Preparation method and system of hierarchical pore activated coke

Abstract

The present invention discloses a preparation method and system for hierarchically porous activated coke. The preparation method includes: carbonizing raw coal particles under the protection of an inert gas to obtain carbonized materials; cooling the carbonized materials and then impregnating them in a first impregnating solution containing calcium ions, magnesium ions and ammonia nitrogen ions to obtain a second impregnating solution containing the carbonized materials; filtering the second impregnating solution to obtain impregnated materials; subjecting the impregnated materials to steam activation to obtain activated materials; and cooling the activated materials to obtain hierarchically porous activated coke rich in nitrogen functional groups. In the preparation method of the hierarchically porous activated coke of the present invention, raw coal particles are directly used to prepare activated coke. Since the preparation process does not undergo complex processes such as bonding, kneading, and extrusion, the collapse and blockage of pores during the forming process are avoided. Utilizing the pore structure initially formed by the carbonized materials, the intrusion and pore formation of the activating agent are easier. The calcium ions, magnesium ions and ammonia nitrogen ions jointly play a role in catalytic pore expansion to form a hierarchically porous structure, and the adsorption performance is good.

Description

Technical Field

[0001] The present invention relates to the technical field of material preparation, and particularly to a preparation method and system for hierarchically porous activated coke. Background Art

[0002] The existing preparation process for granular columnar activated coke is as follows: different raw coals are mixed, ground into coal powder, a certain proportion of tar and water are added for kneading and granulation, and after drying, it enters a carbonization furnace for carbonization, followed by cooling and screening, and then enters an activation furnace for steam activation to form pores. Finally, after cooling, it is packaged to obtain a cylindrical granular activated coke product (as Figure 1 shown). The granular columnar activated coke prepared by the existing preparation process for granular columnar activated coke has the following defects:

[0003] (1) The cylindrical granular activated coke has a microporous distribution and poor adsorption performance: In the preparation process of the cylindrical granular activated coke, the addition of a binder and compaction molding will reduce the specific surface area and pore volume of the carbonaceous precursor pores, resulting in poor diffusivity and reactivity of the activation medium during the activation process. This leads to the fact that the prepared activated coke generally shows a microporous distribution and a large internal diffusion resistance for pollutants;

[0004] (2) The pores of the cylindrical granular activated coke mainly exist on the surface layer, and the internal pore structure is underdeveloped: The micropores of the cylindrical granular activated coke mainly exist on the surface layer of the particles, and the internal pore structure is underdeveloped, with low utilization rate, resulting in poor adsorption performance of the activated coke. During the adsorption / desorption process of moving bed desulfurization and denitrification, the collision between the activated cokes will cause the physical loss of the coke itself to be as high as 60 - 80%. As the physical wear process progresses, the outer surface with developed pores of the columnar activated coke is consumed, which will greatly reduce the desulfurization and denitrification performance.

[0005] (3) The content of active functional groups is low and the desulfurization and denitrification performance is poor: The conventional activated coke is prepared by the method of direct steam activation, and the content of active functional groups in its pore structure is low. However, during the process of pollutant removal, the active functional groups play a very important catalytic role, resulting in poor desulfurization and denitrification performance of the conventional activated coke.

[0006] (4) The preparation process is complex and the cost is high: 30 - 50% of binder needs to be added during the preparation of columnar coke, and it needs to undergo complex treatment processes such as grinding, strip forming, and compaction. The process flow is long, the equipment is numerous, and the preparation cost is high; in addition, for the conventional modified activated coke loading process, finished coke impregnation and calcination treatment are adopted, with a large consumption of impregnating solution and an additional increase in process flow and equipment, resulting in high modification cost.

[0007] In addition, in the conventional impregnation modification process for finished coke, the impregnating salts are unevenly distributed and easily clog the pores of activated carbon, resulting in a decrease in porosity and adsorption performance after modification. In addition, most of the modified active functional groups are present in the mesopores and macropores and are difficult to enter the micropores, affecting the desulfurization and denitrification performance of the activated coke after modification, and the modification effect is not ideal.

[0008] The pH of the existing desulfurization wastewater is 4 - 6, containing a calcium ion concentration of 500 - 20,000 mg / L, a magnesium ion concentration of 1,000 - 20,000 mg / L, and an ammonia nitrogen ion concentration of 5,000 - 20,000 mg / L. The treatment process for desulfurization wastewater is relatively single, usually using the traditional triple - box treatment process, which is purified through processes such as pH adjustment, metal ion precipitation, and flocculation in sequence. The treatment process is complex and costly. Summary of the Invention

[0009] In view of this, an object of the present invention is to provide a method for preparing hierarchical - pore activated coke to solve or at least partially solve the above - mentioned problems.

[0010] Another object of the present invention is to provide a preparation system for hierarchical - pore activated coke.

[0011] To achieve the above object, the first - aspect embodiment of the present invention proposes a method for preparing hierarchical - pore activated coke, including carbonizing raw coal particles under the protection of inert gas to obtain carbonized material;

[0012] After cooling the carbonized material, impregnating it in a first impregnating solution containing calcium ions, magnesium ions, and ammonia nitrogen ions to obtain a second impregnating solution containing the carbonized material;

[0013] Filtering the second impregnating solution to obtain impregnated material;

[0014] Performing steam activation on the impregnated material to obtain activated material;

[0015] Cooling the activated material to obtain hierarchical - pore activated coke rich in nitrogen functional groups.

