] Preferably, the organic affinity silane is any one or several of phenyltrimethoxysilane, vinyltrimethoxysilane and octyltrimethoxysilane; further preferably, phenyltrimethoxysilane and octyltrimethoxysilane;

[0006] Preferably, the hydrophobic agent is any one of methyltrimethoxysilane and hexadecyltrimethoxysilane;

[0007] Another aspect of the present application is to provide a preparation method of an enhanced activated carbon for organic waste gas, which specifically comprises the following steps:

[0008] S1: coconut shell activated carbon is added into 0.3-0.5M hydrochloric acid solution, and soaked and washed for 30-60min, then washed repeatedly with deionized water until neutral, and dried at 110°C until constant weight to obtain activated activated carbon; Mn(NO3)2·4H2O and Ce(NO3)3·6H2O are dissolved in deionized water, and the volume is made constant, and stirred and dissolved uniformly to obtain a core precursor solution;

[0009] S2: the activated activated carbon of step S1 is slowly added into the core precursor solution of step S1 in 3 batches, and rolled and homogenized for 15-30min, and aged at room temperature for 0.5-2h, and filtered and drained;

[0010] S3: The activated carbon treated in step S2 is added into a calcination furnace, and is subjected to a staged temperature rising treatment in a nitrogen atmosphere. After the calcination is completed, the calcined activated carbon is naturally cooled to room temperature;

[0011] S4: 3-glycidyloxypropyltrimethoxysilane is dissolved in a 95wt% ethanol solution, and 0.1wt% glacial acetic acid is used to adjust the pH to 4.3-4.8. The solution is hydrolyzed at room temperature for 30-60min, and is diluted to a constant volume to obtain a 2wt% silane solution. The silane solution is sprayed onto the calcined activated carbon of step S3 in a fluidized bed, and is subjected to an aging treatment at 60℃ for 60-90min, and then is solidified at 105-110℃ for 30-60min to obtain a silane-activated carbon;

[0012] S5: The organic affinity silane is dissolved in a 95wt% ethanol solution, and 0.1wt% glacial acetic acid is used to adjust the pH to 4.3-4.8. The solution is hydrolyzed at room temperature for 20-30min, and is diluted to a constant volume to obtain a 1-2wt% affinity silane solution. The affinity silane solution is sprayed onto the silane-activated carbon of step S4 in a fluidized bed, and is solidified at 105-110℃ for 30-60min to obtain an affinity-activated carbon;

[0013] S6: The hydrophobic agent is dissolved in a 95wt% ethanol solution, and 0.1wt% glacial acetic acid is used to adjust the pH to 4.3-4.8. The solution is hydrolyzed at room temperature for 15-20min, and is diluted to a constant volume to obtain a 0.3-0.5wt% hydrophobic agent solution. The hydrophobic agent solution is sprayed onto the affinity-activated carbon of step S5 in a fluidized bed, and is solidified at 85-90℃ for 30-60min, and then is naturally aged in a ventilated and dried area for 12-24h to obtain an enhanced activated carbon;

[0014] Preferably, in step S1, the ratio of the amounts of Mn(NO3)2·4H2O, Ce(NO3)3·6H2O and deionized water is 7-7.5g: 1.2-1.3g: 80-85mL;

[0015] Preferably, in step S2, the ratio of the amounts of the activated activated carbon and the inner core precursor solution is 1g: 0.8-0.85mL;

[0016] Preferably, in step S3, the staged temperature rising treatment is specifically performed as follows: the temperature is raised to 120℃ at a rate of 2℃ / min, and is maintained for 60min. Then the temperature is raised to 200-220℃ at a rate of 1.5℃ / min, and is maintained for 60-90min. Air is input at a rate of 2-3L / min·kg, and the temperature is maintained at 200-220℃ for 30-45min. After the temperature maintaining is completed, the air is replaced by nitrogen.

[0017] Preferably, in step S4, the fluidized bed spray parameters are: bed temperature 45-55℃, atomization gas 1.2-1.6 bar, liquid 10-15 mL / min; pick-up amount 0.08-0.12 mL silane solution / g calcined activated carbon;

[0018] Preferably, in step S5, the fluidized bed spray parameters are: bed temperature 45-55℃, atomization gas 1.2-1.6 bar, liquid 6-12 mL / min; pick-up amount 0.06-0.1 mL affinity silane solution / g silane activated carbon;

[0019] Preferably, in step S6, the fluidized bed spray parameters are: bed temperature 40-50℃, atomization gas 1.2-1.8 bar, liquid 4-6 mL / min; pick-up amount 0.03-0.05 mL hydrophobic agent solution / g affinity activated carbon.

