Preparation process of modified activated carbon for benzene adsorption in natural gas

Abstract

The application discloses a preparation process of modified activated carbon for benzene adsorption of natural gas, and comprises the following steps: S1, graphite powder and milk are weighed according to a mass ratio of 1:100, and the weighed graphite powder is added into the weighed milk to be mixed to obtain a mixed solution; S2, the mixed solution in the step S1 is added into a homogenizer to be peeled, the setting pressure of the homogenizer is 50-100 MPa, and the homogenizer is circulated for 10-50 times to obtain a graphene dispersion liquid; and S3, the graphene dispersion liquid in the step S2 is washed by hot water at 60-80 DEG C to remove protein and lecithin in the solution, and the washing times are 3-8 times. The application effectively solves the problems of small activated carbon adsorption capacity, poor selectivity, complex process and high cost in the prior art.

Description

Technical Field

[0001] This invention belongs to the technical field of preparation of modified activated carbon for benzene removal adsorption of natural gas, and relates to a preparation process of modified activated carbon for benzene removal adsorption of natural gas. Background Technology

[0002] Natural gas, as a high-quality, efficient, green, and clean low-carbon energy source, is one of the main energy sources in my country's modern clean energy system. Currently, one way to utilize natural gas is through liquefied natural gas (LNG). However, the presence of heavy hydrocarbons in natural gas can cause freezing blockages in the main heat exchanger of the cold box, so it is necessary to remove them at low temperatures before they enter the low-temperature section of the main heat exchanger. However, due to the presence of benzene, conventional low-temperature methods cannot remove benzene. Benzene will cool and solidify to form irregular solids, which will remain in the pipelines, blocking the cold box, access ports, and valves. In severe cases, this can cause the equipment to stop operating. Currently, methods for removing benzene from natural gas during LNG liquefaction include adsorption, washing, membrane separation, and catalytic combustion. Among these, adsorption is a commonly used method due to its good adsorption effect, low cost, and lack of subsequent separation issues. Considering cost-effectiveness and regeneration energy consumption, activated carbon is often used as the adsorbent material in industry. However, commercially available activated carbon suffers from problems such as small adsorption capacity, poor selectivity, high regeneration energy consumption, and pore clogging, resulting in high benzene removal costs for large-scale liquefaction plants. Chinese patent CN1903703A discloses a method for preparing modified activated carbon with high regeneration rate and high specific surface area. The superhydrophobic nano-coating on the modified activated carbon prepared by this method does not block or shield the pore structure of the activated carbon, thus allowing the activated carbon to still have a high specific surface area, high regeneration rate, and good moisture resistance. However, the modified activated carbon prepared by this patent has poor selectivity for benzene adsorption. Chinese patent CN113522237A discloses a method for preparing activated carbon for benzene series adsorption and the prepared activated carbon for benzene series adsorption. This paper introduces a method for preparing activated carbon for benzene series adsorption and the prepared activated carbon material for benzene series adsorption. The activated carbon is modified by grafting silane coupling agent through gas-phase chemical reaction. The activated carbon prepared by this invention can reduce the mutual inhibition between coexisting components of benzene series when purifying and adsorbing benzene series coexisting systems, and achieve synergistic and efficient purification of benzene series-containing waste gas. However, the method has a complex operation process, is difficult to prepare on a large scale, and has high cost. Therefore, there is an urgent need for a preparation process of modified activated carbon for benzene removal adsorption from natural gas. Summary of the Invention

[0003] To address the aforementioned problems, this invention proposes a preparation process for modified activated carbon used in the benzene removal adsorption of natural gas, which effectively solves the problems of small adsorption capacity, poor selectivity, complex process, and high cost of activated carbon in the prior art.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A process for preparing modified activated carbon for benzene removal adsorption from natural gas includes the following steps: S1: Weigh graphite powder and milk at a mass ratio of 1:100, add the weighed graphite powder to the weighed milk, mix, and obtain a mixture. S2: Add the mixture from step S1 to a homogenizer for peeling. The set pressure of the homogenizer is 50-100MPa, and the cycle is 10-50 times to obtain a graphene dispersion. S3: Wash the graphene dispersion in step S2 with hot water at 60-80℃ to remove proteins and lecithin from the solution. The number of washes is 3-8. S4: Place the graphene dispersion washed in step S3 into a forced-air drying oven and dry it for 6-12 hours. The temperature of the forced-air drying oven is set at 60-120℃. After drying in the forced-air drying oven, graphene powder is obtained. S5: Add the graphene powder and activated carbon from step S4 to a ball mill jar at a ratio of 0.1-0.4:1 and mix them. The ball mill jar rotates at 100-500 rpm and the ball milling time is 2-6 hours to obtain modified activated carbon powder. S6: The modified activated carbon powder from step S5 is dried in a vacuum oven at a temperature of 80-200℃ for 6-24 hours to obtain dried modified activated carbon powder.