[0016] In some embodiments of the present invention, the pH of the first impregnating solution is 4 - 6, the concentration of calcium ions is 500 - 20,000 mg / L, the concentration of magnesium ions is 1,000 - 20,000 mg / L, and the concentration of ammonia nitrogen ions is 5,000 - 20,000 mg / L.

[0017] In some embodiments of the present invention, the first impregnating solution further includes sodium ions and potassium ions; the first impregnating solution is desulfurization wastewater.

[0018] In some embodiments of the present invention, the method for preparing hierarchical - pore activated coke further includes: after filtering the second impregnating solution, sending the filtrate to the desulfurization system.

[0019] In some embodiments of the present invention, the volume ratio of the first impregnating solution to the carbonized material is 2-10:1, and the impregnation time is 0.5-3 h.

[0020] In some embodiments of the present invention, the carbonization temperature is 400-600 °C, and the carbonization time is 2-5 h; the inert gas is at least one of nitrogen, argon, and helium.

[0021] In some embodiments of the present invention, the temperature of steam activation is 700-900 °C, and the time of steam activation is 4-10 h.

[0022] To achieve the above object, an embodiment of the second aspect of the present invention provides a preparation system for hierarchical pore activated coke, including

[0023] A carbonization furnace, which is provided with a raw coal particle inlet, an inert gas inlet, and a first outlet;

[0024] An impregnation tank, which is provided with a carbonized material inlet, an impregnation solution inlet, and a second outlet, and the carbonized material inlet is communicated with the first outlet;

[0025] A filtration unit, which is provided with an impregnating solution inlet, a filtrate outlet, and an impregnated material outlet, and the impregnating solution inlet is communicated with the second outlet;

[0026] An activation furnace, which is provided with an impregnated material inlet, an activation gas inlet, and an activated material outlet, and the impregnated material inlet is communicated with the impregnated material outlet.

[0027] In some embodiments of the present invention, the filtration unit is a vacuum belt filter.

[0028] In some embodiments of the present invention, the filtrate outlet is communicated with the desulfurization tower slurry pool.

[0029] The beneficial effects of the preparation method of the hierarchical pore activated coke are as follows:

[0030] (1) The hierarchical pore distribution of activated coke and good adsorption performance: The activated coke is directly prepared from raw coal particles. Since the preparation process does not go through complex processes such as bonding, kneading, and extrusion, the collapse and blockage of pores during the forming process are avoided. Using the pore structure initially formed by the carbonized material, the intrusion and pore formation of the activator are easier. Calcium ions, magnesium ions, and ammonia nitrogen ions jointly play a role in catalytic pore expansion, forming a hierarchical pore structure with good adsorption performance.

[0031] (2) The activated coke has a good internal and external uniformity in pore structure: The raw coal is carbonized to first form a certain pore structure, and then impregnated. Calcium ions, magnesium ions, and ammonia nitrogen ions are adsorbed in large amounts in the pore structure during the carbonization process. During activation, through continuous catalytic pore expansion inside the material, the original micropores and mesopores continuously develop and expand, and a dendritic hierarchical pore structure is formed both inside and outside the material, with good uniformity.

[0032] (3) High content of active functional groups and good desulfurization and denitrification performance: The ammonia nitrogen ions in the first impregnating solution are first adsorbed in the pore structure of the carbonized material. During the activation process, a large number of nitrogen-containing active functional groups are generated on the pore surface. The nitrogen-containing active functional groups can significantly improve the sulfur capacity of activated coke for desulfurization and the catalytic denitrification efficiency.

[0033] (4) Simple preparation process, realizing the regulation of pore structure and functional groups in one step: Calcium ions, magnesium ions, and ammonia nitrogen ions in the first impregnating solution are jointly adsorbed onto the surface of the carbonized material, coupling and developing the processes of catalytically expanding the hierarchical pore structure and promoting the formation of nitrogen-containing functional groups in one step. The preparation process is simple, reliable, and efficient.

[0034] (5) Coordinately treating desulfurization wastewater and realizing the resource utilization of desulfurization wastewater: When desulfurization wastewater is used as the first impregnating solution, the raw coal particles after carbonization treatment have initially formed a pore structure. After mixing and impregnating with desulfurization wastewater, they can effectively adsorb metal ions and ammonia nitrogen ions in the desulfurization wastewater. It can not only be used as the precursor solution for modified activated coke but also play a role in purifying desulfurization wastewater, realizing the resource utilization of desulfurization wastewater.

[0035] The beneficial effects of the preparation system of the hierarchical pore activated coke in the embodiments of the present invention are basically the same as those of the preparation method of the hierarchical pore activated coke in the embodiments of the present invention, and will not be elaborated here.

[0036] The additional aspects and advantages of the present invention will be partially given in the following description, partially will become obvious from the following description, or will be understood through the practice of the present invention. Description of the Drawings

[0037] The above-mentioned and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the following description of the embodiments in conjunction with the drawings.

