CN115259152A - Method for preparing corncob-based activated carbon in one step by nitrogen doping and KOH activation and application thereof - Google Patents

Method for preparing corncob-based activated carbon in one step by nitrogen doping and KOH activation and application thereof Download PDF

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CN115259152A
CN115259152A CN202210765987.0A CN202210765987A CN115259152A CN 115259152 A CN115259152 A CN 115259152A CN 202210765987 A CN202210765987 A CN 202210765987A CN 115259152 A CN115259152 A CN 115259152A
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corncob
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王霞
曾伍兰
张洪艳
辛春玲
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Weifang University
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Abstract

The invention relates to the technical field of preparation of activated carbon, in particular to a method for preparing corncob-based activated carbon in one step by nitrogen doping and KOH activation and application thereof. The method for preparing the corncob-based activated carbon by one step of nitrogen doping and KOH activation comprises the following steps of: pretreating the corncobs, a nitrogen source and an activating agent; mixing an activating agent and corn flour, flatly paving the mixture in a tubular furnace, introducing inert gas, replacing air, heating to the nitriding temperature of 400-450 ℃ at the speed of 3-10 ℃/min, nitriding at the constant temperature for 0.5-1.0h, continuously heating to the activating temperature of 600-800 ℃, activating at the constant temperature for 0.5-1.0h, introducing the inert gas, and cooling to 100-110 ℃ to obtain an activated sample; drying the activated sample to obtain the corncob-based activated carbon at different activation temperatures; the invention provides a method for preparing corncob-based activated carbon in one step by nitrogen doping and KOH activation, which has good adsorption performance.

Description

Method for preparing corncob-based activated carbon in one step by nitrogen doping and KOH activation and application thereof
Technical Field
The invention relates to the technical field of preparation of activated carbon, in particular to a method for preparing corncob-based activated carbon in one step by nitrogen doping and KOH activation and application thereof.
Background
High smoke discharge rate and CO content in coal-fired power plant2The concentration is 9-15 vol%, the temperature after desulfurization and denitrification is 40-70 ℃, the pressure is close to normal pressure, and the desulfurization and denitrification catalyst contains water vapor. CO22The trapping method includes a solution absorption method, a membrane separation method, a cryogenic separation method, a solid adsorption method, and the like. The alcohol amine solution absorption method is CO which is already applied in large scale2Method for capturing CO from alcohol amine solution2The absorption capacity is large, the technology is mature, but the absorption capacity is volatile, strong in corrosivity and easy to degrade, so that the bottleneck for realizing long-term large-scale application is formed; the refrigeration cost of the low-temperature separation method is high; membrane separation processes, while low cost, do not have the desired selectivity and durability of the membrane. The solid adsorbent, especially solid amine adsorbent, can be used for treating CO at 40-70 deg.C2The adsorption rate is high, the adsorption capacity is large, the regeneration is easy (the regeneration performance at 100 ℃) is good, the corrosion is avoided, and the water in the flue gas promotes the amino and the CO2The reaction is carried out without pre-dehumidification before adsorption, the cost is saved, and the CO with application potential energy is formed2An adsorbent. Fiveyand stated that adsorption is certainly a competitive CO if a cost effective, efficient solid adsorbent could be developed2A trapping technique.
The biomass is the fourth largest energy next to coal, petroleum and natural gas, is a renewable resource, can obtain activated carbon with a developed specific surface through physical or chemical activation treatment, and is widely applied to the fields of wastewater treatment, air purification and the like.
Corncobs can be used as feed in the traditional treatment mode, are processed into furfural through biological fermentation after being crushed, and are used in the industries of papermaking, biological sugar making and the like in the high and new technology industry because the corncobs contain rich cellulose, hemicellulose, lignin and the like; the corncob also has strong adsorption performance, can adsorb dust particles and the like, and has wear resistance, energy consumption and strong toughness; but the application of the adsorbent is less in the industry of the adsorbent, and particularly, the adsorbent is still to be developed in the industry of adsorbing carbon dioxide.
