A method for treating waste vinyl chloride gas

Abstract

The present application provides a kind of containing vinyl chloride waste gas processing method, belong to waste gas treatment technical field, including the following steps: adsorption enrichment step: vinyl chloride containing waste gas is contacted with adsorption catalytic material, so that vinyl chloride in waste gas is adsorbed on the adsorption catalytic material;Catalytic degradation step: the adsorption catalytic material of completing the adsorption enrichment step is heated by temperature, so that the adsorbed vinyl chloride is catalytically degraded;Wherein, the adsorption catalytic material is porous carbon material, the porous carbon material is cyclodextrin metal organic framework as precursor, in KCl-K2CO3 molten salt system, after mixing with thiourea, it is prepared by carbonization under air atmosphere.The present application is prepared by cyclodextrin metal organic framework as precursor, molten salt porous carbon material, with first adsorption enrichment, then catalytic degradation process design, constructs a kind of set high efficiency adsorption and deep purification in one of vinyl chloride waste gas processing scheme.

Description

Technical Field

[0001] This invention belongs to the field of waste gas treatment technology, specifically relating to a method for treating waste gas containing vinyl chloride. Background Technology

[0002] Vinyl chloride (VCM) is an important chemical monomer widely used in the production of polyvinyl chloride (PVC) and vinyl chloride copolymer resins. However, vinyl chloride is classified as a Group 1 carcinogen, exhibiting strong toxicity and environmental hazards. During its polymerization process, processes such as polymerization reactors, stripping towers, and drying and packaging generate large quantities of vinyl chloride-containing waste gas. Improper treatment of this gas poses a serious threat to the health of operators and the surrounding environment. Therefore, efficient purification and treatment of vinyl chloride-containing waste gas is a critical issue that urgently needs to be addressed by the relevant chemical industries.

[0003] Currently, the industry mainly uses the following technologies for treating vinyl chloride-containing waste gas: Activated carbon adsorption: This method utilizes the large specific surface area and abundant pore structure of activated carbon to physically adsorb vinyl chloride molecules. It has low initial investment and is simple to operate, making it one of the most widely used methods. However, it has significant drawbacks: activated carbon has a limited adsorption capacity for vinyl chloride, easily reaches saturation, and requires frequent replacement or regeneration. Saturated activated carbon itself becomes hazardous waste, the thermal regeneration process is energy-intensive, and there is a risk of incomplete vinyl chloride desorption or secondary pollution. Essentially, this method only transfers, rather than eliminates, pollutants.

[0004] Thermal incineration: This method incinerates vinyl chloride-containing waste gas at high temperatures, completely oxidizing it into CO2, H2O, and HCl. Although the treatment is thorough, this method requires a large amount of fuel to maintain the high temperature, resulting in extremely high operating costs. Furthermore, it may generate more dangerous byproducts such as dioxins at high temperatures, necessitating a complex exhaust gas treatment system.

[0005] Catalytic combustion: This method uses precious metal or transition metal oxides as catalysts to catalytically oxidize vinyl chloride at relatively low temperatures. Compared to thermal incineration, its energy consumption is reduced. However, precious metal catalysts are expensive and sensitive to fluctuations in waste gas concentration, making it difficult to directly treat intermittent, low-concentration, high-volume waste gas from polymerization processes.

[0006] In summary, existing technologies for treating vinyl chloride waste gas present certain contradictions in terms of energy efficiency and deep purification between adsorption and incineration / catalysis: adsorption is simple to operate but does not completely eliminate pollutants, while incineration / catalysis can achieve deep purification but has higher energy consumption and cost. Summary of the Invention

[0007] In view of the above situation and to overcome the defects of the prior art, the purpose of the present invention is to provide a method for treating waste gas containing vinyl chloride, so as to at least partially solve the problems mentioned in the background art.

