Enhanced activated carbon for organic waste gas and preparation method thereof

Abstract

The invention belongs to the technical field of organic waste gas adsorption treatment, and particularly relates to enhanced activated carbon for organic waste gas and a preparation method thereof. The invention discloses a modified coconut shell activated carbon adsorbent, which is prepared from the following raw material components: coconut shell activated carbon, Mn (NO3) 2.4 H2O, Ce (NO3) 3.6 H2O, 3-glycidoxypropyltrimethoxysilane, organic affinity silane and a water repellent agent. According to the method, a Mn-Ce mixed oxide core is generated in situ in an inner hole through equivalent-volume impregnation and staged heat treatment, and is used for digesting oxygen-containing organic matters, adsorbing intermediates and keeping the hole channel clean; forming a silica anchoring layer on the surface of the activated carbon by using GPTMS, and carrying out co-condensation on the silica anchoring layer and organic affinity silane to obtain an organic affinity interface matched with aromatic hydrocarbon and non-polar VOC (Volatile Organic Compounds) without blocking holes; an ultra-thin hydrophobic layer is formed at the tail end through polycondensation of low-dosage hydrophobic silane, moisture permeation is reduced, and meanwhile, an organic small molecule diffusion channel is reserved; and the pore structure is effectively protected by adopting a water / alcohol system and low-temperature curing in the whole process.

Description

Technical Field

[0001] This invention belongs to the field of organic waste gas adsorption treatment technology, specifically relating to an enhanced activated carbon for organic waste gas and its preparation method. Background Technology

[0002] Activated carbon originates from porous adsorbent materials obtained through carbonization and activation of carbon-containing raw materials such as coal, wood, and coconut shells. It possesses a well-developed microporous structure and a high specific surface area, enabling it to remove volatile organic compounds (VOCs) from air and process exhaust gases through physical adsorption. It is widely used in solvent recovery, exhaust gas purification for spraying and printing, fine chemicals, and electronics manufacturing. To adapt to complex waste gases and varying operating conditions, current technologies often modify the surface of activated carbon. For example, impregnating it with metal salts or metal oxides to impart catalytic functionality, using organosilicon or polymer coatings to enhance hydrophobicity, or introducing specific chemical groups to enhance selectivity for certain pollutants. However, existing modification pathways exhibit multiple limitations in real-world mixed organic waste gas and high-humidity environments: First, water vapor strongly competes with micropores; as humidity increases, water clustering and capillary condensation easily occur in micropores, leading to the occupation of effective sites and inducing adsorption-desorption fluctuations. Second, competitive adsorption and coverage effects exist among mixed VOC components; high-boiling-point, aromatic, or polarity-differentiated components preferentially occupy pores, reducing the selectivity and stability of target pollutant removal. Third, mass transfer limitations and external boundary layer problems are more pronounced in granular beds or honeycomb packing; without a reasonable interface and pore design, it is difficult to simultaneously achieve both initial rate and long-term breakthrough performance. Targeted modification also presents inherent contradictions: surface catalytic impregnation is prone to deactivation and accelerated fouling under high humidity and multi-component conditions; while overall hydrophobic coatings can reduce water competition, they often simultaneously cause pore blockage and increased pressure drop; amination modification targeting aldehydes lacks universality for mixed VOCs and is prone to migration and degradation under warm air or light steam regeneration, resulting in odor re-entry and shortened lifespan. In terms of regeneration, high-temperature or vacuum-based regeneration methods are energy-intensive and require sophisticated equipment, making them difficult to integrate with conventional end-of-pipe treatment facilities. Regarding process consistency, co-impregnating multiple functional components on the same surface can easily lead to mutual shielding and uneven distribution, resulting in pulverization, coating peeling, and performance drift after long-term cycling. Given these contradictions and shortcomings, it is essential to develop an activated carbon that maintains stability and is regeneration-friendly under conditions of mixed VOCs and fluctuating humidity. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the purpose of this invention is to provide an enhanced activated carbon for organic waste gas and a method for preparing the same. Traditional hydrophobically modified or catalytically impregnated activated carbon is easily competed for by water and covered by multiple components under mixed organic waste gas and high humidity conditions. The surface catalytic sites are deactivated, the polymer coating is prone to pore blockage, and the regeneration energy consumption is high and the capacity decay is rapid. To address this problem, this solution constructs a gradient structure with a core of Mn-Ce self-cleaning, a surface organic affinity, and an outermost hydrophobic control: First, an in-situ Mn-Ce mixed oxide core is generated in the inner pores by equal-volume impregnation and staged heat treatment, which is used to dissolve oxygen-containing organic matter and adsorb intermediates and maintain pore cleanliness. Then, 3-glycidoxypropyltrimethoxysilane (GPTMS) is used to form a silicon-oxygen anchoring layer on the activated carbon surface and co-condenses with organic affinity silane to obtain an organic affinity interface that matches aromatic hydrocarbons and non-polar VOCs without pore blockage. Finally, a low-dose hydrophobic silane is condensed into an ultrathin hydrophobic layer to reduce water penetration while retaining diffusion channels for small organic molecules. The entire process uses a water / alcohol system and low-temperature curing to effectively protect the pore structure.

