Activated carbon desulfurizer and its preparation method and application
By introducing oxygen-containing functional groups and nitrogen-containing species on the surface of activated carbon, an activated carbon desulfurizer with high efficiency in desulfurization in an oxygen-free atmosphere was prepared, which solved the limitation of traditional activated carbon desulfurizer requiring oxygen and achieved the effect of wide application and cost reduction.
Patent Information
- Application Number
- CN202311776935.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-21
- Publication Date
- 2025-09-26
- Estimated Expiration
- 2043-12-21
AI Technical Summary
Existing activated carbon desulfurizers need to work effectively in an oxygen-containing atmosphere and cannot efficiently remove H2S in an oxygen-free atmosphere, increasing safety risks and costs in industrial production.
By immersing activated carbon in nitric acid solution and calcining it under an inert atmosphere, oxygen-containing functional groups and nitrogen-containing species are introduced to the surface of the activated carbon. The activated carbon itself is used as an oxygen source for desulfurization in an oxygen-free atmosphere. An activated carbon desulfurizer with oxygen-containing functional groups such as carboxyl, ester, quinone, ketone and hydroxyl groups and nitrogen-containing species such as pyridinic nitrogen, pyrrolic nitrogen and graphene nitrogen on the surface is prepared.
It achieves efficient H2S removal in an oxygen-free atmosphere, broadens the scope of application, reduces preparation costs, and exhibits excellent desulfurization performance in oxygen-free industrial gases such as coal gas and natural gas, with a maximum sulfur capacity of 300 mg/g.
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Figure CN117643867B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of gas purification and desulfurization, and in particular to an activated carbon desulfurizer and a preparation method and application thereof. Background Art
[0002] As my country continues to advance its dual carbon goals, there's an urgent need to find innovative ways to utilize traditional fossil fuels like coal, oil, and natural gas in a clean, efficient, and low-carbon manner. However, the presence of sulfur impurities in fossil fuels inevitably leads to the production of sulfides, primarily H2S, during their clean and efficient utilization. H2S is a toxic and corrosive gas with a rotten egg odor. It not only corrodes pipelines and poisons downstream catalysts, creating safety risks and economic losses for industrial production, but also harms the environment and endangers human health.
[0003] Activated carbon is a common dry desulfurizer at room temperature in industry with high desulfurization efficiency. However, most of the activated carbon desulfurizers currently used in industry need to be in an oxygen-containing atmosphere to perform their desulfurization function, and their desulfurization performance is extremely low in an oxygen-free atmosphere. Fossil raw gas such as coal gasification and natural gas are mostly reducing gases containing trace amounts of oxygen or no oxygen. If activated carbon desulfurizers are used, additional oxygen must be added. The addition of oxygen not only increases the safety risks of industrial production, but if subsequent processes need to be carried out in an oxygen-free atmosphere, the raw gas must also be deoxygenated, which will significantly increase the cost of industrial production. Therefore, it is particularly important to develop an activated carbon desulfurizer that does not need to be used in an oxygen-containing atmosphere. Summary of the Invention
[0004] The purpose of the present invention is to at least partially solve the above technical problems and to provide an activated carbon desulfurizer and a preparation method and application thereof.
[0005] In one aspect of the present invention, an activated carbon desulfurizer is provided, wherein the desulfurizer is obtained by impregnating activated carbon into a nitric acid solution, followed by drying and calcining, and the surface of the activated carbon desulfurizer contains oxygen-containing functional groups and nitrogen-containing species.
[0006] In some embodiments, the oxygen-containing functional group includes at least one of a carboxyl group, an ester group, a quinone group, a ketone group, and a hydroxyl group, or any combination thereof.
[0007] In some embodiments, the nitrogen-containing species includes pyridinic nitrogen and any one of pyridinic nitrogen, pyrrolic nitrogen, and graphene nitrogen, or any combination thereof.
[0008] In some embodiments, the nitrogen-containing species are introduced into the framework structure of the activated carbon by calcination.
[0009] In some embodiments, oxygen-containing functional groups and nitrogen-containing species are introduced to the surface of the activated carbon by impregnating the activated carbon into a nitric acid solution.