[0020] The beneficial effects of the present application are as follows:

[0021] The enhanced activated carbon of the present application takes porous activated carbon as the skeleton, and adopts a gradient process from inside to outside to construct a multi-functional hierarchical structure. First, manganese and cerium precursors are introduced into the interior of the particles by isovolume impregnation, and after drying and staged heat treatment, a stable mixed oxide core is generated in situ on the inner pore wall; this core neither blocks the mass transfer channels of the outer surface layer nor provides persistent active sites for gas-solid reactions in the pores. Subsequently, epoxy silane treatment is performed on the outer edge of the particles, and the hydrolysis condensation product thereof forms siloxane bridges with the oxygen-containing groups on the surface of the activated carbon, so that the epoxy end groups are oriented and distributed in the near-surface layer. On this basis, organic functional silane is introduced for co-condensation to construct a continuous organic affinity layer, aiming to improve the adsorption selectivity of aromatic hydrocarbons and non-polar organic matter, while maintaining the connectivity of the pores and a low pressure drop. Finally, a low-dose hydrophobic silane is used for condensation on the outermost side to form a uniform hydrophobic micro-layer, which effectively suppresses the capillary condensation and clustering of water in the micropores through surface energy regulation, while avoiding significant impact on the diffusion resistance of small organic molecules, thereby achieving a balance between moisture resistance and mass transfer efficiency in the process.

[0022] Specifically, the epoxy silane first forms a siloxane bond with the carrier to provide anchor sites with controllable density; the organofunctional silane further condenses on the anchor sites to form a regeneratively resistant silicone network, making the outer layer have higher affinity for aromatic hydrocarbons, esters, ethers, ketones and alcohols and reducing the tendency of surface fouling. The manganese oxide in the inner core provides active sites through valence state conversion, and the oxygen storage and defect sites of cerium oxide help maintain surface activity and alleviate the active site poisoning effect caused by the competition of water molecules for adsorption, enabling the inner core to mildly decompose part of the oxygen-containing organic matter and intermediates generated during the adsorption process, thereby reducing the accumulation burden on the outer layer and delaying capacity decay. The hydrophobic thin layer on the outermost layer selectively blocks water, ensuring the efficient passage of organic molecules and not significantly affecting the diffusion process of small organic molecules to the outer layer and into the pores. In actual use, the exhaust gas components are first selectively enriched by the organic affinity layer and then diffuse into the inner core; the inner core converts active components, effectively reducing pore blockage and surface coverage, maintaining the long-term cleanliness of the material structure; the hydrophobic micro-layer significantly reduces water intrusion, ensuring that the material still maintains its preferential adsorption capacity for organic pollutants and stable breakthrough curves under high humidity or complex component conditions. The spatial separation of the functional layers avoids direct conflict between catalytic activity and surface affinity, and the interface is based on a siloxane network, reducing the risk of migration, pulverization and coating detachment during operation and regeneration. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The enhanced activated carbon adsorption test removal rate result graph of examples 1-3 and comparative examples 1-3 of the present application;

[0024] Figure 2 The enhanced activated carbon adsorption test adsorption capacity result graph of examples 1-3 and comparative examples 1-3 of the present application;

[0025] Figure 3 The enhanced activated carbon 50% RH humidity resistance adsorption test removal rate result graph of examples 1-3 and comparative examples 1-3 of the present application;

[0026] Figure 4 The enhanced activated carbon 70% RH humidity resistance adsorption test removal rate result graph of examples 1-3 and comparative examples 1-3 of the present application;

[0027] Figure 5 The enhanced activated carbon humidity resistance adsorption test humidity back-off removal rate result graph of examples 1-3 and comparative examples 1-3 of the present application;

[0028] Figure 6 The enhanced activated carbon regeneration adsorption test result graph of examples 1-3 and comparative examples 1-3 of the present application;

[0029] Figure 7SEM scanning electron microscope images of the enhanced activated carbon of Example 1 and Comparative Example 3 of the present application; the left image is Example 1, and the right image is Comparative Example 3. DETAILED DESCRIPTION

[0030] The technical solutions of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Unless otherwise specified, the raw materials involved in the present application are purchased through the conventional commercial channel. The experimental methods without specific conditions are the conventional methods and conventional conditions familiar to the person skilled in the art, or according to the conditions recommended by the instrument manufacturer.

[0031] Example 1: An enhanced activated carbon for organic waste gas, the raw material composition thereof includes the following components: coconut shell activated carbon, Mn(NO3)2·4H2O, Ce(NO3)3·6H2O, 3-glycidoxypropyltrimethoxysilane, organic affinity silane and hydrophobic agent.