[0004] The technical effects described in this invention are achieved through the following technical solution: an enhanced activated carbon for organic waste gas, the raw material composition of which includes the following components: coconut shell activated carbon, Mn(NO3)2·4H2O, Ce(NO3)3·6H2O, 3-glycidoxypropyltrimethoxysilane, organic affinity silane and hydrophobic agent.

[0005] Preferably, the organoaffinity silane is any one or more of phenyltrimethoxysilane, vinyltrimethoxysilane, and octyltrimethoxysilane; more preferably, it is phenyltrimethoxysilane and octyltrimethoxysilane.

[0006] Preferably, the hydrophobic agent is either methyltrimethoxysilane or hexadecyltrimethoxysilane;

[0007] Another aspect of the present invention is to provide a method for preparing enhanced activated carbon for organic waste gas, specifically comprising the following steps:

[0008] S1: Add coconut shell activated carbon to 0.3-0.5M hydrochloric acid solution, soak for 30-60 min, wash repeatedly with deionized water until neutral, and dry at 110℃ to constant weight to obtain activated carbon; dissolve Mn(NO3)2·4H2O and Ce(NO3)3·6H2O in deionized water, make up to volume, stir to dissolve evenly, and obtain core precursor solution;

[0009] S2: Slowly add the activated carbon from step S1 into the core precursor solution from step S1 in 3 batches, roll and homogenize for 15-30 minutes, let it stand at room temperature for 0.5-2 hours, and then filter and drain.

[0010] S3: Add the activated carbon processed in step S2 into a calcining furnace, and heat it in stages under a nitrogen atmosphere. After calcination, allow it to cool naturally to room temperature to obtain calcined activated carbon.

[0011] S4: Dissolve 3-glycidoxypropyltrimethoxysilane in 95wt% ethanol solution, adjust pH to 4.3-4.8 with 0.1wt% glacial acetic acid, hydrolyze at room temperature for 30-60 min, and bring to volume to obtain 2wt% silane solution; spray the silane solution onto the calcined activated carbon from step S3 in a fluidized bed, age at 60℃ for 60-90 min, and then solidify at 105-110℃ for 30-60 min to obtain silane activated carbon;

[0012] S5: Dissolve the organic affinity silane in a 95wt% ethanol solution, adjust the pH to 4.3-4.8 with 0.1wt% glacial acetic acid, bring the volume to a constant, and hydrolyze at room temperature for 20-30 min to obtain a 1-2wt% affinity silane solution. Spray the affinity silane solution onto the silane activated carbon obtained in step S4 in a fluidized bed, and cure at 105-110℃ for 30-60 min to obtain affinity activated carbon.

[0013] S6: Dissolve the hydrophobic agent in a 95wt% ethanol solution, adjust the pH to 4.3-4.8 with 0.1wt% glacial acetic acid, hydrolyze at room temperature for 15-20 min, and bring to a final volume to obtain a 0.3-0.5wt% hydrophobic agent solution; spray the hydrophobic agent solution onto the affinity activated carbon obtained in step S5 in a fluidized bed, cure at 85-90℃ for 30-60 min, and then place it in a ventilated and dry area for natural aging for 12-24 h to obtain reinforced 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 activated carbon to core precursor solution is 1g:0.8-0.85mL;

[0016] Preferably, in step S3, the specific operation of the staged heating process is as follows: heat up to 120°C at a rate of 2°C / min, hold for 60 min, then heat up to 200-220°C at a rate of 1.5°C / min, hold for 60-90 min, switch to continuous air input at 2-3 L / min·kg, continue to hold at 200-220°C for 30-45 min, and after the holding is completed, switch to nitrogen input;

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

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

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

[0020] The beneficial effects of this invention are as follows:

[0021] The enhanced activated carbon of this invention uses porous activated carbon as a framework and employs a gradient process from the inside out to construct a multifunctional hierarchical structure. First, manganese and cerium precursors are introduced into the particles through equal-volume impregnation. After drying and staged heat treatment, a stable mixed oxide core is generated in situ on the inner pore walls. This core neither blocks the mass transfer channels on the outer surface nor obstructs the gas-solid reactions within the pores, but provides persistent active sites. Subsequently, epoxy silane treatment is performed on the outer edge of the particles. The hydrolysis and condensation products form silicon-oxygen bridges with oxygen-containing groups on the activated carbon surface, causing the epoxy end groups to be directionally distributed in the near-surface region. Based on this, organofunctional silanes are introduced for co-condensation to construct a continuous organic affinity layer, aiming to improve the adsorption selectivity for aromatic hydrocarbons and non-polar organic compounds while maintaining pore connectivity and a low pressure drop. Finally, a low dose of hydrophobic silane is used for condensation on the outermost layer to form a uniform hydrophobic microlayer. This layer effectively inhibits capillary condensation and clustering of moisture in the micropores through surface energy regulation, while avoiding significant impact on the diffusion resistance of small organic molecules. Thus, a balance between moisture resistance and mass transfer efficiency is achieved in the process.