[0010] In another aspect of the present invention, a method for preparing an activated carbon desulfurizer is provided. The activated carbon desulfurizer is the above-mentioned activated carbon desulfurizer, and the preparation method comprises the following steps:
[0011] (1) Immerse the granular activated carbon in an appropriate amount of nitric acid solution and let it stand for 2-3 hours;
[0012] (2) Drying the activated carbon after nitric acid impregnation at 30-50°C for 10-12 hours;
[0013] (3) The dried activated carbon is heated to 300-600°C in a N2 or Ar atmosphere, calcined for 2-3 hours at a heating rate of 1-2°C / min and a N2 or Ar flow rate of 100-150 ml / min, and finally an activated carbon desulfurizer is obtained.
[0014] In some embodiments, in step (1), the ratio of activated carbon to nitric acid is 1 g: 1-3 ml, and the concentration of the nitric acid solution is 4-12 mol / L.
[0015] In some embodiments, in step (2), the activated carbon impregnated with nitric acid is placed in an oven for drying.
[0016] In some embodiments, in step (3), the dried activated carbon is placed in a tubular furnace for calcination.
[0017] In another aspect of the present invention, an application of an activated carbon desulfurizer for removing H2S is provided. The activated carbon desulfurizer is the above-mentioned activated carbon desulfurizer, or an activated carbon desulfurizer prepared by the above-mentioned method for preparing the activated carbon desulfurizer. The activated carbon desulfurizer uses its own oxygen-containing functional groups as an oxygen source in an oxygen-free atmosphere, and nitrogen-containing species and oxygen-containing functional groups are simultaneously introduced onto the surface of the activated carbon desulfurizer, wherein the oxygen-containing functional groups provide an oxygen source for the oxidation of H2S; the role of the nitrogen-containing species is to provide alkaline sites and stimulate the oxygen-containing functional groups on the surface of the activated carbon, so that it has the ability to oxidize H2S.
[0018] The activated carbon desulfurizer according to the embodiment of the present invention and its preparation method and application have at least one of the following advantages:
[0019] Activated carbon is impregnated in a nitric acid solution, then dried and calcined under an inert atmosphere to produce an activated carbon desulfurizer. The surface of the activated carbon desulfurizer contains oxygen-containing functional groups such as carboxyl, ester, quinone, ketone, and hydroxyl groups, as well as nitrogen-containing species such as pyridinic, pyrrolic, and graphene nitrogen. The oxygen-containing functional groups provide an oxygen source for H2S oxidation. The nitrogen-containing species serve both to provide alkaline sites, promoting the dissociation of H2S during the desulfurization process, and to stimulate the oxygen-containing functional groups on the activated carbon surface, enabling it to oxidize H2S. The desulfurizer has a maximum sulfur capacity of 300 mg / g.
[0020] The present invention is particularly suitable for removing H2S gas from industrial gases containing trace oxygen or no oxygen, such as coal gas, natural gas, biogas and synthesis gas, and is also suitable for removing H2S in an oxygen-containing atmosphere, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] These and / or other aspects and advantages of the present invention will become apparent and readily understood from the following description of the preferred embodiments taken in conjunction with the accompanying drawings, in which:
[0022] Figure 1 The figure is a schematic flow chart of a method for preparing an activated carbon desulfurizer according to an embodiment of the present invention. DETAILED DESCRIPTION
[0023] The technical solution of the present invention will be further described in detail below through examples and in conjunction with the accompanying drawings. In the specification, the same or similar reference numerals indicate the same or similar components. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the overall inventive concept of the present invention and should not be construed as limiting the present invention.
[0024] The purpose of the present invention is to provide an activated carbon desulfurizer under normal temperature conditions, as well as a preparation method and application thereof, to solve the problem that activated carbon has poor desulfurization activity in an oxygen-free atmosphere under normal temperature conditions.
[0025] The desulfurizer described in the embodiment of the present invention is obtained by impregnating activated carbon into a nitric acid solution, and then undergoing processes such as heating and drying and calcining under an inert atmosphere, wherein the surface of the desulfurizer contains oxygen-containing functional groups such as carboxyl groups, ester groups, quinone groups, ketone groups and hydroxyl groups, as well as nitrogen-containing species such as pyridinic nitrogen, pyrrolic nitrogen and graphene nitrogen.
[0026] See also Figure 1 According to an embodiment of the present invention, the technical implementation scheme of the method for preparing an activated carbon desulfurizer includes the following steps:
[0027] (1) Immerse granular activated carbon in an appropriate amount of nitric acid solution and let it stand for 2-3 hours. The ratio of activated carbon to nitric acid is 1g: 1-3ml, and the concentration of the nitric acid solution is 4-12mol / L.