[0032] The preparation of the enhanced activated carbon for organic waste gas includes the following steps:

[0033] S1: 100g of coconut shell activated carbon is added to 0.4M hydrochloric acid solution, soaked and washed for 45min, repeatedly washed with deionized water until neutral, dried at 110℃ to constant weight, and activated activated carbon is obtained; 7.3g of Mn(NO3)2·4H2O and 1.25g of Ce(NO3)3·6H2O are dissolved in deionized water, and the volume is made up to 83mL, and stirred and dissolved uniformly to obtain a core precursor solution;

[0034] S2: 100g of activated activated carbon of step S1 is slowly added to 83mL of core precursor solution of step S1 in 3 batches, and rolled and homogenized for 25min, and aged at room temperature for 1h, and filtered and drained;

[0035] S3: The activated carbon treated in step S2 is added to a calcination furnace, heated to 120℃ at a rate of 2℃ / min under nitrogen atmosphere, and kept for 60min, then heated to 210℃ at a rate of 1.5℃ / min, and kept for 75min, then air with a flow rate of 2.5L / min·kg is continuously input, and kept at 210℃ for 40min, and then replaced with nitrogen input after keeping; after calcination, it is naturally cooled to room temperature to obtain calcined activated carbon;

[0036] S4: 3-glycidoxypropyltrimethoxysilane was dissolved in 95wt% ethanol solution, 0.1wt% glacial acetic acid was used to adjust the pH to 4.5, hydrolysis was carried out at room temperature for 45min, constant volume, 2wt% silane solution was obtained; the silane solution was sprayed on the activated carbon in step S3 by fluidized bed, the bed temperature was 50℃, the atomizing gas was 1.4bar, the liquid was 12mL / min; the pickup amount was 0.1mL silane solution / g activated carbon; aging treatment was carried out at 60℃ for 75min, then curing was carried out at 108℃ for 45min, silane activated carbon was obtained;

[0037] S5: phenyltrimethoxysilane and octyltrimethoxysilane were dissolved in 95wt% ethanol solution in a ratio of 1:1, 0.1wt% glacial acetic acid was used to adjust the pH to 4.5, constant volume, hydrolysis was carried out at room temperature for 25min, 1.5wt% affinity silane solution was obtained; the affinity silane solution was sprayed on the silane activated carbon in step S4 by fluidized bed, the bed temperature was 50℃, the atomizing gas was 1.4bar, the liquid was 8mL / min; the pickup amount was 0.08mL affinity silane solution / g silane activated carbon; curing was carried out at 108℃ for 45min, affinity activated carbon was obtained;

[0038] S6: cetyltrimethoxysilane was dissolved in 95wt% ethanol solution, 0.1wt% glacial acetic acid was used to adjust the pH to 4.5, hydrolysis was carried out at room temperature for 18min, constant volume, 0.4wt% hydrophobic agent solution was obtained; the hydrophobic agent solution was sprayed on the affinity activated carbon in step S5 by fluidized bed, the bed temperature was 45℃, the atomizing gas was 1.5bar, the liquid was 5mL / min; 0.04mL hydrophobic agent solution / g affinity activated carbon; curing treatment was carried out at 88℃ for 45min, then it was placed in a ventilated and dry area for natural aging for 18h, enhanced activated carbon was obtained.

[0039] Example 2: an enhanced activated carbon for organic waste gas, the raw material composition includes the following components: coconut shell activated carbon, Mn(NO3)2·4H2O, Ce(NO3)3·6H2O, 3-glycidoxypropyltrimethoxysilane, organic affinity silane and hydrophobic agent.

[0040] The preparation of the enhanced activated carbon for organic waste gas includes the following steps:

[0041] S1: 100g coconut shell activated carbon was immersed in 0.3M hydrochloric acid solution for 60min, repeated washing with deionized water until neutral, oven dried at 110℃ until constant weight, activated activated carbon was obtained; 7.5g Mn(NO3)2·4H2O and 1.3g Ce(NO3)3·6H2O were dissolved in deionized water, constant volume to 85mL, stirred to dissolve uniformly, core precursor solution was obtained;

[0042] S2: 100 g of activated activated carbon from step S1 was slowly added in 3 batches to 85 mL of the core precursor solution from step S1, rolled and homogenized for 15 min, and aged at room temperature for 2 h, and then filtered and drained;

