CN114733485B - High-thermal-stability carbonaceous adsorbent based on boron-nitrogen modified lignin and application thereof - Google Patents
High-thermal-stability carbonaceous adsorbent based on boron-nitrogen modified lignin and application thereof Download PDFInfo
- Publication number
- CN114733485B CN114733485B CN202210471869.9A CN202210471869A CN114733485B CN 114733485 B CN114733485 B CN 114733485B CN 202210471869 A CN202210471869 A CN 202210471869A CN 114733485 B CN114733485 B CN 114733485B
- Authority
- CN
- China
- Prior art keywords
- nitrogen
- adsorbent
- lignin
- boron
- adsorption
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
- B01J20/20—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising free carbon; comprising carbon obtained by carbonising processes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
- B01D53/04—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
- B01D53/04—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
- B01D53/0454—Controlling adsorption
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
- B01J20/28002—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their physical properties
- B01J20/28011—Other properties, e.g. density, crush strength
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/30—Processes for preparing, regenerating, or reactivating
- B01J20/3078—Thermal treatment, e.g. calcining or pyrolizing
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2256/00—Main component in the product gas stream after treatment
- B01D2256/10—Nitrogen
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2256/00—Main component in the product gas stream after treatment
- B01D2256/12—Oxygen
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2257/00—Components to be removed
- B01D2257/20—Halogens or halogen compounds
- B01D2257/206—Organic halogen compounds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2257/00—Components to be removed
- B01D2257/70—Organic compounds not provided for in groups B01D2257/00 - B01D2257/602
- B01D2257/702—Hydrocarbons
- B01D2257/7027—Aromatic hydrocarbons
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2258/00—Sources of waste gases
- B01D2258/02—Other waste gases
- B01D2258/0283—Flue gases
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2220/00—Aspects relating to sorbent materials
- B01J2220/40—Aspects relating to the composition of sorbent or filter aid materials
- B01J2220/48—Sorbents characterised by the starting material used for their preparation
- B01J2220/4812—Sorbents characterised by the starting material used for their preparation the starting material being of organic character
- B01J2220/4837—Lignin
Abstract
The invention relates to a high-thermal-stability carbonaceous adsorbent based on boron nitrogen modified lignin and application thereof, wherein the adsorbent takes lignin as a carbon source, lignin, boric acid and urea are mixed, and the lignin-based B-C-N adsorbent with stable lignin is obtained after high-temperature heat treatment, wherein the nitrogen element content in the adsorbent is controlled to be more than 2 percent of the proportion of all elements, the existence form of nitrogen element is mainly pyridine nitrogen and pyrrole nitrogen, the sum of the pyridine nitrogen and the pyrrole nitrogen is controlled to be more than 30 percent of the relative proportion of all nitrogen-containing substances, and the thermal stability reduction rate of the adsorbent is controlled to be less than 10 percent. According to the method, the boron carbon nitrogen is subjected to synergistic effect under specific conditions, so that the thermal stability of the carbon material is obviously improved, the reduction rate of the adsorption capacity of the material after heat treatment is controlled within 10%, and the replacement cost of the adsorbent is reduced.
Description
Technical Field
The invention belongs to the field of environmental pollution control, and particularly relates to a high-thermal-stability carbonaceous adsorbent based on boron-nitrogen modified lignin and application thereof.
Background
The chlorinated aromatic hydrocarbon pollutants such as dioxin and the like with high toxicity in the incineration flue gas have three effects of carcinogenesis, teratogenesis and mutagenesis, and form threat to environmental safety and human survival. The adsorption technology is the most commonly used gas purification technology, is one of the mainstream technology of dioxin treatment at present, and has the advantages of low energy consumption, high efficiency, mature technology and the like. Activated carbon has higher specific surface area and rich porosity, and is the most commonly used adsorption material. However, the high heat condition in the thermal desorption regeneration process of the saturated carbonaceous adsorbent causes oxidization of the carbonaceous material when meeting oxygen, influences the adsorption capacity after regeneration, and increases the replacement cost of the adsorbent. Therefore, the preparation of the carbonaceous adsorbent with high thermal stability has important research value on the low-cost and high-efficiency purification of the chlorinated aromatic hydrocarbon.