CN202111271922.2 discloses a preparation method of nitrogen-doped activated carbon and multi-hydroxide/biomass porous carbon nano composite electrode material, which utilizes corncobs and NH4HCO3The composite porous material doped with cobalt and nickel is prepared by using the active carbon matrix of the composite porous material after high-temperature carbonization, is used for forming a capacitor, has excellent electrochemical performance, and has the specific surface area of 800-900m after the active carbon is carbonized at high temperature2/g。
CN03111949.2 discloses an activated carbon with high specific surface area and its preparation method, which comprises using corncob as raw material, carbonizing at high temperature, and treating with activated penetrating fluid, wherein the penetrating fluid is adjuvant and activator, the adjuvant is composed of sodium peroxide and KOH, and the activator is JFC, MP and soap; then continuing high-temperature activation, then performing acid treatment, and drying to prepare active carbon; the preparation steps of the method are required to be a dried corncob carbonization step, a drying step after infiltration and activation solution impregnation and a high-temperature activation step, and the steps are complex.
Disclosure of Invention
The invention aims to solve the technical problem of providing a method for preparing the corncob-based activated carbon in one step by nitrogen doping and KOH activation, which has good adsorption performance; the preparation steps are simple and quick; in application, the adsorption of CO in the flue gas of the coal-fired power plant is more facilitated2。
The method for preparing the corncob-based activated carbon by one step of nitrogen doping and KOH activation comprises the following steps of:
(1) Pretreatment: cleaning corn cob, oven drying, pulverizing, and sieving; pulverizing nitrogen source and activating agent, and sieving;
(2) "N doping + activation" one-step preparation of activated samples: mixing an activating agent with the corn flour and flatly paving the mixture in a tube furnace; introducing inert gas to replace air, heating to the nitriding temperature of 400-450 ℃ at the speed of 3-10 ℃/min, nitriding at the constant temperature for 0.5-1.0h, continuously heating to the activation temperature of 600-800 ℃, activating at the constant temperature for 0.5-1.0h, introducing the inert gas, and cooling to 100-110 ℃ to obtain an activated sample;
(3) Washing an activated sample to be neutral by using hydrochloric acid and deionized water, and drying to obtain corncob-based activated carbon at different activation temperatures;
the nitrogen source is urea; the activating agent is KOH;
the mass ratio of the activating agent to the corncobs is 0.1-1;
the mass ratio of the nitrogen source to the corncobs is 0.5-1.5.
In the step (1), the drying temperature of the corncobs is 120-130 ℃; the drying time is 16-20h.
The mesh number sieved in the step (1) is below 120 meshes.
And (3) introducing inert gas Ar into the tubular furnace in the step (2), wherein the flow rate is 210-300mL/min, and the time is 20-25min.
The step of washing the activated sample to be neutral in the step (3) is to wash the activated sample by hydrochloric acid with the concentration of 2mol/L firstly and then wash the activated sample by deionized water.
In the step (3), the drying temperature is 90-100 ℃, and the time is 24-28h.
The application of the one-step preparation of the corncob-based activated carbon by the nitrogen doping and the KOH activation comprises the following steps: in a fixed bed adsorption evaluation device, the air inlet flow rate is 20-60mL/min, the adsorption temperature is 20-70 ℃, and the on-line evaluation of the corncob-based active carbon prepared in one step through nitrogen doping and KOH activation in the flue gas of a coal-fired power plant2The adsorption performance and the adsorption capacity are large.
Specifically, the method for preparing the corncob-based activated carbon in one step by using the 'nitrogen doping + KOH activation' process comprises the following steps:
(1) Pretreatment: respectively cleaning corncobs with tap water and deionized water, drying in an oven at 120-130 deg.C for 16-20h, pulverizing with a pulverizer, sieving to below 120 meshes, and drying; pulverizing KOH and urea, and sieving with a sieve of less than 120 meshes for later use;
(2) "N doping + activation" one-step preparation of activated samples: mixing and flatly paving a nitrogen source, an activating agent and corncobs in a tubular furnace according to a mass ratio; introducing Ar gas at the speed of 200-300mL/min to replace air for 20-25min, blowing off the air attached to the surface of the tubular furnace and the sample, heating to the nitriding temperature of 400-450 ℃ at the speed of 3-10 ℃/min, nitriding at the constant temperature for 0.5-1.0h, continuously heating to the activation temperature of 600-800 ℃, activating at the constant temperature for 0.5-1.0h, introducing Ar gas, and cooling to 100-110 ℃ to obtain an activated sample;
(3) Washing an activated sample with 2mol/LHCl and deionized water until the pH is =7, and drying at 90-100 ℃ for 24-28h to obtain the corncob-based activated carbon at different activation temperatures; the expression CNbKa-T (T) is used, wherein C represents the activated carbon based on corncobs, N represents the urea as a nitrogen source, b represents the mass ratio of the urea to the corncobs, K represents an activator KOH, a represents the mass ratio of the KOH to the corncobs, T represents the activation temperature (DEG C), and T represents the activation time (h).
