Activated carbon based on pre-oxidation-Fe catalytic combined process and preparation method and application thereof

Abstract

The present application relates to the technical field of activated carbon preparation, and particularly relates to activated carbon based on a pre-oxidation-Fe catalytic combined process and a preparation method and application thereof, the preparation method comprising the following steps: mixing anthracite powder, coal tar and water, and forming to obtain raw material particles; sequentially performing pre-oxidation treatment and carbonization treatment on the raw material particles to obtain carbonized material; using Fe 3+ After the carbonized material is soaked in a salt solution and activated, activated carbon is obtained. The present application uses anthracite powder with high fixed carbon content and low ash content as raw material to prepare activated carbon, and uses the combined action of pre-oxidation treatment and Fe 3+ solution to effectively control the pore structure of activated carbon through a simple preparation process. On the premise of controlling production cost and environmental pollution, the optimal pore structure distribution for separating CH4 / N2 in activated carbon can be effectively controlled, and thus excellent activated carbon material can be obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of activated carbon preparation, and particularly relates to an activated carbon based on a pre-oxidation-Fe catalysis combined process and a preparation method and application thereof. BACKGROUND

[0002] Unconventional natural gas is rich in types, such as shale gas, coalbed gas and tight sandstone gas, which are all unconventional natural gas. These natural gases are widely distributed and have a huge resource amount, but the development and utilization degree is low. Increasing the development and utilization of unconventional natural gas resources has important strategic significance for the economic and energy development of China and maintaining the long-term stability of the natural gas industry.

[0003] Due to the distribution characteristics of self-generation, self-storage and diffusion migration of unconventional natural gas, the methane content cannot generally meet the use standard. Therefore, it is very meaningful to enrich and concentrate the low-concentration methane in unconventional natural gas.

[0004] In the enrichment process of low-concentration methane, CH4 / N2 mixed gas is the most difficult separation problem. At present, the separation technologies of CH4 / N2 include cryogenic separation technology, membrane separation technology and pressure swing adsorption separation technology. For the pressure swing adsorption separation technology, using activated carbon as the adsorbent is the most widely used method. However, there are very few activated carbons for CH4 / N2 separation on the market, and the non-special activated carbons have the problem of poor separation capacity for CH4 / N2.

[0005] Therefore, the prior art still needs to be improved and developed. SUMMARY

[0006] In view of the above problems of the prior art, the present application aims to provide an activated carbon based on a pre-oxidation-Fe catalysis combined process and a preparation method and application thereof, so as to solve the problem of poor separation capacity for CH4 / N2 of the existing activated carbon.

[0007] The technical scheme of the present application is as follows:

[0008] A preparation method of an activated carbon based on a pre-oxidation-Fe catalysis combined process, comprising the following steps:

[0009] Mixing anthracite powder, coal tar and water, and performing molding treatment to obtain raw material particles;

[0010] Performing pre-oxidation treatment and carbonization treatment on the raw material particles in sequence to obtain carbonized material;

[0011] Soaking the carbonized material in a Fe 3+ solution, and then performing activation treatment to obtain activated carbon.

[0012] The preparation method of the activated carbon based on the pre-oxidation-Fe catalytic combined process, wherein the fixed carbon mass content of the anthracite powder is between 87% and 95%, the volatile matter mass content is between 8% and 8.5%, the ash content is between 3% and 3.5%, and the moisture content is less than 2%.

[0013] The preparation method of the activated carbon based on the pre-oxidation-Fe catalytic combined process, wherein the mass percentage ratio of the anthracite powder, the coal tar and the water is (65%-74%):(21%-32%):(3%-10%).

[0014] The preparation method of the activated carbon based on the pre-oxidation-Fe catalytic combined process, wherein the pre-oxidation treatment temperature is 280-320℃, the pre-oxidation treatment time is 1-2h, and the pre-oxidation treatment is carried out under an air flow of 380-420ml·min -1 .

[0015] The preparation method of the activated carbon based on the pre-oxidation-Fe catalytic combined process, wherein the carbonization treatment temperature is 580-620℃, and the carbonization treatment time is 2-3h.

