Porous carbon-based adsorption material as well as preparation method and application thereof

Abstract

The invention discloses a porous carbon-based adsorption material as well as a preparation method and application thereof. The specific surface area of the porous carbon-based adsorption material is 600-3200m < 2 > / g, the pore volume is 0.8-3.1 cm < 3 > / g, the micropore rate is 80-93%, the carbon content is 89-98% by mass, the oxygen content is 1-10% by mass, and the nitrogen content is 0.5-6% by mass. The preparation method comprises the following steps: (1) taking a carbon material as an original matrix, and fully contacting the original matrix with a modifier and a solvent to prepare a mixed contact body; (2) desolventizing and demetalizing the mixed contact body to obtain a desolventized contact body; and (3) carrying out heat treatment on the removed contact body to obtain the porous carbon-based adsorption material. The preparation method of the porous adsorption material is simple, the cost is low, and light hydrocarbon molecules can be effectively adsorbed and removed.

Description

Technical Field

[0001] This invention relates to the field of adsorption materials technology, specifically to a porous carbon-based adsorption material, its preparation method, and its application. Background Technology

[0002] Adsorption, catalytic oxidation, high-temperature incineration, absorption, condensation, and membrane separation are widely used for the recovery and treatment of various waste gases containing volatile organic compounds (VOCs). For tank farms, loading docks, and ship loading terminals, a combination of condensation and adsorption, or a combination of membrane, condensation, and adsorption, is commonly used to treat VOC-containing waste gases. However, the low-carbon light hydrocarbons (including but not limited to C2-C5 hydrocarbons) in the waste gases have low boiling points and high volatility, making them difficult to treat effectively with this method. The contribution of light hydrocarbons to the waste gas often leads to excessive non-methane total hydrocarbons at the tail gas outlet. A condensation and adsorption coupling process for low-carbon light hydrocarbons is reported in Chinese invention patent 202110562057.0. In this process, the gas containing low-carbon light hydrocarbons undergoes four stages of condensation, and at the end, adsorption materials (activated carbon, diatomaceous earth, and puffed soybean powder) are used to remove the light hydrocarbons. In this method, the light hydrocarbons are almost entirely removed through deep cooling (minimum condensation temperature of -120℃) and pressurization, resulting in high energy consumption. To address the difficulty in adsorbing light hydrocarbons, Chinese invention patent 201810329017.X constructed a metal-organic framework material with pyrazine metal ligands. Chinese invention patent 202010904777.6 disclosed a polymer-formed associative structure and a copper-based metal-organic framework material loaded within the associative structure. Metal-organic framework materials have shown certain advantages in the separation and purification of light hydrocarbon compounds, but their preparation process is complex and costly, and they generate waste gas, wastewater, and structural performance changes during molding, making them unsuitable for large-scale industrial applications. Chinese invention patent 202110696075.8 addresses the structural performance loss problem during the molding process of solid Cu-MOFs by designing a porous liquid, HKUST-1, based on MOFs materials / ionic liquids. It achieves a static adsorption of 13.5% of ethane, but the cost and dynamic adsorption effect of the porous liquid are not described, and the actual static adsorption process differs from the dynamic adsorption process in industry.

[0003] Therefore, there is an urgent need in the existing technology for an adsorbent that can be manufactured at low cost, has good adsorption properties for low-carbon light hydrocarbons in VOCs, exhibits excellent stability, and can be used for a long period of time. Summary of the Invention

[0004] To achieve the above objectives, the present invention provides a porous carbon-based adsorbent material, its preparation method, and its application.

[0005] The technical solution adopted in this invention is: A porous carbon-based adsorbent material with a specific surface area of ​​600~3200 m² 2 / g, pore volume 0.8~3.1cm 3 / g, with a microporosity of 80-93%, a carbon content of 89-98% by mass, an oxygen content of 1-10% by mass, and a nitrogen content of 0.5-6% by mass. More preferably, the carbon content is 91-97% by mass, the oxygen content is 1-7% by mass, and the nitrogen content is 0.9-5% by mass. Even more preferably, the carbon content is 95-97% by mass, the oxygen content is 1-5% by mass, and the nitrogen content is 1.1-4.2% by mass.

