Waste gas purification method for crude benzene hydrogenation production and processing

Abstract

The invention discloses a method for purifying waste gas generated in hydrogenation production and processing of crude benzene, which belongs to the technical field of waste gas purification, and specifically comprises the following steps: introducing hydrogen-removed waste gas into a low-temperature tower to obtain methane liquid and purified gas, namely preparing porous modified polystyrene which is compatible with benzene series; the preparation method comprises the following steps: introducing a fluorine group to improve the tolerance to acid and alkali gases, introducing a zirconium 1, 4-phthalic acid frame structure into the structure to improve the adsorbability to benzene series pollutants, carrying out acid and alkali removal treatment, adsorbing hydrogen through platinum-loaded titanium dioxide particles coated with the zirconium 1, 4-phthalic acid frame structure of which the surface is modified with photosensitive molecules, and removing the hydrogen. The methane-containing waste gas is greatly different from the boiling point of air components, and methane and purified gas are obtained after low-temperature removal.

Description

Technical Field

[0001] The present invention relates to the technical field of waste gas purification, and particularly to a waste gas purification method for the production and processing of crude benzene hydrogenation. Background Art

[0002] The development of the waste gas purification method for the crude benzene hydrogenation process has evolved from simple treatment to high-efficiency purification technology. In the early 20th century, the waste gas from crude benzene hydrogenation was mainly discharged directly or treated by dilution, ignoring environmental pollution. In the mid-20th century, with the enhancement of environmental awareness, adsorption and absorption methods began to be used to remove benzene series and acidic gases, but with low efficiency and high cost. In the 1970s, catalytic combustion technology emerged, and volatile organic compounds in the waste gas were oxidized and decomposed at high temperatures, improving the purification effect, but with high energy consumption and prone to secondary pollution. In the 1980s, pressure swing adsorption and membrane separation technologies were introduced, which had higher separation efficiency for hydrogen and methane, marking the beginning of the era of precise separation. At the beginning of the 21st century, photocatalytic technology and metal-organic framework materials emerged, achieving high-efficiency and low-energy consumption purification by using photo-induced reactions and pore selectivity, while reducing the corrosion of acid-base gases. In recent years, composite technologies integrating physical adsorption, chemical absorption, and photocatalysis have significantly improved the separation purity of benzene series, hydrogen, and methane, reducing energy consumption and emissions, meeting the requirements of sustainable development.

[0003] For example, Chinese Patent CN102125802B provides a waste gas recovery and purification method in the production of crude benzene hydrogenation refining, including sending the analytical gas in the production of crude benzene hydrogenation refining to an analytical gas buffer, and then mixing it with coke oven gas at a rate of 300 - 600 m 3 / h, sending the bleeder gas in the production of crude benzene hydrogenation refining to a bleeder gas collection tank, controlling the temperature of the bleeder gas to 35°C, and collecting and recovering the condensed benzene substances. Then, mixing it with coke oven gas at a rate of 70 - 100 m 3 / h, sending the hydrogen sulfide in the production of crude benzene hydrogenation refining to a buffer, collecting and recovering the droplets in the hydrogen sulfide, and then mixing it with coke oven gas at a rate of 10 - 30 m 3 / h and carrying out purification treatment together, and no longer discharging the waste gas in the production of crude benzene hydrogenation refining, which not only realizes the comprehensive recovery and utilization of resources, reduces the pollution to the environment caused by waste gas discharge, but also recovers valuable chemical raw materials such as ammonia, sulfur, and benzene substances in the waste gas.

[0004] However, the above method only purifies the gas by mixing it with coke oven gas, but it cannot effectively separate low-boiling-point hydrogen and methane, resulting in these high-value components being mixed into the purified gas, with low resource utilization rate. The wash oil absorption and solution absorption only target polar impurities, and have poor separation effects on non-polar gases or trace volatile organic compounds, resulting in insufficient purity of the purified gas, low resource utilization rate, and restricted downstream applications. Economically, due to high energy consumption, complex equipment, and catalyst costs, the operating cost is high, so the purification degree and economy of this method need to be further improved. Summary of the Invention

[0005] The purpose of the present invention is to provide a waste gas purification method for the production and processing of crude benzene hydrogenation, aiming to solve the technical problem that the purification degree and economy of the waste gas from crude benzene hydrogenation in the prior art need to be further improved.

[0006] The purpose of the present invention can be achieved through the following technical solutions: A waste gas purification method for the production and processing of crude benzene hydrogenation includes the following steps:

[0007] S1. Add porous polystyrene, zirconium chloride, deionized water, and N,N-dimethylformamide into an ultrasonic instrument and ultrasonicate for 10 - 12 min. Then transfer the reaction system to a high-pressure reaction kettle. After the high-pressure reaction kettle is sealed, raise the temperature to 100 - 120 °C, keep the temperature for reaction for 24 - 28 h, and perform post-treatment to obtain modified polystyrene resin.

[0008] The reaction principle for preparing the modified polystyrene resin is as follows: Induced by the carboxyl groups on the surface of polystyrene, the growth of the zirconium terephthalate framework occurs. The N,N-dimethylformamide / water solvent and hydrothermal conditions promote the formation of metal-organic framework crystals. By integrating the mechanical support of polystyrene and the high adsorption performance of the zirconium terephthalate framework, the modified polystyrene resin is finally prepared.

[0009] S2. Pass the pre-treated waste gas through an adsorption bed loaded with the modified polystyrene resin to obtain benzene-removed waste gas.

[0010] S3. Pass the benzene-removed waste gas through an alkaline solution absorption tower and an acidic solution absorption tower successively to obtain neutral waste gas.

[0011] S4. Pass the neutral waste gas through an adsorption bed loaded with a photocatalytic adsorption material to obtain hydrogen-removed waste gas, and perform degassing treatment on the adsorption bed to obtain hydrogen.

[0012] S5. Pass the hydrogen-removed waste gas into a low-temperature tower to obtain methane liquid and purified gas.