[0022] Specifically, epoxy silanes first form silicon-oxygen bonds with the support, providing anchoring sites with controllable density. Organofunctional silanes then further condense at these anchoring sites, forming a regenerable organosilicon network. This network gives the outer layer a higher affinity for aromatic hydrocarbons, esters, ethers, ketones, and alcohols, while reducing surface fouling tendency. Manganese oxides in the core provide active sites through valence state transitions, while cerium oxides, with their oxygen storage and defect sites, help maintain surface activity and mitigate the poisoning effect of active sites caused by competitive adsorption of water molecules. This allows for the gentle decomposition of some oxygen-containing organic matter and intermediates generated during adsorption within the pores, thereby reducing the accumulation burden on the outer layer and delaying capacity decay. The outermost hydrophobic thin layer selectively blocks water, ensuring the passage efficiency of organic molecules and not significantly affecting the diffusion process of small organic molecules to the outer layer and into the pores. In practical applications, exhaust gas components are first selectively enriched by the organic affinity layer and then diffuse into the pores. The core transforms the active components, effectively reducing pore blockage and surface coverage, and maintaining the long-term cleanliness of the material structure. The hydrophobic microlayer significantly reduces moisture intrusion, ensuring that the material maintains its preferential adsorption capacity for organic pollutants and a stable breakthrough curve even under high humidity or complex composition conditions. The spatial separation of each functional layer avoids a direct conflict between catalytic activity and surface affinity. The interface uses a silicon-oxygen network as a framework, reducing the risks of migration, pulverization, and coating peeling during operation and regeneration. Attached Figure Description

[0023] Figure 1 The graph shows the removal rate results of the enhanced activated carbon adsorption test in Examples 1-3 and Comparative Examples 1-3 of this invention;

[0024] Figure 2 The graph shows the adsorption capacity results of the enhanced activated carbon in Examples 1-3 and Comparative Examples 1-3 of this invention.

[0025] Figure 3 The graph shows the removal rate results of the enhanced activated carbon in Examples 1-3 and Comparative Examples 1-3 of this invention under 50%RH wet adsorption test.

[0026] Figure 4 The graph shows the removal rate results of the enhanced activated carbon in Examples 1-3 and Comparative Examples 1-3 of this invention under 70%RH wet adsorption test.

[0027] Figure 5 The graph shows the humidity removal rate results of the enhanced activated carbon anti-humidity adsorption test in Examples 1-3 and Comparative Examples 1-3 of this invention.

[0028] Figure 6 The graph shows the test results of the regenerability adsorption of the enhanced activated carbon in Examples 1-3 and Comparative Examples 1-3 of this invention.

[0029] Figure 7The images are SEM (Scanning Electron Microscopy) images of the enhanced activated carbon of Example 1 and Comparative Example 3 of the present invention; the left image is of Example 1 and the right image is of Comparative Example 3. Detailed Implementation

[0030] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Unless otherwise specified, the raw materials involved in the present invention are all purchased through conventional commercial channels. Experimental methods without specific conditions are conventional methods and conditions well known 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 of which 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: Add 100g of coconut shell activated carbon to 0.4M hydrochloric acid solution, soak for 45min, wash repeatedly with deionized water until neutral, and dry at 110℃ to constant weight to obtain activated carbon; dissolve 7.3g of Mn(NO3)2·4H2O and 1.25g of Ce(NO3)3·6H2O in deionized water, make up to 83mL, stir to dissolve evenly, and obtain core precursor solution;

[0034] S2: Slowly add 100g of activated carbon from step S1 into 83mL of the core precursor solution from step S1 in 3 batches, roll and homogenize for 25min, let stand at room temperature for 1h for aging, filter and drain.

[0035] S3: Add the activated carbon treated in step S2 into the calcination furnace. Under a nitrogen atmosphere, heat the carbon to 120°C at a rate of 2°C / min and hold for 60 min. Then, heat the carbon to 210°C at a rate of 1.5°C / min and hold for 75 min. Switch to continuous air input at 2.5 L / min·kg and continue holding at 210°C for 40 min. After holding, switch to nitrogen input. After calcination, allow the carbon to cool naturally to room temperature to obtain calcined activated carbon.