Ajayan et al studied a method for preparing boron-nitrogen-carbon (BCN) material with mesoporous carbon as a template, the preparation process being as follows: 20mg of mesoporous carbon and 200mg of boron oxide are mixed and reacted for 30min at 1450-1550 ℃ under the condition of nitrogen to obtain the mesoporous BCN material (Chemistry ofMaterals,2005,17,24), and the boron carbon nitrogen material obtained by the method has higher operation temperature, and the thermal stability is still lower although nitrogen and boron are introduced, so that the thermal stability is still required to be further improved. Therefore, the preparation of carbonaceous adsorption with excellent thermal stability and high-efficiency chlorinated aromatic hydrocarbon pollutant adsorption capacity is a technical problem to be solved urgently.
Disclosure of Invention
The invention aims to provide a high-thermal-stability carbonaceous adsorbent based on boron-nitrogen modified lignin and application thereof, and the method obviously improves the thermal stability of a carbon material by making boron-carbon-nitrogen generate synergistic effect under specific conditions, so that the reduction rate of the adsorption capacity of the material after heat treatment is controlled within 10 percent, and the replacement cost of the adsorbent is reduced.
The invention is realized by the following technical scheme:
the high-thermal-stability carbonaceous adsorbent based on boron nitrogen modified lignin is characterized in that lignin is used as a carbon source, lignin, boric acid and urea are mixed, and the lignin-based B-C-N adsorbent with stable lignin is obtained after high-temperature heat treatment, wherein the nitrogen element content in the adsorbent is controlled to be more than 2% of the proportion of all elements, the existence form of nitrogen element is mainly pyridine nitrogen and pyrrole nitrogen, the sum of the pyridine nitrogen and the pyrrole nitrogen is controlled to be more than 30% of the relative proportion of all nitrogen-containing substances, and the thermal stability reduction rate of the adsorbent is controlled to be within 10%.
On one hand, the aromatic nature of the lignin promotes the carbon material to be more favorable for graphitization transformation under boron-nitrogen modification, and the pollutant adsorption capacity of chlorinated aromatic hydrocarbon is improved through pi-pi conjugation; in the pyrolysis process, boron nitrogen reacts with carbon elements in the lignin aromatic structure, the generated boron carbonitride forms a thermally stable hexagonal boron nitride structure in a single-layer carbon structure, boron doping promotes the conversion of nitrogen existence form from graphitized nitrogen to pyridine nitrogen and pyrrole nitrogen, the proportion of the graphitized nitrogen to the pyridine nitrogen and the pyrrole nitrogen is improved, the modified carbonaceous material is caused to change in the aspects of surface oxygen functional groups and electronic structures, and the oxidation resistance sintering capacity of the adsorbent is improved.
The high temperature heat treatment temperature is 400-700 ℃, preferably 450-650 ℃.
The high-temperature heat treatment temperature is 490-550 ℃, the heating rate is 4-6 ℃/min, the heat treatment time is 2-6h, and the heat stability reduction rate of the adsorbent is controlled within 5%.
A high-thermal-stability carbonaceous adsorbent based on boron-nitrogen modified lignin comprises the following steps:
(1) And (3) preparing a boron carbon nitrogen mixed material: cleaning lignin, vacuum drying at 60-70 ℃ for 24 hours, grinding and sieving with a 100-130 mesh sieve, mixing the ground lignin, boric acid and urea with water according to a mass ratio of 10:3:30, and putting the mixture into a ball milling tank for ball milling for 20-30 hours; the ball-milled mixture was then dried overnight in a vacuum oven at 75-85 ℃ to give a dried solid. Wherein the water is added in an amount to ensure complete wetting or dissolution of lignin, boric acid and urea.
(2) Boron carbon nitrogen adsorbent preparation: and (3) placing the dried solid obtained in the step (1) in a pyrolysis furnace, and carrying out pyrolysis reaction in a nitrogen atmosphere to obtain the high-thermal-stability carbonaceous adsorbent of boron-nitrogen modified lignin, wherein the pyrolysis temperature is 400-700 ℃, the heating rate is 3-8 ℃/min, and the heat treatment time is 2-6h. Preferably the pyrolysis temperature is 450-650 ℃.