[0008] The technical solution adopted in this invention is as follows: This invention proposes a method for treating waste gas containing vinyl chloride, comprising the following steps: Adsorption and enrichment step: The waste gas containing vinyl chloride is brought into contact with the adsorption catalyst material, so that the vinyl chloride in the waste gas is adsorbed onto the adsorption catalyst material; Catalytic degradation step: The adsorption catalytic material that has completed the adsorption enrichment step is heated to catalytically degrade the adsorbed vinyl chloride; The adsorption catalytic material is a porous carbon material, which is prepared by carbonizing a mixture of thiourea and cyclodextrin metal-organic framework as a precursor in a KCl-K2CO3 molten salt system under an air atmosphere.

[0009] In some embodiments of the present invention, the temperature at which the vinyl chloride-containing waste gas contacts the adsorption catalyst material in the adsorption enrichment step is 30-60°C.

[0010] In some embodiments of the present invention, the catalytic degradation specifically includes the following steps: when the adsorption catalytic material is saturated, the flow of waste gas is stopped, and the material is heated to a target temperature of 200-400°C at a rate of 1-10°C / min in an air atmosphere, and kept at that temperature for 0.5-2 hours.

[0011] In some embodiments of the present invention, the adsorption enrichment step and the catalytic degradation step are carried out intermittently and alternately in the same reactor.

[0012] In some embodiments of the present invention, the following pretreatment step is further included before the adsorption and enrichment step: S1. The chloroethylene-containing waste gas from the polymerization reaction process is condensed in the first stage to obtain the first gas-liquid mixture; S2. The first gas-liquid mixture is subjected to gas-liquid separation. The separated gas phase is compressed and then subjected to two-stage condensation to obtain a second gas-liquid mixture. S3. The second gas-liquid mixture is subjected to gas-liquid separation. The separated liquid phase, vinyl chloride, is recovered and reused in the production system, and the separated gas phase is non-condensable waste gas. The chloroethylene-containing waste gas introduced for the adsorption and enrichment step is the non-condensable waste gas generated after separation in step S3.

[0013] In some embodiments of the present invention, the cooling medium in step S1 is circulating cooling water, and the condensation temperature is controlled between 10°C and 25°C.

[0014] In some embodiments of the present invention, the compression in step S2 is achieved by a gas compressor, and the exhaust pressure is controlled to be between 0.6 MPa and 1.0 MPa; the cooling medium for the secondary condensation is low-temperature chilled water, and the condensation temperature is controlled between -10°C and -25°C.

[0015] In some embodiments of the present invention, the degradation products generated in the catalytic degradation step include hydrogen chloride, which is absorbed by alkaline spraying.

[0016] In some embodiments of the present invention, the cyclodextrin metal-organic framework is prepared by a method comprising the following steps: crystallizing γ-cyclodextrin and potassium salt in an alcohol-water mixed solvent at 50-70°C to obtain the cyclodextrin metal-organic framework.

[0017] In some embodiments of the present invention, the preparation method of the adsorption catalytic material includes: The γ-cyclodextrin metal-organic framework, KCl, and K2CO3 were mixed in a mass ratio of 1:(3-4):(5-6), and thiourea, accounting for 10%-15% of the mass of the γ-cyclodextrin metal-organic framework, was added. After grinding together, the mixture was heated to 700-800℃ at a programmed rate of 5-10℃ / min in air and held at that temperature for 2-4 hours. After cooling, washing, and drying, the adsorption catalyst material was obtained.

[0018] The beneficial effects achieved by this invention are as follows: This invention presents a novel treatment solution for vinyl chloride waste gas. It utilizes a cyclodextrin-metal-organic framework as a precursor and molten salt to prepare porous carbon materials. Combined with a process design of adsorption-enrichment followed by catalytic degradation, this solution integrates highly efficient adsorption and deep purification. The solution not only leverages the physical adsorption of the material for rapid enrichment but also achieves complete low-temperature decomposition of pollutants through its surface chemical catalysis. This effectively solves the saturation and decomposition problem of traditional activated carbon and significantly reduces the high energy consumption of traditional incineration methods. Therefore, it provides a promising new strategy for the economical, efficient, and in-depth treatment of vinyl chloride waste gas. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention. The preferred embodiments and materials described herein are for illustrative purposes only and do not limit the scope of this application.

[0021] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0022] To address the problems raised in the background art, this invention provides a method for treating waste gas containing vinyl chloride, comprising the following steps: Adsorption enrichment step: The vinyl chloride-containing waste gas is contacted with the adsorption catalyst material, so that the vinyl chloride in the waste gas is adsorbed onto the adsorption catalyst material, and the adsorbed adsorption catalyst material is obtained. Catalytic degradation step: The adsorbed catalytic material is heated to increase the temperature to catalytically degrade vinyl chloride; Among them, the adsorption catalyst is a porous carbon material, which is prepared by carbonizing thiourea in an air atmosphere after mixing with cyclodextrin metal-organic framework as a precursor in a KCl-K2CO3 molten salt system.

[0023] The method for treating vinyl chloride-containing waste gas provided in this invention combines adsorption enrichment with temperature-programmed catalytic degradation, and uses porous carbon prepared by the molten salt method with cyclodextrin metal-organic framework as a precursor as the adsorption catalyst material. This method has achieved significant improvements in the treatment efficiency of vinyl chloride waste gas, energy consumption control, and solving the problem of adsorbent regeneration.

[0024] First, this invention employs a cyclodextrin metal-organic framework as a precursor. This precursor possesses an inherently ordered porous structure and abundant carbon and oxygen sources, laying the foundation for the high specific surface area and hierarchical pore structure of the final carbon material. This structure is particularly beneficial for the rapid diffusion and efficient adsorption and enrichment of vinyl chloride molecules.

[0025] Secondly, this invention utilizes a KCl-K2CO3 molten salt system for one-step carbonization and activation in an air atmosphere. This method offers multiple advantages: the molten salt system acts as a high-temperature template and activator, effectively etching the carbon framework and creating abundant micropores and mesopores; simultaneously, the molten salt covers the material surface, forming a physical barrier that allows the carbonization process to take place in ambient air without relying on expensive and energy-intensive inert gases (such as argon or nitrogen) for protection, greatly simplifying equipment and reducing production costs. During this process, the simultaneously added thiourea undergoes thermal decomposition, releasing nitrogen- and sulfur-containing precursors, successfully incorporating nitrogen atoms (in the form of pyridine nitrogen, pyrrole nitrogen, etc.) and sulfur atoms (in the form of thiophene sulfur, etc.) into the carbon matrix. These heteroatom functional groups not only improve the surface polarity of the material and enhance its adsorption affinity for vinyl chloride, but more importantly, they act as catalytic active sites, significantly improving the material's ability to catalytically break C-Cl bonds and deeply oxidize vinyl chloride in subsequent steps.

[0026] Subsequently, this invention designs a two-step treatment process: adsorption enrichment followed by catalytic degradation. In the adsorption enrichment step, the material is used to efficiently capture and concentrate low-concentration vinyl chloride waste gas, a process with extremely low energy consumption. In the catalytic degradation step, once the material is saturated with adsorption, the material itself is heated in a programmed manner to trigger the catalytic degradation reaction of the adsorbed vinyl chloride under suitable temperature conditions, converting it into small molecules such as CO2, H2O, and HCl. This achieves complete elimination of pollutants, rather than their transfer; furthermore, compared to direct high-temperature incineration of waste, the required energy consumption is significantly reduced.

[0027] Furthermore, the processing method of this invention exhibits good process controllability and economy. By adjusting the proportion of molten salt, carbonization temperature, and time, the specific surface area and pore size distribution of the resulting carbon material can be optimized; by controlling the amount of thiourea added, the types and concentrations of N and S heteroatoms on the material surface can be adjusted, thereby balancing its adsorption performance and catalytic activity. This material can achieve intermittent alternating operation of adsorption and regeneration in a reactor, or continuous processing through a dual-bed system. The hydrogen chloride byproduct generated in the catalytic degradation step can be efficiently absorbed by a conventional alkaline spray tower, avoiding secondary pollution.

[0028] In summary, this invention constructs a vinyl chloride waste gas treatment solution that integrates high-efficiency adsorption and deep purification by using cyclodextrin metal-organic frameworks as precursors, preparing porous carbon materials with molten salts, and combining this with a process design of first adsorption enrichment and then catalytic degradation. This solution not only utilizes the physical adsorption of materials for rapid enrichment but also achieves complete low-temperature decomposition of pollutants through its surface chemical catalysis function. It effectively solves the saturation failure problem of traditional activated carbon and significantly reduces the high energy consumption burden of traditional incineration methods, providing a promising new strategy for the economical, efficient, and in-depth treatment of vinyl chloride waste gas.

[0029] In some embodiments, during the adsorption enrichment step, the temperature at which the vinyl chloride-containing waste gas contacts the adsorption catalyst is 30-60°C. By setting the adsorption temperature within a suitable range, it helps to enhance the diffusion kinetic energy of vinyl chloride gas molecules, enabling them to enter the deep pores of the adsorption catalyst more quickly, thereby increasing the adsorption rate.

[0030] In some embodiments, the catalytic degradation specifically includes the following steps: after the adsorption catalytic material is saturated, the flow of waste gas is stopped, and the material is heated to a target temperature of 200-400°C at a rate of 1-10°C / min in an air atmosphere, and held at this temperature for 0.5-2 hours. The moderate heating rate ensures stable desorption of the adsorbate, avoiding runaway reactions; the temperature window of 200-400°C activates the catalytic activity of the porous carbon material, achieving efficient decomposition of vinyl chloride, while significantly reducing the energy consumption compared to direct incineration; oxygen in the air serves as an economical oxidant, further reducing operating costs. Simultaneously, the 0.5-2 hour holding time ensures a deep reaction, allowing the material to recover its adsorption capacity, achieving a balance between efficient regeneration and complete elimination of pollutants.

[0031] In some embodiments, the adsorption enrichment step and the catalytic degradation step are carried out intermittently and alternately in the same reactor. This setup significantly improves system architecture, eliminating complex material conveying and reactor switching devices, and reducing equipment investment and maintenance costs. Secondly, this design enables in-situ regeneration of the adsorption catalyst, avoiding secondary pollution and safety risks that may occur during the transfer of the adsorption catalyst.

[0032] In some embodiments, the following pretreatment step is further included prior to the adsorption enrichment step: S1. The chloroethylene-containing waste gas from the polymerization reaction process is condensed in the first stage to obtain the first gas-liquid mixture; S2. The first gas-liquid mixture is subjected to gas-liquid separation. The separated gas phase is compressed and then subjected to two-stage condensation to obtain the second gas-liquid mixture. S3. The second gas-liquid mixture is subjected to gas-liquid separation. The separated liquid phase, vinyl chloride, is recovered and reused in the production system, and the separated gas phase is non-condensable waste gas. The chloroethylene-containing waste gas introduced for the adsorption and enrichment step is the non-condensable waste gas generated after separation in step S3.

[0033] By incorporating a multi-stage condensation pretreatment system before the adsorption and enrichment step, efficient graded treatment and resource recovery of waste gas are achieved. Firstly, primary condensation recovers most of the high-concentration vinyl chloride monomer. Then, through the synergistic effect of compression heating and secondary deep condensation, vinyl chloride is further purified and recovered. This stepped condensation design significantly reduces the concentration of vinyl chloride in the waste gas entering subsequent adsorption units, shifting the main load from the energy-intensive catalytic degradation stage to the energy-efficient physical condensation stage, thus greatly reducing the overall operating cost of the system. Simultaneously, the recovered high-purity vinyl chloride can be directly returned to the production process for recycling, reducing raw material consumption and lowering pollutant emissions at the source, achieving a balance between environmental and economic benefits.

[0034] In some embodiments, the cooling medium in step S1 is circulating cooling water, and the condensation temperature is controlled between 10°C and 25°C. This temperature control requirement can be achieved using a conventional circulating cooling water system, reducing equipment investment and operating costs. The temperature range of 10°C to 25°C can effectively condense and recover most of the high-boiling-point vinyl chloride components in the exhaust gas, while avoiding problems such as water vapor freezing or a surge in energy consumption caused by excessively low temperatures.

[0035] In some embodiments, compression in step S2 is achieved using a gas compressor, with the exhaust pressure controlled at 0.6 MPa to 1.0 MPa; the cooling medium for secondary condensation is cryogenic chilled water, and the condensation temperature is controlled between -10°C and -25°C. The pressurization process effectively increases the partial pressure of vinyl chloride in the gas phase, significantly enhancing the condensation mass transfer efficiency; while the low-temperature conditions of -10°C to -25°C ensure deep condensation and recovery of residual vinyl chloride. The synergistic effect of these two processes significantly improves the overall vinyl chloride recovery rate while substantially reducing the organic load on the subsequent adsorption catalytic unit.

[0036] In some embodiments, the degradation products generated in the catalytic degradation step include hydrogen chloride, which is absorbed and treated by alkaline spraying. By utilizing alkaline solutions such as sodium hydroxide to undergo an efficient neutralization reaction with acidic hydrogen chloride, a stable sodium chloride solution is generated. This alkaline spraying absorption of hydrogen chloride in the catalytic degradation products achieves the harmless treatment of hydrogen chloride.

[0037] In some embodiments, cyclodextrin metal-organic frameworks are prepared by a method comprising the following steps: crystallizing γ-cyclodextrin with a potassium salt in an alcohol-water mixed solvent at 50-70°C to obtain the cyclodextrin metal-organic framework. The use of the alcohol-water mixed solvent ensures good solubility of the raw materials and effectively controls the crystallization rate by adjusting the solvent polarity, thus contributing to the formation of well-structured metal-organic framework crystals. The mild reaction conditions of 50-70°C not only reduce energy consumption but also avoid the structural decomposition of cyclodextrin that may occur at high temperatures, ensuring the integrity of the product structure.

[0038] In some embodiments, the preparation method of the adsorption catalytic material includes: A γ-cyclodextrin metal-organic framework, KCl, and K₂CO₃ were mixed at a mass ratio of 1:(3-4):(5-6), and thiourea (10%-15% by mass of the γ-cyclodextrin metal-organic framework) was added. After grinding, the mixture was heated to 700-800℃ at a programmed rate of 5-10℃ / min in air and held for 2-4 hours. After cooling, washing, and drying, the adsorption catalytic material was obtained. The specific salt ratio helps to form a suitable melting medium, providing some protection to the carbon framework while constructing a porous structure. The controllable heating rate facilitates the steady formation of the material structure. The addition of thiourea helps to achieve nitrogen and sulfur doping, introducing potential catalytic active sites into the material. Notably, this method can be completed in air, which offers the possibility of reducing production costs compared to conventional processes that require inert gas protection. The material prepared by this process is expected to possess both porous characteristics and surface catalytic activity, providing support for subsequent adsorption and catalytic steps.

[0039] The present invention will be further described below by way of specific embodiments.

[0040] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods already existing in the art; unless otherwise specified, the experimental materials used in the following embodiments are all purchased from commercial channels.

[0041] Example 1: 10g of γ-cyclodextrin and 5g of potassium hydroxide were dissolved in 200mL of a 1:1 methanol / water mixture and crystallized at 60℃ for 24 hours to obtain a cyclodextrin metal-organic framework.

[0042] Cyclodextrin metal-organic framework, KCl and K2CO3 were mixed in a mass ratio of 1:3.5:5.5, and thiourea, accounting for 12.5% ​​of the mass of cyclodextrin metal-organic framework, was added. The mixture was then ground together until homogeneous.

[0043] The material was heated to 750°C at a rate of 8°C / min in air and held for 3 hours. After cooling, it was washed with deionized water until neutral and dried to obtain the adsorption catalyst material.

[0044] The vinyl chloride-containing waste gas undergoes primary condensation using circulating cooling water as the cooling medium, with the condensation temperature controlled at 15°C, yielding a first gas-liquid mixture. After gas-liquid separation, the gas phase is compressed to an exhaust pressure of 0.8 MPa by a gas compressor, followed by secondary condensation using low-temperature chilled water as the cooling medium, with the condensation temperature controlled at -15°C, yielding a second gas-liquid mixture. This second gas-liquid mixture undergoes further gas-liquid separation; the liquid phase vinyl chloride is recovered, and the non-condensable gas phase waste gas is used in the adsorption and enrichment step.

[0045] The pretreated non-condensable waste gas was introduced into a fixed-bed reactor and brought into contact with the prepared adsorption catalyst. The adsorption temperature was controlled at 45°C, and the waste gas flow rate was 0.5 L / min. Adsorption continued until saturation. After adsorption saturation, the waste gas flow was stopped, and the gas was heated to 300°C at a rate of 5°C / min under air atmosphere and held at that temperature for 1 hour. The generated hydrogen chloride was absorbed by spraying with a 5% NaOH alkaline solution.

[0046] Example 2: Similar to Example 1, except that the temperature of the adsorption enrichment step is 30°C, and the temperature of the catalytic degradation step is increased to 200°C at a rate of 1°C / min and held for 2 hours.

[0047] Example 3: Similar to Example 1, except that the temperature of the adsorption enrichment step is 60°C, and the temperature of the catalytic degradation step is increased to 400°C at 10°C / min and held for 0.5 hours.

[0048] Example 4: Similar to Example 1, except that in the preparation of the adsorption catalytic material, the mass ratio of cyclodextrin metal-organic framework, KCl and K2CO3 is 1:3:5, the amount of thiourea added is 10%, and the carbonization temperature is 700℃ for 4 hours.

[0049] Example 5: Similar to Example 1, except that in the preparation of the adsorption catalytic material, the mass ratio of cyclodextrin metal-organic framework, KCl and K2CO3 is 1:4:6, the amount of thiourea added is 15%, and the carbonization temperature is 800℃ for 2 hours.

[0050] Comparative Example 1: Consistent with Example 1, except that commercial activated carbon (BET specific surface area 800 m²) was used. 2 / g) as an adsorption catalytic material.

[0051] Comparative Example 2: In the preparation of adsorption catalytic materials, the KCl-K2CO3 molten salt system is not used; instead, cyclodextrin metal-organic frameworks are directly carbonized under a nitrogen atmosphere.

[0052] Test method: Adsorption performance test: The concentration of vinyl chloride at the reactor outlet was detected using an online gas chromatograph. The total amount of vinyl chloride adsorbed per unit mass of adsorbent was calculated using the concentration curves at the inlet and outlet. Saturation determination: Adsorption was considered saturated when the outlet concentration reached 10% of the inlet concentration. Test results are shown in Table 1.

[0053] Catalytic degradation performance test: After adsorption saturation, the waste gas supply was stopped and replaced with air. During the degradation process, the residual vinyl chloride concentration was monitored using an online gas chromatograph, and the HCl concentration in the tail gas was analyzed using a hydrochloric acid gas-sensitive electrode or ion chromatography. Degradation rate = (1 - amount of residual vinyl chloride on the degraded material / total amount of vinyl chloride adsorbed at adsorption saturation) × 100%. The test results are shown in Table 1.

[0054] Table 1

[0055] Referring to the test results in Table 1, all Examples 1-5 exhibited excellent comprehensive performance, with vinyl chloride adsorption capacities all exceeding 130 mg / g and catalytic degradation rates all reaching over 98%. This fully demonstrates that the technical solution claimed in claim 1, using porous carbon materials prepared by a specific method, combined with a two-step method of adsorption enrichment and catalytic degradation, can efficiently and thoroughly treat vinyl chloride-containing waste gas. Comparative Example 1 used commercial activated carbon, whose adsorption capacity and degradation rate were far lower than all the examples. Although its adsorption rate was acceptable, its catalytic degradation ability was severely insufficient, resulting in a large amount of vinyl chloride not being completely decomposed and being desorbed or remaining. Comparative Example 2, due to the absence of the KCl-K2CO3 molten salt system and thiourea, showed a significant decrease in specific surface area, adsorption capacity, and catalytic degradation rate. This proves that the molten salt system is crucial for forming a high specific surface area porous structure in an air atmosphere, while the introduction of thiourea greatly enhances the catalytic activity of the material and is key to achieving a high degradation rate.

[0056] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0057] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the protection scope of the present invention.

Claims

1. A method for treating waste gas containing vinyl chloride, characterized in that, Includes the following steps: Adsorption and enrichment step: The waste gas containing vinyl chloride is brought into contact with the adsorption catalyst material, so that the vinyl chloride in the waste gas is adsorbed onto the adsorption catalyst material; Catalytic degradation step: The adsorption catalytic material that has completed the adsorption enrichment step is heated to catalytically degrade the adsorbed vinyl chloride; The adsorption catalytic material is a porous carbon material, which is prepared by carbonizing a mixture of thiourea and cyclodextrin metal-organic framework as a precursor in a KCl-K2CO3 molten salt system under an air atmosphere. The cyclodextrin metal-organic framework is prepared by a method including the following steps: γ-cyclodextrin and potassium salt are crystallized in an alcohol-water mixed solvent at 50-70°C to obtain the cyclodextrin metal-organic framework. The preparation method of the adsorption catalytic material includes: mixing γ-cyclodextrin metal-organic framework, KCl and K2CO3 in a mass ratio of 1:(3-4):(5-6), adding thiourea accounting for 10%-15% of the mass of γ-cyclodextrin metal-organic framework, grinding them together, and then heating them to 700-800℃ at a rate of 5-10℃ / min in air atmosphere and holding them at that temperature for 2-4 hours. After cooling, washing and drying, the adsorption catalytic material is obtained.

2. The method according to claim 1, characterized in that, In the adsorption and enrichment step, the temperature at which the vinyl chloride-containing waste gas comes into contact with the adsorption catalyst is 30-60℃.

3. The method according to claim 1, characterized in that, The catalytic degradation specifically includes the following steps: when the adsorption catalytic material is saturated, the waste gas is stopped from flowing in, and the material is heated to a target temperature of 200-400℃ at a rate of 1-10℃ / min in an air atmosphere, and kept at that temperature for 0.5-2 hours.

4. The method according to claim 1, characterized in that, The adsorption enrichment step and the catalytic degradation step are carried out intermittently and alternately in the same reactor.

5. The method according to claim 1, characterized in that, Prior to the adsorption and enrichment step, the following pretreatment step is also included: S1. The chloroethylene-containing waste gas from the polymerization reaction process is condensed in the first stage to obtain the first gas-liquid mixture; S2. The first gas-liquid mixture is subjected to gas-liquid separation. The separated gas phase is compressed and then subjected to two-stage condensation to obtain a second gas-liquid mixture. S3. The second gas-liquid mixture is subjected to gas-liquid separation. The separated liquid phase, vinyl chloride, is recovered and reused in the production system, and the separated gas phase is non-condensable waste gas. The chloroethylene-containing waste gas introduced for the adsorption and enrichment step is the non-condensable waste gas generated after separation in step S3.

6. The method according to claim 5, characterized in that, The cooling medium in step S1 is circulating cooling water, and the condensation temperature is controlled between 10°C and 25°C.

7. The method according to claim 5, characterized in that, The compression in step S2 is achieved by a gas compressor, with the exhaust pressure controlled at 0.6 MPa to 1.0 MPa; the cooling medium for the secondary condensation is low-temperature chilled water, with the condensation temperature controlled between -10°C and -25°C.

8. The method according to claim 1, characterized in that, The degradation products generated in the catalytic degradation step include hydrogen chloride, which is absorbed by alkaline spraying.

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