[0013] Furthermore, during the process of preparing the modified polystyrene resin,

[0014] Further, in step S1, the dosage ratio of porous polystyrene, zirconium chloride, deionized water and N,N-dimethylformamide is 9-12 g: 3.6-4.0 g: 10-12 mL: 80-100 mL. The post-treatment includes: after the reaction is completed, when the temperature of the reaction kettle drops to room temperature, filter the reaction solution by suction to collect the filter cake. After washing the filter cake 3-5 times with ethanol and deionized water, transfer the filter cake to a vacuum drying oven at 60-80 °C and dry it in vacuum until constant weight to obtain the modified polystyrene resin;

[0015] Further, in step S2, the pretreatment operation includes: circulating the waste gas through a cyclone dust collector for dust removal to obtain intermediate gas I, and circulating intermediate gas I through a bag filter to obtain the dust-removed gas;

[0016] Further, the gas flow rate of the cyclone dust collector is 20000-40000 Nm³ / h, and the particle concentration of the waste gas is lower than 80 mg / Nm 3 After that, the circulation is ended to obtain intermediate gas I; the gas flow rate of the bag filter is 10000-20000 Nm³ / h, and the particle concentration of intermediate gas I is lower than 8 mg / Nm 3 After that, the circulation is ended to obtain the pretreated waste gas;

[0017] Further, in step S2, the diameter of the adsorption bed is 2.0-2.4 m, the height is 1.2-1.5 m, the temperature is 20-30 °C, the pressure is 0.1-0.2 Mpa, the gas volume is 800-1000 m³ / h, and the contact time is 2-3 s; in step S4, the diameter of the adsorption bed is 1.8-2.1 m, the height is 1.0-1.2 m, the temperature is 20-30 °C, the pressure is 0.1-0.2 Mpa, the gas volume is 800-1000 m³ / h, and the contact time is 4-6 s. The degassing treatment includes: after the adsorption is completed, take out the photocatalytic adsorption material, transfer it to the adsorption device for light-shielding treatment for 10-15 min, then use a vacuum pump to reduce the pressure in the adsorption device to 0.3-0.5 bar and keep it for 5-10 min to collect hydrogen; in step S5, the temperature of the low-temperature tower is -162 °C;

[0018] Further, in step S3, the alkali solution in the alkali solution absorption tower is a 2-4 wt% sodium hydroxide aqueous solution, the temperature is 20-40 °C, the pressure is 0.1-0.2 MPa, the liquid-gas ratio is 8-10 L / m 3 , the gas flow rate is 800-1000 m³ / h, the gas residence time is 3-5 s, and the alkali solution circulation is 8-10 m 3 / h; the acid solution in the acid solution absorption tower is a 2-4 wt% sulfuric acid aqueous solution, the temperature is 20-30 °C, the pressure is 0.1-0.2 MPa, the liquid-gas ratio is 12-15 L / m 3, the gas flow rate is 800 - 1000 m³ / h, the gas residence time is 3 - 5 s, and the lye circulation is 12 - 15 m 3 / h.

[0019] Furthermore, the preparation method of the porous polystyrene includes the following steps:

[0020] A1. Add the emulsion precursor to the reaction kettle and stir. After stirring at a stirring rate of 60 - 80 rpm for 10 - 15 min at room temperature, while adding deionized water to the reaction kettle, the stirring rate is increased to 800 - 1000 rpm, and after stirring for 25 - 30 min at room temperature, an emulsion is obtained;

[0021] A2. Add the emulsion to the reaction kettle, raise the temperature of the reaction kettle to 60 - 80 °C, keep the temperature for reaction for 10 - 12 h, and perform post-treatment to obtain porous modified polystyrene.

[0022] The reaction equation for preparing the porous modified polystyrene is:

[0023]

[0024] The reaction principle for preparing the porous modified polystyrene is: during the dispersion process of styrene, vinyl terephthalic acid, and m-trifluoromethylstyrene in the emulsion droplets, sorbitan oleate forms micelles to stabilize the oil-water interface. Through high-speed stirring and the addition of the aqueous phase to induce microemulsification, the monomers in the droplets provide a confined space for polymerization, laying the foundation for the porous structure, and forming functionalized polystyrene containing fluorine groups and carboxyl groups through free radical copolymerization. Finally, the formation of the porous structure is induced by the emulsion droplet template and phase separation, and the pores are solidified by washing and drying, and finally, the porous modified polystyrene with benzene series affinity and acid-base tolerance is prepared.

[0025] Furthermore, in step A1, the dosage ratio of the emulsion precursor to deionized water is 10 - 13 g:72 - 84 mL, wherein the emulsion precursor is obtained by mixing vinyl terephthalic acid, styrene, m-trifluoromethylstyrene, sorbitan oleate, and azodiisobutyronitrile according to the dosage ratio of 2 - 3 g:6 - 7 g:1 - 2 g:0.5 g:0.5 g;

[0026] Furthermore, in step A2, the post-treatment includes: after the reaction is completed, wait for the temperature of the reaction kettle to drop to room temperature, filter the reaction solution by suction to collect the filter cake, wash the filter cake 3 - 5 times with ethanol and deionized water, then transfer the filter cake to a vacuum drying oven at a temperature of 60 - 80 °C, and vacuum dry to constant weight to obtain the porous modified polystyrene.

[0027] Furthermore, the preparation method of the photocatalytic adsorption material includes the following steps:

[0028] B1. Add the titanium source solution and the platinum source solution into a high-pressure reactor. After stirring at room temperature for 20 - 30 min, seal the high-pressure reactor, and raise the temperature of the high-pressure reactor to 180 - 200 °C. Keep the temperature for reaction for 10 - 12 h, and then perform post-treatment to obtain titanium-platinum microparticles;

[0029] B2. Add zirconium chloride, terephthalic acid, acetic acid, and N,N-dimethylformamide into a high-pressure reactor. After stirring at room temperature for 10 - 15 min, add titanium-platinum microparticles into the high-pressure reactor, seal the high-pressure reactor, and raise the temperature of the high-pressure reactor to 100 - 120 °C. Keep the temperature for reaction for 20 - 24 h, and then perform post-treatment to obtain the supported microparticles;

[0030] B3. Add tetrakis(4-carboxyphenyl)porphyrin and ethanol into a reactor. After stirring in the dark for 10 - 15 min, add the supported microparticles into the reactor, and stir in the dark for 10 - 12 h to obtain the photocatalytic adsorption material.

[0031] The reaction principle for preparing the supported microparticles is as follows: tetrabutyl titanate hydrolyzes and polycondenses to form a titanium dioxide framework, and chloroplatinic acid is thermally reduced to generate platinum particles, which synergistically form titanium-platinum microparticles with high photocatalytic activity and high hydrogen affinity. Zirconium ions coordinate and assemble with terephthalic acid to form a metal-organic framework, and the Ti-OH on the surface of the titanium-platinum microparticles induces the growth of the metal-organic framework. By integrating the photocatalytic performance of titanium dioxide and the high adsorption capacity of the metal-organic framework, the supported microparticles are finally prepared. Tetrakis(4-carboxyphenyl)porphyrin is anchored on the surface of the metal-organic framework or titanium dioxide structure through carboxyl coordination. The porphyrin ring captures visible light-excited electrons, and synergistically with the titanium-platinum microparticle structure and the metal-organic framework structure, realizes light-induced hydrogen adsorption, and finally the photocatalytic adsorption material is prepared.