[0036] S4: Dissolve 3-glycidoxypropyltrimethoxysilane in 95wt% ethanol solution, adjust pH to 4.5 with 0.1wt% glacial acetic acid, hydrolyze at room temperature for 45 min, and bring to a final volume to obtain a 2wt% silane solution; spray the silane solution onto the calcined activated carbon from step S3 in a fluidized bed at a bed temperature of 50℃, atomizing gas at 1.4 bar, and liquid flow rate of 12 mL / min; pick up 0.1 mL silane solution / g calcined activated carbon; age at 60℃ for 75 min, then cure at 108℃ for 45 min to obtain silane activated carbon;

[0037] S5: Phenyltrimethoxysilane and octyltrimethoxysilane were dissolved in a 1:1 ratio in a 95wt% ethanol solution. The pH was adjusted to 4.5 with 0.1wt% glacial acetic acid, and the solution was brought to a final volume. The solution was hydrolyzed at room temperature for 25 min to obtain a 1.5wt% affinity silane solution. The affinity silane solution was then fluidized bed sprayed onto the silane activated carbon obtained in step S4. The bed temperature was 50℃, the atomizing gas was 1.4 bar, and the liquid flow rate was 8 mL / min. The pick-up rate was 0.08 mL affinity silane solution / g silane activated carbon. The solution was cured at 108℃ for 45 min to obtain affinity activated carbon.

[0038] S6: Dissolve hexadecyltrimethoxysilane in 95wt% ethanol solution, adjust pH to 4.5 with 0.1wt% glacial acetic acid, hydrolyze at room temperature for 18 min, and bring to volume to obtain a 0.4wt% hydrophobic agent solution; spray the hydrophobic agent solution onto the affinity activated carbon from step S5 in a fluidized bed at a bed temperature of 45℃, atomizing gas at 1.5 bar, and liquid at 5 mL / min; 0.04 mL hydrophobic agent solution / g affinity activated carbon; cure at 88℃ for 45 min, and then place in a ventilated and dry area for natural aging for 18 h to obtain reinforced activated carbon.

[0039] Example 2: An enhanced activated carbon for organic waste gas, the raw material composition of which 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: Add 100g of coconut shell activated carbon to 0.3M hydrochloric acid solution, soak for 60min, wash repeatedly with deionized water until neutral, and dry at 110℃ to constant weight to obtain activated carbon; dissolve 7.5g of Mn(NO3)2·4H2O and 1.3g of Ce(NO3)3·6H2O in deionized water, make up to 85mL, stir to dissolve evenly, and obtain core precursor solution;

[0042] S2: Slowly add 100g of activated carbon from step S1 into 85mL of the core precursor solution from step S1 in 3 batches, roll and homogenize for 15min, let stand at room temperature for 2h for aging, filter and drain.

[0043] S3: Add the activated carbon treated in step S2 into the calcination furnace. Under a nitrogen atmosphere, heat the carbon to 120°C at a rate of 2°C / min and hold for 60 min. Then, heat the carbon to 200°C at a rate of 1.5°C / min and hold for 90 min. Switch to continuous air input at 2 L / min·kg and continue holding at 200°C for 45 min. After holding, switch to nitrogen input. After calcination, allow the carbon to cool naturally to room temperature to obtain calcined activated carbon.

[0044] S4: Dissolve 3-glycidoxypropyltrimethoxysilane in 95wt% ethanol solution, adjust pH to 4.3 with 0.1wt% glacial acetic acid, hydrolyze at room temperature for 30 min, and bring to a final volume to obtain a 2wt% silane solution; spray the silane solution onto the calcined activated carbon from step S3 in a fluidized bed at a bed temperature of 45℃, atomizing gas at 1.6 bar, and liquid flow rate of 15 mL / min; pick up 0.08 mL silane solution / g calcined activated carbon; age at 60℃ for 60 min, then cure at 105℃ for 60 min to obtain silane activated carbon;

[0045] S5: Dissolve octyltrimethoxysilane in 95wt% ethanol solution, adjust pH to 4.3 with 0.1wt% glacial acetic acid, bring to volume, and hydrolyze at room temperature for 20 min to obtain 1wt% affinity silane solution. Spray the affinity silane solution onto the silane activated carbon from step S4 in a fluidized bed at 45℃, atomizing gas at 1.6 bar, and liquid flow rate at 6 mL / min; pick up 0.06 mL affinity silane solution / g silane activated carbon; cure at 105℃ for 60 min to obtain affinity activated carbon.

[0046] S6: Dissolve hexadecyltrimethoxysilane in 95wt% ethanol solution, adjust pH to 4.3 with 0.1wt% glacial acetic acid, hydrolyze at room temperature for 15 min, and bring to volume to obtain a 0.3wt% hydrophobic agent solution; spray the hydrophobic agent solution onto the affinity activated carbon from step S5 in a fluidized bed at a bed temperature of 40℃, atomizing gas at 1.8 bar, and liquid flow rate of 4 mL / min; 0.03 mL hydrophobic agent solution / g affinity activated carbon; cure at 85℃ for 60 min, and then place in a ventilated and dry area for natural aging for 24 h to obtain reinforced activated carbon.