The invention relates to a method for preparing corncob-based activated carbon by one step of nitrogen doping and KOH activation, which takes corncobs as a substrate, adopts a nitrogen source urea and an activating agent KOH for one step of mixing and then carries out temperature programming to realize urea decomposition and KOH one step of activation.
Compared with the prior art, the invention has the beneficial effects that:
(1) The prepared corncob-based activated carbon is prepared by one step of nitrogen doping and KOH activation, so that the utilization rate is high, the cost is low, the economic benefit is high, and the method is suitable for large-scale application;
(2) The prepared nitrogen-doped and KOH-activated corncob-based activated carbon is prepared in one step, and the N-doped corncob-based activated carbon prepared by one-step activation contains N and O functional groups, so that the N-doped corncob-based activated carbon is more beneficial to low-temperature CO2And (4) performing physical adsorption.
Drawings
FIG. 1 is a graph representing the adsorption capacity of corn cob based activated carbon at different pressures using KOH activated and "Urea + KOH activated";
FIG. 2 is a graphical representation of pore size distribution at different pressures using corncob based activated carbon that is KOH activated and "Urea + KOH activated";
FIG. 3 is an XPS spectrum of oxygen-containing functional groups using corncob-based activated carbon that is KOH activated and "Urea + KOH activated";
FIG. 4 is an XPS spectrum of nitrogen-containing functional groups using corncob-based activated carbon that is KOH activated and "Urea + KOH activated";
FIG. 5 is an SEM surface topography of a corncob based activated carbon using KOH activation and "Urea + KOH activation";
FIG. 6 is a graph of CO2 breakthrough adsorption profile and adsorption capacity using corncob based activated carbon for KOH activation and "Urea + KOH activation".
Detailed Description
The present invention will be further described with reference to the following specific examples.
Example 1
The method for preparing the corncob-based activated carbon in one step by using the 'nitrogen doping + KOH activation' process comprises the following steps of:
(1) Pretreatment: respectively cleaning corncobs with tap water and deionized water, drying in a 120 ℃ oven for 18h, pulverizing with a pulverizer, sieving to below 120 meshes, and drying for later use; pulverizing KOH and urea, and sieving with a sieve of less than 120 meshes for later use;
(2) "N doping + activation" one-step preparation of activated samples: mixing KOH, urea and corncobs and flatly paving the mixture in a tubular furnace; introducing Ar gas at the speed of 300mL/min to replace air for 20min, blowing off the air attached to the surfaces of the tubular furnace and the sample, heating to the nitriding temperature of 400 ℃ at the speed of 10 ℃/min, carrying out constant-temperature nitriding for 1h, continuously heating to the activation temperature of 700 ℃, carrying out constant-temperature activation for 1.0h, continuously introducing Ar gas into the tubular furnace, cooling to 100 ℃ to obtain an activated sample;
the mass ratio of the KOH to the corncobs is 0.3; the mass ratio of the urea to the corncobs is 0.5;
(3) Washing an activated sample with 2mol/LHCl and deionized water to pH =7, and drying at 90 ℃ for 28h to obtain corncob-based activated carbon at different activation temperatures; is marked as CN0.5K0.3-700 (1).
Example 2
The method for preparing the corncob-based activated carbon by one step of nitrogen doping and KOH activation comprises the following steps of:
(1) Pretreatment: respectively cleaning corncobs with tap water and deionized water, drying in an oven at 130 ℃ for 16h, pulverizing with a pulverizer, sieving to below 120 meshes, and drying for later use; pulverizing KOH and urea, and sieving with a sieve of less than 120 meshes for later use;
(2) "N doping + activation" one-step preparation of activated samples: mixing KOH, urea and corncobs according to a mass ratio and flatly paving the mixture in a tubular furnace; introducing Ar gas at a rate of 200mL/min to displace air for 25min, blowing off the air attached to the surfaces of the tubular furnace and the sample, heating to a nitriding temperature of 450 ℃ at a rate of 3 ℃/min, nitriding at a constant temperature for 0.5h, continuously heating to an activation temperature of 700 ℃, activating at a constant temperature for 1.0h, continuously introducing Ar gas into the tubular furnace, and cooling to 110 ℃ to obtain an activated sample;
the mass ratio of the KOH to the corncobs is 0.3; the mass ratio of the urea to the corncobs is 1;
(3) Washing an activated sample with 2mol/LHCl and deionized water until the pH is =7, and drying at 100 ℃ for 24h to obtain corncob-based activated carbon at different activation temperatures; is marked as CN1K0.3-700 (1).