[0006] Preferably, the porous carbon-based adsorbent material is spherical, cylindrical, or irregularly shaped.

[0007] The preparation method of any of the above porous carbon-based adsorbent materials includes the following steps: (1) Using carbon materials as the original matrix, a mixed contact body is prepared by fully contacting the modifier and solvent; (2) The mixed contact body is subjected to solvent removal and metal removal treatment to obtain the desolventized contact body; (3) The desorbed contact body is subjected to heat treatment to obtain a porous carbon-based adsorbent material.

[0008] In step (1), the contact step can be carried out at any temperature from 0°C to 150°C, for example at room temperature.

[0009] In step (2), the solvent removal and metal removal processes can be carried out in any manner known in the art, such as filtration, washing, and drying.

[0010] The heat treatment temperature in step (3) is not particularly limited, and can be 200~900℃, preferably 300~850℃, and more preferably 350~800℃. The atmosphere for heat treatment is a gas with an oxygen volume concentration of less than 0.1%, which can be one or a combination of two or more of nitrogen, helium, argon, carbon dioxide, and water vapor.

[0011] Preferably, the carbon material is at least one of wood-based carbon, coal-based carbon, and petroleum-based carbon. Wood-based carbon is further preferred, and coconut shell carbon is even more preferred.

[0012] In the preferred step (1), the mass ratio of the original matrix, modifier, and solvent is 10:(1~7):(0.5~8). There are no particular restrictions on the contact order of the carbon-based original matrix, modifier, and solvent, as long as sufficient mixing and contact of each raw material component can be achieved to form a uniform contact product. For example, the raw material components can be mixed (with auxiliary stirring if necessary) in any manner known in the art until homogeneous.

[0013] Preferably, the modifier is selected from one of nitrogen-containing compounds and / or oxygen-containing compounds, and more preferably, a combination of nitrogen-containing compounds and oxygen-containing compounds.

[0014] Further preferably, the nitrogen-containing compound is at least one selected from the following: nitrogen heterocyclic structure, fluorenyl structure, nitrogen anthracene, aromatic amine, melamine, urea, amide, alkaloid, and biological protein. Even more preferably, the nitrogen heterocyclic structure is pyridine, pyrimidine, or triazine; and the aromatic amine is aniline or aromatic amine containing substituents.

[0015] Preferably, the oxygen-containing compound is at least one of an acid and a base.

[0016] Further preferably, the acid is one or a combination of two or more of the following: phosphoric acid, sulfuric acid, nitric acid, perchloric acid, acetic acid, peracetic acid, oxalic acid, adipic acid, malic acid, tartaric acid, citric acid, and stearic acid. Further preferably, the alkali is one or a combination of two or more of lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, and zinc hydroxide.

[0017] Preferably, the solvent is at least one of water and alcohol, and the alcohol is more preferably at least one of monohydric alcohol and polyhydric alcohol.

[0018] As the monohydric alcohol, various monohydric alcohols known in the art can be used, such as C16 alcohols with one hydroxyl group. 1-20 Alkanes, for example, include methanol, ethanol, n-propanol, isopropanol, n-butanol, and isobutanol.

[0019] As the polyol, various polyols known in the art can be used, such as those with 2 to 10 (preferably 3 to 6) hydroxyl groups. 2-20 Alkanes, such as ethylene glycol, diethylene glycol, propylene glycol, glycerol, pentaerythritol, or polymers of such polyols, such as polyethylene glycol, polyvinyl alcohol, etc., or may be those contained in the C... 2-20 Polyhydroxyalkyl (poly)amines are obtained by inserting one or more nitrogen atoms into an alkane chain, such as monoethanolamine and triethanolamine.

[0020] Application of any of the above porous carbon-based adsorbent materials in the adsorption treatment of volatile organic compounds containing low-carbon hydrocarbons.

[0021] Furthermore, the application includes: filling a reactor with porous carbon-based adsorbent material, and introducing VOCs gas containing low-carbon hydrocarbons at a gas space velocity of 500~20000 h⁻¹. -1 The adsorption temperature is 10~100℃, the desorption temperature is 70~120℃, and vacuum or inert gas purging is used.