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

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

[0049] S1: Add 100g of coconut shell activated carbon to 0.5M hydrochloric acid solution, soak for 30min, wash repeatedly with deionized water until neutral, and dry at 110℃ to constant weight to obtain activated carbon; dissolve 7g of Mn(NO3)2·4H2O and 1.2g of Ce(NO3)3·6H2O in deionized water, make up to 80mL, stir to dissolve evenly, and obtain core precursor solution;

[0050] S2: Slowly add 100g of activated carbon from step S1 into 80mL of the core precursor solution from step S1 in 3 batches, roll and homogenize for 30min, let stand at room temperature for 0.5h for aging, filter and drain.

[0051] S3: Add the activated carbon processed in step S2 into the calcination furnace. Under a nitrogen atmosphere, heat the carbon to 120°C at a rate of 2°C / min and hold for 60 min. Then, heat the carbon to 220°C at a rate of 1.5°C / min and hold for 60 min. Switch to continuous air input at 3 L / min·kg and continue holding at 220°C for 30 min. After holding, switch to nitrogen input. After calcination, allow the carbon to cool naturally to room temperature to obtain calcined activated carbon.

[0052] S4: Dissolve 3-glycidoxypropyltrimethoxysilane in 95wt% ethanol solution, adjust pH to 4.8 with 0.1wt% glacial acetic acid, hydrolyze at room temperature for 60 min, and bring to a final volume to obtain a 2wt% silane solution; spray the silane solution onto the calcined activated carbon from step S3 in a fluidized bed at a bed temperature of 55℃, atomizing gas at 1.2 bar, and liquid flow rate of 15 mL / min; pick up 0.12 mL silane solution / g calcined activated carbon; age at 60℃ for 90 min, then cure at 110℃ for 30 min to obtain silane activated carbon;

[0053] S5: Dissolve vinyltrimethoxysilane in 95wt% ethanol solution, adjust pH to 4.8 with 0.1wt% glacial acetic acid, bring to volume, and hydrolyze at room temperature for 30 min to obtain a 2wt% affinity silane solution. Fluidized bed spray the affinity silane solution onto the silane activated carbon from step S4, at a bed temperature of 55℃, atomizing gas of 1.2 bar, and a liquid flow rate of 12 mL / min; pick-up rate: 0.1 mL affinity silane solution / g silane activated carbon; cure at 110℃ for 30 min to obtain affinity activated carbon.

[0054] S6: Dissolve methyltrimethoxysilane in 95wt% ethanol solution, adjust pH to 4.8 with 0.1wt% glacial acetic acid, hydrolyze at room temperature for 20 min, and bring to a final volume to obtain a 0.5wt% hydrophobic agent solution; spray the hydrophobic agent solution onto the affinity activated carbon from step S5 in a fluidized bed at a bed temperature of 50℃, atomizing gas at 1.2 bar, and liquid flow rate of 6 mL / min; 0.05 mL methyltrimethoxysilane solution / g affinity activated carbon; cure at 90℃ for 30 min, and then place in a ventilated and dry area for natural aging for 12 h to obtain reinforced activated carbon.

[0055] Comparative Example 1: The operation process of Comparative Example 1 is basically the same as that of Example 1. The main difference is that the staged heating operation in step S3 of Comparative Example 1 is changed to an all-air program. The specific adjustment parameters are as follows: heat up to 120°C at the same heating rate as in Example 1 and hold for 2 hours to remove the solvent; continue to heat up to the upper limit of the phase fixation temperature of Example 1 and hold for 1 hour to fix the phase; the air flow rate in the furnace is equivalent to the total gas volume of Example 1 and is calibrated at 3 L / min·kg air; the other operating parameters remain the same.

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

[0057] Comparative Example 3: The operation process of Comparative Example 3 is basically the same as that of Example 1. The main difference is that the equal volume impregnation of S2 is cancelled in Comparative Example 3, and instead, a quantitative Mn-Ce mixed nitrate solution is sprayed onto the surface of the dehydrated carrier. The total metal content is the same as that of Example 1, and the spray volume is controlled at 50 mL / kg. The other operating parameters remain the same.

[0058] Performance testing:

[0059] Adsorption test: 2g of the enhanced activated carbon prepared in Examples 1-3 and Comparative Examples 1-3 were respectively packed into quartz columns with an inner diameter of 10mm and an effective bed height of 30mm; the temperature was controlled at 25℃ under a constant temperature sleeve; the inlet air was dry and clean air, and a standard gas mixture was used (the inlet toluene concentration was C). in =100ppmv, volumetric flow rate 300mL / min; timing after gas inlet stabilizes, online recording of outlet concentration C out Record data every 1 minute, and mark the removal efficiency (%) at 1 minute, 5 minutes, 10 minutes, 20 minutes, and 30 minutes. in -C out ) / C in×100%; the test was terminated after 60 minutes of operation, and the adsorption capacity (mg / g) was calculated as follows: (inlet toluene concentration - outlet toluene concentration) × volumetric flow rate × stop time / activated carbon mass (wherein, the inlet toluene concentration - outlet toluene concentration is the average concentration difference from 0 to 60 minutes); each test group was set up in triplicate, and the results are as follows. Figure 1 and Figure 2 As shown.