[0038] Among them:

[0039] Figure 1 is the process flow chart of the preparation of the existing granular columnar activated coke.

[0040] Figure 2 is the (i.e., the simple structural schematic diagram of the preparation system of the hierarchical pore activated coke) of the preparation process of the hierarchical pore activated coke according to an embodiment of the present invention.

[0041] Figure 3Performance comparison diagram of the activated coke of Example 3 and the activated coke of Comparative Example 1 for desulfurization.

[0042] Figure 4 Performance comparison diagram of the activated coke of Example 3 and the activated coke of Comparative Example 1 for denitrification.

[0043] Figure 5 Adsorption isotherm diagram of the activated coke of Example 3.

[0044] Figure 6 Pore size distribution diagram of the activated coke of Example 3.

[0045] Figure 7 Adsorption isotherm diagram of the activated coke of Comparative Example 1.

[0046] Figure 8 Pore size distribution diagram of the activated coke of Comparative Example 1.

[0047] Reference signs:

[0048] 1 - Carbonization furnace; 2 - Impregnation tank; 3 - Activation furnace; 4 - Raw coal particles; 5 - Inert gas; 6 - Impregnation solution; 7 - Filtration unit; 8 - Activation gas; 9 - Hierarchical pore activated coke; 10 - Desulfurization tower slurry tank. Detailed implementation manners

[0049] The embodiments of the present invention will be described in detail below. The examples are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, and should not be construed as a limitation to the present invention.

[0050] The preparation process of the hierarchical pore activated coke and the preparation system of the hierarchical pore activated coke according to the embodiments of the present invention will be described below with reference to the accompanying drawings.

[0051] As Figure 1 shown, the preparation system of the hierarchical pore activated coke according to the embodiments of the present invention includes a carbonization furnace 1, an impregnation tank 2, a filtration unit 7, and an activation furnace 3. The carbonization furnace 1 is provided with a raw coal particle inlet, an inert gas inlet, and a first outlet; the impregnation tank 2 is provided with a carbonized material inlet, an impregnation solution inlet, and a second outlet, and the carbonized material inlet is communicated with the first outlet; the filtration unit 7 is provided with an impregnation solution inlet, a filtrate outlet, and an impregnated material outlet, and the impregnation solution inlet is communicated with the second outlet; the activation furnace 3 is provided with an impregnated material inlet, an activation gas inlet, and an activated material outlet, and the impregnated material inlet is communicated with the impregnated material outlet.

[0052] Optionally, the filtration unit 7 is a vacuum belt filter.

[0053] Optionally, the filtrate outlet is communicated with the desulfurization tower slurry tank 10.

[0054] It should be noted that in the preparation system of the hierarchical pore activated coke in the invention embodiment, the connection modes of the carbonized material inlet and the first outlet, and the impregnating solution inlet and the second outlet are both connected by pipelines. The connection mode of the impregnating material inlet and the impregnating material outlet can adopt a transfer vehicle, etc. In addition, the carbonization furnace, the impregnation tank, the activation furnace, and the vacuum belt conveyor are all existing equipment and do not belong to the content of the present invention. In some embodiments of the present invention, the impregnation tank can also be replaced by other devices that can realize the impregnation function of the carbonized material, such as an impregnation tank, etc.

[0055] Taking the introduction of desulfurized wastewater through the impregnating solution inlet as an example, when the preparation system of the hierarchical pore activated coke in the invention embodiment is in use, the raw coal particles 4 enter the carbonization furnace 1 from the raw coal particle inlet, and the inert gas 5 such as nitrogen enters the carbonization furnace 1 from the inert gas inlet. The raw coal particles are carbonized in the carbonization furnace 1 under the protection of the inert gas such as nitrogen to obtain carbonized material. Subsequently, the carbonized material flows out through the first outlet and then enters the impregnation tank 2 through the carbonized material inlet, and is impregnated in the impregnation tank 2 with the impregnating solution 6 from the impregnating solution inlet. After that, the impregnating solution containing the carbonized material in the impregnation tank 2 is filtered by the filtration unit 7, the filtrate enters the desulfurization tower slurry pool 10, and the filter residue (i.e., the impregnating material) enters the activation furnace 3 through the impregnating material inlet and is activated under the action of the activation gas 8 entering through the activation gas outlet. After that, it flows out through the activated material outlet and is cooled to obtain the hierarchical pore activated coke 9.

[0056] The preparation method of the hierarchical pore activated coke in the invention embodiment includes the following steps:

[0057] (1) Carbonize the raw coal particles under the protection of inert gas to obtain carbonized material;

[0058] (2) Cool the carbonized material obtained in step (1) and then impregnate it in the first impregnating solution containing calcium ions, magnesium ions and ammonia nitrogen ions to obtain the second impregnating solution containing the carbonized material;

[0059] (3) Filter the second impregnating solution in step (2) to obtain the impregnating material;

[0060] (4) Perform steam activation on the impregnating material in step (3) to obtain the activated material;

[0061] (5) Cool the activated material in step (4) to obtain the hierarchical pore activated coke rich in nitrogen functional groups.