[0043] S3: The activated carbon treated in step S2 was placed in a calcination furnace, and heated to 120°C at a rate of 2°C / min under a nitrogen atmosphere, and held for 60 min, then heated to 200°C at a rate of 1.5°C / min, and held for 90 min, then switched to air input at a rate of 2 L / min·kg, and continued to hold at 200°C for 45 min, and then switched back to nitrogen input after the holding was completed; after calcination was completed, the temperature was allowed to decrease to room temperature naturally, and a calcined activated carbon was obtained;

[0044] S4: 3-glycidoxypropyltrimethoxysilane was dissolved in a 95 wt% ethanol solution, and 0.1 wt% glacial acetic acid was used to adjust the pH to 4.3, and hydrolyzed at room temperature for 30 min, and then made up to volume, and a 2 wt% silane solution was obtained; the silane solution was sprayed onto the calcined activated carbon from step S3 using a fluidized bed, with a bed temperature of 45°C, an atomizing gas pressure of 1.6 bar, and a liquid flow rate of 15 mL / min; the pick-up amount was 0.08 mL of silane solution per gram of calcined activated carbon; and then aged at 60°C for 60 min, and then solidified at 105°C for 60 min, and a silane-activated carbon was obtained;

[0045] S5: Octyltrimethoxysilane was dissolved in a 95 wt% ethanol solution, and 0.1 wt% glacial acetic acid was used to adjust the pH to 4.3, and made up to volume, and hydrolyzed at room temperature for 20 min, and a 1 wt% affinity silane solution was obtained; the affinity silane solution was sprayed onto the silane-activated carbon from step S4 using a fluidized bed, with a bed temperature of 45°C, an atomizing gas pressure of 1.6 bar, and a liquid flow rate of 6 mL / min; the pick-up amount was 0.06 mL of affinity silane solution per gram of silane-activated carbon; and then solidified at 105°C for 60 min, and an affinity-activated carbon was obtained;

[0046] S6: Hexadecyltrimethoxysilane was dissolved in a 95 wt% ethanol solution, and 0.1 wt% glacial acetic acid was used to adjust the pH to 4.3, and hydrolyzed at room temperature for 15 min, and made up to volume, and a 0.3 wt% hydrophobic agent solution was obtained; the hydrophobic agent solution was sprayed onto the affinity-activated carbon from step S5 using a fluidized bed, with a bed temperature of 40°C, an atomizing gas pressure of 1.8 bar, and a liquid flow rate of 4 mL / min; the pick-up amount was 0.03 mL of hydrophobic agent solution per gram of affinity-activated carbon; and then solidified at 85°C for 60 min, and then naturally aged in a ventilated and dry area for 24 h, and an enhanced activated carbon was obtained.

[0047] Example 3: An enhanced activated carbon for organic waste gas, which is composed of the following components: coconut shell activated carbon, Mn(NO3)2·4H2O, Ce(NO3)3·6H2O, 3-glycidoxypropyltrimethoxysilane, an organic affinity silane, and a hydrophobic agent.

[0048] The preparation of the enhanced activated carbon for the organic waste gas includes the following steps:

[0049] S1: 100 g of coconut shell activated carbon is added into a 0.5 M hydrochloric acid solution, soaked and washed for 30 min, repeatedly washed with deionized water until neutral, dried at 110°C to constant weight, and activated activated carbon is obtained; 7 g of Mn(NO3)2·4H2O and 1.2 g of Ce(NO3)3·6H2O are dissolved in deionized water, and the volume is made up to 80 mL, and the solution is stirred and dissolved uniformly to obtain a core precursor solution;

[0050] S2: 100 g of activated activated carbon in step S1 is slowly added to 80 mL of the core precursor solution in step S1 in three batches, rolled and homogenized for 30 min, and aged at room temperature for 0.5 h, and filtered and drained;

[0051] S3: The activated carbon treated in step S2 is added to a calcination furnace, heated to 120°C at a rate of 2°C / min under a nitrogen atmosphere, and kept for 60 min, then heated to 220°C at a rate of 1.5°C / min, kept for 60 min, and switched to air input at a rate of 3 L / min·kg, and continued to keep at 220°C for 30 min, and then replaced with nitrogen input after keeping; after calcination, naturally cool to room temperature to obtain calcined activated carbon;

[0052] S4: 3-glycidyloxypropyltrimethoxysilane is dissolved in a 95wt% ethanol solution, 0.1wt% glacial acetic acid is added to adjust the pH to 4.8, hydrolyzed at room temperature for 60 min, and then made up to volume to obtain a 2wt% silane solution; the silane solution is sprayed onto the calcined activated carbon in step S3 in a fluidized bed, the bed temperature is 55°C, the atomizing gas is 1.2 bar, the liquid is 15 mL / min; the pickup amount is 0.12 mL of silane solution per gram of calcined activated carbon; 60°C aging treatment for 90 min, then 110°C curing for 30 min, to obtain silane activated carbon;