[0060] based on Figure 1 and Figure 2 The results analysis showed that the activated carbon prepared in the embodiments of the present invention exhibited excellent removal efficiency and a smoother breakthrough curve at all time points, and also showed excellent total adsorption capacity, remaining stable overall. Based on the results analysis of Comparative Example 1 and Example 1, the removal efficiency curve of Comparative Example 1 lagged significantly in the early and middle stages, and showed a significant decline in the later stages, with a significant decrease in total adsorption capacity. This may be because after the all-air program, the exothermic and oxidative effects of nitrate decomposition in air are more likely to cause mild ablation and pore oxidation of the carbon skeleton micropores, resulting in a decrease in effective micropore volume and pore opening patency. At the same time, when metal salts decompose in the air stage, they tend to form larger oxide aggregates on the outer surface, locally increasing mass transfer resistance and weakening the uniform condensation and anchoring of GPTMS in the near-surface layer, leading to uneven organic affinity layer density and decreased surface energy matching, resulting in a double loss of initial rate and steady-state capacity. Based on the results analysis of Example 1 and Comparative Example 2, Comparative Example 2 showed a lower removal efficiency in the early stage, with accelerated decay in the later stage, and the total adsorption capacity was at a moderately low level. This may be because after Ce removal, the core is composed of a single MnO X Primarily due to the lack of cerium, grain growth and uneven distribution are more likely to occur during heat treatment, with some grains forming shielding in the pore opening region. The lack of cerium's oxygen storage and defect site regulation reduces the adhesion and dispersion stability of metal oxides on the carbon pore walls, making it difficult to maintain the gentle self-cleaning effect of the core on adsorption intermediates. The resulting decrease in pore surface cleanliness and accessibility translates into earlier breakthroughs and lower effective capacity during dynamic adsorption. Based on the results of Example 1 and Comparative Example 3, Comparative Example 3 showed lower removal efficiency and the lowest total adsorption capacity throughout the entire time period. This may be because after the Mn-Ce salt solution was positioned on the surface and sprayed and phase-fixed, the surface oxides preferentially occupied the pore openings and near-surface channels, directly competing with and shielding the silicon-oxygen anchoring points of GPTMS. This makes it difficult for subsequent co-condensation of organofunctional silanes to form a dense, continuous, and non-pore-clogging organic affinity network. Simultaneously, the aggregation of surface metal oxides increases the mass transfer resistance of the boundary layer and pore openings, weakening the surface energy matching and diffusion efficiency for aromatic hydrocarbons. Therefore, the low overall removal rate, earlier breakthroughs, and insufficient capacity occur simultaneously.

[0061] Anti-wet adsorption test: 2g of each of the enhanced activated carbon prepared in Examples 1-3 and Comparative Examples 1-3 was packed into a quartz column with an inner diameter of 10mm and an effective bed height of 30mm; the temperature was controlled at 25℃; the total inlet gas flow rate was 300mL / min; the VOC concentration at the inlet was prepared using a standard mixed gas. in =100ppmv (toluene 40ppmv + ethyl acetate 30ppmv + isopropanol 30ppmv); Under 50% humidity conditions, after the incoming gas stabilizes, start timing and record the outlet concentration C online. out Record data every 1 minute, and calculate the removal efficiency (%) at 1 minute, 5 minutes, 10 minutes, 20 minutes, and 30 minutes = (C in -C out ) / C in ×100%;

[0062] Under 70% humidity conditions, replace with new columns of the same batch and with the same filling volume and repeat the above steps (C). in (Keep the flow rate, etc. consistent), and calculate the removal efficiency at 1 min, 5 min, 10 min, 20 min and 30 min, and calculate the adsorption amount at 60 min;

[0063] Humidity recovery and decline test: The column that completed the 70% humidity test was retested for 30 minutes under a 50% humidity condition (C). in (While maintaining consistent flow rates, etc.), the removal efficiency was recorded at 1 min, 5 min, 10 min, 20 min, and 30 min to assess the degree of recovery after humidity drop. The test results are as follows: Figure 3 , Figure 4 and Figure 5 As shown.