[0005] Preferably, the weighed graphite powder raw material is added to the weighed milk and mixed by magnetic stirring for 1-5 hours.

[0006] Preferably, the homogenizer is set to a pressure of 50 MPa and a cycle count of 30.

[0007] Preferably, in step S5, the graphene powder and activated carbon are mixed in a ratio of 0.3:1.

[0008] Preferably, the milling jar rotates at 100 rpm and the milling time is 2 hours.

[0009] Preferably, the temperature of the vacuum oven is 200℃ and the drying time is 12h.

[0010] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention uses milk as the exfoliation medium to achieve liquid-phase exfoliation of graphite through a homogenizer to obtain a graphene dispersion. Then, the graphene is mixed with activated carbon and subjected to vacuum heating treatment to obtain modified activated carbon.

[0011] 2. In this invention, the adsorption equilibrium amount of the modified activated carbon powder is 353.61 mg·g⁻¹ and the adsorption equilibrium time is 101 min, which are 56.1% and 20.23% higher than the adsorption equilibrium amount of the raw activated carbon (226.53 mg·g⁻¹) and the adsorption equilibrium time (84 min), respectively, proving that the modified activated carbon powder has a stronger adsorption capacity for benzene.

[0012] 3. In this invention, the surface tension of milk is between 38-39 mJ / m2, which can effectively reduce the van der Waals forces between graphite layers, and then graphene is exfoliated and prepared under the action of shear force.

[0013] 4. This invention prepares high-quality graphene with few layers by mixing graphene with milk and then using a homogenizer to exfoliate the graphene in the liquid phase. This process for preparing graphene is simple, uses inexpensive raw materials, and can maintain the complete morphology and properties of graphene. Attached Figure Description

[0014] Figure 1 This is an electron microscope image of the modified activated carbon powder of the present invention.

[0015] Figure 2 This is a schematic diagram of the process for the modified activated carbon powder of the present invention. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Example 1 Please see Figure 1 and Figure 2 This invention provides a technical solution: a preparation process for modified activated carbon for benzene removal adsorption from natural gas, comprising the following steps: S1: Weigh the graphite powder and milk at a mass ratio of 1:100, add the weighed graphite powder to the weighed milk, and mix the graphite powder with magnetic stirring for 1-5 hours. S2: Add the mixture from step S1 to a homogenizer for peeling. The set pressure of the homogenizer is 50-100MPa, and the cycle is 10-50 times to obtain a graphene dispersion. S3: Wash the graphene dispersion in step S2 with hot water at 60-80℃ to remove proteins and lecithin from the solution. The number of washes is 3-8. S4: Place the graphene dispersion washed in step S3 into a forced-air drying oven and dry it for 6-12 hours. The temperature of the forced-air drying oven is set at 60-120℃. After drying in the forced-air drying oven, graphene powder is obtained. S5: Add the graphene powder and activated carbon from step S4 into a ball mill jar at a ratio of 0.1:1 and mix them. The ball mill jar rotates at 100-500 rpm and the ball milling time is 2-6 hours to obtain modified activated carbon powder. S6: The modified activated carbon powder from step S5 is dried in a vacuum oven at a temperature of 80-200℃ for 6 hours to obtain dried modified activated carbon powder.

[0018] Example 2 Please see Figure 1 and Figure 2 The present invention provides another technical solution: a preparation process of modified activated carbon for benzene removal adsorption from natural gas, comprising the following steps: S1: Weigh the graphite powder and milk at a mass ratio of 1:100, add the weighed graphite powder to the weighed milk, and mix the graphite powder with magnetic stirring for 1 hour. S2: Add the mixture from step S1 to a homogenizer for peeling. The set pressure of the homogenizer is 50 MPa, and the cycle is repeated 30 times to obtain a graphene dispersion. S3: Wash the graphene dispersion in step S2 with hot water at 60°C to remove proteins and lecithin from the solution. The washing is performed 3 times. S4: Place the washed graphene dispersion from step S3 into a forced-air drying oven and dry it for 6 hours. The temperature of the forced-air drying oven is set at 60°C. After drying in the forced-air drying oven, graphene powder is obtained. S5: Add the graphene powder and activated carbon from step S4 to a ball mill jar at a ratio of 0.3:1 and mix them. The ball mill jar rotates at 100 rpm and the ball milling time is 2 hours to obtain modified activated carbon powder. S6: The modified activated carbon powder from step S5 is dried in a vacuum oven at a temperature of 80°C for 12 hours to obtain dried modified activated carbon powder.