[0016] The preparation method of the activated carbon based on the pre-oxidation-Fe catalytic combined process, wherein the Fe 3+ salt solution is selected from at least one of FeCl3 solution, Fe(NO3)3 solution and Fe2(SO4)3 solution.

[0017] The preparation method of the activated carbon based on the pre-oxidation-Fe catalytic combined process, wherein the Fe 3+ salt solution has a mass fraction of 4-6wt%.

[0018] The preparation method of the activated carbon based on the pre-oxidation-Fe catalytic combined process, wherein the activation treatment temperature is 880-920℃, the activation treatment time is 1.5-2.5h, and the activation treatment is carried out under a water vapor environment of 4-6ml·min -1 .

[0019] An activated carbon based on a pre-oxidation-Fe catalytic combined process, which is prepared by using the preparation method of the activated carbon based on the pre-oxidation-Fe catalytic combined process.

[0020] The application of the activated carbon based on the pre-oxidation-Fe catalytic combined process in separating CH4 and N2 by pressure swing adsorption.

[0021] Beneficial effects: the application provides a kind of activated carbon based on pre-oxidation-Fe catalytic combined process and its preparation method and application, the preparation method includes the following steps: anthracite powder is mixed with coal tar and water, and is formed to obtain raw material particles;The raw material particles are sequentially subjected to pre-oxidation treatment and carbonization treatment to obtain carbonized material;Fe 3+ After the carbonized material is soaked in salt solution and activated, activated carbon is obtained.The application uses anthracite powder with high fixed carbon content and low ash content as raw material to prepare activated carbon, and uses pre-oxidation treatment and Fe 3+ solution combined process, through simple preparation process, the effective control of activated carbon pore structure is realized, under the premise of controlling production cost and environmental pollution, the optimal pore structure distribution of CH4 / N2 generated in activated carbon can be effectively controlled, and then excellent activated carbon material is obtained. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The preparation method process flow chart of the activated carbon based on pre-oxidation-Fe catalytic combined process of the application;

[0023] Figure 2 The N2 adsorption-desorption isotherm data graph of the activated carbon prepared in example 1;

[0024] Figure 3 The CO2 adsorption-desorption isotherm data graph of the activated carbon prepared in example 1;

[0025] Figure 4 The pore size distribution graph of the activated carbon prepared in example 1;

[0026] Figure 5 The single-component adsorption isotherm data graph of CH4 and N2 of the activated carbon prepared in example 1. DETAILED DESCRIPTION

[0027] The application provides a kind of activated carbon based on pre-oxidation-Fe catalytic combined process and its preparation method and application, to make the purpose, technical scheme and effect of the application more clear and definite, the following will be further detailed in the application.It should be understood that the specific embodiments described herein are only used to explain the application and not to limit the application.

[0028] Those skilled in the art can understand that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as generally understood by those skilled in the art to which the application belongs.It should also be understood that terms such as those defined in general dictionaries should be understood as having meanings consistent with those in the prior art, and unless specifically defined as here, should not be interpreted as idealized or overly formal.

[0029] Based on this, as Figure 1 shown, the present application provides a preparation method of activated carbon based on pre-oxidation-Fe catalytic combined process, comprising the steps of:

[0030] Step S10: mixing anthracite powder with coal tar and water, and performing molding treatment to obtain raw material particles;

[0031] Step S20: sequentially performing pre-oxidation treatment and carbonization treatment on the raw material particles to obtain carbonized material;

[0032] Step S30: soaking the carbonized material in Fe 3+ salt solution and then performing activation treatment to obtain activated carbon.

[0033] In this embodiment, anthracite powder is used as raw material for preparing activated carbon. The carbonized material obtained after pre-oxidation and carbonization treatment is subjected to Fe catalysis and activation treatment to obtain activated carbon. After the molding particles are carbonized, the carbonized material is subjected to Fe 3+ solution impregnation treatment. This is because Fe 3+ can exchange protons with the carboxyl groups on the surface of carbon and be converted into highly dispersed catalysts. In the catalytic process, the Fe-based catalyst exists in the form of Fe3O4. As an intermediate for oxygen transfer, Fe3O4 can accelerate the reaction between water vapor and the surface of carbon, leading to rapid decomposition of residual volatile substances in the pores of carbon. At the same time, iron is impregnated on the surface of carbon in the form of salt solution, forming active sites and uniformly distributed on the surface of carbon, guiding the reaction position of water vapor, thus being beneficial to the formation of uniform pore structure. The formation of abundant pore structure effective for CH4 / N2 separation is realized by adjusting the activation adjustment, and the activated carbon has good cyclic regeneration ability.