Preferably, the lignin of step (1) comprises commercial alkaline lignin, sulfonate lignin, and the like.
The application of the high-thermal-stability carbonaceous adsorbent based on boron-nitrogen modified lignin is that the adsorbent is used for adsorbing and removing chlorinated aromatic hydrocarbon pollutants: the adsorbent is used for adsorbing and removing chlorinated aromatic hydrocarbon pollutants in incineration flue gas, o-dichlorobenzene is used as a representative compound of chlorinated aromatic hydrocarbon, and a fixed bed adsorption-on-line detection device is used for continuously testing the adsorption-desorption performance of the adsorbent; detecting the tail gas by GC-FID, and calculating to obtain the adsorption capacity of the adsorbent; after saturated adsorption, the adsorbent was subjected to thermal desorption regeneration (regeneration temperature: 300 ℃ C.) and subjected to continuous adsorption test again. The effect of boron nitrogen doping on the thermal stability of the carbonaceous adsorbent is demonstrated by comparing the difference in adsorption capacities before and after heat treatment.
The chlorinated aromatic hydrocarbon pollutant comprises dioxin, o-dichlorobenzene, chlorobenzene and the like. The adsorption capacity of the initial adsorbent is higher than 200mg/g.
Compared with the prior art, the invention has the beneficial effects that:
1. according to the invention, the carbon source adopts solid waste lignin, and the thermal stability of the adsorbent is obviously improved through boron and nitrogen modification, so that the adsorption capacity of the regenerated adsorbent after regeneration is reduced to be within 10%, and the replacement cost of the adsorbent is reduced.
2. Lignin contains a large number of aromatic structures, and on one hand, the aromatic property of lignin promotes the graphitization transformation of the carbon material under the modification of boron and nitrogen, and the pollutant adsorption capacity of chlorinated aromatic hydrocarbon is improved through pi-pi conjugation; in the pyrolysis process, on the other hand, boron nitrogen reacts with carbon element in the lignin aromatic structure to form a thermally stable hexagonal boron nitride structure.
3. According to the invention, the synergistic effect of boron nitrogen and lignin is promoted by medium-temperature modification at 400-700 ℃, boron doping promotes the conversion of the existence form of nitrogen element from graphitized nitrogen to pyridine nitrogen pyrrole nitrogen, the relative proportion of the two is improved, the oxygen functional group and the electronic structure on the surface of the modified carbonaceous material are changed, and the oxidation resistance sintering capability of the adsorbent is improved.
Detailed Description
The invention will now be described in detail with reference to specific examples, which are not intended to limit the scope of the invention.
Example 1
1) Preparation of high-thermal-stability carbonaceous adsorbent based on boron-nitrogen modified lignin: weighing 5g of alkaline lignin and active carbon respectively, cleaning to remove impurities, vacuum drying at 60 ℃ for 24 hours, grinding, sieving with a 120-mesh sieve, and storing in a dryer for standby. Respectively mixing alkaline lignin, active carbon, boric acid and urea with a proper amount of water according to a ratio of 10:3:30, putting 5g of the mixture into a 100ml ball milling tank, ball milling for 24 hours at a speed of 200rpm, drying the obtained mixed material in a vacuum oven at 80 ℃ for 8-10 hours, and then pyrolyzing the mixed material at 500 ℃ for 4 hours under nitrogen atmosphere, wherein the temperature rising rate is 5 ℃/min. And fully grinding the pyrolysis product to obtain boron nitrogen modified lignin (BCN-L) and BN modified activated carbon (BCN-A). Unmodified Lignin (LC) adsorbents were prepared as above, except that boric acid and urea were not added.
2) O-dichlorobenzene adsorption experiment process
And (3) evaluating the adsorption capacity of the BCN adsorbent to the o-dichlorobenzene before and after heat treatment by using a fixed bed adsorption-on-line detection system, detecting tail gas by GC-FID, and calculating to obtain the adsorption quantity.