[0064] based on Figure 3 , Figure 4 and Figure 5 Analysis of the results shows that the enhanced activated carbon prepared in the embodiments of the present invention exhibits excellent removal efficiency and a gradual decay rate under different humidity levels, and still shows a relatively good removal rate after the humidity drops from 70% to 50%. Based on the analysis of the results of Comparative Example 1 and Example 1, the removal efficiency curves of Comparative Example 1 under different humidity levels show that the initial removal is low, the decay trend is accelerated, and the recovery effect is poor. This may be because under 70% humidity conditions, the oxide layer at the pore opening and the surface agglomerates are more likely to retain water and amplify water competition, so the curve is low throughout and declines faster over time; after the humidity drops, the pore / interface has undergone irreversible changes, and the recovery is insufficient. Based on the analysis of the results of Example 1 and Comparative Example 2, the removal efficiency curves of Comparative Example 2 under different humidity levels show that the initial removal is slightly lower, the decay is more obvious than that of Comparative Example 1, and the drop is significant at 70% humidity. This may be because, under 70% humidity conditions, MnOX More sensitive to water, the active sites are covered faster, leading to accelerated degradation. After the humidity drops to 50%, due to the coverage within the pores and the residue of intermediates, it is difficult to fully recover in a short time. Compared to Comparative Example 1, its pore connectivity was not further damaged by heat treatment, so the initial removal efficiency did not decline significantly. However, the mid-to-late stages and high humidity sensitivity made the overall curve similar to Comparative Example 1. Based on the analysis of the results of Example 1 and Comparative Example 3, Comparative Example 3 had the lowest overall removal efficiency under different humidity levels, with a significantly low efficiency in the early stages and a continued low efficiency thereafter. The largest drop occurred at 70% humidity, and the recovery after the initial drop was the worst. This may be due to the disruption of the functional order: the surface-sprayed and phase-fixed Mn-Ce tends to form films or aggregate at the pore openings / near the surface, directly shielding the pore openings and increasing external diffusion resistance, thus limiting initial removal; metal oxides and residual acidic sites may compete with or shield GPTMS anchoring sites, making it difficult for subsequent organoaffinity silanes to form a dense, continuous, and non-clogging surface network, thereby reducing the affinity for aromatic hydrocarbons / nonpolar components; under 70% humidity conditions, the outermost catalytic sites are first covered by water and heavy components, rapidly poisoned, and lose the mechanism of continuous consumption of the core and passive renewal of the outer sites, thus exhibiting the characteristics of low early stage, even lower later stage, and difficult recovery.

[0065] Regeneration Test: Based on the above adsorption test, VOCs were cut off, and only the carrier gas branch was retained. The carrier gas was switched to low dew point dry air (RH < 5%, dew point ≤ -20℃), maintaining a total flow rate of 300 mL / min. The temperature was raised to 90℃ and held for 45 min, with the fan running continuously throughout. After the regeneration was completed, the heating was turned off, and dry air was used to purge until the column temperature naturally dropped to 25℃ to complete regeneration. After regeneration, the above 50% humidity adsorption test was repeated 20 times. The retention rate (%) was calculated as follows: Retention rate (%) = Adsorption rate after nth regeneration / Adsorption rate after 1st regeneration × 100%. The results are as follows: Figure 6 As shown.

[0066] based on Figure 6Analysis of the results shows that the enhanced activated carbon prepared in the embodiments of the present invention has superior regeneration performance. Based on the results of Example 1 and Comparative Example 1, the retention rate of Comparative Example 1 began to lag significantly after the 5th regeneration. This may be due to the mild micropore ablation and pore mouth oxidation caused by air decomposition, as well as surface metal agglomeration: the pore mouth is rougher / hydrophilic, easily retaining water and polar residues, which are difficult to remove in one go with 90°C dry air, forming cumulative irreversible occupation; the surface agglomerates increase the boundary layer and pore mouth resistance, and the effective diffusion channels are not fully restored after regeneration; the near-surface anchoring points are unevenly distributed, the continuity of the organosilicon network deteriorates, and the interface affinity / moisture resistance is difficult to return to the initial level after regeneration. Based on the results of Example 1 and Comparative Example 2, the retention rate of Comparative Example 2 was significantly lagging in the early stage, and the decline was more severe in the later stage; this may be due to the lack of cerium for oxygen storage / defect site regulation and water sensitivity buffering, resulting in weakened core self-cleaning ability, and the easy retention of oxygen-containing intermediates and strongly adsorbed fragments in the pores, which repeatedly occupy sites; MnO in the repeated operation-regeneration process X It is more prone to particle size growth / dispersion deterioration, and activity and accessibility decrease; ultimately leading to a retention rate curve with a larger gap with more cycles. Based on the analysis of the results of Comparative Example 3 and Example 1, Comparative Example 3 lagged significantly from the first cycle and the gap continued to widen in subsequent cycles. This may be due to the formation or agglomeration of surface phase-fixed metal oxides at the pore or near the surface, causing pore obstruction and restricted external diffusion. Metal / residual acid sites occupy or shield the silicon-oxygen anchoring points, resulting in discontinuous organic affinity layers and local pore blockage. During the regeneration stage, the heavy VOCs / intermediates below the surface metal area are difficult to be completely removed by 90°C dry air, resulting in structural disadvantages. After high humidity operation, the surface catalyst sites are poisoned first, and it is difficult to fully restore the surface cleanliness and affinity state even after returning to dry air. Therefore, Comparative Example 3 shows the lowest retention rate curve throughout the process, the fastest decay, and the worst recovery.