[0053] S5: Vinyltrimethoxysilane is dissolved in a 95wt% ethanol solution, 0.1wt% glacial acetic acid is added to adjust the pH to 4.8, made up to volume, and hydrolyzed at room temperature for 30 min to obtain a 2wt% affinity silane solution; the affinity silane solution is sprayed onto the silane activated carbon in step S4 in a fluidized bed, the bed temperature is 55°C, the atomizing gas is 1.2 bar, the liquid is 12 mL / min; the pickup amount is 0.1 mL of affinity silane solution per gram of silane activated carbon; 110°C curing for 30 min to obtain affinity activated carbon;

[0054] S6: methyltrimethoxysilane was dissolved in 95wt% ethanol solution, 0.1wt% glacial acetic acid was added to adjust the pH to 4.8, hydrolysis was carried out at room temperature for 20 min, constant volume was obtained, and 0.5wt% hydrophobic agent solution was obtained; the hydrophobic agent solution was fluidized bed sprayed on the affinity activated carbon of step S5, the bed temperature was 50℃, the atomization gas was 1.2bar, the liquid was 6mL / min; 0.05mL methyltrimethoxysilane solution / g affinity activated carbon; 90℃ curing treatment for 30min, then placed in a well-ventilated drying area for natural aging for 12h, to obtain enhanced activated carbon.

[0055] Comparative Example 1: The operation process of Comparative Example 1 and Example 1 is basically the same, the main difference is that in Comparative Example 1, the step S3 stage temperature adjustment is changed to full air program, the specific adjustment parameters are: the same as Example 1, the temperature is increased to 120℃, the desolventization is carried out for 2h; continue to increase to the upper limit of the phase temperature of Example 1, and the phase is kept for 1h; the air flow in the furnace is equivalent to the total gas amount of Example 1, which is calibrated at 3L / min·kg air; the rest of the operation parameters remain the same.

[0056] Comparative Example 2: The operation process of Comparative Example 2 and Example 1 is basically the same, the main difference is that in Comparative Example 2, Ce(NO3)3·6H2O is removed, and Mn(NO3)2·4H2O is added to make up the same total metal mass, and the solution volume is still equal to the impregnation volume; the rest of the operation parameters remain the same.

[0057] Comparative Example 3: The operation process of Comparative Example 3 and Example 1 is basically the same, the main difference is that in Comparative Example 3, the equal volume impregnation of S2 is cancelled, and the Mn-Ce mixed nitrate solution is sprayed on the surface of the dehydrated carrier, the total metal amount is the same as Example 1, and the spraying amount is controlled at 50mL / kg; the rest of the operation parameters remain the same.

[0058] Performance test:

[0059] Adsorption test: 2g of enhanced activated carbon prepared in Examples 1-3 and Comparative Examples 1-3 was loaded into a quartz column with an inner diameter of 10mm and an effective bed height of 30mm; the temperature was controlled at 25℃ by a constant temperature jacket, dry and clean air was used as the inlet gas, and a standard gas mixture was prepared (the inlet toluene concentration C in =100ppmv, the volume flow rate was 300mL / min; after the inlet gas was stabilized, the outlet concentration C out was recorded online every 1min, and the removal efficiency (%) was marked at 1min, 5min, 10min, 20min and 30min, which was (C in -C out ) / C in× 100%; the test was terminated after 60 min of full operation, and the adsorption amount (mg / g) was calculated as (inlet toluene concentration - outlet toluene concentration) × volume flow × stop time / active carbon mass (wherein the inlet toluene concentration - outlet toluene concentration is the average concentration difference from 0 to 60 min); each group of tests was set in triplicate, and the results are shown in Table 1. Figure 1 and Figure 2 as shown.