Adsorption conditions: the total gas flow is 60ml/min,10% O 2 /N 2 The mixed gas is carrier gas, the concentration of o-dichlorobenzene is 100ppm, the mass of the adsorbent is 100mg, and the adsorption temperature is 35 ℃;
heat treatment conditions: the desorption temperature is 300 ℃, the heating rate is 3 ℃/min, and 10% O is adopted 2 /N 2 The mixed gas is used as a heat treatment atmosphere.
3) Saturation capacity q of adsorption of O-dichlorobenzene by adsorbent s The calculation method is as follows:
wherein q s To the saturated adsorption capacity of the adsorbent, t s For the time of saturated adsorption, Q is the total gas flow, m is the mass of the adsorbent, C 0 The initial o-dichlorobenzene concentration (mg/l) and the outlet o-dichlorobenzene concentration C.
TABLE 1 adsorption Capacity reduction before and after Heat treatment of different BCN adsorbents described in example 1
As is clear from Table 1, the unmodified adsorbent (LC) had a decrease in adsorption capacity of LC of 42.8% after heat treatment. Lignin BCN-L after BN modification, whose adsorption capacity after regeneration was reduced to 4.6% (< 10%). The adsorption capacity of the modified BN activated carbon after heat treatment is reduced by 17.8 percent and is still higher than 10 percent, which shows that the heat stability of the modified BN activated carbon is lower than that of the BN modified lignin adsorbent. The experiment shows that BN doping can effectively improve the stability of the carbonaceous adsorbent. Although the BN modified activated carbon can also improve the stability, the thermal stability of the selected activated carbon matrix still cannot meet the requirement, and the synergistic effect of the selected lignin and BN modification in the method obviously improves the thermal stability of the adsorbent and can meet the target requirement.
Example 2
1) Preparation of high-thermal-stability carbonaceous adsorbent based on boron-nitrogen modified lignin: mixing alkaline lignin, boric acid and urea with a proper amount of water according to a ratio of 10:3:30, putting 5g of the mixture into a 100ml ball milling tank, carrying out ball milling for 24 hours at a speed of 200rpm, drying the obtained mixed material in a vacuum oven at 80 ℃ for 8-10 hours, and then carrying out pyrolysis for 4 hours under nitrogen atmosphere at 200 ℃, 300 ℃, 400 ℃, 500 ℃, 700 ℃ and 800 ℃ respectively, wherein the heating rate is 5 ℃/min. And fully grinding the pyrolysis product to obtain the BN modified adsorbent (BCN-L200/300/400/500/700/800).
2) O-dichlorobenzene adsorption experiment process
And (3) evaluating the adsorption capacity of the BCN adsorbent to the o-dichlorobenzene before and after heat treatment by using a fixed bed adsorption-on-line detection system, detecting tail gas by GC-FID, and calculating to obtain the adsorption quantity.
Adsorption conditions: the total gas flow is 60ml/min,10% O 2 /N 2 The mixed gas is carrier gas, the concentration of o-dichlorobenzene is 100ppm, the mass of the adsorbent is 100mg, and the adsorption temperature is 35 ℃;
heat treatment conditions: the desorption temperature is 300 ℃, the heating rate is 3 ℃/min, and 10% O is adopted 2 /N 2 The mixed gas is used as a heat treatment atmosphere.
3) Saturation capacity q of adsorption of O-dichlorobenzene by adsorbent s The calculation method is as follows:
wherein q s To the saturated adsorption capacity of the adsorbent, t s For the time of saturated adsorption, Q is the total gas flow, m is the mass of the adsorbent, C 0 For initial o-dichlorobenzene concentration (mg/l), CIs the outlet o-dichlorobenzene concentration.