Example 3
The method for preparing the corncob-based activated carbon in one step by using the 'nitrogen doping + KOH activation' process comprises the following steps of:
(1) Pretreatment: respectively cleaning corncobs with tap water and deionized water, drying in an oven at 125 ℃ for 16h, pulverizing with a pulverizer, sieving to below 120 meshes, and drying for later use; pulverizing KOH and urea, and sieving with a sieve of less than 120 meshes for later use;
(2) "N doping + activation" one-step preparation of activated samples: mixing KOH, urea and corncobs according to a mass ratio and flatly paving the mixture in a tubular furnace; introducing argon Ar at a rate of 250mL/min, replacing air for 20min, blowing off air attached to the surfaces of the tubular furnace and the sample, heating to a nitriding temperature of 430 ℃ at a rate of 8 ℃/min, nitriding at a constant temperature for 0.8h, continuously heating to an activation temperature of 700 ℃, activating at the constant temperature for 1.0h, continuously introducing Ar into the tubular furnace, and cooling to 100 ℃ to obtain an activated sample;
the mass ratio of the KOH to the corncobs is 0.3; the mass ratio of the urea to the corncobs is 1.5;
(3) Washing an activated sample with 2mol/LHCl and deionized water to pH =7, and drying at 100 ℃ for 24h to obtain corncob-based activated carbon at different activation temperatures; is marked as CN1.5K0.3-700 (1).
Example 4
The method for preparing the corncob-based activated carbon by one step of nitrogen doping and KOH activation comprises the following steps of:
(1) Pretreatment: respectively cleaning corncobs with tap water and deionized water, drying in a 120 ℃ oven for 16h, pulverizing with a pulverizer, sieving to below 120 meshes, and drying for later use; pulverizing KOH and urea, and sieving with a sieve of less than 120 meshes for later use;
(2) "N doping + activation" one-step preparation of activated samples: mixing KOH, urea and corncobs according to a mass ratio and flatly paving the mixture in a tubular furnace; introducing Ar gas at the speed of 20mL/min, replacing air for 25min, blowing off the air attached to the surfaces of the tubular furnace and the sample, heating to the nitriding temperature of 400 ℃ at the speed of 5 ℃/min, carrying out constant-temperature nitriding for 0.5h, continuously heating to the activation temperature of 600 ℃, carrying out constant-temperature activation for 1.0h, continuously introducing Ar gas into the tubular furnace, and cooling to 100 ℃ to obtain an activated sample;
the mass ratio of the KOH to the corncobs is 0.5; the mass ratio of the urea to the corncobs is 1;
(3) Washing an activated sample with 2mol/LHCl and deionized water to pH =7, and drying at 100 ℃ for 24h to obtain corncob-based activated carbon at different activation temperatures; is marked as CN1K0.5-600 (1).
Example 5
The method for preparing the corncob-based activated carbon by one step of nitrogen doping and KOH activation comprises the following steps of:
(1) Pretreatment: respectively cleaning corncobs with tap water and deionized water, drying in a 120 ℃ oven for 16h, pulverizing with a pulverizer, sieving to below 120 meshes, and drying for later use; pulverizing KOH and urea, and sieving with a sieve of less than 120 meshes for later use;
(2) "N doping + activation" one-step preparation of activated samples: mixing KOH, urea and corncobs according to a mass ratio and flatly paving the mixture in a tubular furnace; introducing Ar gas at the speed of 20mL/min, replacing air for 25min, blowing off the air attached to the surfaces of the tubular furnace and the sample, heating to the nitriding temperature of 400 ℃ at the speed of 5 ℃/min, carrying out constant-temperature nitriding for 0.5h, continuously heating to the activation temperature of 700 ℃, carrying out constant-temperature activation for 1.0h, continuously introducing Ar gas into the tubular furnace, and cooling to 100 ℃ to obtain an activated sample;
the mass ratio of the KOH to the corncobs is 0.1; the mass ratio of the urea to the corncobs is 1;
(3) Washing an activated sample with 2mol/LHCl and deionized water to pH =7, and drying at 100 ℃ for 24h to obtain corncob-based activated carbon at different activation temperatures; is marked as CN1K0.1-700 (1).