[0028] (2) drying the activated carbon impregnated with nitric acid at 30-50°C (e.g., in an oven) for 10-12 hours;
[0029] (3) The activated carbon dried in step (2) (for example, placed in a tubular furnace) is heated to 300-600°C in an N2 or Ar atmosphere, and calcined for 2-3 hours at a heating rate of 1-2°C / min and an N2 flow rate of 100-150 ml / min to finally obtain an activated carbon desulfurizer.
[0030] The surface of the activated carbon desulfurizer prepared by the embodiment of the present invention contains oxygen-containing functional groups such as carboxyl, ester, quinone, ketone and hydroxyl groups, as well as nitrogen-containing species such as pyridinic nitrogen, pyrrolic nitrogen and graphene nitrogen. The roasting temperature of step (3) in the preparation process of the present invention must be strictly controlled. The purpose of immersing the activated carbon in nitric acid solution is to introduce oxygen-containing functional groups and nitrogen-containing species to the surface of the activated carbon, and then embed the nitrogen-containing species into the activated carbon skeleton structure by roasting. If the roasting temperature is too low, the nitrogen-containing species cannot be embedded in the skeleton structure of the activated carbon, and the oxygen-containing functional groups on the surface of the activated carbon cannot be stimulated to oxidize H2S. If the roasting temperature is too high, the oxygen-containing functional groups on the surface of the activated carbon will partially decompose, reducing the number of oxygen-containing functional groups on the surface, thereby leading to a decrease in desulfurization performance.
[0031] The desulfurization performance of the activated carbon desulfurizer prepared by the present invention is tested by a dynamic fixed bed. The specific operation is as follows: the prepared desulfurizer is ground and sieved, and the desulfurizer with a particle size of 40-60 mesh is selected and loaded into a U-shaped quartz tube microreactor. The inner diameter of the reactor is 6mm, and the sample filling height is 2cm. Before the experiment begins, the sample is pre-wetted with wet N2 for 2h (N2 is bubbled through the water saturator). The H2S and N2 mixed gas is fully mixed in the gas mixer and bubbled through the water saturator, and then passed into the U-shaped tube reactor. The hydrogen sulfide concentration at the air inlet is 850mg / m 3 The gas flow rate is 100 ml / min, the experimental temperature is 30 ° C, and the experimental pressure is atmospheric pressure. The hydrogen sulfide concentration at the outlet is 0.15 mg / m 3 The experiment was stopped at 9 o'clock and the exhaust gas concentration at different times was recorded.
[0032] The desulfurizer prepared by the present invention is mainly aimed at removing H2S gas from oxygen-free industrial gases such as coal gasification, synthesis gas and natural gas. The adsorption capacity of the desulfurizer for H2S is 150-300 mg / g adsorbent. The desulfurization products of the desulfurizer are mainly elemental sulfur and a small amount of sulfate. In the present invention, both the oxygen-containing functional groups and nitrogen-containing species on the surface of the activated carbon are indispensable, and the nitrogen-containing species must be embedded in the skeleton structure of the activated carbon. The oxygen-containing functional groups such as carboxyl, ester, quinone, ketone and hydroxyl groups on the surface of the desulfurizer provide an oxygen source for the oxidation of H2S. The nitrogen-containing species such as pyridinic nitrogen, pyrrolic nitrogen and graphene nitrogen provide alkaline sites for the dissociation of H2S, promote the dissociation of H2S, and on the other hand, modulate the electronic structure of the activated carbon skeleton, stimulating the above-mentioned surface oxygen-containing functional groups to oxidize H2S to produce elemental sulfur and sulfate.
[0033] One of the key design features of the present invention is that the activated carbon desulfurizer achieves efficient desulfurization in an oxygen-free atmosphere by utilizing its own oxygen-containing functional groups as an oxygen source. This overcomes the drawback of conventional activated carbon desulfurizers, which can only desulfurize in oxygen-containing atmospheres, and significantly broadens the application range of activated carbon desulfurizers. Furthermore, the present invention simultaneously introduces nitrogen and oxygen species onto the activated carbon surface through processes such as nitric acid impregnation and inert atmosphere calcination, avoiding the addition of other nitrogen sources such as urea and dicyandiamide. This simplifies the preparation process and reduces the cost of the desulfurizer.