Table 2 example 2 adsorption capacity reduction before and after BCN adsorbent heat treatment at different pyrolysis temperatures
As is clear from Table 2, when the pyrolysis temperature is too low (< 400 ℃ C.), the adsorption capacity is reduced by more than 10%. Wherein the pyrolysis temperature is 500 ℃, and the reduction of the adsorption capacity is 4.6 percent at minimum. The adsorption stability is reduced by continuously increasing the temperature (> 500 ℃), and the reduction of the adsorption capacity after heat treatment is 9.4% when the pyrolysis temperature is 700 ℃. When the pyrolysis temperature is 800 deg.f, the adsorption capacity is reduced by more than 10%, because the nitrogen content and the nitrogen proportion of pyridine pyrrole in the material are reduced due to the high temperature, resulting in reduced stability of the material. The total content of nitrogen elements and the proportion of pyridine nitrogen and pyrrole nitrogen in the modified adsorbent are influenced by different pyrolysis temperatures, so that the sintering resistance of the adsorbent is different, but the requirement of high thermal stability can be met within a given range, namely the reduction ratio of the adsorption capacity is controlled within 10 percent. In combination, 500℃is preferred as the optimal heat treatment temperature.
Example 3
1) Preparation of boron carbon nitrogen adsorbent: mixing alkaline lignin, boric acid and urea with a proper amount of water according to a ratio of 10:3:30, putting 5g of the mixture into a 100ml ball milling tank, carrying out ball milling for 24 hours at a speed of 200rpm, drying the obtained mixed material in a vacuum oven at 80 ℃ for 8-10 hours, then carrying out pyrolysis at 500 ℃ in a nitrogen atmosphere, wherein the heating rate is 5 ℃/min, and the pyrolysis time of the adsorbent is 2 hours, 4 hours and 6 hours. And fully grinding the pyrolysis product to obtain the BN modified adsorbent (BCN-L2 h/4h/6 h).
2) O-dichlorobenzene adsorption experiment process
And (3) evaluating the adsorption capacity of the BCN-L adsorbent to the o-dichlorobenzene before and after heat treatment by using a fixed bed adsorption-on-line detection system, and detecting tail gas by using GC-FID, and calculating to obtain the adsorption quantity.
Adsorption conditions: the total gas flow is 60ml/min,10% O 2 /N 2 The mixed gas is used as carrier gasThe dichlorobenzene concentration is 100ppm, the mass of the adsorbent is 100mg, and the adsorption temperature is 35 ℃;
heat treatment conditions: the desorption temperature is 300 ℃, the heating rate is 3 ℃/min, and 10% O is adopted 2 /N 2 The mixed gas is used as a heat treatment atmosphere.
3) Saturation capacity q of adsorption of O-dichlorobenzene by adsorbent s The calculation method is as follows:
wherein q s To the saturated adsorption capacity of the adsorbent, t s For the time of saturated adsorption, Q is the total gas flow, m is the mass of the adsorbent, C 0 The initial o-dichlorobenzene concentration (mg/l) and the outlet o-dichlorobenzene concentration C.
TABLE 3 reduction of adsorption capacity before and after thermal treatment of BCN adsorbent at different pyrolysis times as described in example 3
Table 3 further shows that the adsorption capacity of BCN-2h/4h/6h is reduced by less than 5% after BN modification. Too short a pyrolysis time (< 2 hours) results in incomplete pyrolysis of lignin and insufficient reaction with boron nitrogen, possibly resulting in slightly lower adsorption capacity. The pyrolysis time is too long (6 hours), the adsorption capacity reduction is not obviously improved, but extra cost is increased. Comprehensively, we choose 4h as the optimal heat treatment time.
Example 4
1) Preparation of boron carbon nitrogen adsorbent: mixing alkaline lignin, rice hulls and corn stalks with boric acid and urea in a mass ratio of 10:3:30 respectively with a proper amount of water, putting 5g of the mixture into a 100ml ball milling tank, carrying out ball milling for 24 hours at a speed of 200rpm, drying the obtained mixed material in a vacuum oven at 80 ℃ for 8-10 hours, and then carrying out pyrolysis for 4 hours at 500 ℃ under nitrogen atmosphere, wherein the heating rate is 5 ℃/min. And fully grinding the pyrolysis product to obtain the boron carbon nitrogen adsorbents of different types.
2) O-dichlorobenzene adsorption experiment process
And (3) evaluating the adsorption capacity of the BCN adsorbent to the o-dichlorobenzene before and after heat treatment by using a fixed bed adsorption-on-line detection system, detecting tail gas by GC-FID, and calculating to obtain the adsorption quantity.