Example 6
The method for preparing the corncob-based activated carbon in one step by using the 'nitrogen doping + KOH activation' process comprises the following steps of:
(1) Pretreatment: respectively cleaning corncobs with tap water and deionized water, drying in a 120 ℃ oven for 16h, pulverizing with a pulverizer, sieving to below 120 meshes, and drying for later use; pulverizing KOH and urea, and sieving with a sieve of less than 120 meshes for later use;
(2) "N doping + activation" one-step preparation of activated samples: mixing KOH, urea and corncobs according to a mass ratio and flatly paving the mixture in a tubular furnace; introducing Ar gas at a rate of 20mL/min to displace air for 25min, blowing off the air attached to the surfaces of the tubular furnace and the sample, heating to a nitriding temperature of 400 ℃ at a speed of 5 ℃/min, nitriding at a constant temperature for 0.5h, continuously heating to an activation temperature of 800 ℃, activating at a constant temperature for 0.5h, continuously introducing Ar gas into the tubular furnace, and cooling to 100 ℃ to obtain an activated sample;
the mass ratio of the KOH to the corncobs is 1; the mass ratio of the urea to the corncobs is 1;
(3) Washing an activated sample with 2mol/LHCl and deionized water until the pH is =7, and drying at 100 ℃ for 24h to obtain corncob-based activated carbon at different activation temperatures; is marked as CN1K1-800 (0.5).
Example 7
The method for preparing the corncob-based activated carbon by one step of nitrogen doping and KOH activation comprises the following steps of:
(1) Pretreatment: respectively cleaning corncobs with tap water and deionized water, drying in a 120 ℃ oven for 16h, pulverizing with a pulverizer, sieving to below 120 meshes, and drying for later use; pulverizing KOH and urea, and sieving with a sieve of less than 120 meshes for later use;
(2) "N doping + activation" one-step preparation of activated samples: mixing KOH, urea and corncobs according to a mass ratio and flatly paving the mixture in a tubular furnace; introducing Ar gas at the speed of 20mL/min, replacing air for 25min, blowing off the air attached to the surfaces of the tubular furnace and the sample, heating to the nitriding temperature of 400 ℃ at the speed of 5 ℃/min, carrying out constant-temperature nitriding for 0.5h, continuously heating to the activation temperature of 700 ℃, carrying out constant-temperature activation for 1.5h, continuously introducing Ar gas into the tubular furnace, and cooling to 100 ℃ to obtain an activated sample;
the mass ratio of the KOH to the corncobs is 0.3; the mass ratio of the urea to the corncobs is 1;
(3) Washing an activated sample with 2mol/LHCl and deionized water to pH =7, and drying at 100 ℃ for 24h to obtain corncob-based activated carbon at different activation temperatures; it is marked as CN1K0.3-700 (1.5).
Example 8
The method for preparing the corncob-based activated carbon by one step of nitrogen doping and KOH activation comprises the following steps of:
(1) Pretreatment: respectively cleaning corncobs with tap water and deionized water, drying in a 120 ℃ oven for 16h, pulverizing with a pulverizer, sieving to below 120 meshes, and drying for later use; pulverizing KOH and urea, and sieving with a sieve of less than 120 meshes for later use;
(2) "N doping + activation" one-step preparation of activated samples: mixing KOH, urea and corncobs according to a mass ratio and flatly paving the mixture in a tubular furnace; introducing Ar gas at a rate of 20mL/min to displace air for 25min, blowing off the air attached to the surfaces of the tubular furnace and the sample, heating to a nitriding temperature of 400 ℃ at a speed of 5 ℃/min, nitriding at a constant temperature for 0.5h, continuously heating to an activation temperature of 700 ℃, activating at a constant temperature for 0.5h, continuously introducing Ar gas into the tubular furnace, and cooling to 100 ℃ to obtain an activated sample;
the mass ratio of the KOH to the corncobs is 0.3; the mass ratio of the urea to the corncobs is 1;
(3) Washing an activated sample with 2mol/LHCl and deionized water to pH =7, and drying at 100 ℃ for 24h to obtain corncob-based activated carbon at different activation temperatures; it is marked as CN1K0.3-700 (0.5).