[0060] Based on the results analysis, Figure 1 and Figure 2 The active carbon prepared in the examples of the present application showed excellent removal efficiency and a more gentle breakthrough curve at each period, and showed excellent total adsorption capacity and overall stability. Based on the results analysis of Comparative Example 1 and Example 1, the removal efficiency curve of Comparative Example 1 was significantly delayed in the early and middle stages, and significantly decreased in the later stage, and the total adsorption capacity was significantly reduced; this may be due to the fact that after the full air program, the heat release and oxidation of nitrates in the air more easily cause slight ablation of the micropores of the carbon skeleton and oxidation of the pore mouth, thereby causing a decrease in the effective micropore volume and the pore mouth openness; at the same time, the decomposition of metal salts in the air section tends to form larger oxide agglomerates on the outer surface layer, locally increasing the mass transfer resistance and weakening the subsequent uniform condensation and anchoring of GPTMS near the surface layer, resulting in uneven density of the organic affinity layer and a decrease in surface energy matching degree, and the initial rate and steady-state capacity are both impaired. Based on the results analysis of Example 1 and Comparative Example 2, Comparative Example 2 showed lower removal efficiency in the early stage, faster decay in the later stage, and total adsorption capacity at a medium to low level; this may be due to the fact that after the removal of Ce, the core is mainly composed of single MnO X which is more prone to grain growth and uneven distribution during heat treatment, and some of them are located in the pore mouth area to form a shield; the lack of cerium oxygen storage and defect site adjustment reduces the adhesion and dispersion stability of metal oxides on the carbon pore wall, making it difficult to maintain the mild self-cleaning effect of the core on the adsorption intermediates, and the decrease in the cleanliness and accessibility of the pore surface will be converted into earlier breakthrough and lower effective capacity in dynamic adsorption. Based on the results analysis of Example 1 and Comparative Example 3, the removal efficiency of Comparative Example 3 was low at all times, and the total adsorption capacity was the lowest; this may be due to the fact that after the Mn-Ce salt solution is positioned and phase-fixed on the surface layer, the surface layer oxides preferentially occupy the pore mouth and the near-surface channel, directly competing and shielding the silicon-oxygen anchoring sites of GPTMS, making it difficult for the subsequent co-condensation of organic functional silanes to form a dense, continuous and non-blocking organic affinity network; at the same time, the surface layer metal oxide agglomeration increases the mass transfer resistance of the boundary layer and the pore mouth, weakening the surface energy matching and diffusion efficiency of aromatic hydrocarbons, and thus the low removal rate, early breakthrough and insufficient capacity appear in the same direction.

[0061] Anti-moisture adsorption test: 2g of the enhanced activated carbon prepared in Examples 1-3 and Comparative Examples 1-3 were respectively filled in a quartz column with an inner diameter of 10mm and an effective bed height of 30mm; the temperature was controlled at 25℃ by a constant temperature jacket; the total flow rate of the inlet gas was 300mL / min; VOC was prepared by standard gas mixing with an inlet concentration C in =100ppmv (toluene 40ppmv + ethyl acetate 30ppmv + isopropyl alcohol 30ppmv); under the condition of 50% humidity, the outlet concentration C out was recorded online every 1min, and the removal efficiency (%) was calculated at 1min, 5min, 10min, 20min and 30min, and the adsorption amount at 60min was calculated, removal efficiency (%) = (C in -C out ) / C in ×100%.

[0062] The above steps (C in , flow rate, etc. remained the same) were repeated under the condition of 70% humidity with a new column of the same batch and the same filling amount, and the removal efficiency was calculated at 1min, 5min, 10min, 20min and 30min, and the adsorption amount at 60min was calculated.

[0063] Humidity recovery test: the column after the 70% humidity test was retested under the condition of 50% humidity for 30min (C in , flow rate, etc. remained the same), and the removal efficiency at 1min, 5min, 10min, 20min and 30min was recorded to evaluate the recovery degree after the humidity drop; the test results are shown in Table 1. Figure 3 、 Figure 4 and Figure 5 .