Adsorption conditions: the total gas flow is 60ml/min,10% O 2 /N 2 The mixed gas is carrier gas, the concentration of o-dichlorobenzene is 100ppm, the mass of the adsorbent is 100mg, and the adsorption temperature is 35 ℃;
heat treatment conditions: the desorption temperature is 300 ℃, the heating rate is 3 ℃/min, and 10% O is adopted 2 /N 2 The mixed gas is used as a heat treatment atmosphere.
3) Saturation capacity q of adsorption of O-dichlorobenzene by adsorbent s The calculation method is as follows:
wherein q s To the saturated adsorption capacity of the adsorbent, t s For the time of saturated adsorption, Q is the total gas flow, m is the mass of the adsorbent, C 0 The initial o-dichlorobenzene concentration (mg/l) and the outlet o-dichlorobenzene concentration C.
TABLE 4 example 4 reduction of adsorption Capacity of BCN adsorbents of different carbon sources before and after Heat treatment
Table 4 shows that the BN modified lignin maintains higher thermal stability after heat treatment, and the adsorption capacity reduction amplitude of the BN modified rice hulls and the corn stalks after heat treatment is higher than 10 percent, so that the high thermal stability required by the reduction of the adsorption capacity of the application cannot be met. The experiment shows that the BN and the three-dimensional network lignin have synergistic effect, and can maintain higher thermal stability under proper conditions.
The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the precise form disclosed, and any such modifications, equivalents, and alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.
The invention is applicable to the prior art where it is not described.
Claims (9)
1. The high-heat-stability carbonaceous adsorbent based on boron nitrogen modified lignin is characterized in that lignin is taken as a carbon source, lignin, boric acid and urea are mixed, and the lignin-based B-C-N adsorbent with stable lignin is obtained after high-temperature heat treatment, wherein the nitrogen element content in the adsorbent is controlled to be more than 2% of the proportion of all elements, the existence form of nitrogen element is mainly pyridine nitrogen and pyrrole nitrogen, the sum of the pyridine nitrogen and the pyrrole nitrogen is controlled to be more than 30% of the relative proportion of all nitrogen-containing substances, and the heat stability reduction rate of the adsorbent is controlled to be within 10%; the high-temperature heat treatment temperature is 400-700 ℃, and the heat treatment time is 2-6h.
2. The high thermal stability carbonaceous adsorbent based on boron nitrogen modified lignin according to claim 1, wherein the aromatic nature of lignin promotes on the one hand graphitization transformation of carbon material under boron nitrogen modification, and improves adsorption capacity of chlorinated aromatic hydrocarbon such pollutants through pi-pi conjugation; in the pyrolysis process, boron nitrogen reacts with carbon elements in the lignin aromatic structure, the generated boron carbonitride forms a thermally stable hexagonal boron nitride structure in a single-layer carbon structure, boron doping promotes the conversion of nitrogen existence form from graphitized nitrogen to pyridine nitrogen and pyrrole nitrogen, the proportion of the pyridine nitrogen to the pyrrole nitrogen is increased, the modified carbonaceous material is caused to change in the aspects of surface oxygen functional groups and electronic structures, and the oxidation resistance sintering capacity of the adsorbent is improved.
3. The high thermal stability carbonaceous adsorbent based on boron nitrogen modified lignin of claim 1 wherein the high temperature heat treatment temperature is 450-650 ℃.
4. The high thermal stability carbonaceous adsorbent based on boron nitrogen modified lignin according to claim 1, wherein the high temperature heat treatment temperature is 490-550 ℃, the heating rate is 4-6 ℃/min, and the thermal stability decline rate of the adsorbent is controlled within 5%.