Comparative example 1
A method of making corncob-based activated carbon comprising the steps of:
(1) Pretreatment: respectively cleaning corncobs with tap water and deionized water, drying in a 120 ℃ oven for 16h, pulverizing with a pulverizer, sieving to below 120 meshes, and drying for later use; pulverizing KOH, and sieving with a sieve of less than 120 meshes for later use;
(2) Preparation of activated samples: mixing KOH and corncobs according to a mass ratio and flatly paving the mixture in a tubular furnace; introducing Ar gas at a flow rate of 200mL/min, replacing air for 25min, blowing off the air attached to the surfaces of the tubular furnace and the sample, heating to an activation temperature of 700 ℃ at a speed of 3 ℃/min, activating at a constant temperature for 1.0h, continuously introducing Ar gas into the tubular furnace, and cooling to 110 ℃ to obtain an activated sample;
the mass ratio of the KOH to the corncobs is 0.3;
(3) Washing the activated sample with 2mol/LHCl and deionized water to pH =7, and drying at 100 ℃ for 24h to obtain the corncob-based activated carbon, which is marked as CK0.3-700 (1);
comparative example 2
A method of making a corncob-based activated carbon comprising the steps of:
(1) Pretreatment: respectively cleaning corncobs with tap water and deionized water, drying in a 120 ℃ oven for 16h, pulverizing with a pulverizer, sieving to below 120 meshes, and drying for later use; pulverizing urea, and sieving with 120 mesh sieve;
(2) Preparation of activated samples: mixing urea and corncobs according to a mass ratio and flatly paving the mixture in a tubular furnace; introducing Ar gas at a flow rate of 200mL/min, replacing air for 25min, blowing off air attached to the surfaces of the tubular furnace and the sample, heating to a nitriding temperature of 450 ℃ at a speed of 3 ℃/min, carrying out constant-temperature nitriding for 0.5h, continuously heating to an activation temperature of 700 ℃, carrying out constant-temperature activation for 1.0h, continuously introducing Ar gas into the tubular furnace, and cooling to 110 ℃ to obtain an activated sample;
the mass ratio of the urea to the corncobs is 1;
(3) The activated sample was washed with 2mol/LHCl and deionized water to pH =7 and dried at 100 ℃ for 24h to give a corncob based activated carbon, noted CN1-700 (1).
Comparative example 3
A method of making a corncob-based activated carbon comprising the steps of:
(1) Pretreatment: respectively cleaning corncobs with tap water and deionized water, drying in a 120 ℃ oven for 16h, pulverizing with a pulverizer, sieving to below 120 meshes, and drying for later use; pulverizing KOH and urea, and sieving with a sieve of less than 120 meshes for later use;
(2) Preparation of activated samples: mixing KOH, urea and corncobs according to a mass ratio and flatly paving the mixture in a tubular furnace; introducing Ar gas at a flow rate of 200mL/min, replacing air for 25min, blowing off air attached to the surfaces of the tubular furnace and the sample, heating to a nitriding temperature of 450 ℃ at a speed of 3 ℃/min, nitriding at a constant temperature for 0.5h, continuously heating to an activation temperature of 500 ℃, activating at the constant temperature for 1.0h, continuously introducing Ar gas into the tubular furnace, and cooling to 110 ℃ to obtain an activated sample;
the mass ratio of the KOH to the corncobs is 0.3; the mass ratio of the urea to the corncobs is 1;
(3) Washing the activated sample with 2mol/LHCl and deionized water to pH =7, and drying at 100 ℃ for 24h to obtain the corncob-based activated carbon; is marked as CN1K0.3-500 (1).