[0022] The beneficial effects of the present invention are: the preparation method of the porous adsorbent material of the present invention is simple and low in cost, and the adsorbent material can be designed according to the molecular size of light hydrocarbons to effectively adsorb and remove light hydrocarbon molecules.

[0023] The porous adsorbent material of the present invention can efficiently and stably adsorb light hydrocarbon molecules. Furthermore, since it can be regenerated by vacuum desorption or nitrogen desorption, the VOCs treatment efficiency is improved and the service life of the adsorbent material is extended. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the embodiments, but the present invention is not limited to these embodiments.

[0025] Unless otherwise specified, all raw materials used in the following examples and comparative examples are commercially available. The coconut shell activated carbon used conforms to the national standard for wood-based activated carbon (GB / T13803.2-1999).

[0026] In this invention, the surface area is determined by the BET specific surface area measurement method.

[0027] The pore volume was determined using the BJH (Barrett-Joyner-Halenda) method.

[0028] Micropores were calculated using the t-plot method.

[0029] The carbon and nitrogen contents in the porous carbon-based material were determined by elemental analysis, and the oxygen content was determined by X-ray fluorescence spectroscopy.

[0030] In this invention, breakthrough adsorption capacity is defined as the adsorption amount when the concentration of VOCs gas containing low-carbon hydrocarbon molecules reaches 10% of its concentration before entering the adsorption bed after passing through the bed, and breakthrough time is defined as the adsorption time when the concentration of VOCs gas containing low-carbon hydrocarbon molecules reaches 10% of its concentration before entering the adsorption bed after passing through the bed. For example, for ethane, the inlet concentration is 250 mg / m³. 3 The outlet concentration is 25 mg / m³. 3 The corresponding adsorption time is the breakthrough time, and the corresponding adsorption amount is the breakthrough adsorption amount. Example 1

[0031] Coconut shell activated carbon, 50% nitric acid aqueous solution, and melamine were refluxed at 60°C for 5 hours in a mass ratio of 10:4:1.5. The refluxed sample was filtered and calcined at 650°C for 3 hours to obtain porous adsorbent material A with a specific surface area of ​​2133 m². 2 / g, pore volume 2.3cm 3 / g, microporosity 88%, carbon content 94.6% by mass, oxygen content 2.1% by mass, nitrogen content 3.1% by mass. Example 2

[0032] Coconut shell activated carbon, a 70% (w / w) aqueous solution of phosphoric acid, and melamine were refluxed at 110°C for 3 hours in a mass ratio of 10:3:1.9. The refluxed sample was filtered and calcined at 700°C for 3 hours to obtain porous adsorbent material B with a specific surface area of ​​1947 m². 2 / g, pore volume 2.0cm 3 / g, microporosity 87%, carbon content 95.1% by mass, oxygen content 1.4% by mass, nitrogen content 3.1% by mass. Example 3

[0033] Coconut shell activated carbon, a 20% potassium hydroxide aqueous solution, and urea were refluxed at 90°C for 4 hours in a mass ratio of 10:2:6. The refluxed sample was filtered, washed with water until neutral, and calcined at 750°C for 3 hours to obtain porous adsorbent material C with a specific surface area of ​​1711 m². 2 / g, pore volume 1.7cm 3 / g, microporosity 80%, carbon content 96.1% by mass, oxygen content 1.8% by mass, nitrogen content 1.4% by mass. Example 4

[0034] Coconut shell activated carbon, a 40% (w / w) aqueous solution of perchloric acid, and pyridine were refluxed at 110°C for 5 hours in a mass ratio of 10:3:4. The refluxed sample was then filtered and calcined at 650°C for 3 hours to obtain porous adsorbent material D with a specific surface area of ​​1899 m². 2 / g, pore volume 2.0cm 3 / g, microporosity 82%, carbon content 96.7% by mass, oxygen content 2.1% by mass, nitrogen content 1.1% by mass. Example 5

[0035] Coconut shell activated carbon, a 20% sodium hydroxide aqueous solution, isopropanol, and alanine were refluxed at 90°C for 6 hours in a mass ratio of 10:4:1:4. The refluxed sample was filtered and calcined at 660°C for 3 hours to obtain porous adsorbent material E with a specific surface area of ​​1686 m². 2 / g, pore volume 1.9cm 3 / g, microporosity 84%, carbon content 94.1% by mass, oxygen content 2.6% by mass, nitrogen content 1.6% by mass. Example 6

[0036] Coconut shell activated carbon, 40% peracetic acid solution, ethylene glycol, and pyrimidine were refluxed at 110°C for 3 hours in a mass ratio of 10:3:2:2. The refluxed sample was filtered and calcined at 700°C for 3 hours to obtain porous adsorbent material F with a specific surface area of ​​1966 m². 2 / g, pore volume 1.9cm 3 / g, microporosity 89%, carbon content 94.3% by mass, oxygen content 3.3% by mass, nitrogen content 2.1% by mass. Example 7

[0037] Coconut shell activated carbon, a 40% (w / w) aqueous solution of phosphoric acid, and 1,2,3-triazine were refluxed at 100°C for 4 hours in a mass ratio of 10:4:2. The refluxed sample was filtered and calcined at 650°C for 3 hours to obtain porous adsorbent material G with a specific surface area of ​​1465 m². 2 / g, pore volume 1.6cm 3 / g, microporosity 84%, carbon content 95.3% by mass, oxygen content 2.1% by mass, nitrogen content 2.7% by mass. Example 8

[0038] Coconut shell activated carbon, a 40% (w / w) aqueous solution of oxalic acid, and 1,2,3-triazine were refluxed at 100°C for 5 hours in a mass ratio of 10:4:2. The refluxed sample was filtered and calcined at 700°C for 3 hours to obtain porous adsorbent material H with a specific surface area of ​​1379 m². 2 / g, pore volume 1.5cm 3 / g, microporosity 82%, carbon content 96.1% by mass, oxygen content 1.9% by mass, nitrogen content 1.4% by mass. Example 9

[0039] Coconut shell activated carbon, a 20% (w / w) aqueous solution of phosphoric acid, a 20% (w / w) aqueous solution of nitric acid, and melamine were refluxed at 60°C for 7 hours in a mass ratio of 10:4:4:1.5. The refluxed sample was filtered and calcined at 650°C for 3 hours to obtain porous adsorbent material I with a specific surface area of ​​1977 m². 2 / g, pore volume 1.9cm 3 / g, microporosity 84%, carbon content 95.1% by mass, oxygen content 1.6% by mass, nitrogen content 3.1% by mass. Example 10

[0040] Coconut shell activated carbon, a 40% (w / w) aqueous solution of phosphoric acid, and m-phenylenediamine were refluxed at 80°C for 3 hours in a mass ratio of 10:3:4. The refluxed sample was filtered and calcined at 750°C for 3 hours to obtain porous adsorbent material J with a specific surface area of ​​1398 m². 2 / g, pore volume 1.5cm 3 / g, microporosity 81%, carbon content 96.3% by mass, oxygen content 1.8% by mass, nitrogen content 1.2% by mass. Example 11

[0041] Coconut shell activated carbon, a 20% (w / w) aqueous solution of phosphoric acid, a 20% (w / w) aqueous solution of nitric acid, and 3-(1H-imidazol-1-methyl)aniline were refluxed at 90°C for 3 hours in a mass ratio of 10:2:2:3. The refluxed sample was filtered and calcined at 600°C for 5 hours to obtain porous adsorbent material K with a specific surface area of ​​2077 m². 2 / g, pore volume 2.1cm 3 / g, microporosity 87%, carbon content 95.0% by mass, oxygen content 2.7% by mass, nitrogen content 2.2% by mass.

[0042] Comparative Example 1 Coconut shell activated carbon and a 20% nitric acid aqueous solution were refluxed at 60°C for 5 hours at a mass ratio of 10:4. The refluxed sample was filtered and calcined at 650°C for 3 hours to obtain porous adsorbent material A1 with a specific surface area of ​​2009 m². 2 / g, pore volume 2.1cm 3 / g, microporosity 86%, carbon content 96.1% by mass, oxygen content 3.3% by mass, nitrogen content 0.1% by mass.

[0043] Comparative Example 2 Coconut shell activated carbon was used, with a specific surface area of ​​1766 m². 2 / g, pore volume 1.6cm 3 The sample has a density of 82% per gram, a microporosity of 82%, a carbon content of 98.8% by mass, an oxygen content of 0.7% by mass, and a nitrogen content of 0.3% by mass. This sample is labeled A2. Example 12

[0044] The porous adsorption materials from Examples 1-11 and the materials from Comparative Examples 1-2 were loaded into an adsorption bed, and ethane and propane were introduced at concentrations of 250 mg / m³. 3 The adsorption of VOCs in gaseous form (with nitrogen as the equilibrium gas) at an adsorption temperature of 25°C and a space velocity of 5000 h⁻¹ -1At atmospheric pressure, the porous material after adsorption was desorbed and regenerated by hot nitrogen at 130℃. The regenerated porous material was then recycled for further regeneration. The adsorption and recycling results are shown in Table 1.

[0045]

[0046] Although the invention has been described in detail herein with reference to exemplary embodiments, it should be understood that the invention is not limited to the described embodiments. Other variations, modifications, and embodiments within the scope of the invention will be recognized by those skilled in the art and who have access to the teachings herein. Therefore, the invention should be broadly interpreted in accordance with the claims set forth below.

Claims

1. A porous carbon-based adsorbent material, characterized in that, Its specific surface area is 600~3200m² 2 / g, pore volume 0.8~3.1cm 3 / g, with a microporosity of 80~93%, and based on the total mass of the porous carbon-based adsorbent material, the carbon content is 89~98% by mass, the oxygen content is 1~10% by mass, and the nitrogen content is 0.5~6% by mass.

2. The porous carbon-based adsorbent material according to claim 1, characterized in that, Its shape is spherical, cylindrical or irregular granules.

3. A method for preparing a porous carbon-based adsorbent material according to claim 1 or 2, characterized in that, Includes the following steps: (1) Using carbon materials as the original matrix, a mixed contact body is prepared by fully contacting the modifier and solvent; (2) The mixed contact body is subjected to solvent removal and metal removal treatment to obtain the desolventized contact body; (3) The desorbed contact body is subjected to heat treatment to obtain a porous carbon-based adsorbent material.

4. The method for preparing a porous carbon-based adsorbent material according to claim 3, characterized in that, The carbon material is at least one of wood-based carbon, coal-based carbon, and petroleum-based carbon.

5. The method for preparing a porous carbon-based adsorbent material according to claim 3, characterized in that, In step (1), the mass ratio of the original matrix, modifier, and solvent is 10:(1~7):(0.5~8).

6. The method for preparing a porous carbon-based adsorbent material according to claim 3, characterized in that, The modifier Selected from nitrogen-containing compounds and / or oxygen-containing compounds.

7. The method for preparing a porous carbon-based adsorbent material according to claim 6, characterized in that, The nitrogen-containing compound is at least one of the following: nitrogen heterocyclic structure, fluorenyl structure, nitrogen anthracene, aromatic amine, melamine, urea, amide, alkaloid, and biological protein.

8. The method for preparing a porous carbon-based adsorbent material according to claim 6, characterized in that, The oxygen-containing compound is at least one of an acid and a base.

9. The method for preparing a porous carbon-based adsorbent material according to claim 8, characterized in that, The acid is one or a combination of two or more of the following: phosphoric acid, sulfuric acid, nitric acid, perchloric acid, acetic acid, peracetic acid, oxalic acid, adipic acid, malic acid, tartaric acid, citric acid, and stearic acid.

10. The method for preparing a porous carbon-based adsorbent material according to claim 8, characterized in that, The alkali is one or a combination of two or more of lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, and zinc hydroxide.

11. The method for preparing a porous carbon-based adsorbent material according to claim 3, characterized in that, The solvent is at least one of water and alcohol.

12. The application of the porous carbon-based adsorbent material according to claim 1 or 2 in the adsorption treatment of volatile organic compounds containing low-carbon hydrocarbons.

13. The application according to claim 12, characterized in that, A porous carbon-based adsorbent material is packed into the reactor, and VOCs gas containing low-carbon hydrocarbons is introduced at a gas space velocity of 500~20000 h⁻¹. -1 The adsorption temperature is 10~100℃, the desorption temperature is 70~120℃, and vacuum or inert gas purging is used.

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