5. The high-thermal-stability carbonaceous adsorbent based on boron-nitrogen modified lignin is characterized in that the preparation process of the adsorbent is as follows:
(1) And (3) preparing a boron carbon nitrogen mixed material: cleaning lignin, vacuum drying at 60-70deg.C for 15-36 hr, grinding, sieving with 100-130 mesh sieve, mixing the ground lignin, boric acid and urea with water at a mass ratio of 10:3:30, and ball milling for 20-30 hr; then placing the mixture after ball milling in a vacuum oven at 75-85 ℃ for drying overnight to obtain a dried solid; wherein the water is added in an amount to ensure that lignin, boric acid and urea are completely soaked or dissolved;
(2) Boron carbon nitrogen adsorbent preparation: and (3) placing the dried solid obtained in the step (1) in a pyrolysis furnace, and carrying out pyrolysis reaction in a nitrogen atmosphere to obtain the high-thermal-stability carbonaceous adsorbent of boron-nitrogen modified lignin, wherein the pyrolysis temperature is 400-700 ℃, the heating rate is 3-8 ℃/min, and the heat treatment time is 2-6h.
6. The boron nitrogen modified lignin-based high thermal stability carbonaceous adsorbent of claim 5 wherein the lignin of step (1) comprises at least one of a commercial alkaline lignin or a sulfonate lignin; the pyrolysis temperature is 450-650 ℃.
7. Use of the high thermal stability carbonaceous adsorbent based on boron nitrogen modified lignin according to any one of claims 1 to 6, characterized in that the adsorbent is used for adsorbing and removing chlorinated aromatic hydrocarbon pollutants in incineration flue gas, and the adsorption-desorption performance of the adsorbent is continuously tested by using a fixed bed adsorption-on-line detection device; detecting the tail gas by GC-FID, and calculating to obtain the adsorption capacity of the adsorbent; and after saturated adsorption, carrying out thermal desorption regeneration on the adsorbent, and carrying out continuous adsorption test again, wherein the thermal desorption regeneration temperature of the adsorbent is 300 ℃.
8. The use of a boron nitrogen modified lignin based high thermal stability carbonaceous adsorbent according to claim 7 wherein the chlorinated aromatic hydrocarbon contaminant is dioxin, ortho-dichlorobenzene or chlorobenzene.
9. The use of the high thermal stability carbonaceous adsorbent based on boron nitrogen modified lignin according to claim 8, wherein o-dichlorobenzene is used as a representative compound of chlorinated aromatic hydrocarbon, the total gas flow is 60ml/min, the o-dichlorobenzene concentration is 100ppm, the mass of the adsorbent is 100mg, the adsorption temperature is 35 ℃, and the adsorption capacity of the initial adsorbent is higher than 200mg/g in a continuous adsorption test.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210471869.9A CN114733485B (en) | 2022-04-29 | 2022-04-29 | High-thermal-stability carbonaceous adsorbent based on boron-nitrogen modified lignin and application thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210471869.9A CN114733485B (en) | 2022-04-29 | 2022-04-29 | High-thermal-stability carbonaceous adsorbent based on boron-nitrogen modified lignin and application thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114733485A CN114733485A (en) | 2022-07-12 |
| CN114733485B true CN114733485B (en) | 2023-08-01 |
Family
ID=82285833
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210471869.9A Active CN114733485B (en) | 2022-04-29 | 2022-04-29 | High-thermal-stability carbonaceous adsorbent based on boron-nitrogen modified lignin and application thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114733485B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115784668B (en) * | 2022-11-30 | 2023-06-20 | 江苏乐尔环境科技股份有限公司 | Stabilization treatment method of waste incineration fly ash |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104689857A (en) * | 2015-03-26 | 2015-06-10 | 中国科学院青岛生物能源与过程研究所 | Preparing method for nitrogen-doped porous carbon material, catalyst comprising material and application of material |
| CN109336085A (en) * | 2018-09-29 | 2019-02-15 | 中国林业科学研究院林业新技术研究所 | Lignin-base charcoal nanometer sheet energy storage material and its preparation method and application |
| CN113385212A (en) * | 2021-06-11 | 2021-09-14 | 青岛化赫医药科技有限公司 | Non-metal doped carbon-based catalyst for preparing enol and method for preparing enol by using same |