[0034] Example 1
[0035] 5g of activated carbon particles were immersed in 10ml of 8mol / L nitric acid solution and allowed to stand at room temperature for 2 hours. The activated carbon, oxidized with nitric acid, was transferred to an oven and dried at 30°C for 10 hours. Finally, the dried mixture was calcined in a tube furnace at 350°C in a nitrogen atmosphere for 2 hours at a heating rate of 2°C / min and an nitrogen flow rate of 150mL / min to obtain the desired desulfurizer.
[0036] The desulfurizer prepared by the above method has a H2S concentration of 0.15 mg / m 3 When the sulfur content reaches 200 mg / g, the breakthrough sulfur capacity reaches 200 mg / g desulfurizer.
[0037] Example 2
[0038] 5g of activated carbon particles were immersed in 10ml of 8mol / L nitric acid solution and allowed to stand at room temperature for 2 hours. The activated carbon, oxidized with nitric acid, was transferred to an oven and dried at 30°C for 10 hours. Finally, the dried mixture was calcined in a tube furnace at 500°C in a nitrogen atmosphere for 2 hours at a heating rate of 2°C / min and an nitrogen flow rate of 150mL / min to obtain the desired desulfurizer.
[0039] The desulfurizer prepared by the above method has a H2S concentration of 0.15 mg / m 3 When the sulfur content reaches 240 mg / g, the breakthrough sulfur capacity reaches 240 mg / g desulfurizer.
[0040] Example 3
[0041] 5g of activated carbon particles were immersed in 10ml of nitric acid solution with a concentration of 4mol / L and allowed to stand at room temperature for 2h. The activated carbon, oxidized with nitric acid, was transferred to an oven and dried at 30°C for 10h. Finally, the dried mixture was calcined in a tube furnace at 350°C in a nitrogen atmosphere for 2h at a heating rate of 2°C / min and an nitrogen flow rate of 150mL / min to obtain the desired desulfurizer.
[0042] The desulfurizer prepared by the above method has a H2S concentration of 0.15 mg / m 3 When the sulfur content reaches 150mg / g, the breakthrough sulfur capacity reaches 150mg / g desulfurizer.
[0043] Example 4
[0044] 5g of activated carbon particles were immersed in 10ml of nitric acid solution with a concentration of 12mol / L and allowed to stand at room temperature for 2 hours. The activated carbon, oxidized with nitric acid, was transferred to an oven and dried at 30°C for 10 hours. Finally, the dried mixture was calcined in a tube furnace at 500°C in a nitrogen atmosphere for 2 hours at a heating rate of 2°C / min and an nitrogen flow rate of 150mL / min to obtain the desired desulfurizer.
[0045] The desulfurizer prepared by the above method has a H2S concentration of 0.15 mg / m 3 When the sulfur content reaches 300 mg / g, the breakthrough sulfur capacity reaches 300 mg / g desulfurizer.
[0046] Comparative Example 5
[0047] 5g of activated carbon particles were immersed in 10ml of 8mol / L nitric acid solution and allowed to stand at room temperature for 2h. The activated carbon, oxidized with nitric acid, was transferred to an oven and dried at 30°C for 10h. Finally, the dried mixture was calcined in a tube furnace at 200°C in a nitrogen atmosphere for 2h at a heating rate of 2°C / min and an nitrogen flow rate of 150mL / min to obtain the desired desulfurizer.
[0048] The main difference between this embodiment and the above embodiment is that the calcination temperature is 200°C.
[0049] The desulfurizer prepared by the above method has a H2S concentration of 0.15 mg / m 3 When the sulfur content reaches 20 mg / g, the breakthrough sulfur capacity reaches 20 mg / g desulfurizer.
[0050] Comparative Example 6
[0051] 5g of activated carbon particles were immersed in 10ml of 8mol / L nitric acid solution and allowed to stand at room temperature for 2 hours. The activated carbon, oxidized with nitric acid, was transferred to an oven and dried at 30°C for 10 hours. Finally, the dried mixture was calcined in a tube furnace at 800°C for 2 hours in a nitrogen atmosphere at a heating rate of 2°C / min and an nitrogen flow rate of 150mL / min to obtain the desired desulfurizer.
[0052] The main difference between this embodiment and the above embodiment is that the calcination temperature is 800°C.
[0053] The desulfurizer prepared by the above method has a H2S concentration of 0.15 mg / m 3 When the sulfur content reaches 80 mg / g, the breakthrough sulfur capacity reaches 80 mg / g desulfurizer.