[0032] Furthermore, in step B1, the dosage ratio of the titanium source solution to the platinum source solution is 2 mL:1 mL. Among them, the titanium source solution is obtained by mixing tetrabutyl titanate and absolute ethanol according to the dosage ratio of 1 - 2 mL:10 mL, and the platinum source solution is obtained by mixing chloroplatinic acid and deionized water according to the dosage ratio of 0.1 - 0.2 g:50 mL. The post-treatment includes: after the reaction is completed, wait for the temperature of the reactor to drop to room temperature, filter the reaction solution by suction to collect the filter cake, wash the filter cake with ethanol and deionized water for 3 - 5 times, and then transfer the filter cake to a vacuum drying oven at a temperature of 60 - 80 °C, and vacuum dry to constant weight to obtain the titanium-platinum microparticles;

[0033] Further, in step B2, the dosage ratio of zirconium chloride, terephthalic acid, acetic acid, N,N-dimethylformamide and titanium-platinum particles is 2.3 - 2.4 g: 1.6 - 1.7 g: 20 mL: 200 mL: 5 - 6 g. The post-treatment includes: after the reaction is completed, when the temperature of the reaction kettle drops to room temperature, filter the reaction solution to collect the filter cake. After washing the filter cake with ethanol and deionized water 3 - 5 times, transfer the filter cake to a vacuum drying oven at a temperature of 60 - 80 °C and vacuum dry until constant weight to obtain the supported particles.

[0034] Further, in step B3, the dosage ratio of tetrakis(4-carboxyphenyl)porphyrin, ethanol and the supported particles is 0.4 - 0.6 g: 200 mL: 4 - 6 g. The post-treatment includes: after the reaction is completed, when the temperature of the reaction kettle drops to room temperature, filter the reaction solution to collect the filter cake. After washing the filter cake with ethanol and deionized water 3 - 5 times, transfer the filter cake to a vacuum drying oven at a temperature of 60 - 80 °C and vacuum dry until constant weight to obtain the photocatalytic adsorption material.

[0035] The present invention has the following beneficial effects:

[0036] 1. The modified polystyrene resin prepared by the present invention significantly promotes the hydrogen recovery efficiency of the photocatalytic adsorption material by removing benzene compounds in the crude benzene hydrogenation waste gas. It adsorbs aromatic hydrocarbons by using the π-π interaction of the benzene ring and the hydrophobic surface, and the fluorine group enhances the acid-base tolerance. The pores of the zirconium 1,4-benzenedicarboxylate framework capture residual benzene compounds, purifying the waste gas to mainly hydrogen and methane. The waste gas with benzene compounds removed reduces the competitive interference with the adsorption sites of the photocatalytic material, optimizing the separation environment. The photocatalytic material generates an electric field under light irradiation and preferentially adsorbs small molecule hydrogen. The pores repel larger molecules such as methane through size screening. The pre-removal of benzene compounds prevents the surface active sites of the photocatalytic material from being contaminated and protects the light response ability of the photosensitive molecules. Moreover, sodium hydroxide and sulfuric acid solutions remove acidic and basic gases through selective chemical reactions, reducing the interference with the subsequent adsorption material. The dehydration adsorption step removes water vapor through physical drying or molecular sieve adsorption, preventing the surface active sites of the inorganic structure from being occupied by water molecules, thereby improving the selectivity and desorption efficiency of hydrogen adsorption, enhancing the recovery purity, reducing the material regeneration requirement. This pretreatment significantly improves the separation performance and operation stability of the photocatalytic system for hydrogen by purifying the gas phase composition.

[0037] 2. The modified polystyrene prepared in the present invention utilizes its high chemical affinity for benzene series compounds to preferentially adsorb aromatic hydrocarbon molecules through π-π interaction and hydrophobic surface, so as to capture benzene series impurities from the waste gas. The zirconium 1,4-benzenedicarboxylate framework relies on its high specific surface area and adjustable pore structure to adsorb methane and hydrogen through van der Waals force and pore size sieving effect, while restricting the entry of larger molecules. Moreover, the loaded microparticles are modified with photosensitive molecules, which can generate local electric fields under light illumination by exciting electron-hole pairs, enhancing the highly polarized adsorption of hydrogen molecules, repelling methane and nitrogen and oxygen in the air. Sodium hydroxide solution captures acidic gases such as hydrogen sulfide through acid-base neutralization reaction, and sulfuric acid solution removes basic gases such as ammonia through similar reactions, reducing the subsequent adsorption load. At the same time, dehydration treatment removes water vapor to protect the activity of the MOF pores. The remaining methane-containing waste gas enters the low-temperature fractionation system, and separation is achieved through step-by-step condensation by utilizing the boiling point differences between methane and nitrogen and oxygen. The synergistic effect of each step progresses layer by layer to ensure the efficient separation of complex waste gas components.

[0038] 3. The modified polystyrene of the present invention is based on inexpensive polymers and endows the ability to adsorb benzene series compounds through simple chemical modification. The preparation process utilizes mature industrial technologies. The zirconium 1,4-benzenedicarboxylate framework uses low-cost precursors, and the photocatalytic adsorption material synthesized by hydrothermal method is excited by visible light or solar energy to drive the adsorption and desorption of hydrogen. Compared with the refrigeration energy consumption of low-temperature fractionation or the high-pressure requirement of pressure swing adsorption, the operation energy consumption is significantly reduced. Sodium hydroxide and sulfuric acid solutions remove impurities through acid-base reactions, and the solutions can be recycled through neutralization regeneration. Dehydration treatment uses physical drying or low-cost molecular sieves to extend the life of the inorganic structure. The separated hydrogen and methane are purified through adsorption and fractionation and can be used as fuels or chemical raw materials. The air components are discharged after purification. The photocatalytic material is regenerated through light illumination or low-temperature treatment, enabling the structural stability to support long-term use and reducing the replacement frequency. Moreover, the modular design of the process allows for miniaturized equipment, which can flexibly adapt to the waste gas treatment requirements of different scales, taking into account resource recovery and low emissions. Detailed implementation manners

[0039] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] The sorbitan oleate used in the present invention was purchased from Tianjin Sine Chemical Technology Co., Ltd., and the product number is S-0449256 + 500 ml.

[0041] Example 1

[0042] This embodiment provides a method for preparing a modified polystyrene resin for purifying waste gas in the production and processing of crude benzene hydrogenation, including the following steps:

[0043] Step ①, preparing the emulsion

[0044] Weigh: 20.0 g of vinyl terephthalic acid, 60.0 g of styrene, 10.0 g of m-trifluoromethylstyrene, 5.0 g of sorbitan oleate and 5.0 g of azobisisobutyronitrile are mixed to obtain an emulsion precursor

[0045] Weigh: 100.0 g of the emulsion precursor is added to the reaction kettle and stirred. After stirring at a stirring rate of 60 rpm for 10 min at room temperature, while adding 720.0 mL of deionized water to the reaction kettle, the stirring rate is increased to 800 rpm. After stirring for 25 min at room temperature, an emulsion is obtained.

[0046] Step ②, preparing porous modified polystyrene

[0047] Weigh: 800.0 g of the emulsion is added to the reaction kettle. The temperature of the reaction kettle is raised to 60 °C and kept for 10 h. After the reaction is completed, when the temperature of the reaction kettle is lowered to room temperature, the reaction solution is filtered by suction to collect the filter cake. After washing the filter cake 3 times with ethanol and deionized water, the filter cake is transferred to a vacuum drying oven at 60 °C and vacuum dried to constant weight to obtain porous modified polystyrene.