[0064] Based on the results of Figure 3 , Figure 4 and Figure 5 , the enhanced activated carbon prepared in the examples showed excellent removal efficiency and a gentle decay rate under different humidity conditions, and still showed a relatively excellent removal rate after the humidity dropped from 70% to 50%. Based on the analysis of the results of Comparative Example 1 and Example 1, the removal efficiency curve of Comparative Example 1 under different humidity conditions showed a low initial removal, an accelerated decay trend and a poor recovery effect; this may be due to the fact that under the condition of 70% humidity, the pore opening oxidation layer and the surface agglomerates are more likely to retain water and amplify water competition, so the curve is low throughout and slides faster over time; after the humidity drops, the pores / interfaces have been irreversibly changed, and the recovery is insufficient. Based on the analysis of the results of Example 1 and Comparative Example 2, the removal efficiency curve of Comparative Example 2 under different humidity conditions showed a slightly low initial removal, a more obvious decay than Comparative Example 1, and a significant drop under 70% humidity; this may be due to the fact that under the condition of 70% humidity, the MnOX The activity site is covered more quickly, and the decay is more severe. After falling back to 50% humidity, it is difficult to fully recover in a short time due to the coverage in the pores and the residual intermediates. Compared with Comparative Example 1, the pore connection is not further damaged by heat treatment, so the initial removal does not drop significantly, but the middle and late stages and the high humidity sensitivity make the overall curve close to that of Comparative Example 1. Based on the results of Example 1 and Comparative Example 3, Comparative Example 3 has the lowest removal efficiency at different humidities throughout the process, with a significant drop in the initial stage, followed by a sustained low level, with the largest drop at 70% humidity and the worst recovery after falling back. This may be due to the breaking of the functional sequence: Mn-Ce sprayed and phased on the surface is prone to film formation or agglomeration at the pore opening / near-surface, directly shielding the pore opening and increasing the external diffusion resistance, limiting the initial removal; metal oxides and residual acidic sites may compete or shield GPTMS anchoring sites, making it difficult for subsequent organic-affinity silanes to form a dense, continuous, and non-blocking surface network, thereby reducing the affinity for aromatic hydrocarbons / non-polar components; under 70% humidity conditions, the outermost catalytic site is first covered by water and heavy components, quickly poisoned, and loses the support of the mechanism of continuous consumption of the core and passive updating of the outer layer sites, thus exhibiting early low, later lower, and difficult recovery after falling back.

[0065] Regeneration test: Based on the above adsorption test, the VOC is cut off, only the carrier gas branch is retained, the carrier gas is switched to low dew point dry air (RH < 5%, dew point ≤-20℃), and the total flow is maintained at 300 mL / min; the temperature is raised to 90℃ and maintained for 45 min, and the fan is always on throughout the process; after the end, the heating is turned off and the dry air is blown to complete the regeneration when the column temperature naturally falls to 25℃; after regeneration, the above 50% humidity adsorption test is continued, and the cycle is repeated 20 times, the retention rate (%) = adsorption rate after the nth regeneration / first adsorption rate x 100%, and the results are shown in Figure 6

[0066] Based on Figure 6 ​Based on the result analysis of Example 1 and Comparative Example 1, the retention rate of Comparative Example 1 began to lag obviously at the fifth time, which may be due to the slight ablation of micropores and oxidation of pore orifices caused by air decomposition, and surface metal agglomeration: the pore orifices are coarser / hydrophilic, and water and polar residues are easily retained, which are difficult to be removed by 90 DEG C dry air at one time, forming cumulative irreversible occupation; the surface agglomerates increase the boundary layer and pore orifice resistance, and the effective diffusion channel is not fully restored after regeneration; the near-surface anchoring site distribution is uneven, and the continuity of the organic silicon network is poor, and the interface affinity / anti-wetting after regeneration is difficult to return to the initial level. Based on the result analysis of Example 1 and Comparative Example 2, the retention rate of Comparative Example 2 lags obviously in the early stage, and the decline is more intensified in the later stage; this may be due to the lack of cerium oxygen storage / defect site adjustment and water sensitivity buffer, which weakens the self-cleaning ability of the core, and the oxygen-containing intermediates and strong adsorption fragments are easily retained in the pores, which repeatedly occupy the sites; in the repeated operation-regeneration, MnO X is more prone to particle size growth / poor dispersion, and the activity and accessibility decrease; ultimately leading to a retention rate curve that the more the cycles, the greater the gap. Based on the result analysis of Comparative Example 3 and Example 1, Comparative Example 3 lags obviously at the first cycle, and the gap continues to widen in the subsequent cycles, which may be due to the surface phase metal oxide film or agglomeration at the pore orifice / near-surface, causing pore orifice shielding and external diffusion limitation, metal / residual acid site occupation or shielding of silicon oxygen anchoring sites, and discontinuous organic affinity layer, local pore plugging, in the regeneration stage, heavy VOCs / intermediates under the surface metal region are difficult to be completely removed by 90 DEG C dry air, resulting in structural disadvantage; after high-humidity operation, the surface catalytic site is first poisoned, and it is difficult to completely restore the surface cleanliness and affinity state even after returning to dry air, so Comparative Example 3 presents the lowest retention rate curve, the fastest decay, and the worst recovery.

[0067] Spectrum test: the enhanced activated carbon of Example 1 and Comparative Example 3 after completing the step S3 operation is scanned by using a scanning electron microscope, and a SEM scanning electron microscope image is obtained, and the results are shown in Figure 7 .

[0068] Based on Figure 7 analysis, the activated carbon of Example 1 has clear pore orifice profile and few BSE bright spots; the activated carbon of Comparative Example 3 has high-brightness agglomeration / film zone near the pore orifice, which effectively proves that the different preparation paths of the two kinds of activated carbon result in different surface / pore orifice states and catalytic component distributions.

[0069] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirits of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. An enhanced activated carbon for organic exhaust gas, characterized by, The raw material composition comprises the following components: coconut shell activated carbon, Mn(NO3)2.4H2O, Ce(NO3)3.6H2O, 3-glycidoxypropyltrimethoxysilane, organic affinity silane and hydrophobic agent; The organic affinity silane is any one or several of phenyltrimethoxysilane, vinyltrimethoxysilane and octyltrimethoxysilane; The hydrophobic agent is any one of methyltrimethoxysilane and hexadecyltrimethoxysilane; The preparation method of the enhanced activated carbon for organic waste gas comprises the following steps: S1: coconut shell activated carbon is added into a hydrochloric acid solution, and then washed, and washed repeatedly with deionized water until neutral, and dried until constant weight to obtain activated activated carbon; Mn(NO3)2.4H2O and Ce(NO3)3.6H2O are dissolved in deionized water, and then stirred and dissolved uniformly to obtain a core precursor solution; S2: the activated activated carbon in step S1 is slowly added into the core precursor solution in step S1 in batches, and then rolled and homogenized, and then aged at room temperature, and then filtered and drained; S3: the activated carbon treated in step S2 is added into a calcination furnace, and then treated by stage heating under nitrogen atmosphere, and then naturally cooled to room temperature after calcination to obtain calcined activated carbon; S4: 3-glycidoxypropyltrimethoxysilane is dissolved in an ethanol solution, and then the pH is adjusted with glacial acetic acid, and then hydrolyzed at room temperature, and then diluted to a certain volume to obtain a silane solution; the silane solution is sprayed on the calcined activated carbon in step S3 by a fluidized bed, and then aged and treated, and then solidified to obtain silane activated carbon; S5: organic affinity silane is dissolved in an ethanol solution, and then the pH is adjusted with glacial acetic acid, and then diluted to a certain volume, and then hydrolyzed at room temperature to obtain an affinity silane solution; the affinity silane solution is sprayed on the silane activated carbon in step S4 by a fluidized bed, and then solidified to obtain affinity activated carbon; S6: a hydrophobic agent is dissolved in an ethanol solution, and then the pH is adjusted with glacial acetic acid, and then hydrolyzed at room temperature, and then diluted to a certain volume to obtain a hydrophobic agent solution; the hydrophobic agent solution is sprayed on the affinity activated carbon in step S5 by a fluidized bed, and then solidified, and then naturally aged in a ventilated and dried area to obtain enhanced activated carbon.

2. The enhanced activated carbon for organic exhaust gas according to claim 1, characterized by, In step S1, the ratio of the amounts of Mn(NO3)2.4H2O, Ce(NO3)3.6H2O and deionized water is 7-7.5 g:1.2-1.3 g:80-85 mL.

3. The enhanced activated carbon for organic exhaust gas according to claim 2, characterized by, In step S2, the ratio of the amounts of activated activated carbon and core precursor solution is 1 g:0.8-0.85 mL.

4. The enhanced activated carbon for organic exhaust gas according to claim 3, characterized by, In step S3, the stage heating treatment is specifically performed as follows: heated to 120℃ at a rate of 2℃ / min, and then kept for 60 min, and then heated to 200-220℃ at a rate of 1.5℃ / min, and then kept for 60-90 min, and then air with a flow rate of 2-3 L / min·kg is continuously input, and then kept at 200-220℃ for 30-45 min, and then replaced with nitrogen input after the completion of the keeping.

5. The enhanced activated carbon for organic exhaust gas according to claim 4, characterized by In step S4, the fluidized bed spraying parameters are as follows: bed temperature 45-55℃, atomization gas 1.2-1.6 bar, liquid 10-15 mL / min; pick-up amount 0.08-0.12 mL of silane solution per gram of calcined activated carbon.

6. The enhanced activated carbon for organic exhaust gas according to claim 5, characterized by In step S5, the fluidized bed spray parameters are: bed temperature 45-55°C, atomizing gas 1.2-1.6 bar, liquid 6-12 mL / min; pick-up 0.06-0.1 mL affinity silane solution / g silane activated carbon.

7. The enhanced activated carbon for organic exhaust gas according to claim 6, characterized by, In step S6, the fluidized bed spray parameters are: bed temperature 40-50°C, atomizing gas 1.2-1.8 bar, liquid 4-6 mL / min; 0.03-0.05 mL hydrophobic agent solution / g affinity activated carbon.

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