CN111604031B - Modified non-carbon-based mercury removal adsorbent and preparation method thereof - Google Patents

Modified non-carbon-based mercury removal adsorbent and preparation method thereof Download PDF

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CN111604031B
CN111604031B CN202010474009.1A CN202010474009A CN111604031B CN 111604031 B CN111604031 B CN 111604031B CN 202010474009 A CN202010474009 A CN 202010474009A CN 111604031 B CN111604031 B CN 111604031B
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adsorbent
polyvinyl chloride
mercury
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CN111604031A (en
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罗光前
吉庆钰
邹仁杰
方灿
李显
姚洪
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Huazhong University of Science and Technology
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Abstract

The invention belongs to the technical field related to environmental protection, and discloses a modified carbon-based/non-carbon-based mercury removal adsorbent and a preparation method thereof, wherein the preparation method comprises the following steps: grinding and mixing polyvinyl chloride with a carbon-based adsorbent and a non-carbon-based adsorbent respectively, and then putting the mixture into a tubular furnace for closed heating treatment to enrich chlorine elements in the polyvinyl chloride on the surface of the adsorbent, thereby obtaining a modified carbon-based/non-carbon-based demercuration adsorbent; when heating, the low molecular substance in the mixture volatilizes, then the two reactions of decomposition and polycondensation are carried out to separate out tar and gas, so as to form active vacancy, and in the process, the polyvinyl chloride and the carbon-based adsorbent/non-carbon-based adsorbent are mixed and interacted; the polyvinyl chloride can be combined with active vacancies due to the thermoplasticity of the polyvinyl chloride and the chlorine element released in the thermal conversion process to be adsorbed on the micropores or the surface of the adsorbent to form mercury removal active sites, so that the mercury removal performance is greatly improved. The preparation method has the advantages of simple preparation process, high efficiency and lower cost.

Description

Modified non-carbon-based mercury removal adsorbent and preparation method thereof
Technical Field
The invention belongs to the technical field related to environmental protection, and particularly relates to a modified non-carbon-based mercury removal adsorbent and a preparation method thereof.
Background
In recent years, with the increase of population and the rapid development of economy, the living standard of people is improved, the living standard of cities is improved, the quantity of urban solid wastes is increased unprecedentedly, and the urbanization, the population growth and the industrialization are three main reasons for generating a large amount of garbage. The social, environmental and financial impact of increasing waste production is receiving increasing attention, and improving the collection, recovery and disposal of municipal domestic waste is a problem that is currently of great concern. At present, the disposal mode corresponding to the municipal solid waste mainly comprises landfill, incineration and pyrolysis. Landfill is a traditional solid waste treatment mode, has the advantages of low construction investment, low operation cost and the like, but has a plurality of problems in the disposal of waste containing plastics; the problem of long treatment period and poor treatment effect is caused because the plastics are difficult to biodegrade, a great amount of available plastics can be wasted by burying a great amount of plastics, which is contrary to the sustainable utilization, and the problem of polluting underground water, atmosphere and soil is caused because the current landfill technology level is low. The incineration disposal occupies a small area, has large treatment capacity and can realize energy recovery, but the incineration of plastics can generate waste gas with complex components and toxic pollutants, such as dioxin and the like. On the other hand, the incineration method has large investment, high equipment loss and maintenance and operation cost, and compared with the former two treatment modes, the pyrolysis technology has better economy, less secondary pollution and more environmental friendliness, can convert various organic components into a more easily utilized energy form, has wide application prospect, and can generate great influence on the environment when the wastes are improperly treated. Therefore, the method has important significance for harmless and resource treatment of municipal solid waste.
Mercury is a transition metal, has attracted much attention because it is a heavy metal pollutant with strong toxicity, volatility and bioaccumulation, and is also a secondary SO of coal-fired power plantsx、NOxAnd the fourth large pollutant after dust. The mercury is mainly present in the coal-fired flue gas as elemental mercury, oxidized mercury and granular mercury. The oxidized mercury is easy to dissolve in water and can be removed by a wet desulphurization device at the tail part of the coal-fired power plant, and the granular mercury is easy to be removed by a dust removal device together with fly ash in coal-fired flue gas. But is insoluble due to elemental mercuryThe mercury in the coal-fired power plant is difficult to remove due to high water volatility and long existence time, and the emission control of the mercury in the coal-fired power plant is mainly the removal of the mercury in the elemental state at present.