[0062] The technical principle of the preparation method of the hierarchical pore activated coke in the invention embodiment is as follows:

[0063] The raw coal particles form a preliminary pore structure after carbonization, and then are impregnated and adsorbed with a first impregnating solution containing calcium ions, magnesium ions and ammonium ions. The calcium ions, magnesium ions and ammonium ions in the first impregnating solution can penetrate into the internal structure of the carbonized material. During the activation process, the calcium ions, magnesium ions and ammonium ions play roles both inside and outside the material. Among them, the calcium ions and magnesium ions act as catalysts to activate the reaction between water molecules and carbon atoms, accelerating the further expansion of the pore structure, while the role of ammonium ions is to produce NH3 to react with the coal structure to form C-N bonds. The reaction formulas are as follows:

[0064] C + H2O → CO + H2

[0065] NH3 + C → CH4 + N2

[0066] NH3 + C → HCN + H2

[0067] At the same time, the calcium ions, magnesium ions and ammonium ions couple and act together, organically combining the processes of catalyzing the expansion of the pore structure and forming active functional groups on the surface of the pore structure, promoting each other, and finally forming a hierarchical pore activated coke rich in nitrogen-containing functional groups.

[0068] It should be noted that for the preparation method of the hierarchical pore activated coke in the embodiment of the present invention, if the raw coal particles are not carbonized but directly impregnated in the first impregnating solution and then steam-activated, it is very difficult to form the hierarchical pore structure of the hierarchical pore activated coke prepared by the preparation method of the embodiment of the present invention. The reason is that: in the embodiment of the present invention, during the carbonization process of the raw coal particles, the internal moisture and volatile components decompose to expand the macropores, and the organic compounds in the coal thermally decompose and thermally condense, releasing a large amount of small molecule gases to expand the mesopores and micropores. The coal particles gradually form a structural framework with large, medium and small pores from the inside to the outside, and already have strong adsorption performance. Then, when impregnated, the modified ions calcium ions, magnesium ions and ammonium ions in the first impregnating solution can be deeply enriched in the large, medium and small pores, and finally a dendritic hierarchical pore structure can be formed during activation. Without the carbonization process, the raw coal particles cannot form a structural framework with large, medium and small pores with strong adsorption performance, and naturally cannot make the modified ions calcium ions, magnesium ions and ammonium ions in the first impregnating solution deeply enriched in the large, medium and small pores during impregnation, and activate to form the dendritic hierarchical pore structure of the activated coke in the embodiment of the present invention.

[0069] In addition, it should also be noted that for the preparation method of the hierarchical pore activated coke in the embodiment of the present invention, if the first impregnating solution contains calcium ions and magnesium ions but no ammonium ions, it is also impossible to form the hierarchical pore structure of the activated coke prepared by the preparation method of the embodiment of the present invention, and the desulfurization and denitrification effects of the prepared activated coke are not ideal. The reason is that nitrogen-containing functional groups cannot be formed.

[0070] Optionally, the pH of the first impregnating solution is 4 - 6, the concentration of calcium ions is 500 - 20,000 mg / L, the concentration of magnesium ions is 1,000 - 20,000 mg / L, and the concentration of ammonia nitrogen ions is 5,000 - 20,000 mg / L. Preferably, the first impregnating solution is preferably an aqueous solution containing calcium ions, magnesium ions and ammonia nitrogen ions. More preferably, the first impregnating solution further includes sodium ions and potassium ions, wherein the concentration of sodium ions is 500 - 10,000 mg / L and the concentration of potassium ions is 500 - 10,000 mg / L. In order to simultaneously treat the desulfurized wastewater, the first impregnating solution can directly use the desulfurized wastewater meeting the above requirements, such as the desulfurized wastewater obtained by filtering the vacuum belt filter of the limestone wet desulfurization system in a coal-fired power plant. In addition to the above calcium ions, magnesium ions and ammonia nitrogen ions, the cations also include: Na + (500 - 10,000 mg / L), K + (500 - 10,000 mg / L), and the anions include Cl - (5,000 - 30,000 mg / L), SO4 2- (500 - 30,000 mg / L). The above cations in the desulfurized wastewater are all beneficial to the formation and expansion of pores during the preparation of activated coke, while the anions have no effect on the pore structure of activated coke. At this time, after the second impregnating solution is filtered, the filtrate is sent to the desulfurization system.

[0071] Optionally, the volume ratio of the first impregnating solution to the carbonized material is 2 - 10:1, and the impregnation time is 0.5 - 3 h.

[0072] Optionally, the carbonization temperature is 400 - 600 °C, and the carbonization time is 2 - 5 h; the inert gas is at least one of nitrogen, argon, and helium, preferably nitrogen.

[0073] Optionally, the temperature of steam activation is 700 - 900 °C, and the time of steam activation is 4 - 10 h.

[0074] Optionally, the particle size of the raw coal particles is between 3 - 15 mm.