[0034] In some embodiments, the fixed carbon mass content of the anthracite powder is between 87% and 95%, the volatile matter mass content is between 8% and 8.5%, the ash content is between 3% and 3.5%, and the moisture content is less than 2%. Using anthracite with high fixed carbon content and low ash content as raw material for preparing activated carbon is beneficial to the preparation of activated carbon material with rich micropore structure.

[0035] In some embodiments, the anthracite powder is obtained by crushing and grinding anthracite, specifically comprising the step of: passing the crushed and ground anthracite through a 100-160 mesh sieve to obtain the anthracite powder. Passing the crushed and ground anthracite through a 100-160 mesh sieve ensures that the coal powder particles are small enough to be fully reacted and pore-formed by the activator in the later activation treatment.

[0036] In a preferred embodiment, the anthracite is Chongqing anthracite, i.e., the anthracite powder is obtained by crushing and grinding Chongqing anthracite and then sieving the powder through a 100-160 mesh sieve.

[0037] In some embodiments, the anthracite powder, the coal tar, and the water are mixed in a mass ratio of (65%-74%):(21%-32%):(3%-10%). The anthracite powder, the coal tar, and the water are mixed in a mass ratio of (65%-74%):(21%-32%):(3%-10%). The anthracite powder is agglomerated by adding the coal tar, and the viscosity of the mixture is adjusted by adding a small amount of water. After sufficient mixing, the mixture has a uniform viscosity. The mixture is extruded into a strip with uniform density, and then the strip is dried and cut into granules to obtain the raw granules.

[0038] In a preferred embodiment, the anthracite powder, the coal tar, and the water are mixed in a mass ratio of 66.67%:26.67%:6.66%.

[0039] In some embodiments, in the step S10, the forming process includes extruding the mixture of the anthracite powder, the coal tar, and the water into a strip with uniform density, drying the strip at 60-80°C for 24-36h, and cutting the strip into granules to obtain the raw granules. The raw granules should not be too large, as a large size can affect the uniformity of the pore structure distribution of the activated carbon.

[0040] In a preferred embodiment, the raw granules have a length of 3-8mm and a diameter of 2-5mm.

[0041] In some embodiments, the pre-oxidation process is performed at a temperature of 280-320°C for 1-2h under an air flow of 380-420ml·min -1 . This can sufficiently oxidize the raw granules to form a well-developed initial pore network, and the pre-oxidation process is beneficial for the formation of a large number of ultra-micro pores (<1nm) in the activated carbon. Subsequently, the air flow is stopped, and a carbonization process is performed.

[0042] In a preferred embodiment, the pre-oxidation process is performed by increasing the temperature to 300°C at a rate of 10°C·min -1 , introducing an air flow of 400ml·min -1 , and pre-oxidizing for 1h.

[0043] In some embodiments, the temperature of the carbonization treatment is 580-620 DEG C, the time of the carbonization treatment is 2-3 h, and the carbonization treatment is performed to further diffuse volatile components in the raw material particles in a gaseous form, and to further develop initial pores in the particles to provide a basic pore structure for the invasion of subsequent activators.

[0044] In a preferred embodiment, the temperature of the carbonization treatment is 600 DEG C, the carbonization is performed for 2.5 h at a constant temperature, and then the carbonization material is naturally cooled to room temperature.

[0045] In some embodiments, the Fe 3+ The salt solution is selected from at least one of FeCl3 solution, Fe(NO3)3 solution, and Fe2(SO4)3 solution; Fe 3+ The salt solution is used to soak the carbonization material, and the core mechanism is that Fe elements have obvious catalytic effects on the water vapor activation pore preparation of activated carbon through oxygen transfer characteristics, and Fe elements also have catalytic effects on the gasification of coal tar. Therefore, after the carbonization material is sufficiently impregnated with the Fe 3+ salt solution, Fe elements can be uniformly distributed on the carbon surface, and in the activation process, on the one hand, the coal tar that is not completely volatilized in the carbonization stage can be cleaned up in the pore, and on the other hand, the active sites for the reaction of the carbon surface with water vapor can be increased to guide the formation of a more uniform pore structure of activated carbon.

[0046] In some embodiments, the Fe 3+ The mass fraction of the Fe 3+ salt solution is 4-6 wt%, and the combination of a small amount of flowing air and a low concentration of Fe 3+ salt solution can effectively regulate the pore structure of activated carbon through a simple preparation process, and provides activated carbon with strong CH4 / N2 separation capacity under the premise of controlling production cost and environmental pollution.

[0047] In some embodiments, the temperature of the activation treatment is 880-920 DEG C, the time of the activation treatment is 1.5-2.5 h, and the activation treatment is performed in a 4-6 ml·min -1 water vapor environment.

[0048] In addition, the application also provides activated carbon based on a pre-oxidation-Fe catalysis combined process, which is prepared by using a preparation method of the activated carbon based on the pre-oxidation-Fe catalysis combined process.

[0049] In the embodiment, the activated carbon prepared by using the preparation method has a uniform pore size distribution, contains rich pore structures effective for CH4 / N2 separation, has strong CH4 / N2 separation capacity, and also has good cyclic regeneration performance.

[0050] Meanwhile, the application also provides application of the activated carbon based on the pre-oxidation-Fe catalytic combined process in separation of CH4 and N2 by pressure swing adsorption.

[0051] The application will be further illustrated in detail by examples. It should be understood that the following examples are only used to further illustrate the application and cannot be understood as limitation to the protection scope of the application. Some non-essential improvements and adjustments made by the person skilled in the art according to the above content of the application are within the protection scope of the application.

[0052] Example 1

[0053] The application provides an activated carbon based on a pre-oxidation-Fe catalytic combined process, and a preparation method thereof includes the following steps:

[0054] Raw material source: Chongqing anthracite with fixed carbon content of 87%-95%, volatile content of 8%-8.5%, ash content of 3%-3.5%, and water content of less than 2% is selected.

[0055] Step 1: 500g of Chongqing anthracite is crushed into coarse particle powder by a crusher, and then is ground by a ball mill, and is passed through a 160-mesh sieve to obtain anthracite powder;

[0056] Step 2: 500g of the anthracite powder and 200g of coal tar and 50g of water are poured into a blender and stirred for 40min, and after sufficient mixing, the mixed material is immediately taken out and extruded into a strip in a molding machine, and is dried in an oven at 80℃ for 24h, and is cut into raw material particles with a length of 5mm and a diameter of 3mm;

[0057] Step 3: 100g of the raw material particles are weighed and placed in a muffle furnace, and are heated to 300℃ at a heating rate of 10℃·min -1 , and an air flow of 400ml·min -1 is introduced, and pre-oxidation is performed for 1h, and then the air is stopped, and then heating is continued to 600℃, and carbonization is performed for 2.5h at constant temperature, and natural cooling is performed to room temperature to obtain carbonized material;

[0058] Step 4: the carbonized material obtained in step 3 is soaked in 100ml of 5wt% 6H2O FeCl3 solution for 4h, and after being taken out with a strainer, is placed in a muffle furnace, and is heated to 900℃ at a heating rate of 10℃·min -1 , and water vapor of 5ml·min -1 is introduced, and activation is performed for 2h, and then the water vapor is stopped, and natural cooling is performed to 30℃ to obtain activated carbon.