[0019] Example 3 Please see Figure 1 and Figure 2 The present invention provides another technical solution: a preparation process of modified activated carbon for benzene removal adsorption from natural gas, comprising the following steps: S1: Weigh graphite powder and milk at a mass ratio of 1:100, add the weighed graphite powder to the weighed milk, and mix the graphite powder with magnetic stirring for 5 hours. S2: Add the mixture from step S1 to a homogenizer for peeling. The set pressure of the homogenizer is 100 MPa, and the cycle is 50 times to obtain a graphene dispersion. S3: Wash the graphene dispersion in step S2 with hot water at 80°C to remove proteins and lecithin from the solution. The washing number is 8 times. S4: Place the washed graphene dispersion from step S3 into a forced-air drying oven and dry it for 12 hours. The temperature of the forced-air drying oven is set at 120°C. After drying in the forced-air oven, graphene powder is obtained. S5: Add the graphene powder and activated carbon from step S4 into a ball mill jar at a ratio of 0.4:1 and mix them. The ball mill jar rotates at 500 rpm and the ball milling time is 6 hours to obtain modified activated carbon powder. S6: The modified activated carbon powder from step S5 is dried in a vacuum oven at a temperature of 200°C for 24 hours to obtain dried modified activated carbon powder.

[0020] The surface tension of milk is between 38-39 mJ / m2, which can effectively reduce the van der Waals forces between graphite layers, and then graphene can be exfoliated and prepared under the action of shear force.

[0021] from Figure 1 As can be seen in part (b), the graphene with a two-dimensional sheet structure is tightly "attached" to the activated carbon particles, and the distribution of graphene in the activated carbon is relatively uniform, without any graphene "agglomeration".

[0022] Table 1. Benzene adsorption performance parameters of activated carbon and modified activated carbon Activated carbon 12.58 226.53 84 Modified activated carbon 18.56 353.61 101 Table 1 shows that the adsorption equilibrium capacity of the modified activated carbon powder is 353.61 mg·g⁻¹ and the adsorption equilibrium time is 101 min, which are 56.1% and 20.23% higher than those of the raw activated carbon (226.53 mg·g⁻¹ and 84 min, respectively), demonstrating that the modified activated carbon has a stronger adsorption capacity for benzene.

[0023] In use, this invention first weighs graphite powder and milk at a mass ratio of 1:100, then adds the weighed graphite powder to the weighed milk and mixes them to obtain a mixture. The mixture is then added to a homogenizer for separation, with the homogenizer set at a pressure of 50-100 kcal / kg. The graphene dispersion was obtained by cycling at MPa for 10-50 times. The graphene dispersion was then washed with hot water at 60-80℃ to remove proteins and lecithin, 3-8 times. The washed graphene dispersion was then dried in a forced-air oven at 60-120℃ for 6-12 hours to obtain graphene powder. The graphene powder and activated carbon were added to a ball mill at a ratio of 0.1-0.4:1 and mixed at 100-500 rpm for 2-6 hours to obtain modified activated carbon powder. The modified activated carbon powder was then dried in a vacuum oven at 80-200℃ for 6-24 hours to obtain dry modified activated carbon powder.

[0024] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for preparing modified activated carbon for benzene removal adsorption from natural gas, characterized in that: Includes the following steps: S1: Weigh graphite powder and milk with a surface tension between 38-39 mJ / m2 at a mass ratio of 1:100, add the weighed graphite powder to the weighed milk and mix by magnetic stirring for 1-5 hours to obtain a mixture. S2: Add the mixture from step S1 to a homogenizer for peeling. The set pressure of the homogenizer is 50-100MPa, and the cycle is 10-50 times to obtain a graphene dispersion. S3: Wash the graphene dispersion in step S2 with hot water at 60-80℃ to remove proteins and lecithin from the solution. The number of washes is 3-8. S4: Place the graphene dispersion washed in step S3 into a forced-air drying oven and dry it for 6-12 hours. The temperature of the forced-air drying oven is set at 60-120℃. After drying in the forced-air drying oven, graphene powder is obtained. S5: Add the graphene powder and activated carbon from step S4 to a ball mill jar at a ratio of 0.3:1 and mix them. The ball mill jar rotates at 100-500 rpm and the ball milling time is 2-6 hours to obtain modified activated carbon powder. S6: The modified activated carbon powder from step S5 is dried in a vacuum oven at a temperature of 80-200℃ for 6-24 hours to obtain dried modified activated carbon powder.

2. The preparation process of modified activated carbon for benzene removal adsorption from natural gas according to claim 1, characterized in that: The homogenizer is set to a pressure of 50 MPa and a cycle count of 30.

3. The preparation process of modified activated carbon for benzene removal adsorption from natural gas according to claim 1, characterized in that: The ball mill jar rotates at 100 rpm, and the milling time is 2 hours.

4. The preparation process of modified activated carbon for benzene removal adsorption from natural gas according to claim 1, characterized in that: The temperature of the vacuum oven is 200℃, and the drying time is 12 hours.

Images