[0075] The preparation process of the hierarchical pore activated coke according to the embodiments of the present invention can be carried out with the aid of the preparation system of the hierarchical pore activated coke according to the embodiments of the present invention. When the first impregnating solution (i.e., the impregnating solution entering the impregnating tank of the preparation system of the hierarchical pore activated coke according to the embodiments of the present invention) is desulfurized wastewater, the preparation process of the hierarchical pore activated coke according to the embodiments of the present invention includes: screening raw coal particles of a certain particle size, first entering a carbonization furnace for oxygen-free carbonization under the protection of inert gases such as nitrogen to initially form a pore structure. After the carbonized material is cooled, it is added to an impregnating tank, and calcium ions, magnesium ions, and ammonia nitrogen ions in the first impregnating solution of desulfurized wastewater are fully adsorbed by the pore structure already formed in the carbonized material. After impregnation for a certain time, it is filtered, added to an activation furnace for steam activation, and finally, after cooling, an activated coke with a hierarchical pore structure rich in nitrogen-containing functional groups is obtained.

[0076] The preparation process of the hierarchical pore activated coke according to the embodiments of the present invention will be described below in conjunction with specific examples and comparative examples.

[0077] It should be noted that the raw materials involved in the following examples and comparative examples, unless otherwise specified, are all raw materials that can be obtained through commercial channels; the methods involved in the following examples and comparative examples, unless otherwise specified, are all conventional methods.

[0078] The desulfurization and denitrification performance experiments of the activated coke were all carried out on a fixed-bed simulated flue gas test bench. After the activated coke was broken, 20 - 40 μm was screened out, and after weighing a certain mass, it was filled into a quartz reactor. The fixed-bed temperature was set at 120 °C, and the desulfurization and denitrification experiments were carried out separately.

[0079] The simulated flue gas composition during the desulfurization process was: 6% (volume percentage) oxygen, 2600 mg / m 3 SO2, the water vapor content was 3% (volume percentage), and the rest was N2; the desulfurization sulfur capacity was the mass of SO2 absorbed by unit mass of activated coke, which was obtained by measuring the sulfur content in the sample before and after 2 hours of desulfurization. The desulfurization sulfur capacity calculation formula was:

[0080] Desulfurization sulfur capacity = (S content in the sample after desulfurization - S content in the sample before desulfurization) / 32 * 64 / mass of the sample before desulfurization.

[0081] The simulated flue gas composition during the denitrification process was: 6% (volume percentage) oxygen, 350 mg / m 3 NO, 350 mg / m 3 NH3, and the rest was N2; the denitrification efficiency calculation formula after 2 hours was:

[0082] Denitrification efficiency after 2 hours = (inlet NO concentration - outlet NO concentration) / inlet NO concentration * 100%.

[0083] Example 1

[0084] Screen 3 - 15 mm raw coal particles and add them into the carbonization furnace. Set the carbonization temperature at 400 °C and the carbonization time at 5 h. After water cooling, screen and remove the crushed materials, and add them to the desulfurized wastewater (the pH of the desulfurized wastewater is 4, the concentration of calcium ions in the desulfurized wastewater is 500 mg / L, the concentration of magnesium ions is 1569 mg / L, the concentration of ammonia nitrogen ions is 5020 mg / L, the concentration of sodium ions is 580 mg / L, and the concentration of potassium ions is 678 mg / L) for impregnation treatment. The desulfurized wastewater comes from the filtered water of the vacuum belt filter in the limestone wet desulfurization system of a coal-fired power plant. The impregnation volume ratio of the desulfurized wastewater to the activated coke carbonized material is 5:1. After 1 h of impregnation time, filter the water through a vacuum belt filter. The filtrate is directly sent to the slurry pool of the desulfurization tower for further desulfurization. The impregnated material enters the activation furnace for activation treatment. The activation temperature is 900 °C and the activation time is 4 h. After water cooling, further screen to obtain the finished product of hierarchical pore activated coke.

[0085] After testing, the specific surface area of the activated coke prepared in this example is 535 m 2 / g, the proportion of the specific surface area of medium and large pores is 62.6%, the proportion of the pore volume of medium and large pores is 74.1%, and the nitrogen content of the activated coke is 2.3%; the desulfurization sulfur capacity in 2 h is 35 mg / g, and the denitrification efficiency after 2 h is 62%.

[0086] Example 2

[0087] This example is basically the same as Example 1, except that: the carbonization temperature is 500 °C, the carbonization time is 2 h, the impregnation volume ratio of the desulfurized wastewater to the activated coke carbonized material is 4:1, the impregnation time is 2 h, the activation temperature is 800 °C, and the activation time is 5 h; the pH of the desulfurized wastewater is 5, the concentration of calcium ions in the desulfurized wastewater is 20000 mg / L, the concentration of magnesium ions is 10955 mg / L, the concentration of ammonia nitrogen ions is 5000 mg / L, the concentration of sodium ions is 5069 mg / L, and the concentration of potassium ions is 5698 mg / L.

[0088] After testing, the specific surface area of the activated coke prepared in this example is 491 m 2 / g, the proportion of the specific surface area of medium and large pores is 65%, the proportion of the pore volume of medium and large pores is 73.2%, and the nitrogen content of the activated coke is 2.2%; the desulfurization sulfur capacity in 2 h is 33 mg / g, and the denitrification efficiency after 2 h is 65%.

[0089] Example 3

[0090] This example is basically the same as Example 1, except that: the carbonization temperature is 600 °C, the carbonization time is 3 h, the impregnation volume ratio of desulfurized wastewater to activated coke carbonized material is 2:1, the impregnation time is 0.5 h, the activation temperature is 700 °C, and the activation time is 6 h; the pH of the desulfurized wastewater is 6, the concentration of calcium ions in the desulfurized wastewater is 18590 mg / L, the concentration of magnesium ions is 20000 mg / L, the concentration of ammonia nitrogen ions is 13496 mg / L, the concentration of sodium ions is 3860 mg / L, and the concentration of potassium ions is 781 mg / L.

[0091] After testing, the specific surface area of the activated coke prepared in this example is 455.1 m 2 / g, the proportion of the specific surface area of medium and large pores is 57.6%, the proportion of the pore volume of medium and large pores is 80.1%, the nitrogen content of the activated coke is 1.9%; the desulfurization sulfur capacity in 2 h is 30.8 mg / g, and the denitrification efficiency after 2 h is 67%.

[0092] Example 4

[0093] This example is basically the same as Example 1, except that: the carbonization temperature is 450 °C, the carbonization time is 4 h, the impregnation volume ratio of desulfurized wastewater to activated coke carbonized material is 10:1, the impregnation time is 3 h, the activation temperature is 850 °C, and the activation time is 10 h; the pH of the desulfurized wastewater is 4.5, the concentration of calcium ions in the desulfurized wastewater is 20000 mg / L, the concentration of magnesium ions is 17432 mg / L, the concentration of ammonia nitrogen ions is 19885 mg / L, the concentration of sodium ions is 2532 mg / L, and the concentration of potassium ions is 5025 mg / L.

[0094] After testing, the specific surface area of the activated coke prepared in this example is 472 m 2 / g, the proportion of the specific surface area of medium and large pores is 58.7%, the proportion of the pore volume of medium and large pores is 78%, the nitrogen content of the activated coke is 2.8%; the desulfurization sulfur capacity in 2 h is 40.1 mg / g, and the denitrification efficiency after 2 h is 70%.

[0095] Example 5

[0096] This example is basically the same as Example 1, except that: the carbonization temperature is 500 °C, the carbonization time is 4 h, the impregnation volume ratio of desulfurized wastewater to activated coke carbonized material is 3:1, the impregnation time is 2 h, the activation temperature is 750 °C, and the activation time is 8 h; the pH of the desulfurized wastewater is 5.5, the concentration of calcium ions in the desulfurized wastewater is 15851 mg / L, the concentration of magnesium ions is 1067 mg / L, the concentration of ammonia nitrogen ions is 8914 mg / L, the concentration of sodium ions is 9970 mg / L, and the concentration of potassium ions is 7580 mg / L.

[0097] After testing, the specific surface area of the activated coke prepared in this example is 504 m 2 / g, the specific surface area of medium and large pores accounts for 70.3%, the pore volume of medium and large pores accounts for 76.4%, the nitrogen content of activated coke is 2.4%; the desulfurization sulfur capacity after 2 h is 36 mg / g, and the denitrification efficiency after 2 h is 69%.

[0098] Example 6

[0099] This example is basically the same as Example 1, except that: the carbonization temperature is 550 °C, the activation temperature is 800 °C, and the activation time is 6 h; the pH of the desulfurized wastewater is 5, and the concentrations of calcium ions, magnesium ions, ammonia nitrogen ions, sodium ions, and potassium ions in the desulfurized wastewater are 3871 mg / L, 12070 mg / L, 18861 mg / L, 4451 mg / L, and 1071 mg / L, respectively.

[0100] After testing, the specific surface area of the activated coke prepared in this example is 560 m 2 / g, the specific surface area of medium and large pores accounts for 69.9%, the pore volume of medium and large pores accounts for 67.2%, the nitrogen content of activated coke is 2.5%; the desulfurization sulfur capacity after 2 h is 32 mg / g, and the denitrification efficiency after 2 h is 60%.

[0101] Example 7

[0102] This example is basically the same as Example 1, except that: the carbonization temperature is 600 °C, the carbonization time is 3 h, the impregnation volume ratio of desulfurized wastewater to activated coke carbonized material is 8:1, the impregnation time is 1.5 h, and the activation temperature is 750 °C; the pH of the desulfurized wastewater is 5, and the concentrations of calcium ions, magnesium ions, ammonia nitrogen ions, sodium ions, and potassium ions in the desulfurized wastewater are 10360 mg / L, 19477 mg / L, 20316 mg / L, 5071 mg / L, and 5000 mg / L, respectively.

[0103] After testing, the specific surface area of the activated coke prepared in this example is 583 m 2 / g, the specific surface area of medium and large pores accounts for 67.4%, the pore volume of medium and large pores accounts for 76.3%, the nitrogen content of activated coke is 3.2%; the desulfurization sulfur capacity after 2 h is 43.2 mg / g, and the denitrification efficiency after 2 h is 72%.

[0104] Example 8

[0105] This example is basically the same as Example 1, except that: the carbonization temperature is 600 °C, the carbonization time is 4 h, the impregnation volume ratio of desulfurized wastewater to activated coke carbonized material is 6:1, the impregnation time is 3 h, the activation temperature is 700 °C, and the activation time is 5 h; the impregnation uses an aqueous solution containing only calcium ions, magnesium ions and ammonia nitrogen ions, the pH of this aqueous solution is 4, the concentration of calcium ions in the aqueous solution is 800 mg / L, the concentration of magnesium ions is 10000 mg / L, and the concentration of ammonia nitrogen ions is 16000 mg / L.

[0106] After testing, the specific surface area of the activated coke prepared in this example is 540 m 2 / g, the proportion of the specific surface area of medium and large pores is 72.1%, the proportion of the pore volume of medium and large pores is 78.1%, and the nitrogen content of the activated coke is 2.7%; the desulfurization sulfur capacity after 2 h is 39.8 mg / g, and the denitrification efficiency after 2 h is 69.8%.

[0107] Example 9

[0108] The method for preparing activated coke in this example is basically the same as that in Example 3, except that: the impregnation uses a deionized aqueous solution containing only calcium ions, magnesium ions and ammonia nitrogen ions, the pH of this deionized aqueous solution is 6, and the concentration of calcium ions therein is 20000 mg / L, the concentration of magnesium ions is 20000 mg / L, and the concentration of ammonia nitrogen ions is 20000 mg / L.

[0109] After testing, the specific surface area of the activated coke prepared in this comparative example is 452.3 m 2 / g, the proportion of the specific surface area of medium and large pores is 58.9%, the proportion of the pore volume of medium and large pores is 82.3%, and the nitrogen content of the activated coke is 0%; the desulfurization sulfur capacity after 2 h is 32.4 mg / g, and the denitrification efficiency after 2 h is 68%.

[0110] Comparative Example 1

[0111] The method for preparing activated coke in this comparative example is basically the same as that in Example 3, except that: after carbonizing the raw coal particles, they are directly activated without impregnation treatment with desulfurized wastewater.

[0112] After testing, the specific surface area of the activated coke prepared in this comparative example is 345.9 m 2 / g, the proportion of the specific surface area of medium and large pores is 13.8%, the proportion of the pore volume of medium and large pores is 37.3%, and the nitrogen content of the activated coke is 0%; the desulfurization sulfur capacity after 2 h is 21.4 mg / g, and the denitrification efficiency after 2 h is 20%.

[0113] Comparative Example 2

[0114] The preparation method of activated coke in this comparative example is basically the same as that in Example 3, except that: the impregnation uses deionized aqueous solution containing only sodium ions, potassium ions and ammonia nitrogen ions, the pH of the deionized aqueous solution is 6, the concentration of sodium ions is 4000 mg / L, the concentration of potassium ions is 700 mg / L, and the concentration of ammonia nitrogen ions is 5000 mg / L.

[0115] After testing, the specific surface area of the activated coke prepared in this comparative example is 231 m 2 / g, the proportion of the specific surface area of medium and large pores is 21%, the proportion of the pore volume of medium and large pores is 19%, the nitrogen content of the activated coke is 0.5%; the desulfurization sulfur capacity in 2 h is 15.9 mg / g, and the denitrification efficiency after 2 h is 29.7%.

[0116] Comparative Example 3

[0117] The preparation method of activated coke in this comparative example is basically the same as that in Example 3, except that: the impregnation uses deionized aqueous solution containing only sodium ions and potassium ions, and the pH of the deionized aqueous solution is 6.

[0118] After testing, the specific surface area of the activated coke prepared in this comparative example is 231 m 2 / g, the proportion of the specific surface area of medium and large pores is 21%, the proportion of the pore volume of medium and large pores is 19%, the nitrogen content of the activated coke is 0%; the desulfurization sulfur capacity in 2 h is 15.9 mg / g, and the denitrification efficiency after 2 h is 16.7%.

[0119] The main process parameters of the preparation methods of activated coke in Examples 1-9 and Comparative Examples 1-3 and the performance test results of the prepared activated coke are shown in Table 1.

[0120] Table 1 The main process parameters of the preparation methods of activated coke in Examples 1-9 and Comparative Examples 1-3 and the performance test results of the prepared activated coke

[0121]

[0122] Note: In the table, Examples are represented by "S" and Comparative Examples are represented by "D".

[0123] It can be seen from Table 1 that the activated coke prepared by the preparation method of the hierarchical pore activated coke in the examples of the present invention has a pore structure with hierarchical pore distribution, and its desulfurization and denitrification performance are significantly improved compared with the activated coke in Comparative Example 1 where the carbonized material is not impregnated with a solution containing calcium ions, magnesium ions and ammonia nitrogen ions. The activated coke prepared by impregnating the carbonized material with deionized aqueous solution containing only sodium ions, magnesium ions and ammonia nitrogen ions (Comparative Example 2) has a much lower specific surface area, proportion of medium and large pore volume and desulfurization and denitrification performance, but is slightly better than the performance of the activated coke prepared by impregnating the carbonized material with deionized aqueous solution containing only sodium ions and magnesium ions (Comparative Example 3).