| CN114408917A (en) * | 2022-01-17 | 2022-04-29 | 华南理工大学 | Lignin-based nitrogen-doped porous carbon material with high specific surface area and preparation method and application thereof |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10293329B2 (en) * | 2008-06-18 | 2019-05-21 | Board Of Trustees Of The University Of Arkansas | Doped-carbon composites, synthesizing methods and applications of the same |
-
2022
- 2022-04-29 CN CN202210471869.9A patent/CN114733485B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104689857A (en) * | 2015-03-26 | 2015-06-10 | 中国科学院青岛生物能源与过程研究所 | Preparing method for nitrogen-doped porous carbon material, catalyst comprising material and application of material |
| CN109336085A (en) * | 2018-09-29 | 2019-02-15 | 中国林业科学研究院林业新技术研究所 | Lignin-base charcoal nanometer sheet energy storage material and its preparation method and application |
| CN113385212A (en) * | 2021-06-11 | 2021-09-14 | 青岛化赫医药科技有限公司 | Non-metal doped carbon-based catalyst for preparing enol and method for preparing enol by using same |
| CN114408917A (en) * | 2022-01-17 | 2022-04-29 | 华南理工大学 | Lignin-based nitrogen-doped porous carbon material with high specific surface area and preparation method and application thereof |
Non-Patent Citations (1)
| Title |
|---|
| Chang-Mao Hung等.Suppression of polycyclic aromatic hydrocarbon formation during pyrolytic production of lignin-based biochar via nitrogen and boron co-doping.2022,第355卷第127246-1页至第127246-8页. * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN114733485A (en) | 2022-07-12 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Azmi et al. | Recent advances in biomass based activated carbon for carbon dioxide capture–A review | |
| CN114733485B (en) | High-thermal-stability carbonaceous adsorbent based on boron-nitrogen modified lignin and application thereof | |
| CN110327879B (en) | Is suitable for flue gas CO2Preparation method and product of adsorbed biomass porous carbon | |
| CN115043479B (en) | Nitrogen-doped biochar as well as preparation method and application thereof | |
| CN101716491A (en) | Method for preparing heavy metal adsorbent by carbonizing lakebed sludge | |
| CN110935280A (en) | Nitrogen-doped mesoporous bamboo-based biochar and application thereof | |
| CN104525110A (en) | Nitrogen-enriched active biomass coke and preparation method thereof | |
| CN102658084A (en) | Preparation method of nickel nitrate modified sludge activated carbon | |
| JP2688386B2 (en) | SOx removal method using carbon catalyst | |
| CN112675814A (en) | Silicon-rich biomass-based biochar/mesoporous silica composite material and preparation method and application thereof | |
| CN112938969A (en) | Method for preparing nitrogen-sulfur co-doped activated carbon by pore-forming/doping integrated activating agent and application of method | |
| CN114797766A (en) | Porous biochar and preparation method and application thereof | |
| CN104801306B (en) | A kind of powder activity Pd/carbon catalyst prepared using turf as raw material and preparation method | |
| US9120079B1 (en) | High capacity carbon dioxide sorbent | |
| CN113101925B (en) | Preparation method and application of lignin-based adsorption-catalysis material | |
| CN113800517B (en) | Preparation method of water-resistant rice hull-based granular activated carbon | |
| CN111974357B (en) | Method for preparing chlorinated aromatic hydrocarbon composite adsorbent for incineration flue gas by using lignin | |
| CN112479206A (en) | Preparation method of high-performance active coke for flue gas purification | |
| CN106732511B (en) | A kind of biomass carbon denitrating catalyst and its preparation method and application | |
| CN114700036B (en) | Modified tobacco stem-based biomass hierarchical porous carbon and preparation method and application thereof | |
| CN113753893B (en) | Method for preparing coke by regenerating worn waste coke of flue gas purification active coke | |
| CN115254023B (en) | Preparation method of metal-loaded alkaline porous biochar and application of metal-loaded alkaline porous biochar in odor adsorption | |
| CN115557496B (en) | Method for preparing desulfurization and denitrification active carbon based on mineral catalysis index coal blending | |
| CN220766514U (en) | High-temperature carbonization activation furnace | |
| CN107539986B (en) | A kind of activated coke and preparation method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |