Preparation method of phenol-based porous carbon material and application thereof

Abstract

This invention belongs to the field of functional materials for clean oil products and new technologies for polycyclic aromatic hydrocarbon (PAH) adsorption, specifically relating to a preparation method and application of phenol-based porous carbon materials. The phenol-based porous carbon adsorbent is obtained by carbonizing an organic porous material polymerized from phenolic hydroxyl compounds. The specific steps are: polymerizing phenol compounds, dimethoxymethane, and anhydrous ferric chloride in a dichloromethane solvent system; filtering, washing, and drying; and finally carbonizing to obtain the phenol-based porous carbon adsorbent. The prepared material can be applied to the adsorption of PAHs, mainly for removing PAHs naphthalene and anthracene from simulated catalytic cracking diesel fuel. Results show that its adsorption capacity for PAHs naphthalene and anthracene can reach up to 96 mg / g and 175 mg / g (500 ppm), respectively. The phenol-based porous carbon adsorbent prepared by this invention has advantages such as simple operation, high adsorption efficiency, good cycle stability, and low cost.

Description

Technical Field

[0001] This invention belongs to the field of functional materials for cleaning oils and new technologies for the adsorption of polycyclic aromatic hydrocarbons, specifically relating to a preparation method based on phenol porous carbon materials and its application. Background Technology

[0002] Catalytic cracked diesel is a major component of automotive diesel. Aromatics constitute over 60% of catalytic cracked diesel, with polycyclic aromatic hydrocarbons (PAHs) of two or more rings accounting for approximately 75% by volume. The China VI standard (GB 19147-2016) requires that the PAH content in automotive diesel not exceed 7%. Extracting PAHs, especially bicyclic aromatics, from catalytic cracked diesel before hydrorefining can effectively reduce hydrogen consumption in subsequent hydrorefining processes. The resulting aromatic components can also be used in pharmaceuticals, rubber, and other chemical industries, aligning with my country's transformation from oil refining to chemical processing. Therefore, finding suitable technologies for PAH removal from oil products is crucial.

[0003] Existing technologies for removing aromatics from oil products mainly include hydrogenation, sulfonation, extraction, and adsorption separation. Hydrogenation is widely used in industry, but its operating conditions are harsh, and hydrogen consumption is high, which is not conducive to the current goal of carbon neutrality. Sulfonation separates the acid phase by reacting aromatics with a sulfonating agent to remove aromatics, but the resulting acid sludge is difficult to treat, and there is significant loss of solvent oil with high aromatic content. Extraction is a relatively mature process with mild operating conditions and simple technology, but the organic extractants used, such as sulfolane, are environmentally harmful, corrode equipment, and have high energy consumption for reuse. Adsorption has a relatively simple process, is easy to elute, and offers a variety of adsorbents. Adsorption mainly achieves adsorption through π-π interactions, π-complexation, acid center interactions, and hydrophobic interactions between the adsorbent and polycyclic aromatic hydrocarbons. Currently, widely studied porous adsorbents mainly include carbon materials (such as activated carbon, graphene, and carbon nanotubes), silicon-based mesoporous materials, and molecular sieves. However, some adsorbents suffer from drawbacks such as high preparation costs, difficulty in recycling, and weak adsorption capacity. Therefore, designing and synthesizing economical and inexpensive adsorbent materials with high stability, high adsorption selectivity, and reusability is crucial for adsorption methods.

[0004] Porous materials, with their designable structures and pore sizes, are ideal adsorbents. Several different porous materials, such as zeolites, metal-organic frameworks (MOFs), porous organic polymers (POPs), and derived porous carbon materials (PCMs), have been well-studied for adsorbing gases, metal ions, and organic pollutants. Due to their tunable pore size, good stability, and high porosity, POPs are ideal precursors for obtaining PCMs. Compared to template-based methods for synthesizing PCMs, the direct carbonization of POPs avoids the use of acids or bases, making the process economical and time-saving. Summary of the Invention

[0005] The technical problem to be solved by this invention is: to address the current situation where polycyclic aromatic hydrocarbons (PAHs) degrade catalytic cracking diesel, and to research a simple, efficient, and low-cost phenol-based porous carbon material adsorbent that can be used to adsorb PAHs from catalytic cracking diesel.