In order to remove the elemental mercury in the coal-fired flue gas efficiently, a great deal of research is carried out by researchers, and several ways such as catalytic oxidation and activated carbon injection technologies are proposed for removing the elemental mercury by utilizing the conventional pollutant control device of a coal-fired power plant in a synergic manner. Among them, Activated Carbon Injection (ACI) is considered to be one of the most effective demercuration techniques, which has been commercially used in the united states for a long time, and others are under study. But the mercury removal efficiency of the original activated carbon is not high, so that the cost of the technology is greatly increased, and the economic benefit of a coal-fired power plant is negatively influenced. In response to this problem, a large number of researchers have attempted to improve the mercury removal performance of activated carbon by chemical impregnation, and have attempted to improve the mercury removal efficiency of non-carbon-based adsorbents by chemical impregnation. The chemical impregnation method can greatly improve the demercuration performance of the adsorbent, but the chemical impregnation method is complex in modification, consumes a large amount of time and consumes a large amount of chemical reagents, so that the preparation cost of the adsorbent is undoubtedly increased, and the development of the ACI technology is limited. In the face of increasingly strict mercury emission requirements, it is imperative to develop a demercuration adsorbent which is simple in preparation process, efficient and relatively low in preparation cost.
Disclosure of Invention
Aiming at the defects or improvement requirements in the prior art, the invention provides a modified non-carbon-based mercury removal adsorbent and a preparation method thereof, wherein the non-carbon-based mercury removal adsorbent is modified at low temperature/medium and high temperature respectively, and is applied by utilizing different mechanisms generated at low temperature/medium and high temperature respectively, and the purpose is as follows: firstly, in the process that polyvinyl chloride loses moisture and part of organic carbon, inorganic chlorine ions in original polyvinyl chloride can be partially converted into organic chlorine, and the organic chlorine is combined with macromolecular groups of a carbon-based adsorbent to form high-mercury reactive groups, and the high-mercury reactive groups are adsorbed on micropores and surfaces of the carbon-based adsorbent; on the other hand, part of organic chlorine in the polyvinyl chloride can be reformed and combined under the heat treatment environment to form a high-mercury reaction activity gene and is adhered to the surface of the carbon-based/non-carbon-based adsorbent due to the influence of thermoplasticity of the gene to form a demercuration activity site; secondly, the polyvinyl chloride can not generate pollutants such as hydrogen chloride and dioxin in the subsequent solid waste treatment, so that the waste is harmlessly utilized, and waste is changed into valuable.
In order to achieve the above objects, according to one aspect of the present invention, there is provided a method for preparing a modified carbon-based/non-carbon-based demercuration adsorbent, the method comprising the steps of: grinding and mixing polyvinyl chloride with a carbon-based adsorbent and a non-carbon-based adsorbent respectively, and then putting the mixture into a tubular furnace for closed heating treatment to enrich chlorine elements in the polyvinyl chloride on the surface of the adsorbent, thereby obtaining a modified carbon-based/non-carbon-based demercuration adsorbent;
when heating, the low molecular substance in the mixture volatilizes, then the two reactions of decomposition and polycondensation are carried out to separate tar and gas, so as to form active vacancy, in the process, polyvinyl chloride can be mixed and interacted with carbon-based adsorbent/non-carbon-based adsorbent, and polyvinyl chloride can be combined with the active vacancy due to the thermoplasticity of the polyvinyl chloride and the chlorine element released in the thermal conversion process to be adsorbed on the micropore or the surface of the adsorbent.
Further, the carbon-based adsorbent is any one of activated carbon, carbon nanotubes, graphene, activated carbon fibers and carbon molecular sieves.
Further, the non-carbon-based adsorbent is any one of kaolin, bentonite, activated alumina and calcium oxide.
Further, the mass ratio of the polyvinyl chloride to the carbon-based adsorbent is 1: 6-3: 1, and the mass ratio of the polyvinyl chloride to the non-carbon-based adsorbent is 1: 6-3: 1.
Further, the heat treatment is closed heating in a tubular furnace, the adopted heating temperature is 250-900 ℃, and the heating time is 10-30 min.
Furthermore, the polyvinyl chloride and the carbon-based adsorbent/non-carbon-based adsorbent are powder with the particle size of 0.5 mm-10 mm.
Further, when the carbon-based adsorbent is coconut shell activated carbon and the non-carbon-based adsorbent is zeolite molecular sieve, at 250-600 ℃, when waste polyvinyl chloride is respectively mixed and heated with the coconut shell activated carbon or the zeolite molecular sieve, part of the organic chlorine can be reformed and combined to form high-mercury reactive groups under the heat treatment environment, and is adhered to the coconut shell activated carbon or the zeolite molecular sieve under the influence of the thermoplasticity of the polyvinyl chloride, and chlorine elements in the polyvinyl chloride are fixed on the coconut shell activated carbon or the zeolite molecular sieve after being reformed and combined, so that more active functional groups are formed, and the mercury adsorption is promoted.
Further, when the waste polyvinyl chloride is respectively mixed with coconut shell activated carbon or a zeolite molecular sieve and heated at 600-900 ℃, part of active functional groups formed by the zeolite molecular sieve at 250-600 ℃ can be broken; for the coconut shell activated carbon, certain denitrification and deoxidation reactions can be carried out, the specific surface area of the coconut shell activated carbon is increased, the pore structure is developed, carbon atom vacancies can be formed, and polyvinyl chloride can be combined with the carbon atom vacancies formed by the coconut shell activated carbon to be adsorbed on micropores or surfaces of the coconut shell activated carbon due to the thermoplasticity of the polyvinyl chloride and chlorine released in the thermal conversion process to form high-mercury reactive groups, so that the demercuration performance of the adsorbent is improved.
Further, the temperature adopted when the polyvinyl chloride and the carbon-based adsorbent are subjected to heating treatment is 250 ℃ or 900 ℃; the temperature adopted when the polyvinyl chloride and the non-carbon-based adsorbent are subjected to heating treatment is 300 ℃.
According to another aspect of the invention, a modified carbon-based/non-carbon-based demercuration adsorbent is provided, wherein the modified carbon-based/non-carbon-based demercuration adsorbent is prepared by adopting the preparation method of the modified carbon-based/non-carbon-based demercuration adsorbent.
Generally, compared with the prior art, the modified carbon-based/non-carbon-based mercury removal adsorbent and the preparation method thereof provided by the invention have the following beneficial effects:
1. the polyvinyl chloride is used as urban solid waste, has wide source and convenient acquisition, and is beneficial to harmless utilization of the waste by modifying the demercuration adsorbent by utilizing the waste.
2. The preparation method of the modified demercuration adsorbent by heat treatment has the advantages of simple production process, less time consumption (10-30 min), short production period, reduction of production procedures, improvement of production efficiency and saving of energy consumption and time for preparation of the demercuration adsorbent.
3. In the subsequent treatment process of solid waste such as polyvinyl chloride, pollutants such as hydrogen chloride, dioxin and the like can be generated, and great influence is caused on the environment; the carbon-based/non-carbon-based adsorbent is modified by the polyvinyl chloride under the heat treatment condition (inert atmosphere), the generation of hydrogen chloride can be controlled in the process, the generation of dioxin hypertoxic substances is avoided, and meanwhile, chlorine elements in the polyvinyl chloride are enriched in the carbon-based/non-carbon-based adsorbent, so that the demercuration performance of the carbon-based/non-carbon-based adsorbent is greatly improved, waste is changed into wealth, and harmless and resource utilization of waste is really realized.
4. The adopted carbon-based adsorbent has rich pore channel structures, and can load more active substances no matter at high temperature/low temperature; although the pore channel structure of the adopted non-carbon-based adsorbent is poor, the active group formed by the polyvinyl chloride in the thermal conversion process after the polyvinyl chloride is mixed with the polyvinyl chloride can still obtain a better modified mercury removal adsorbent under the influence of the thermoplasticity of the polyvinyl chloride.
5. The preparation method of the modified mercury removal adsorbent by adopting heat treatment does not use any chemical medicine in the later period, avoids a large amount of chemical reagents used for modification by a chemical immersion method, protects equipment from being corroded by the chemical medicine, and saves the cost required by a large amount of chemical medicines, thereby reducing the preparation cost of the mercury removal adsorbent.
6. The method can be used as a method for treating chlorine element in polyvinyl chloride and simultaneously can be used as a method for modifying carbon-based/non-carbon-based adsorbent, so that the demercuration performance of the polyvinyl chloride is greatly improved, the method is simple in process, short in production period, environment-friendly and good in economic benefit, and harmless and recycling treatment of waste is realized.
Drawings
Fig. 1 is a schematic flow diagram of a method for preparing a modified carbon-based/non-carbon-based demercuration adsorbent provided by the invention;
FIGS. 2a and 2b are X-ray photoelectron spectra before and after mercury absorption by the modified demercuration adsorbent;
fig. 3 is a schematic diagram of a test device for mercury adsorption experiments of the mercury removal adsorbent prepared by the preparation method of the modified carbon-based/non-carbon-based mercury removal adsorbent in fig. 1.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
Referring to fig. 1, the mercury removal adsorbent prepared by the preparation method of the modified carbon-based/non-carbon-based mercury removal adsorbent provided by the invention is used for removing mercury in coal-fired flue gas, so that harmless and resource utilization of waste is achieved. The raw materials selected by the invention are carbon-based adsorbent, non-carbon-based adsorbent and solid waste polyvinyl chloride.
The preparation method mainly comprises the following steps: grinding and mixing polyvinyl chloride with a carbon-based adsorbent and a non-carbon-based adsorbent respectively, and then putting the mixture into a tubular furnace for closed heating treatment to enrich chlorine elements in the polyvinyl chloride on the surface of the adsorbent, thus obtaining the polyvinyl chloride modified carbon-based/non-carbon-based mercury removal adsorbent under the heat treatment condition.
When heating, the low molecular substance in the mixture volatilizes first, then the two reactions of decomposition and polycondensation are carried out to separate tar and gas, and thus active vacancies are formed. In this process, the polyvinyl chloride undergoes a mixing interaction with the carbon-based adsorbent/non-carbon-based adsorbent.
In this embodiment, the carbon-based adsorbent is any one of activated carbon, carbon nanotubes, graphene, activated carbon fibers, and carbon molecular sieves; the non-carbon-based adsorbent is any one of kaolin, bentonite, activated alumina and calcium oxide.
The mass ratio of the polyvinyl chloride to the carbon-based adsorbent is 1: 6-3: 1, and the mass ratio of the polyvinyl chloride to the non-carbon-based adsorbent is 1: 6-3: 1. The heat treatment is closed heating in a tubular furnace, the adopted heating temperature is 250-900 ℃, and the heating time is 10-30 min. The polyvinyl chloride and the carbon-based adsorbent/non-carbon-based adsorbent are powder with the particle size of 0.5 mm-10 mm.
When the carbon-based adsorbent is coconut shell activated carbon and the non-carbon-based adsorbent is a zeolite molecular sieve, the corresponding heating temperatures are respectively low temperature (250-600 ℃) and medium-high temperature (600-900 ℃), the adopted protective atmosphere is inert atmosphere nitrogen, and the heating time is 30 min.
Taking the carbon-based adsorbent as coconut shell activated carbon and the non-carbon-based adsorbent as zeolite molecular sieve to be respectively mixed with waste polyvinyl chloride as an example:
at low temperature (250-600 ℃), when waste polyvinyl chloride is mixed and heated with coconut shell activated carbon or zeolite molecular sieve respectively, part of organic chlorine can be reformed and combined to form high mercury reactive groups under the heat treatment environment, the organic chlorine is adhered with the coconut shell activated carbon or zeolite molecular sieve under the influence of thermoplasticity of the polyvinyl chloride, chlorine elements in the polyvinyl chloride are fixed on the coconut shell activated carbon or zeolite molecular sieve after being reformed and combined, and therefore more active functional groups are formed to promote mercury adsorption.
At the middle and high temperature (600-900 ℃), when the waste polyvinyl chloride is respectively mixed with coconut shell activated carbon or zeolite molecular sieve and heated, for zeolite molecular sieves, due to the poor pore structure of the zeolite molecular sieve, part of active functional groups formed at low temperature can be broken at high temperature, therefore, the mercury removal efficiency of the mixture is not high at high temperature, and for coconut shell activated carbon, due to the developed pore structure, can generate certain reactions of denitrification, deoxidation and the like at high temperature, increases the specific surface area of the coconut shell activated carbon, leads the pore structure to be more developed, simultaneously forms carbon atom vacancy, and the polyvinyl chloride can be combined with carbon atom vacancy formed by the coconut shell activated carbon to be adsorbed on micropores or the surface of the coconut shell activated carbon due to the thermoplasticity of the polyvinyl chloride and the chlorine element released in the thermal conversion process to form high-mercury reaction active groups, so that the demercuration performance of the adsorbent is greatly improved.
Through mercury adsorption experiments and characterization means, the Hg adsorbed by the prepared adsorbent is found0Oxidized to mercury chloride on the surface of the sorbent, and the C-Cl active functional groups in the sorbent are reduced, Cl-The increase in content is shown in fig. 2a and 2b, and the chemisorption is evident in the process. Meanwhile, experiments show that the adsorption efficiency of the prepared adsorbent at high temperature is far higher than that at normal temperature, and the adsorption effect on mercury is mainly chemical adsorption.
Of course, the carbon-based adsorbent can be any one of activated carbon, carbon nano tube, graphene, activated carbon fiber and carbon molecular sieve, and the coconut shell activated carbon selected herein shows good mercury removal performance under low temperature and high temperature treatment, wherein the mercury removal performance under high temperature is optimal. The non-carbon-based adsorbent can be any one of kaolin, zeolite, bentonite, activated alumina and calcium oxide, and the zeolite molecular sieve selected here has a good mercury removal effect after being modified at a low temperature (the mercury removal performance is poor due to poor pore structure of the non-carbon-based adsorbent at a high temperature and decomposition of some functional groups at the high temperature).
In the polyvinyl chloride modified carbon-based adsorbent, good heating temperatures are respectively low temperature (250 ℃) and high temperature (900 ℃); in the polyvinyl chloride-modified non-carbon-based adsorbent, a good heating temperature was exhibited at a low temperature (300 ℃).
Heating in the polyvinyl chloride modified carbon-based/non-carbon-based adsorbent for 10-30 min, introducing nitrogen, argon or carbon dioxide and other gases as protective gas, and introducing nitrogen as protective gas.
In order to fully mix the polyvinyl chloride with the carbon-based adsorbent/non-carbon-based adsorbent, the polyvinyl chloride and the carbon-based adsorbent/non-carbon-based adsorbent are crushed to fully contact with each other, and powder with the particle size of 0.5-10 mm is selected after full mixing and crushing for experiments.
Compared with methods such as modification by a chemical impregnation method, the preparation process in the embodiment of the invention is simpler and more convenient, and the polyvinyl chloride is used for modifying the carbon-based adsorbent/the non-carbon-based adsorbent under the heat treatment condition, so that a large amount of chemicals and later modification steps are saved.
The invention also provides a modified carbon-based/non-carbon-based demercuration adsorbent, which is prepared by the preparation method of the modified carbon-based/non-carbon-based demercuration adsorbent.
The present invention is further described in detail below with reference to several specific examples.
Example 1
The preparation method of the modified carbon-based/non-carbon-based mercury removal adsorbent provided by the embodiment 1 of the invention mainly comprises the following steps:
(1) respectively grinding and screening the polyvinyl chloride and the coconut shell activated carbon to obtain powder with the particle size of 0.5-10 mm.
(2) And respectively putting the screened polyvinyl chloride powder and the coconut shell activated carbon into a constant-temperature drying oven at 105 ℃ for drying for 24 hours to remove the influence of moisture on the experiment.
(3) Selecting the dried polyvinyl chloride powder and the coconut shell activated carbon in a mass ratio of 1:1, and fully mixing in a reactor.
(4) And (3) putting the mixture fully mixed in the reactor into a tubular furnace, selecting nitrogen as heating atmosphere, heating the tubular furnace to 250 ℃ at the heating rate of 10 ℃/min, heating the mixture for 30min, and cooling to room temperature to obtain the demercuration adsorbent for the polyvinyl chloride modified coconut shell activated carbon, wherein the flow rate of the nitrogen is 1L/min.
The demercuration adsorbent prepared in the example 1 has a BET specific surface area of 684.14m2G, average pore diameter of 3.11nm and pore volume of 0.53cm3(ii) in terms of/g. As shown in FIG. 3, the initial mercury concentration is 80 μ g/m3The experimental atmosphere is nitrogen, the flow rate of the nitrogen is 1L/min, the dosage of the adsorbent is 80mg, the adsorption temperature is 140 ℃, and the average demercuration efficiency within 10min is 70%.
Example 2
The preparation method of the modified carbon-based/non-carbon-based mercury removal adsorbent provided by the embodiment 2 of the invention mainly comprises the following steps:
(1) the polyvinyl chloride and zeolite molecular sieve are respectively ground and sieved to obtain powder with the particle size of 0.5 mm-10 mm.
(2) And respectively putting the screened polyvinyl chloride powder and the zeolite molecular sieve into a constant-temperature drying oven at 105 ℃ for drying for 24 hours to remove the influence of moisture on the experiment.
(3) Selecting the dried polyvinyl chloride powder and the zeolite molecular sieve according to the mass ratio of 1:1, and fully mixing in a reactor.
(4) And (3) putting the mixture fully mixed in the reactor into a tubular furnace, selecting nitrogen as a heating atmosphere, heating the tubular furnace to 300 ℃ at the heating rate of 10 ℃/min, heating the mixture for 30min, and cooling to room temperature to obtain the demercuration adsorbent of the polyvinyl chloride modified zeolite molecular sieve.
The demercuration adsorbent prepared in the example 2 has a BET specific surface area of 3.934m2G, average pore diameter of 9.00nm and pore volume of 0.008cm3(ii)/g; as shown in FIG. 3, the initial mercury concentration is 80 μ g/m3The experimental atmosphere is nitrogen, the flow rate of the nitrogen is 1L/min, the dosage of the adsorbent is 80mg, the adsorption temperature is 140 ℃, and the average demercuration efficiency within 10min is 71%.
Example 3
The preparation method of the modified carbon-based/non-carbon-based mercury removal adsorbent provided by the embodiment 3 of the invention mainly comprises the following steps:
(1) respectively grinding and screening the polyvinyl chloride and the coconut shell activated carbon to obtain powder with the particle size of 0.5-10 mm.
(2) And respectively putting the screened polyvinyl chloride powder and the coconut shell activated carbon into a constant-temperature drying oven at 105 ℃ for drying for 24 hours to remove the influence of moisture on the experiment.
(3) Selecting the dried polyvinyl chloride powder and the coconut shell activated carbon in a mass ratio of 1:1, and fully mixing in a reactor.
(4) And (3) putting the mixture fully mixed in the reactor into a tubular furnace, selecting nitrogen as heating atmosphere, heating the tubular furnace to 900 ℃ at the heating rate of 10 ℃/min, heating the mixture for 30min, and cooling to room temperature to obtain the demercuration adsorbent for the polyvinyl chloride modified coconut shell activated carbon, wherein the flow rate of the nitrogen is 1L/min.
The demercuration adsorbent prepared in the example 3 has a BET specific surface area of 695.98m2G, average pore diameter of 3.39nm and pore volume of 0.59cm3(ii)/g; as shown in FIG. 3, the initial mercury concentration is 80 μ g/m3The experimental atmosphere is nitrogen, the flow rate of the nitrogen is 1L/min, the dosage of the adsorbent is 80mg, the adsorption temperature is 140 ℃, and the average demercuration efficiency is 78% within 30 min.
The zeolite molecular sieve modified by polyvinyl chloride has lower specific surface area and poorer pore structure, but shows better result on mercury adsorption efficiency at high temperature, which indicates that the chemical adsorption occupies a main position in the mercury adsorption process; the coconut shell activated carbon (low-temperature modified and high-temperature modified) modified by polyvinyl chloride shows excellent results in mercury adsorbent efficiency at high temperature, and the chemical adsorption in the adsorption process is proved to occupy the main position; on one hand, in the process that the polyvinyl chloride loses moisture and part of organic carbon, inorganic chlorine ions in the original polyvinyl chloride can be partially converted into organic chlorine to be combined with carbon atom vacancies remained after denitrification, oxygen and other reactions of coconut shell activated carbon to form high-mercury reactive groups and be adsorbed on micropores and surfaces of a carbon-based adsorbent, on the other hand, part of organic chlorine ions in the polyvinyl chloride can be reformed and combined under heat treatment to form the high-mercury reactive groups and be adhered to the surfaces of the carbon-based/non-carbon-based adsorbent due to the thermoplastic influence of the high-mercury reactive groups to form demercuration active sites, and the feasibility of the invention is proved again.
In the actual flue gas demercuration process, the contact time of the sprayed adsorbent and mercury is very short, and the adsorbent prepared by the adopted process flow can completely meet the emission limit standard of mercury pollutants of a coal-fired power plant. Therefore, the process flow can be selected according to the content of mercury in the flue gas of the coal-fired power plant when the adsorbent is prepared, and when the mercury content is not high, the carbon-based/non-carbon-based adsorbent modified by polyvinyl chloride at low temperature can be selected to meet the demercuration requirement of the coal-fired power plant; when the mercury content is higher, the preparation process flow with better mercury removal performance of the carbon-based adsorbent modified by polyvinyl chloride at high temperature can be selected, the mercury removal requirement of a coal-fired power plant is met, and the mercury removal agent is used for symptomatic medicine administration.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (6)

1. A preparation method of a modified non-carbon-based demercuration adsorbent is characterized by comprising the following steps: grinding and mixing polyvinyl chloride and a non-carbon-based adsorbent, and then putting the mixture into a tubular furnace for closed heating treatment to enrich chlorine elements in the polyvinyl chloride on the surface of the adsorbent, thereby obtaining a modified non-carbon-based mercury removal adsorbent;
when heating, the low molecular substance in the mixture volatilizes, then the two reactions of decomposition and polycondensation are carried out to separate tar and gas, so as to form active vacancy, in the process, polyvinyl chloride can carry out mixing interaction with a non-carbon-based adsorbent, and the polyvinyl chloride can be adsorbed on the micropores or the surface of the adsorbent due to the thermoplasticity of the polyvinyl chloride and the combination of chlorine element released in the thermal conversion process and the active vacancy;
the non-carbon-based adsorbent is a zeolite molecular sieve, when waste polyvinyl chloride is mixed with the zeolite molecular sieve and heated at 250-600 ℃, part of organic chlorine can be reformed and combined under a heat treatment environment to form high-mercury reactive groups, the organic chlorine is adhered to the zeolite molecular sieve under the influence of thermoplasticity of the polyvinyl chloride, chlorine elements in the polyvinyl chloride are fixed on the zeolite molecular sieve after being reformed and combined, and therefore more active functional groups are formed, and the adsorption of mercury is promoted.
2. The method of preparing the modified non-carbon-based demercuration adsorbent of claim 1, wherein: the mass ratio of the polyvinyl chloride to the non-carbon-based adsorbent is 1: 6-3: 1.
3. The method of preparing the modified non-carbon-based demercuration adsorbent of claim 1, wherein: the heat treatment is closed heating in a tubular furnace, the heating temperature is 250-600 ℃, and the heating time is 10-30 min.
4. The method of preparing the modified non-carbon-based demercuration adsorbent of claim 1, wherein: the polyvinyl chloride and the non-carbon-based adsorbent are powder with the particle size of 0.5 mm-10 mm.
5. The method of preparing the modified non-carbon-based demercuration adsorbent of claim 1, wherein: the temperature adopted when the polyvinyl chloride and the non-carbon-based adsorbent are subjected to heating treatment is 300 ℃.
6. A modified non-carbon-based demercuration adsorbent is characterized in that: the modified non-carbon-based demercuration adsorbent is prepared by the preparation method of the modified non-carbon-based demercuration adsorbent as claimed in any one of claims 1 to 5.
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