[0124] In addition, the activated coke prepared by the preparation method of the hierarchical pore activated coke in Example 3 of the present invention (hereinafter referred to as the activated coke of Example 3) and the activated coke obtained by the preparation method of Comparative Example 1 (hereinafter referred to as the activated coke of Comparative Example 1) are compared in terms of desulfurization performance, denitrification performance, adsorption isotherm and pore size distribution, and specific surface area. Among them:

[0125] Figure 3 It is a comparison chart of the desulfurization performance of the activated coke of Example 3 and the activated coke of Comparative Example 1. From Figure 3 it can be seen that the desulfurization performance of the activated coke of Example 3 is significantly improved. The desulfurization sulfur capacity at 2 h is 30.8 mg / g, while the desulfurization sulfur capacity of the activated coke of Comparative Example 1 at 2 h is only 21.4 mg / g. Compared with Comparative Example 1, the desulfurization sulfur capacity of the activated coke of Example 3 at 2 h is increased by 40.2%.

[0126] Figure 4 It is a comparison chart of the denitrification performance of the activated coke of Example 3 and the activated coke of Comparative Example 1. From Figure 4 it can be seen that the denitrification performance of the activated coke of Example 3 is significantly enhanced. The denitrification efficiency after 2 h is still 67%, while the denitrification efficiency of the activated coke of Comparative Example 1 after 2 h is only 20%.

[0127] Figure 5 It is the adsorption isotherm diagram of the activated coke of Example 3, Figure 6 It is the pore size distribution diagram of the activated coke of Example 3, Figure 7 It is the adsorption isotherm diagram of the activated coke of Comparative Example 1, Figure 8 It is the pore size distribution diagram of the activated coke of Comparative Example 1. From Figures 5 - 8 it can be seen that in addition to the developed micropores on the surface of the activated coke of Example 3, there are also a large number of medium and large pores, and there is an obvious hierarchical pore structure, while the pore size structure on the surface of the activated coke of Comparative Example 1 is mainly micropores.

[0128] Table 2 shows the specific surface area analysis results of the activated coke of Example 3 and the activated coke of Comparative Example 1. It can be seen from Table 2 that the specific surface area of the activated coke of Example 3 is significantly increased. The proportion of the specific surface area of micropores is 42.4%, the proportion of the specific surface area of medium and large pores is 57.6%, the proportion of the pore volume of medium and large pores is 80.1%, and the average pore diameter is 4.023 nm. While the specific surface area of the activated coke of Comparative Example 1 is small, the proportion of the specific surface area of micropores is as high as 86.2%, the proportion of the specific surface area of medium and large pores is only 13.8%, the proportion of the pore volume of medium and large pores is 37.3%, and the average pore diameter is 2.916 nm.

[0129] Table 2 Specific surface area analysis results of the activated coke of Example 3 and the activated coke of Comparative Example 1

[0130]

[0131] Note: SBET is the total specific surface area, S mic is the micropore specific surface area, V t is the total pore volume, V mic is the micropore volume, V meso-macro is the mesopore and macropore volume, D is the average pore diameter.

[0132] In summary, for the preparation method of the hierarchical pore activated coke according to the embodiments of the present invention, raw coal particles are directly carbonized to form a certain pore structure during the carbonization process; the carbonized material is impregnated with a first impregnating solution containing calcium ions, magnesium ions and ammonia nitrogen ions, so that the carbonized material fully adsorbs calcium ions, magnesium ions and ammonia nitrogen ions in the wastewater; during the steam activation process, calcium ions, magnesium ions and ammonia nitrogen ions jointly play a role in catalytic pore expansion, and the activated coke gradually forms a pore structure with a hierarchical pore distribution, and nitrogen-containing functional groups are rich in both micropores and mesopores, and the desulfurization and denitrification performance is significantly improved.

[0133] In the present invention, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0134] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A preparation method of hierarchical pore activated coke, characterized in that including Carbonizing raw coal particles under the protection of an inert gas to obtain carbonized material; After cooling the carbonized material, adding it to a first impregnating solution containing calcium ions, magnesium ions, and ammonia nitrogen ions for impregnation to obtain a second impregnating solution containing the carbonized material; Filtering the second impregnating solution to obtain impregnated material; Performing steam activation on the impregnated material to obtain activated material; Cooling the activated material to obtain hierarchical pore activated coke rich in nitrogen functional groups; The pH of the first impregnating solution is 4 - 6, the concentration of calcium ions is 500 - 20000 mg / L, the concentration of magnesium ions is 1000 - 20000 mg / L, and the concentration of ammonia nitrogen ions is 5000 - 20000 mg / L; The hierarchical pore activated coke has micropores, hollows, and macropores, and all of the micropores, hollows, and macropores are rich in nitrogen-containing functional groups; The volume ratio of the first impregnating solution to the carbonized material is 2 - 10:1, and the impregnation time is 0.5 - 3 h; The carbonization temperature is 400 - 600 °C, and the carbonization time is 2 - 5 h; the inert gas is at least one of nitrogen, argon, and helium; The temperature of the steam activation is 700 - 900 °C, and the time of the steam activation is 4 - 10 h.

2. The preparation method according to claim 1, wherein The first impregnating solution further includes sodium ions and potassium ions; the first impregnating solution is desulfurized wastewater.

3. The preparation method according to claim 2, characterized in that, It further includes: After filtering the second impregnating solution, the filtrate is sent to the desulfurization system.

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