[0054] By comparing Examples 1-4 with Comparative Example 5 in which the calcination temperature is too low or Comparative Example 6 in which the calcination temperature is too high, it can be seen that when the calcination temperature is not appropriately selected, at the same outlet H2S concentration, the breakthrough sulfur capacity will show huge differences, which also indicates that the effect of the desulfurizer is significantly deteriorated.
[0055] The activated carbon desulfurizer according to the embodiment of the present invention and its preparation method and application have at least one of the following advantages:
[0056] Activated carbon is impregnated in a nitric acid solution, then dried and calcined under an inert atmosphere to produce an activated carbon desulfurizer. The surface of the activated carbon desulfurizer contains oxygen-containing functional groups such as carboxyl, ester, quinone, ketone, and hydroxyl groups, as well as nitrogen-containing species such as pyridinic, pyrrolic, and graphene nitrogen. The oxygen-containing functional groups provide an oxygen source for H2S oxidation. The nitrogen-containing species serve both to provide alkaline sites, promoting the dissociation of H2S during the desulfurization process, and to stimulate the oxygen-containing functional groups on the activated carbon surface, enabling it to oxidize H2S. The desulfurizer has a maximum sulfur capacity of 300 mg / g.
[0057] The present invention is particularly suitable for removing H2S gas from industrial gases containing trace oxygen or no oxygen, such as coal gas, natural gas, biogas and synthesis gas, and is also suitable for removing H2S in an oxygen-containing atmosphere, and has a wide range of applications.
[0058] Although some embodiments of the present general inventive concept have been shown and described, it will be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the present general inventive concept, the scope of which is defined in the claims and their equivalents.
Claims
1. A method for preparing an activated carbon desulfurizer, comprising the following steps: (1) Immerse the granular activated carbon in an appropriate amount of nitric acid solution and let it stand for 2-3 hours, wherein the activated carbon: The ratio of nitric acid is 1g:2ml, and the concentration of nitric acid solution is 12mol / L; (2) Drying the activated carbon after nitric acid impregnation at 30-50°C for 10-12 hours; (3) The dried activated carbon was heated to 500°C in an N2 or Ar atmosphere and calcined for 2 h at a heating rate of 2°C / min and an N2 or Ar flow rate of 150 ml / min to obtain an activated carbon desulfurizer. The surface of the activated carbon desulfurizer contains oxygen-containing functional groups; The activated carbon desulfurizer contains nitrogen-containing species in its skeleton structure.
2. The method for preparing an activated carbon desulfurizer according to claim 1, wherein In step (2), the activated carbon impregnated with nitric acid is placed in an oven for drying.
3. The method for preparing an activated carbon desulfurizer according to claim 2, wherein: In step (3), the dried activated carbon is placed in a tubular furnace for calcination.
4. An activated carbon desulfurizer, which is obtained by the preparation method of the activated carbon desulfurizer according to any one of claims 1 to 3, characterized in that: By impregnating the activated carbon into a nitric acid solution which provides the only nitrogen source, oxygen-containing functional groups are introduced onto the surface of the activated carbon. Then, nitrogen-containing species are introduced into the skeleton structure of activated carbon by roasting. The activated carbon desulfurizer realizes desulfurization in an oxygen-free atmosphere.
5. The activated carbon desulfurizer according to claim 4, characterized in that The oxygen-containing functional group includes at least one of a carboxyl group, an ester group, a quinone group, a ketone group and a hydroxyl group, or any combination thereof.
6. The activated carbon desulfurizer according to claim 4, characterized in that The nitrogen-containing species include pyridinic nitrogen.
7. The activated carbon desulfurizer according to claim 6, characterized in that The nitrogen-containing species further includes any one of pyrrolic nitrogen and graphene nitrogen or any combination thereof.
8. An application of an activated carbon desulfurizer for removing H2S, wherein the activated carbon desulfurizer is an activated carbon desulfurizer prepared by the method for preparing an activated carbon desulfurizer according to any one of claims 1 to 3 or an activated carbon desulfurizer according to any one of claims 4 to 7, characterized in that: The surface of the activated carbon desulfurizer contains oxygen-containing functional groups. The skeleton structure of the activated carbon desulfurizer contains nitrogen-containing species. The activated carbon desulfurizer provides an oxygen source for H2S oxidation through its own oxygen-containing functional groups in an oxygen-free atmosphere. The role of nitrogen-containing species is to provide alkaline sites and stimulate the oxygen-containing functional groups on the surface of activated carbon, enabling it to oxidize H2S.