[0006] This invention proposes a method for preparing porous carbon materials based on phenol. Phenol compounds are used as building blocks, and a Friedel-Crafts alkylation reaction is carried out with dimethoxymethane, anhydrous ferric chloride, and dichloromethane under a nitrogen atmosphere. Organic porous materials are obtained through the Friedel-Crafts alkylation reaction to obtain precursors for carbon materials. Then, phenol porous carbon materials are synthesized through a one-step direct carbonization method to improve the specific surface area, microporosity, and heteroatom oxygen content of the materials, thereby enhancing their adsorption capacity for polycyclic aromatic hydrocarbons.

[0007] To achieve the above objectives, the present invention adopts the following technical solution;

[0008] A method for preparing phenol-based porous carbon materials, comprising the following steps:

[0009] Using phenol compounds as building blocks, the phenol compounds are first mixed with anhydrous ferric chloride (FeCl3) catalyst to obtain a mixture; then the mixture is pretreated several times; the pretreatment is as follows: the mixture is first degassed and evacuated, and then nitrogen is introduced; the phenol compounds include any one of catechol, resorcinol, hydroquinone, or phloroglucinol;

[0010] Dimethoxymethane and dichloromethane were added to the pretreated mixture, and the mixture was refluxed in an oil bath under shaking conditions. After reflux, the mixture was cooled to room temperature and filtered to obtain a solid product.

[0011] The solid product was collected and washed sequentially with hydrochloric acid solution and methanol. After washing, it was subjected to Soxhlet extraction with methanol. The collected product was then dried under vacuum to obtain the dried product.

[0012] Finally, the dried product is calcined, cooled to room temperature, and then washed and dried to obtain phenol porous carbon material.

[0013] Preferably, the preprocessing is performed 3-5 times.

[0014] Preferably, the ratio of the amount of phenol compound, anhydrous ferric chloride, dichloromethane and dimethoxymethane is 0.005 mol: 0.02 mol: 150 mL: 1.125–1.5 mL.

[0015] Preferably, the oscillation conditions are 500 rpm / min, the oil bath reflux temperature is 45°C, and the time is 48 h.

[0016] Preferably, the concentration of the hydrochloric acid solution is 1 mol·L⁻¹. -1 The Soxhlet extraction time was 24 hours.

[0017] Preferably, the vacuum drying temperature is 120°C and the time is 12 hours.

[0018] Preferably, the calcination is carried out under a nitrogen atmosphere, with a heating rate of 5°C / min. -1 The calcination temperature is 800-1000℃ and the time is 2 hours.

[0019] Preferably, the solution used for washing the calcined material is methanol, and the drying temperature is 80°C for 8 hours.

[0020] application:

[0021] The phenol porous carbon material prepared based on this invention is used as an adsorbent for the adsorption of polycyclic aromatic hydrocarbon organic pollutants; specifically, it is used to adsorb and remove polycyclic aromatic hydrocarbons naphthalene and anthracene from catalytic cracking diesel.

[0022] Using the described phenol-based porous carbon material as the adsorbent, adsorption treatment was carried out on polycyclic aromatic hydrocarbons (PAHs) in simulated catalytic cracking diesel as an example. The adsorption process employed a static adsorption method, where simulated catalytic cracking diesel was adsorbed within a closed adsorption container. The ratio of adsorbent to simulated catalytic cracking diesel was 1 g / L, and the initial concentration of the simulated catalytic cracking diesel ranged from 100 to 500 mg / L. The adsorption capacity increased with increasing concentration, eventually reaching a maximum adsorption capacity of 175 mg / g. The adsorption capacity increased with adsorption time and reached near equilibrium after 2 hours.

[0023] Compared with existing technologies, the advantages of this invention are:

[0024] (1) The main raw material for synthesizing phenol porous carbon material in this invention is phenol compound, which is easy to obtain and inexpensive.

[0025] (2) The preparation process and operation of the phenol porous carbon material synthesized in this invention are very simple, the preparation cycle is short, the product is non-toxic, environmentally friendly, does not require special chemical equipment, and is easy to realize industrial production.

[0026] (3) The phenol porous carbon material of the present invention has a relatively high adsorption capacity for polycyclic aromatic hydrocarbon organic pollutants. By further studying the effect of its carbonization temperature on the performance of the adsorbent, the optimal carbonization temperature was determined, and its adsorption effect on polycyclic aromatic hydrocarbon organic pollutants was significantly increased. For example, the adsorption capacity of anthracene was increased from 102 mg / g to 175 mg / g, with an increase rate of 71.57%, which achieved unexpected and significant results. Detailed Implementation

[0027] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0028] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0029] Various improvements and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, which will be obvious to those skilled in the art.

[0030] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0031] Example 1:

[0032] 0.005 mol of catechol and 0.02 mol of anhydrous FeCl3 were added to a 250 mL double-necked round-bottom flask, and the mixture was then pretreated three times. The pretreatment was as follows: the mixture was degassed by a pump for 15 min and then filled with nitrogen.

[0033] After pretreatment, CH2Cl2 (150 mL) and dimethoxymethane (1.5 mL) were injected into a two-necked round-bottom flask using a syringe. The mixture was then refluxed in a constant-temperature shaking oil bath at 45 °C and 500 rpm / min for 48 hours. After cooling to room temperature, the product was collected by filtration. The product was then treated with 1 mol·L⁻¹ water. -1 The sample was washed sequentially with hydrochloric acid solution and methanol until the filtrate was a colorless, transparent liquid. Then, it was subjected to Soxhlet extraction with methanol for 24 hours to completely remove unreacted monomers, catalysts, and oligomers. After Soxhlet extraction, the product was collected and dried under vacuum at 120°C for 12 hours to obtain P1.

[0034] The obtained P1 polymer was placed in a ceramic boat and then placed in a tube furnace. Before heating, N2 was passed through for half an hour. P1 was placed in the tube furnace under a nitrogen atmosphere. The heating program of the tube furnace was set as follows: heating from room temperature to the set temperature at a heating rate of 5℃ / min, holding for 2 hours, and finally cooling naturally to room temperature. The product was collected, washed with methanol, and then dried at 80℃ for 8 hours to obtain phenol porous carbon material. A series of porous carbon materials (denoted as P1-800, P1-900, and P1-1000) were prepared at different carbonization temperatures (800℃, 900℃, and 1000℃).

[0035] Adsorption capacity comparison experiment of adsorbents:

[0036] Five mL of simulated cracked diesel oil (n-hexadecane) containing naphthalene / anthracene with an initial concentration of 500 mg / L was prepared and placed in a glass bottle. Five mg of each of the adsorbents P1, P1-800, P1-900, and P1-1000 prepared in Example 1 were added. Static adsorption was performed at 400 rpm / min for 2 hours at room temperature until adsorption equilibrium was reached. The polymer was then removed by filtration. The concentration of polycyclic aromatic hydrocarbons was determined by gas chromatography, and the adsorption capacity was calculated. The results are shown in Table 1.

[0037] Table 1 Adsorption capacity data of different adsorbents at an initial polycyclic aromatic hydrocarbon concentration of 500 mg / L

[0038]

[0039] As can be seen from Table 1, carbonization of P1 significantly increased its adsorption capacity for polycyclic aromatic hydrocarbons naphthalene and anthracene, increasing from 12 mg / g and 23 mg / g to 96 mg / g and 175 mg / g, respectively.

[0040] Example 2:

[0041] 0.005 mol resorcinol and 0.02 mol anhydrous FeCl3 were added to a 250 mL double-necked round-bottom flask. The mixture was then pretreated three times: the mixture was degassed by a pump for 15 min and then purged with nitrogen. After pretreatment, CH2Cl2 (150 mL) and dimethoxymethane (1.5 mL) were injected into the double-necked round-bottom flask using a syringe, mixed with the existing mixture, and refluxed in a constant-temperature shaking oil bath at 45 °C and 500 rpm / min for 48 hours. After cooling to room temperature, the product was collected by filtration and analyzed with 1 mol·L⁻¹ water. -1 The sample was washed sequentially with hydrochloric acid solution and methanol until the filtrate was a colorless, transparent liquid. Then, it was subjected to Soxhlet extraction with methanol for 24 hours to completely remove unreacted monomers, catalysts, and oligomers. After Soxhlet extraction, the product was collected and dried under vacuum at 120°C for 12 hours to obtain P2.

[0042] The obtained P2 polymer was placed in a ceramic boat and then placed in a tube furnace. Before heating, N2 was passed through for half an hour. Under a nitrogen atmosphere, P2 was placed in the tube furnace. The heating program of the tube furnace was set as follows: heating from room temperature at a rate of 5℃ / min to the set temperature, holding for 2 hours, and finally allowing it to cool naturally to room temperature. The product was collected, washed with methanol, and then dried at 80℃ for 8 hours to obtain phenol porous carbon material. A series of porous carbon materials (denoted as P2-800, P2-900, and P2-1000) were prepared at different carbonization temperatures (800℃, 900℃, and 1000℃).

[0043] Comparison experiment of adsorption capacity of four adsorbents:

[0044] Five mL of simulated cracked diesel oil (n-hexadecane) containing naphthalene / anthracene with an initial concentration of 500 mg / L was prepared and placed in a glass bottle. Five mg of each of the adsorbents prepared in Example 2 (P2, P2-800, P2-900, and P2-1000) were added, and static adsorption was performed at 400 rpm / min for 2 hours at room temperature until adsorption equilibrium was reached. The polymer was then removed by filtration. The concentration of polycyclic aromatic hydrocarbons was determined by gas chromatography, and the adsorption capacity was calculated. The results are shown in Table 2.

[0045] Table 2 Adsorption capacity data of different adsorbents at an initial polycyclic aromatic hydrocarbon concentration of 500 mg / L

[0046]

[0047] As can be seen from Table 2, carbonization of P2 significantly increased its adsorption capacity for polycyclic aromatic hydrocarbons naphthalene and anthracene, increasing from 0.18 mg / g and 22 mg / g to 61 mg / g and 115 mg / g, respectively.

[0048] Example 3:

[0049] 0.005 mol hydroquinone and 0.02 mol anhydrous FeCl3 were added to a 250 mL double-necked round-bottom flask. The mixture was then pretreated three times: the mixture was degassed by a pump for 15 min and then purged with nitrogen. After pretreatment, CH2Cl2 (150 mL) and dimethoxymethane (1.5 mL) were injected into the double-necked round-bottom flask using a syringe. After mixing with the existing mixture, the mixture was refluxed in a constant-temperature shaking oil bath at 45 °C and 500 rpm / min for 48 hours. After cooling to room temperature, the product was collected by filtration and treated with 1 mol·L⁻¹ water. -1 The sample was washed sequentially with hydrochloric acid solution and methanol until the filtrate was a colorless, transparent liquid. Then, it was subjected to Soxhlet extraction with methanol for 24 hours to completely remove unreacted monomers, catalysts, and oligomers. After Soxhlet extraction, the product was collected and dried under vacuum at 120°C for 12 hours to obtain P3.

[0050] The obtained P3 polymer was placed in a ceramic boat and then placed in a tube furnace. Before heating, N2 was passed through for half an hour. Under a nitrogen atmosphere, P3 was placed in the tube furnace. The heating program of the tube furnace was set as follows: heating from room temperature at a rate of 5℃ / min to the set temperature, holding for 2 hours, and finally allowing it to cool naturally to room temperature. The product was collected, washed with methanol, and then dried at 80℃ for 8 hours to obtain phenol porous carbon material. A series of porous carbon materials (denoted as P3-800, P3-900, and P3-1000) were prepared at different carbonization temperatures (800℃, 900℃, and 1000℃).

[0051] Comparison experiment of adsorption capacity of four adsorbents:

[0052] Five mL of simulated cracked diesel fuel (n-hexadecane) containing naphthalene / anthracene with an initial concentration of 500 mg / L was prepared and placed in a glass bottle. Five mg of each of the adsorbents P3, P3-800, P3-900, and P3-1000 prepared in Example 3 were added. Static adsorption was performed at 400 rpm / min for 2 hours at room temperature until adsorption equilibrium was reached. The polymer was then removed by filtration. The concentration of polycyclic aromatic hydrocarbons was determined by gas chromatography, and the adsorption capacity was calculated. The results are shown in Table 3.

[0053] Table 3: Adsorption capacity data of different adsorbents at an initial polycyclic aromatic hydrocarbon concentration of 500 mg / L

[0054]

[0055] As can be seen from Table 3, carbonization of P3 significantly increases its adsorption capacity for polycyclic aromatic hydrocarbons naphthalene and anthracene, increasing from 3 mg / g and 15 mg / g to 26 mg / g and 88 mg / g, respectively.

[0056] Example 4:

[0057] 0.005 mol of m-triphenol and 0.015 mol of anhydrous FeCl3 were added to a 250 mL double-necked round-bottom flask. The mixture was then pretreated three times: the mixture was degassed by a pump for 15 min and then purged with nitrogen. After pretreatment, CH2Cl2 (150 mL) and dimethoxymethane (1.125 mL) were injected into the double-necked round-bottom flask using a syringe, mixed with the existing mixture, and refluxed in a constant-temperature shaking oil bath at 45 °C and 500 rpm / min for 48 hours. After cooling to room temperature, the product was collected by filtration and analyzed with 1 mol·L⁻¹ water. -1The sample was washed sequentially with hydrochloric acid solution and methanol until the filtrate was a colorless, transparent liquid. Then, it was subjected to Soxhlet extraction with methanol for 24 hours to completely remove unreacted monomers, catalysts, and oligomers. After Soxhlet extraction, the product was collected and dried under vacuum at 120°C for 12 hours to obtain P4.