Comparative example 4
A method of making a corncob-based activated carbon comprising the steps of:
(1) Pretreatment: respectively cleaning corncobs with tap water and deionized water, drying in a 120 ℃ oven for 16h, pulverizing with a pulverizer, sieving to below 120 meshes, and drying for later use; pulverizing KOH and urea, and sieving with a sieve of less than 120 meshes for later use;
(2) Preparation of activated samples: mixing KOH, urea and corncobs according to a mass ratio and flatly paving the mixture in a tubular furnace; introducing Ar gas at a flow rate of 200mL/min, replacing air for 25min, blowing off air attached to the surfaces of the tubular furnace and the sample, heating to a nitriding temperature of 450 ℃ at a speed of 3 ℃/min, carrying out constant-temperature nitriding for 0.5h, continuously heating to an activation temperature of 700 ℃, carrying out constant-temperature activation for 1.0h, continuously introducing Ar gas into the tubular furnace, and cooling to 110 ℃ to obtain an activated sample;
the mass ratio of the KOH to the corncobs is 0.05; the mass ratio of the urea to the corncobs is 0.1;
(3) Washing the activated sample with 2mol/LHCl and deionized water to pH =7, and drying at 100 ℃ for 24h to obtain the corncob-based activated carbon; is marked as CN1K0.05-700 (1).
The corncob-based activated carbon prepared in examples 1 to 8 and comparative examples 1 to 4 was treated according to the critical temperature N2BET detection is carried out according to adsorption and desorption standards, and the detection results are shown in the following table 1:
TABLE 1 BET test results of the floral corn cob-based activated carbon
Figure BDA0003722134810000081
The corncob-based activated carbon prepared in examples 1 to 8 and comparative examples 1 to 4 was measured for the ratio of oxygen-containing functional groups to nitrogen-containing functional groups according to the X-ray photoelectron spectroscopy (XPS) technique, and the results of the measurements are shown in tables 2 and 3 below:
TABLE 2 oxygen-containing functional group content ratio of corncob-based activated carbon
Item Name(s) C-O/％ C＝O/％ O-H/％ -COOH/％
Example 1 CN0.5K0.3-700(1) 12.76 35.03 26.13 26.08
Example 2 CN1K0.3-700(1) 15.95 31.16 30.11 22.78
Example 3 CN1.5K0.3-700(1) 14.62 34.21 27.47 23.7
Example 4 CN1K0.5-600(1) 13.61 26.9 25.73 33.76
Example 5 CN1K0.1-700(1) 12.68 28.84 28.35 30.13
Example 6 CN1K1-800(0.5) 16.85 22.77 25.17 35.21
Example 7 CN1K0.3-700(1.5) 15.62 32.55 28.97 22.86
Example 8 CN1K0.3-700(0.5) 15.39 33.63 29.01 21.97
Comparative example 1 CK0.3-700(1) 11.04 29.65 24.08 39.23
Comparative example 2 CN1-700(1) 11.38 21.73 21.53 45.36
Comparative example 3 CN1K0.3-500(1) 9.76 21.42 16.75 52.07
Comparative example 4 CN0.1K0.05-700(1) 10.06 20.17 22.12 47.65
TABLE 3 proportion of nitrogen-containing functional groups of corncob-based activated carbon
Figure BDA0003722134810000082
Figure BDA0003722134810000091
Applications of
The corncob-based activated carbon prepared in examples 1-8 and comparative examples 1-4 was used to perform CO in a fixed bed adsorption apparatus2Evaluating the adsorption performance, and applying the adsorption performance to simulated flue gas CO2The adsorption capacity of the catalyst to CO in the flue gas of a coal-fired power plant2Simulating the flue gas composition of coal-fired power plant 85%2+15％CO2The inlet flow rate was 20-60mL/min, the adsorption temperature was 20-30 ℃, and the adsorbent results are shown in Table 2:
TABLE 4 adsorption capacity of corncob-based activated carbon
Item Name(s) Amount of adsorption (mmol/g)
Example 1 CN0.5K0.3-700(1) 4.24
Example 2 CN1K0.3-700(1) 4.58
Example 3 CN1.5K0.3-700(1) 4.26
Example 4 CN1K0.5-600(1) 3.89
Example 5 CN1K0.1-700(1) 4.09
Example 6 CN1K1-800(0.5) 3.81
Example 7 CN1K0.3-700(1.5) 4.56
Example 8 CN1K0.3-700(0.5) 4.53
Comparative example 1 CK0.3-700(1) 2.87
Comparative example 2 CN1-700(1) 2.63
Comparative example 3 CN1K0.3-500(1) 1.57
Comparative example 4 CN0.1K0.05-700(1) 2.55
As can be seen from the schematic diagram of the invention, the corn cob based activated carbon in the diagram, which adopts KOH activation and 'urea + KOH activation', is a test of activated carbon prepared under the optimal condition, and only the activating agent is different, and other conditions are the same; compared with KOH activation, the activated carbon prepared by one step of urea and KOH activation is mainly microporous, but has larger specific surface area and pore volume, more developed pore structure and more abundant functional groups containing O and N, and is particularly beneficial to CO2The content of adsorbed C-O, O-H and-NH-is obviously increased, the surface of the activated carbon is rougher, the porosity is more developed, the adsorption capacity is improved from 2.87 to 4.58mmol/g, and is improved by 60%. The corncob-based activated carbon prepared by one step of 'nitrogen doping and KOH activation' has simple and convenient preparation process, developed micropore pore structure, high content of O-H, C-O and-NH-functional groups, CO2The adsorption capacity is higher than 3.80mmol/g, and the industrial application requirement is met.
Of course, the foregoing is only a preferred embodiment of the invention and should not be taken as limiting the scope of the embodiments of the invention. The present invention is not limited to the above examples, and equivalent changes and modifications made by those skilled in the art within the spirit of the present invention should be included in the scope of the present invention.

Claims (7)

1. A method for preparing corncob-based activated carbon in one step by 'nitrogen doping and KOH activation' is characterized by comprising the following steps: the method comprises the following steps:
(1) Pretreatment: cleaning corn cob, oven drying, pulverizing, and sieving; pulverizing nitrogen source and activator, and sieving;
(2) "N doping + activation" one-step preparation of activated samples: mixing an activating agent with corn flour and flatly paving the mixture in a tube furnace; introducing inert gas to replace air, heating to the nitriding temperature of 400-450 ℃ at the speed of 3-10 ℃/min, nitriding at constant temperature for 0.5-1.0h, continuing heating to the activating temperature of 600-800 ℃, activating at constant temperature for 0.5-1.0h, introducing the inert gas, cooling to 100-110 ℃ to obtain an activated sample;
(3) Washing an activated sample to be neutral by using hydrochloric acid and deionized water, and drying to obtain corncob-based activated carbon at different activation temperatures;
the nitrogen source is urea; the activating agent is KOH;
the mass ratio of the activating agent to the corncobs is 0.1-1;
the mass ratio of the nitrogen source to the corncobs is 0.5-1.5.
2. The "nitrogen doped + KOH activated" one-step process for the production of corncob based activated carbon as claimed in claim 1, wherein: in the step (1), the drying temperature of the corncobs is 120-130 ℃; the drying time is 16-20h.
3. The "nitrogen doped + KOH activated" one-step process for manufacturing corncob based activated carbon as claimed in claim 1 wherein: the mesh number sieved in the step (1) is below 120 meshes.
4. The "nitrogen doped + KOH activated" one-step process for the production of corncob based activated carbon as claimed in claim 1, wherein: and (2) introducing inert gas Ar into the tube furnace at the flow rate of 210-300mL/min for 20-25min.
5. The "nitrogen doped + KOH activated" one-step process for the production of corncob based activated carbon as claimed in claim 1, wherein: the step of washing the activated sample to be neutral in the step (3) is to wash the activated sample by hydrochloric acid with the concentration of 2mol/L and then wash the activated sample by deionized water.
6. The "nitrogen doped + KOH activated" one-step process for the production of corncob based activated carbon as claimed in claim 1, wherein: in the step (3), the drying temperature is 90-100 ℃, and the time is 24-28h.
7. Use of the "nitrogen doped + KOH activated" one-step manufactured corncob based activated carbon as described in any of claims 1-6 wherein: in a fixed bed adsorption evaluation device, the air inlet flow rate is 20-60mL/min, the adsorption temperature is 20-70 ℃, and the corncob-based active carbon prepared in one step by 'nitrogen doping and KOH activation' is evaluated on line for CO in the flue gas of a coal-fired power plant2The adsorption performance and the adsorption capacity are large.
CN202210765987.0A 2022-06-30 2022-06-30 Method for preparing corncob-based activated carbon in one step by nitrogen doping and KOH activation and application thereof Withdrawn CN115259152A (en)

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