[0059] 1. The activated carbon obtained in Example 1 is tested for pore structure characteristics:

[0060] The N2 adsorption-desorption isotherm of the activated carbon obtained in Example 1 at 77K is as shown inFigure 2 The CO2 adsorption-desorption isotherm at 273K is shown in Figure 1. Figure 3 The N2 adsorption-desorption isotherm is calculated by QSDFT model for the part with pore diameter > 1 nm, and the CO2 adsorption-desorption isotherm is calculated by NLDFT model for the part with pore diameter < 1 nm, and the relationship between pore diameter and pore content is shown in Figure 2. Figure 4

[0061] The pore structure characteristic parameters of the activated carbon prepared in Example 1 are shown in Table 1:

[0062]

[0063] 2. The CH4 and N2 adsorption performance test of the activated carbon prepared in Example 1 was carried out at 25℃ and 1MPa, and the test results are shown in Figure 3. Figure 5

[0064] As shown in Figure 4, the single-component adsorption amount of CH4 and N2 of the activated carbon prepared in Example 1 is shown in Figure 4. Figure 5

[0065] Table 2:

[0066]

[0067] 3. The service life of the activated carbon prepared in Example 1 was verified

[0068] When the activated carbon is used for pressure swing adsorption separation of CH4 / N2, and the vacuum pump with a vacuum degree of 40KPa or less is used for cyclic regeneration, it can be used for at least one year.

[0069] In summary, the activated carbon based on the pre-oxidation-Fe catalytic combined process and the preparation method and application thereof provided by the application, the preparation method comprises the following steps: mixing anthracite powder, coal tar and water, and forming to obtain raw material particles; the raw material particles are sequentially subjected to pre-oxidation treatment and carbonization treatment to obtain carbonized material; the carbonized material is soaked with Fe 3+ salt solution and then subjected to activation treatment to obtain activated carbon. The application uses anthracite powder with high fixed carbon content and low ash content as raw material to prepare activated carbon, and uses pre-oxidation treatment and Fe 3+ solution combined process to effectively control the pore structure of the activated carbon through a simple preparation process, and under the premise of controlling production cost and environmental pollution, the optimal pore structure distribution for separating CH4 / N2 in the activated carbon can be effectively controlled, and then the activated carbon material with excellent performance can be obtained.

[0070] ​​​It is to be understood that the application is not limited to the examples described above, which can be modified or adapted in several ways by those skilled in the art without departing from the scope of the present application, as defined by the appended claims.

Claims

1. A method for producing activated carbon based on a pre-oxidized-Fe catalytic combined process, characterized by, The method comprises the steps of: mixing anthracite powder, coal tar and water to obtain raw material particles through a molding process; carrying out pre-oxidation and carbonization on the raw material particles to obtain carbonized material; Using Fe 3+ After the carbonized material is soaked in the salt solution, the activated carbon is obtained through activation treatment. The temperature of the pre-oxidation treatment is 280-320℃, the time of the pre-oxidation treatment is 1-2h, and the pre-oxidation treatment is carried out under an air flow of 380-420ml·min -1 . The Fe 3+ The mass fraction of the salt solution is 4-6 wt%. The temperature of the activation treatment is 880-920℃, the time of the activation treatment is 1.5-2.5h, and the activation treatment is carried out at 4-6ml·min -1 under water vapor environment.

2. The method for preparing activated carbon based on pre-oxidized-Fe catalytic combined process according to claim 1, characterized in that, the fixed carbon content of the anthracite powder is 87-95%, the volatile content is 8-8.5%, the ash content is 3-3.5%, and the moisture content is less than 2%.

3. The method for preparing activated carbon based on pre-oxidized-Fe catalytic combined process according to claim 1, characterized in that, the mass percentage ratio of the anthracite powder, the coal tar and the water is (65-74):(21-32):(3-10).

4. The method for preparing activated carbon based on pre-oxidized-Fe catalytic combined process according to claim 1, characterized in that, the carbonization temperature is 580-620℃, and the carbonization time is 2-3h.

5. The method for preparing activated carbon based on pre-oxidized-Fe catalytic combined process according to claim 1, characterized in that, The Fe 3+ The salt solution is selected from at least one of FeCl3solution, Fe(N03)3solution, Fe2(S04)3solution.

6. An activated carbon based on a pre-oxidized-Fe catalytic combined process, characterized in that, The method is prepared by using the method for preparing activated carbon based on the pre-oxidation-Fe catalytic combined process according to any one of claims 1-5.

7. The application of the activated carbon based on the pre-oxidation-Fe catalytic combined process according to claim 6 in the separation of CH4 and N2 by pressure swing adsorption.

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