[0067] Image testing: The enhanced activated carbon of Example 1 and Comparative Example 3 after completing step S3 was scanned using a scanning electron microscope (SEM) to obtain SEM images. The results are as follows: Figure 7 As shown.

[0068] based on Figure 7 Analysis showed that the activated carbon in Example 1 had clear pore outlines and few BSE bright spots; while the activated carbon in Comparative Example 3 showed high-brightness agglomeration / film areas near the pores. This result effectively proves that the different preparation paths lead to significant differences in the surface / pore state and the distribution of catalytic components.

[0069] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A type of enhanced activated carbon for organic waste gas, characterized in that, Its 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.

2. The enhanced activated carbon for organic waste gas according to claim 1, characterized in that, The organoaffinity silane is any one or more of phenyltrimethoxysilane, vinyltrimethoxysilane, and octyltrimethoxysilane.

3. The enhanced activated carbon for organic waste gas according to claim 2, characterized in that, The hydrophobic agent is either methyltrimethoxysilane or hexadecyltrimethoxysilane.

4. A method for preparing enhanced activated carbon for organic waste gas according to any one of claims 1-3, characterized in that, Specifically, the following steps are included: S1: Add coconut shell activated carbon to hydrochloric acid solution, soak and wash, wash repeatedly with deionized water until neutral, dry to constant weight to obtain activated carbon; dissolve Mn(NO3)2·4H2O and Ce(NO3)3·6H2O in deionized water, make up to volume, stir to dissolve evenly to obtain core precursor solution. S2: Add the activated carbon from step S1 slowly in batches to the core precursor solution from step S1, roll to homogenize, let it stand at room temperature for aging, and then filter and drain. S3: Add the activated carbon processed in step S2 into a calcining furnace, and heat it in stages under a nitrogen atmosphere. After calcination, allow it to cool naturally to room temperature to obtain calcined activated carbon. S4: Dissolve 3-glycidoxypropyltrimethoxysilane in an ethanol solution, adjust the pH with glacial acetic acid, hydrolyze at room temperature, and bring to a final volume to obtain a silane solution; spray the silane solution onto the calcined activated carbon from step S3 in a fluidized bed, age it, and then solidify it to obtain silane activated carbon. S5: Dissolve the organic affinity silane in an ethanol solution, adjust the pH with glacial acetic acid, bring the volume to a constant, and hydrolyze at room temperature to obtain an affinity silane solution. Spray the affinity silane solution onto the silane activated carbon from step S4 in a fluidized bed and perform a solidification treatment to obtain the affinity activated carbon. S6: Dissolve the hydrophobic agent in an ethanol solution, adjust the pH with glacial acetic acid, hydrolyze at room temperature, and bring to a final volume to obtain a hydrophobic agent solution; spray the hydrophobic agent solution onto the affinity activated carbon from step S5 in a fluidized bed, perform a curing treatment, and then place it in a ventilated and dry area for natural aging treatment to obtain reinforced activated carbon.

5. A method for preparing enhanced activated carbon for organic waste gas according to claim 4, characterized in that, 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.

6. A method for preparing enhanced activated carbon for organic waste gas according to claim 5, characterized in that, In step S2, the ratio of activated carbon to core precursor solution is 1g:0.8-0.85mL.

7. A method for preparing enhanced activated carbon for organic waste gas according to claim 6, characterized in that, In step S3, the specific operation of the staged heating process is as follows: heat up to 120°C at a rate of 2°C / min, hold for 60 min, then heat up to 200-220°C at a rate of 1.5°C / min, hold for 60-90 min, switch to continuous air input at 2-3 L / min·kg, continue to hold at 200-220°C for 30-45 min, and after the holding is completed, switch to nitrogen input.

8. A method for preparing enhanced activated carbon for organic waste gas according to claim 7, characterized in that, In step S4, the fluidized bed spraying parameters are: bed temperature 45-55℃, atomizing gas 1.2-1.6 bar, liquid 10-15 mL / min; and pick-up rate 0.08-0.12 mL silane solution / g calcined activated carbon.

9. A method for preparing enhanced activated carbon for organic waste gas according to claim 8, characterized in that, In step S5, the fluidized bed spraying parameters are: bed temperature 45-55℃, atomizing gas 1.2-1.6 bar, liquid 6-12 mL / min; and pick-up amount 0.06-0.1 mL of affinity silane solution / g of silane activated carbon.

10. A method for preparing enhanced activated carbon for organic waste gas according to claim 9, characterized in that, In step S6, the fluidized bed spraying parameters are: bed temperature 40-50℃, 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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