[0058] The obtained P4 polymer was placed in a ceramic boat and then placed in a tube furnace. Before heating, N2 was passed through for half an hour. Under a nitrogen atmosphere, P4 was placed in the tube furnace. The heating program of the tube furnace was set as follows: heating from room temperature at a rate of 5℃ / min to the set temperature, holding for 2 hours, and finally allowing it to cool naturally to room temperature. The product was collected, washed with methanol, and then dried at 80℃ for 8 hours to obtain phenol porous carbon material. A series of porous carbon materials (denoted as P4-800, P4-900, and P4-1000) were prepared at different carbonization temperatures (800℃, 900℃, and 1000℃).

[0059] Comparison experiment of adsorption capacity of four adsorbents:

[0060] Five mL of simulated cracked diesel fuel (n-hexadecane) containing naphthalene / anthracene with an initial concentration of 500 mg / L was prepared and placed in a glass bottle. Five mg of each of the adsorbents prepared in Example 4 (P4, P4-800, P4-900, and P4-1000) were added, and static adsorption was performed at 400 rpm / min for 2 hours at room temperature until adsorption equilibrium was reached. The polymer was then removed by filtration. The concentration of polycyclic aromatic hydrocarbons was determined by gas chromatography, and the adsorption capacity was calculated. The results are shown in Table 4.

[0061] Table 4: Adsorption capacity data of different adsorbents at an initial polycyclic aromatic hydrocarbon concentration of 500 mg / L

[0062]

[0063] As can be seen from Table 4, carbonization of P4 significantly increased its adsorption capacity for polycyclic aromatic hydrocarbons naphthalene and anthracene, increasing from 10 mg / g and 22 mg / g to 72 mg / g and 138 mg / g, respectively.

[0064] Note: The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Therefore, although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the present invention. All technical solutions and improvements that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing phenol-based porous carbon materials, characterized in that, Includes the following steps: Using phenol compounds as building blocks, the phenol compounds are first mixed with anhydrous ferric chloride catalyst to obtain a mixture; then the mixture is pretreated several times; the pretreatment is as follows: the mixture is first degassed and evacuated, and then nitrogen is introduced; Dimethoxymethane and dichloromethane were added to the pretreated mixture, and the mixture was refluxed in an oil bath under shaking conditions. After reflux, the mixture was cooled to room temperature and filtered to obtain a solid product. The phenolic compound included any one of catechol, resorcinol, hydroquinone, or phloroglucinol. The ratio of the phenolic compound, anhydrous ferric chloride, dichloromethane, and dimethoxymethane in the steps was 0.005 mol: 0.02 mol: 150 mL: 1.125~1.5 mL. The solid product was collected and washed sequentially with hydrochloric acid solution and methanol. After washing, it was subjected to Soxhlet extraction with methanol. The collected product was then dried under vacuum to obtain the dried product. Finally, the dried product was calcined under a nitrogen atmosphere at a heating rate of 5 °C / min. -1 The calcination temperature is 800~1000 °C; after calcination, the material is cooled to room temperature, and then washed and dried to obtain phenol porous carbon material.

2. The method for preparing phenol-based porous carbon materials according to claim 1, characterized in that, The preprocessing steps are performed 3-5 times.

3. The method for preparing phenol-based porous carbon materials according to claim 1, characterized in that, The oscillation conditions described in the steps are 500 rpm / min, oil bath reflux temperature of 45 °C, and time of 48 h.

4. The method for preparing phenol-based porous carbon materials according to claim 1, characterized in that, The concentration of the hydrochloric acid solution mentioned in the step is 1 mol·L⁻¹ -1 The Soxhlet extraction time was 24 hours.

5. The method for preparing phenol-based porous carbon materials according to claim 1, characterized in that, The vacuum drying process described in this step is carried out at a temperature of 120 °C for 12 hours.

6. The method for preparing phenol-based porous carbon materials according to claim 1, characterized in that, The calcination time mentioned in the steps is 2 hours.

7. The method for preparing phenol-based porous carbon materials according to claim 1, characterized in that, The solution used for washing the calcined material in the step is methanol, and the drying temperature is 80℃ for 8 hours.

8. The use of the phenol porous carbon material prepared by the method according to any one of claims 1-7 for the adsorption and removal of polycyclic aromatic hydrocarbons naphthalene and anthracene from catalytic cracking diesel.

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