[0048] Step ③, preparing the modified polystyrene resin

[0049] Weigh: 90.0 g of porous polystyrene, 36.0 g of zirconium chloride, 100.0 mL of deionized water and 800.0 mL of N,N-dimethylformamide are added to an ultrasonic instrument and ultrasonicated for 10 min. Then the reaction system is transferred to a high-pressure reaction kettle. After the high-pressure reaction kettle is sealed, the temperature is raised to 100 °C and kept for 24 h. After the reaction is completed, when the temperature of the reaction kettle is lowered to room temperature, the reaction solution is filtered by suction to collect the filter cake. After washing the filter cake 3 times with ethanol and deionized water, the filter cake is transferred to a vacuum drying oven at 60 °C and vacuum dried to constant weight to obtain the modified polystyrene resin.

[0050] Example 2

[0051] This embodiment provides a method for preparing a modified polystyrene resin for purifying waste gas in the production and processing of crude benzene hydrogenation, including the following steps:

[0052] Step ①, preparing the emulsion

[0053] Weigh: 30.0 g of vinyl terephthalic acid, 70.0 g of styrene, 20.0 g of m-trifluoromethylstyrene, 5.0 g of sorbitan oleate and 5.0 g of azobisisobutyronitrile are mixed to obtain an emulsion precursor

[0054] Weigh: Add 130.0 g of the emulsion precursor to the reaction kettle and stir. After stirring at a stirring rate of 80 rpm for 15 min at room temperature, while adding 840.0 mL of deionized water to the reaction kettle, the stirring rate is increased to 1000 rpm. After stirring for 30 min at room temperature, an emulsion is obtained.

[0055] Step ②, Preparation of porous modified polystyrene

[0056] Weigh: Add 960.0 g of the emulsion to the reaction kettle. Raise the temperature of the reaction kettle to 80 °C and keep the temperature for 12 h. After the reaction is completed, wait for the temperature of the reaction kettle to drop to room temperature. Filter the reaction solution by suction to collect the filter cake. After washing the filter cake 5 times with ethanol and deionized water, transfer the filter cake to a vacuum drying oven at 80 °C and vacuum dry to constant weight to obtain porous modified polystyrene.

[0057] Step ③, Preparation of modified polystyrene resin

[0058] Weigh: Add 120.0 g of porous polystyrene, 40.0 g of zirconium chloride, 120.0 mL of deionized water, and 1000.0 mL of N,N-dimethylformamide to the ultrasonic instrument and ultrasonicate for 12 min. Then transfer the reaction system to a high-pressure reaction kettle. After the high-pressure reaction kettle is sealed, raise the temperature to 120 °C and keep the temperature for 28 h. After the reaction is completed, wait for the temperature of the reaction kettle to drop to room temperature. Filter the reaction solution by suction to collect the filter cake. After washing the filter cake 5 times with ethanol and deionized water, transfer the filter cake to a vacuum drying oven at 80 °C and vacuum dry to constant weight to obtain modified polystyrene resin.

[0059] Example 3

[0060] This example provides a preparation method of modified polystyrene resin for purifying waste gas in the production and processing of crude benzene hydrogenation, including the following steps:

[0061] Step ①, Preparation of emulsion

[0062] Weigh: Mix 25.0 g of vinyl terephthalic acid, 64.0 g of styrene, 18.0 g of m-trifluoromethylstyrene, 5.0 g of sorbitan oleate, and 5.0 g of azobisisobutyronitrile to obtain an emulsion precursor

[0063] Weigh: Add 110.0 g of the emulsion precursor to the reaction kettle and stir. After stirring at a stirring rate of 70 rpm for 12 min at room temperature, while adding 800.0 mL of deionized water to the reaction kettle, the stirring rate is increased to 900 rpm. After stirring for 27 min at room temperature, an emulsion is obtained.

[0064] Step ②, Preparation of porous modified polystyrene

[0065] Weigh: Add 900.0 g of the emulsion into the reaction kettle. Raise the temperature of the reaction kettle to 70 °C and keep the temperature for 12 h. After the reaction is completed, wait for the temperature of the reaction kettle to drop to room temperature. Filter the reaction solution by suction to collect the filter cake. Wash the filter cake 4 times with ethanol and deionized water, then transfer the filter cake to a vacuum drying oven at 70 °C and dry it under vacuum until constant weight to obtain porous modified polystyrene.

[0066] Step ③: Prepare modified polystyrene resin

[0067] Weigh: Add 100.0 g of porous polystyrene, 36.0 g of zirconium chloride, 120.0 mL of deionized water and 900.0 mL of N,N-dimethylformamide into an ultrasonic device and ultrasonic for 12 min. Then transfer the reaction system to a high-pressure reaction kettle. After the high-pressure reaction kettle is sealed, raise the temperature to 120 °C and keep the temperature for 28 h. After the reaction is completed, wait for the temperature of the reaction kettle to drop to room temperature. Filter the reaction solution by suction to collect the filter cake. Wash the filter cake 4 times with ethanol and deionized water, then transfer the filter cake to a vacuum drying oven at 70 °C and dry it under vacuum until constant weight to obtain modified polystyrene resin.

[0068] Example 4

[0069] This example provides a preparation method of a photocatalytic adsorption material for purifying waste gas in the production and processing of crude benzene hydrogenation, including the following steps:

[0070] Step Ⅰ: Prepare titanium-platinum particles

[0071] Weigh: Mix 60.0 mL of tetrabutyl titanate and 600.0 mL of absolute ethanol to obtain a titanium source solution;

[0072] Weigh: Mix 6.0 g of chloroplatinic acid and 300.0 mL of deionized water to obtain a platinum source solution;

[0073] Weigh: Add 600.0 mL of the titanium source solution and 300.0 mL of the platinum source solution into a high-pressure reaction kettle. Stir at room temperature for 20 min, then seal the high-pressure reaction kettle and raise the temperature of the high-pressure reaction kettle to 180 °C. Keep the temperature for 10 h. After the reaction is completed, wait for the temperature of the reaction kettle to drop to room temperature. Filter the reaction solution by suction to collect the filter cake. Wash the filter cake 3 times with ethanol and deionized water, then transfer the filter cake to a vacuum drying oven at 60 °C and dry it under vacuum until constant weight to obtain titanium-platinum particles.

[0074] Step Ⅱ: Prepare supported particles

[0075] Weigh: 23.0 g of zirconium chloride, 16.0 g of terephthalic acid, 200.0 mL of acetic acid and 2000.0 mL of N,N-dimethylformamide are added to a high-pressure reactor. After stirring at room temperature for 10 min, 50.0 g of titanium-platinum particles are added to the high-pressure reactor. The high-pressure reactor is sealed, and the temperature of the high-pressure reactor is raised to 100 °C, and the reaction is carried out under insulation for 20 h. After the reaction is completed, when the temperature of the reactor drops to room temperature, the reaction solution is filtered by suction to collect the filter cake. After washing the filter cake 3 times with ethanol and deionized water, the filter cake is transferred to a vacuum drying oven at 60 °C and vacuum dried to constant weight to obtain the supported particles.

[0076] Step III, preparation of photocatalytic adsorption material

[0077] Weigh: 4.0 g of tetrakis(4-carboxyphenyl)porphyrin and 2000.0 mL of ethanol are added to a reactor. After stirring in the dark for 10 min, 40.0 g of supported particles are added to the reactor. After stirring in the dark for 10 h, after the reaction is completed, when the temperature of the reactor drops to room temperature, the reaction solution is filtered by suction to collect the filter cake. After washing the filter cake 3 times with ethanol and deionized water, the filter cake is transferred to a vacuum drying oven at 60 °C and vacuum dried to constant weight to obtain the photocatalytic adsorption material.

[0078] Example 5

[0079] This example provides a preparation method of a photocatalytic adsorption material for purifying waste gas in the production and processing of crude benzene hydrogenation, including the following steps:

[0080] Step I, preparation of titanium-platinum particles

[0081] Weigh: 120.0 mL of tetrabutyl titanate and 600.0 mL of absolute ethanol are mixed to obtain a titanium source solution;

[0082] Weigh: 12.0 g of chloroplatinic acid and 300.0 mL of deionized water are mixed to obtain a platinum source solution;

[0083] Weigh: 600.0 mL of the titanium source solution and 300.0 mL of the platinum source solution are added to a high-pressure reactor. After stirring at room temperature for 30 min, the high-pressure reactor is sealed, and the temperature of the high-pressure reactor is raised to 200 °C, and the reaction is carried out under insulation for 12 h. After the reaction is completed, when the temperature of the reactor drops to room temperature, the reaction solution is filtered by suction to collect the filter cake. After washing the filter cake 5 times with ethanol and deionized water, the filter cake is transferred to a vacuum drying oven at 80 °C and vacuum dried to constant weight to obtain the titanium-platinum particles.

[0084] Step II, preparation of supported particles

[0085] Weigh: 24.0 g of zirconium chloride, 17.0 g of terephthalic acid, 200.0 mL of acetic acid and 2000.0 mL of N,N-dimethylformamide were added to a high-pressure reactor. After stirring at room temperature for 15 min, 60.0 g of titanium-platinum microparticles were added to the high-pressure reactor. The high-pressure reactor was sealed, and the temperature of the high-pressure reactor was raised to 120 °C, and the reaction was carried out under insulation for 24 h. After the reaction was completed, when the temperature of the reactor decreased to room temperature, the reaction solution was filtered by suction to collect the filter cake. After washing the filter cake 5 times with ethanol and deionized water, the filter cake was transferred to a vacuum drying oven at 80 °C and vacuum dried to constant weight to obtain the supported microparticles.

[0086] Step III. Preparation of photocatalytic adsorption material

[0087] Weigh: 6.0 g of tetrakis(4-carboxyphenyl)porphyrin and 2000.0 mL of ethanol were added to a reactor. After stirring in the dark for 15 min, 60.0 g of supported microparticles were added to the reactor. After stirring in the dark for 12 h, after the reaction was completed, when the temperature of the reactor decreased to room temperature, the reaction solution was filtered by suction to collect the filter cake. After washing the filter cake 5 times with ethanol and deionized water, the filter cake was transferred to a vacuum drying oven at 80 °C and vacuum dried to constant weight to obtain the photocatalytic adsorption material.

[0088] Example 6

[0089] This example provides a preparation method of a photocatalytic adsorption material for purifying waste gas in the production and processing of crude benzene hydrogenation, including the following steps:

[0090] Step I. Preparation of titanium-platinum microparticles

[0091] Weigh: 90.0 mL of tetrabutyl titanate and 600.0 mL of absolute ethanol were mixed to obtain a titanium source solution;

[0092] Weigh: 9.0 g of chloroplatinic acid and 300.0 mL of deionized water were mixed to obtain a platinum source solution;

[0093] Weigh: 600.0 mL of the titanium source solution and 300.0 mL of the platinum source solution were added to a high-pressure reactor. After stirring at room temperature for 25 min, the high-pressure reactor was sealed, and the temperature of the high-pressure reactor was raised to 200 °C, and the reaction was carried out under insulation for 12 h. After the reaction was completed, when the temperature of the reactor decreased to room temperature, the reaction solution was filtered by suction to collect the filter cake. After washing the filter cake 4 times with ethanol and deionized water, the filter cake was transferred to a vacuum drying oven at 70 °C and vacuum dried to constant weight to obtain the titanium-platinum microparticles.

[0094] Step II. Preparation of supported microparticles

[0095] Weigh: 24.0 g of zirconium chloride, 16.0 g of terephthalic acid, 200.0 mL of acetic acid and 2000.0 mL of N,N-dimethylformamide were added to a high-pressure reactor. After stirring at room temperature for 12 min, 54.0 g of titanium-platinum particles were added to the high-pressure reactor. The high-pressure reactor was sealed, and the temperature of the high-pressure reactor was raised to 120 °C. After holding the reaction for 21 h, after the reaction was completed, when the temperature of the reactor decreased to room temperature, the reaction solution was filtered by suction to collect the filter cake. After washing the filter cake 4 times with ethanol and deionized water, the filter cake was transferred to a vacuum drying oven at 70 °C and vacuum dried to constant weight to obtain the supported particles.

[0096] Step III. Preparation of photocatalytic adsorption material

[0097] Weigh: 5.0 g of tetrakis(4-carboxyphenyl)porphyrin and 2000.0 mL of ethanol were added to a reactor. After stirring in the dark for 12 min, 50.0 g of supported particles were added to the reactor. After stirring in the dark for 12 h, after the reaction was completed, when the temperature of the reactor decreased to room temperature, the reaction solution was filtered by suction to collect the filter cake. After washing the filter cake 4 times with ethanol and deionized water, the filter cake was transferred to a vacuum drying oven at 70 °C and vacuum dried to constant weight to obtain the photocatalytic adsorption material.

[0098] Example 7

[0099] This example provides a method for purifying waste gas in the production and processing of crude benzene hydrogenation, including the following steps:

[0100] Step 1. Preparation of benzene-removing waste gas

[0101] The waste gas was circulated through a cyclone dust collector. The gas flow rate of the cyclone dust collector was 20000 Nm³ / h, and the particle concentration of the waste gas was lower than 80 mg / Nm 3 After that, the circulation was ended to obtain intermediate gas I. Intermediate gas I was circulated through a bag filter. The gas flow rate of the bag filter was 10000 Nm³ / h, and the particle concentration of intermediate gas I was lower than 8 mg / Nm 3 After that, the circulation was ended to obtain the pre-treated waste gas;

[0102] The pre-treated waste gas was introduced into an adsorption bed loaded with the modified polystyrene resin prepared in Example 1. The diameter of the adsorption bed was 2.0 m, the height was 1.2 m, the temperature was 20 °C, the pressure was 0.1 Mpa, and the gas volume was 800 m³ / h to obtain the benzene-removing waste gas.

[0103] Step 2. Preparation of neutral waste gas

[0104] The benzene-removing waste gas was introduced into an alkaline solution absorption tower containing 2.0 wt% sodium hydroxide aqueous solution. The temperature of the alkaline solution absorption tower was 20 °C, the pressure was 0.1 MPa, and the liquid-gas ratio was 8 L / m 3, the gas flow rate is 800 m³ / h, the gas residence time is 3 s, and the caustic solution circulation is 8 m 3 / h, and the gas is introduced into an acid solution absorption tower filled with a 2.0 wt% sulfuric acid aqueous solution. The temperature of the acid solution absorption tower is 20 °C, the pressure is 0.1 MPa, and the liquid-gas ratio is 12 L / m 3 , the gas flow rate is 800 m³ / h, the gas residence time is 3 s, and the caustic solution circulation is 12 m 3 / h, obtaining neutral waste gas.

[0105] Step 3: Prepare hydrogen-removing waste gas

[0106] The neutral waste gas is introduced into an adsorption bed filled with the photocatalytic adsorption material prepared in Example 4. The diameter of the adsorption bed is 1.8 m, the height is 1.0 m, the temperature is 20 °C, the pressure is 0.1 Mpa, the gas volume is 800 m³ / h, and the contact time is 4 s, obtaining hydrogen-removing waste gas. After the adsorption is completed, the photocatalytic adsorption material is taken out, transferred to an adsorption device for light-shielding treatment for 10 min, and then the pressure in the adsorption device is reduced to 0.3 bar using a vacuum pump and maintained for 5 min to collect hydrogen.

[0107] Step 4: Prepare methane liquid and purified gas

[0108] The hydrogen-removing waste gas is introduced into a low-temperature tower with a temperature of -162 °C to obtain methane liquid and purified gas.

[0109] Example 8

[0110] This example provides a waste gas purification method for the production and processing of crude benzene hydrogenation, including the following steps:

[0111] Step 1: Prepare benzene-removing waste gas

[0112] The waste gas is circulated and introduced into a cyclone dust collector with a gas flow rate of 40,000 Nm³ / h. The particle concentration of the waste gas is lower than 80 mg / Nm 3 After that, the circulation ends to obtain intermediate gas I. Intermediate gas I is circulated through a bag filter with a gas flow rate of 20,000 Nm³ / h. The particle concentration of intermediate gas I is lower than 8 mg / Nm 3 After that, the circulation ends to obtain pre-treated waste gas;

[0113] The pre-treated waste gas is introduced into an adsorption bed filled with the modified polystyrene resin prepared in Example 2. The diameter of the adsorption bed is 2.4 m, the height is 1.5 m, the temperature is 30 °C, the pressure is 0.2 Mpa, and the gas volume is 1000 m³ / h to obtain benzene-removing waste gas.

[0114] Step 2: Prepare neutral waste gas

[0115] The benzene-containing waste gas is introduced into an alkaline solution absorption tower filled with a 4.0 wt% aqueous sodium hydroxide solution. The temperature of the alkaline solution absorption tower is 40 °C, the pressure is 0.2 MPa, and the liquid-gas ratio is 10 L / m 3 , the gas flow rate is 1000 m³ / h, the gas residence time is 5 s, and the alkaline solution circulation is 10 m 3 / h, and the passed gas is introduced into an acidic solution absorption tower filled with a 4.0 wt% aqueous sulfuric acid solution. The temperature of the acidic solution absorption tower is 30 °C, the pressure is 0.2 MPa, and the liquid-gas ratio is 15 L / m 3 , the gas flow rate is 1000 m³ / h, the gas residence time is 5 s, and the alkaline solution circulation is 15 m 3 / h to obtain neutral waste gas.

[0116] Step 3: Prepare hydrogen-removing waste gas

[0117] The neutral waste gas is introduced into an adsorption bed loaded with the photocatalytic adsorption material prepared in Example 5. The diameter of the adsorption bed is 2.1 m, the height is 1.2 m, the temperature is 30 °C, the pressure is 0.2 Mpa, the gas volume is 1000 m³ / h, and the contact time is 6 s to obtain hydrogen-removing waste gas. After the adsorption is completed, the photocatalytic adsorption material is taken out, transferred to an adsorption device for light-shielding treatment for 15 min, and then the pressure in the adsorption device is reduced to 0.5 bar using a vacuum pump and maintained for 10 min to collect hydrogen.

[0118] Step 4: Prepare methane liquid and purified gas

[0119] The hydrogen-removing waste gas is introduced into a low-temperature tower. The temperature of the low-temperature tower is -162 °C to obtain methane liquid and purified gas.

[0120] Example 9

[0121] This example provides a waste gas purification method for the production and processing of crude benzene hydrogenation, including the following steps:

[0122] Step 1: Prepare benzene-containing waste gas

[0123] The waste gas is circulated and introduced into a cyclone dust collector. The gas flow rate of the cyclone dust collector is 30000 Nm³ / h, and the particle concentration of the waste gas is lower than 80 mg / Nm 3 After that, the circulation is ended to obtain intermediate gas I. Intermediate gas I is circulated through a bag filter. The gas flow rate of the bag filter is 15000 Nm³ / h, and the particle concentration of intermediate gas I is lower than 8 mg / Nm 3 After that, the circulation is ended to obtain pre-treated waste gas;

[0124] The pretreated waste gas is introduced into an adsorption bed filled with the modified polystyrene resin prepared in Example 3. The adsorption bed has a diameter of 2.1 m, a height of 1.5 m, a temperature of 25 °C, a pressure of 0.2 Mpa, and a gas flow rate of 900 m³ / h, and the benzene-removed waste gas is obtained.

[0125] Step 2: Prepare neutral waste gas

[0126] The benzene-removed waste gas is introduced into an alkaline solution absorption tower filled with 3.0 wt% sodium hydroxide aqueous solution. The temperature of the alkaline solution absorption tower is 30 °C, the pressure is 0.2 MPa, the liquid-gas ratio is 9 L / m 3 , the gas flow rate is 900 m³ / h, the gas residence time is 4 s, and the alkaline solution circulation is 9 m 3 / h, and the passed gas is introduced into an acidic solution absorption tower filled with 3.0 wt% sulfuric acid aqueous solution. The temperature of the acidic solution absorption tower is 25 °C, the pressure is 0.2 MPa, the liquid-gas ratio is 12 L / m 3 , the gas flow rate is 900 m³ / h, the gas residence time is 4 s, and the alkaline solution circulation is 15 m 3 / h, and the neutral waste gas is obtained.

[0127] Step 3: Prepare hydrogen-removed waste gas

[0128] The neutral waste gas is introduced into an adsorption bed filled with the photocatalytic adsorption material prepared in Example 6. The adsorption bed has a diameter of 2.0 m, a height of 1.2 m, a temperature of 25 °C, a pressure of 0.2 Mpa, a gas flow rate of 900 m³ / h, and a contact time of 5 s, and the hydrogen-removed waste gas is obtained. After the adsorption is completed, the photocatalytic adsorption material is taken out, transferred to an adsorption device for light-shielding treatment for 12 min, and then the pressure in the adsorption device is reduced to 0.4 bar by a vacuum pump and maintained for 8 min to collect hydrogen.

[0129] Step 4: Prepare methane liquid and purified gas

[0130] The hydrogen-removed waste gas is introduced into a low-temperature tower with a temperature of -162 °C to obtain methane liquid and purified gas.

[0131] Comparative Example 1

[0132] The difference between this comparative example and Example 9 is that step ③ is cancelled in the preparation process of the modified polystyrene resin used in step 1.

[0133] Comparative Example 2

[0134] The difference between this comparative example and Example 9 is that step Ⅱ is cancelled in the preparation process of the modified polystyrene resin used in step 3.

[0135] Comparative Example 3

[0136] The difference between this comparative example and Example 9 is that Step III is cancelled during the preparation of the modified polystyrene resin used in Step 3.

[0137] Performance test:

[0138] Refer to the national standard GB 16297-1996 "Integrated Emission Standard of Air Pollutants" to test the benzene content, toluene content and xylene content of the purified gas prepared in Examples 7-9 and Comparative Examples 1-3;

[0139] Refer to the national standard GB 14554-1993 "Emission Standard of Odor Pollutants" to test the ammonia content and hydrogen sulfide content of the purified gas prepared in Examples 7-9 and Comparative Examples 1-3;

[0140] Refer to the national standard GB / T 3634.2-2011 "Hydrogen - Part 2: Pure hydrogen, high purity hydrogen and ultra-high purity hydrogen" to test the purity of the hydrogen prepared in Examples 7-9 and Comparative Examples 1-3;

[0141] Refer to the national standard HJ 38-2017 "Determination of total hydrocarbons, methane and non-methane total hydrocarbons in flue gas from stationary sources - Gas chromatography method" to test the total hydrocarbon content of the purified gas prepared in Examples 7-9 and Comparative Examples 1-3. See Table 1 for details.

[0142] Table 1 - Performance test data table of each sample

[0143]

[0144] Data analysis:

[0145] After comparative analysis of the data in Table 1, it can be found that the benzene content in the purified gas obtained after the waste gas treatment of the present invention is 7 mg·m -3 , the toluene content is 30 mg·m -3 , the xylene content is 46 mg·m -3 , the ammonia content is 0.4 mg·m -3 , the hydrogen sulfide content is 0.01 mg·m -3 , the methane content is 0.27 mg·m -3 , and the purity of the simultaneously separated hydrogen is 99.99%. All data are better than those of the comparative examples, indicating that:

[0146] The modified polystyrene resin prepared by the present invention can significantly promote the efficiency of recovering hydrogen by photocatalytic adsorption materials by removing benzene compounds in crude benzene hydrogenation waste gas, utilize the π-π interaction of benzene rings and the hydrophobic surface to adsorb aromatic hydrocarbons, enhance the acid-base tolerance by fluorine groups, and capture residual benzene compounds in the zirconium 1,4-phthalic acid framework pores to purify waste gas to mainly hydrogen and methane. The waste gas with benzene compounds removed reduces the competitive interference with the adsorption sites of photocatalytic materials, optimizes the separation environment, and the photocatalytic material generates an electric field under light to preferentially adsorb small molecular hydrogen. The pores exclude larger molecules by size screening. The pre-removal of methane and benzene series prevents the active sites on the surface of the photocatalytic material from being contaminated, protects the light response ability of the photosensitive molecules, and the sodium hydroxide and sulfuric acid solutions remove acidic and alkaline gases through selective chemical reactions to reduce interference with subsequent adsorption materials. The dehydration adsorption step removes water vapor through physical drying or molecular sieve adsorption to prevent the active sites on the surface of the inorganic structure from being occupied by water molecules, thereby improving the selectivity and desorption efficiency of hydrogen adsorption, enhancing the recovery purity, and reducing the need for material regeneration. This pretreatment significantly improves the separation performance and operational stability of the photocatalytic system for hydrogen by purifying the gas phase composition;

[0147] The modified polystyrene prepared by the present invention utilizes its high chemical affinity for benzene series to preferentially adsorb aromatic hydrocarbon molecules through π-π interaction and hydrophobic surface, thereby capturing benzene series impurities from waste gas; the zirconium 1,4-phthalic acid framework relies on high specific surface area and adjustable pore structure to adsorb methane and hydrogen through van der Waals force and pore size screening effect, while restricting the entry of larger molecules; the loaded microparticles are modified by photosensitive molecules to excite electron-hole pairs under light to generate a local electric field, thereby enhancing the high polarizability adsorption of small hydrogen molecules and repelling methane and nitrogen and oxygen in the air; the sodium hydroxide solution captures acidic gases such as hydrogen sulfide through an acid-base neutralization reaction; the sulfuric acid solution removes alkaline gases such as ammonia through a similar reaction, thereby reducing the subsequent adsorption load; the water vapor is removed through dehydration treatment to protect the MOF pore activity; the remaining methane-containing waste gas enters a low-temperature fractionation system, and separation is achieved through step-by-step condensation by utilizing the difference in boiling points between methane and nitrogen and oxygen; the steps act synergistically and progressively, thereby ensuring efficient separation of complex waste gas components;

[0148] The modified polystyrene of the present invention is based on inexpensive polymers. The ability to adsorb benzene series substances is imparted through simple chemical modification. The preparation process utilizes mature industrial technologies. The zirconium 1,4-benzenedicarboxylate framework uses low-cost precursors and is synthesized by a hydrothermal method. The photocatalytic adsorption material is excited by visible light or solar energy to drive hydrogen adsorption and desorption. Compared with the refrigeration energy consumption of low-temperature fractionation or the high-pressure requirement of pressure swing adsorption, the operating energy consumption is significantly reduced. Impurities are removed by the acid-base reaction of sodium hydroxide and sulfuric acid solutions, and the solution can be recycled through neutralization regeneration. The dehydration treatment uses physical drying or low-cost molecular sieves to extend the life of the inorganic structure. The separated hydrogen and methane are purified by adsorption and fractionation and can be used as fuels or chemical raw materials. The air components are discharged after purification. The photocatalytic material is regenerated by light irradiation or low-temperature treatment, enabling the structural stability to support long-term use and reducing the replacement frequency. Moreover, the modular design of the process allows for miniaturized equipment, which can flexibly adapt to the exhaust gas treatment requirements of different scales, taking into account resource recovery and low emissions;

[0149] The present invention is to prepare porous modified polystyrene that is affinity for benzene series substances, improve its tolerance to acid-base gases by introducing fluorine groups, introduce the zirconium 1,4-benzenedicarboxylate framework structure into its structure to enhance its adsorption property, absorb acidic gases such as hydrogen sulfide with an aqueous sodium hydroxide solution, absorb alkaline gases with a sulfuric acid solution, perform dehydration treatment, and then adsorb and remove hydrogen through the titanium dioxide particles loaded with platinum coated with the zirconium 1,4-benzenedicarboxylate framework structure modified with photosensitive molecules on the surface, to obtain hydrogen and hydrogen-removed exhaust gas, and finally obtain methane-containing exhaust gas with a large boiling point difference from air components. After low-temperature removal, methane and purified gas are obtained.

[0150] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor limit the invention to the specific embodiments. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. An exhaust gas purification method for the production and processing of crude benzene hydrogenation, characterized in that, It includes the following steps: S1. Add porous polystyrene, zirconium chloride, deionized water and N,N-dimethylformamide into an ultrasonic instrument and ultrasonicate for 10 - 12 min. Then transfer the reaction system to a high-pressure reaction kettle. After sealing the high-pressure reaction kettle, raise the temperature to 100 - 120 °C, keep the temperature for reaction for 24 - 28 h, and perform post-treatment to obtain modified polystyrene resin; S2. Pass the pretreated waste gas through an adsorption bed loaded with modified polystyrene resin to obtain benzene-removed waste gas; S3. Pass the benzene-removed waste gas through an alkaline solution absorption tower and an acidic solution absorption tower successively to obtain neutral waste gas; S4. Pass the neutral waste gas through an adsorption bed loaded with a photocatalytic adsorption material to obtain hydrogen-removed waste gas, and perform degassing treatment on the adsorption bed to obtain hydrogen; S5. Pass the hydrogen-removed waste gas into a low-temperature tower to obtain methane liquid and purified gas.

2. The exhaust gas purification method for the production and processing of crude benzene hydrogenation according to claim 1, characterized in that, In step S1, the dosage ratio of porous polystyrene, zirconium chloride, deionized water and N,N-dimethylformamide is 9 - 12 g: 3.6 - 4.0 g: 10 - 12 mL: 80 - 100 mL; in step S2, the diameter of the adsorption bed is 2.0 - 2.4 m, the height is 1.2 - 1.5 m, the temperature is 20 - 30 °C, the pressure is 0.1 - 0.2 Mpa, the gas volume is 800 - 1000 m³ / h, and the contact time is 2 - 3 s; in step S4, the diameter of the adsorption bed is 1.8 - 2.1 m, the height is 1.0 - 1.2 m, the temperature is 20 - 30 °C, the pressure is 0.1 - 0.2 Mpa, the gas volume is 800 - 1000 m³ / h, and the contact time is 4 - 6 s; in step S5, the temperature of the low-temperature tower is -162 °C.

3. The exhaust gas purification method for the production and processing of crude benzene hydrogenation according to claim 1, characterized in that, In step S3, the lye in the lye absorption tower is a 2-4 wt% aqueous sodium hydroxide solution, with a temperature of 20-40 °C, a pressure of 0.1-0.2 MPa, and a liquid-gas ratio of 8-10 L / m 3 , the gas flow rate is 800-1000 m³ / h, the gas residence time is 3-5 s, and the lye circulation is 8-10 m 3 / h; the acid solution in the acid solution absorption tower is a 2-4 wt% aqueous sulfuric acid solution, with a temperature of 20-30 °C, a pressure of 0.1-0.2 MPa, and a liquid-gas ratio of 12-15 L / m 3 , the gas flow rate is 800-1000 m³ / h, the gas residence time is 3-5 s, and the lye circulation is 12-15 m 3 / h.

4. The exhaust gas purification method for the production and processing of crude benzene hydrogenation according to claim 1, characterized in that, The preparation method of the porous polystyrene includes the following steps: A1. Add the emulsion precursor into a reaction kettle and stir. Stir at a stirring rate of 60 - 80 rpm at room temperature for 10 - 15 min. Then, while adding deionized water to the reaction kettle, raise the stirring rate to 800 - 1000 rpm and stir at room temperature for 25 - 30 min to obtain an emulsion; A2. Add the emulsion into the reaction kettle, raise the temperature of the reaction kettle to 60 - 80 °C, keep the temperature for reaction for 10 - 12 h, and perform post-treatment to obtain porous modified polystyrene.

5. The exhaust gas purification method for the production and processing of crude benzene hydrogenation according to claim 4, characterized in that, In step A1, the dosage ratio of the emulsion precursor and deionized water is 10 - 13 g: 72 - 84 mL, where the emulsion precursor is obtained by mixing vinyl terephthalic acid, styrene, m-trifluoromethylstyrene, sorbitan oleate and azobisisobutyronitrile according to the dosage ratio of 2 - 3 g: 6 - 7 g: 1 - 2 g: 0.5 g: 0.5 g.

6. The exhaust gas purification method for the production and processing of crude benzene hydrogenation according to claim 1, characterized in that, The preparation method of the photocatalytic adsorption material includes the following steps: B1. Add the titanium source solution and the platinum source solution into a high-pressure reaction kettle and stir at room temperature for 20 - 30 min. Then seal the high-pressure reaction kettle and raise the temperature of the high-pressure reaction kettle to 180 - 200 °C, keep the temperature for reaction for 10 - 12 h, and perform post-treatment to obtain titanium-platinum microparticles; B2. Add zirconium chloride, terephthalic acid, acetic acid, and N,N-dimethylformamide into a high-pressure reactor. After stirring at room temperature for 10 - 15 min, add titanium-platinum microparticles into the high-pressure reactor. Seal the high-pressure reactor and raise the temperature of the high-pressure reactor to 100 - 120 °C. Keep the temperature for reaction for 20 - 24 h, and then perform post-treatment to obtain the supported microparticles. B3. Add tetrakis(4-carboxyphenyl)porphyrin and ethanol into a reactor. After stirring in the dark for 10 - 15 min, add the supported microparticles into the reactor. After stirring in the dark for 10 - 12 h, obtain the photocatalytic adsorption material.

7. The exhaust gas purification method for the production and processing of crude benzene hydrogenation according to claim 6, characterized in that, In step B1, the dosage ratio of the titanium source solution to the platinum source solution is 2 mL:1 mL. Among them, the titanium source solution is obtained by mixing tetrabutyl titanate and absolute ethanol in a dosage ratio of 1 - 2 mL:10 mL, and the platinum source solution is obtained by mixing chloroplatinic acid and deionized water in a dosage ratio of 0.1 - 0.2 g:50 mL; in step B2, the dosage ratio of zirconium chloride, terephthalic acid, acetic acid, N,N-dimethylformamide, and titanium-platinum microparticles is 2.3 - 2.4 g:1.6 - 1.7 g:20 mL:200 mL:5 - 6 g; in step B3, the dosage ratio of tetrakis(4-carboxyphenyl)porphyrin, ethanol, and the supported microparticles is 0.4 - 0.6 g:200 mL:4 - 6 g.

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