Raw material gasification method for preparing styrene through ethylbenzene dehydrogenation

Abstract

The invention discloses a raw material gasification method for preparing styrene by ethylbenzene dehydrogenation, which comprises the following steps: selecting ethylbenzene as a raw material, and heating the ethylbenzene in three stages through a'segmented heating 'technology, the first stage is 250-300 DEG C, the second stage is 400-450 DEG C, and the third stage is 450-500 DEG C, so that temperature mutation is avoided, the gasification of the ethylbenzene is promoted, and a catalyst compounded by silicon dioxide and bauxite is used, the catalyst contains 5%-15% of sodium molybdate and sodium tungstate, ethylbenzene is dehydrogenated at the temperature of 500-650 DEG C, the hydrogen concentration in the reaction atmosphere is controlled to be 5%-20%, hydrogen removal is promoted, styrene selectivity is improved, a two-stage cooling system is adopted, spray cooling is carried out at the first stage to 300 DEG C, heat exchange cooling is carried out at the second stage to 100 DEG C or below, and styrene degradation is prevented. Therefore, by optimizing reaction conditions and recycling resources, the problems of poor reaction selectivity, low energy efficiency and high exhaust emission in the prior art are solved, the production efficiency is improved, and the environmental influence is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of raw material gasification, and particularly to a method for gasifying raw materials for ethylbenzene dehydrogenation to styrene. Background Art

[0002] Existing methods for ethylbenzene dehydrogenation to styrene usually adopt catalytic reaction technologies, using metal oxides or acidic catalysts to carry out the dehydrogenation reaction of ethylbenzene under high-temperature conditions. Most of these traditional methods operate in the temperature range of 500°C to 650°C and can effectively convert ethylbenzene to styrene under the action of suitable catalysts. However, most of the existing technologies adopt conventional heating methods and simple catalyst designs, with inaccurate control of reaction conditions, resulting in low selectivity yield of styrene, more by-products generated, and high energy consumption during the reaction process. The disadvantages of the existing technologies are mainly reflected in several aspects: First, the traditional methods fail to precisely control the temperature change during the heating process, easily causing uneven reactions or rapid temperature rise, leading to the pyrolysis of ethylbenzene molecules and the generation of by-products, affecting the purity of styrene. Second, the selectivity and stability of the catalysts are usually limited, resulting in low reaction efficiency and the need for frequent catalyst replacement. In addition, the efficiency of traditional separation processes is low, the purity of styrene often fails to meet the requirements, and the problems of recovery and treatment of by-products have not been effectively solved. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems in the related technologies to a certain extent.

[0004] For this purpose, the object of the present invention is to propose a method for gasifying raw materials for ethylbenzene dehydrogenation to styrene, which is a method for ethylbenzene dehydrogenation reaction under the conditions of precisely controlling the reaction temperature and hydrogen concentration by using the "stepwise heating" technology and optimizing the composite material of the catalyst, significantly improving the selectivity yield of styrene and the utilization efficiency of raw materials, and solving the problems of poor reaction selectivity, low product purity and many by-products in the existing technologies through a fractionating tower, membrane separation and gas recovery system, and improving the reaction efficiency and resource recovery rate.

[0005] To achieve the above object, the present invention proposes a method for gasifying raw materials for ethylbenzene dehydrogenation to styrene, including the following steps: S1. Select ethylbenzene as the raw material and heat ethylbenzene in three stages through the "stepwise heating" technology. The first stage is from 250°C to 300°C, the second stage is from 400°C to 450°C, and the third stage is from 450°C to 500°C, avoiding sudden temperature changes and promoting the gasification of ethylbenzene; S2. Use a catalyst composed of a composite of silica and bauxite, containing 5% to 15% sodium molybdate and sodium tungstate, and dehydrogenate ethylbenzene at a temperature range of 500°C to 650°C to increase the styrene yield; S3. Control the hydrogen concentration in the reaction atmosphere to be 5% to 20% to promote hydrogen removal, improve styrene selectivity, and reduce by-products. S4. Through a two-stage cooling system, spray cool to 300 °C in the first stage and heat exchange cool to below 100 °C in the second stage to prevent styrene degradation. S5. Use a composite material molecular sieve fractionating tower, adopting a composite material of ZSM-5 molecular sieve and activated carbon to separate styrene and by-products, ensuring that the styrene purity reaches more than 98%. S6. For unreacted ethylbenzene and by-products, use nanoscale membrane separation technology and conduct a secondary reaction through a reflux technology to improve the raw material utilization rate. S7. Through a gas recovery device, the condensed gas is filtered and purified and then refluxed to the reaction system. Precisely control the reflux ratio to improve energy efficiency and reduce waste gas. S8. Adopt a combination of biocatalysis and chemical catalysis to treat by-products, convert harmful by-products into recyclable chemicals, improve the resource recovery rate, and reduce pollution.

[0006] The raw material gasification method for dehydrogenating ethylbenzene to produce styrene according to the present invention improves the efficiency and product quality of dehydrogenating ethylbenzene to produce styrene through an optimized reaction process and innovative technical solutions. First, the segmented heating technology is adopted to precisely control the heating process, avoid temperature sudden changes, and improve the gasification efficiency of ethylbenzene. Second, a composite catalyst containing sodium molybdate and sodium tungstate is used to dehydrogenate ethylbenzene efficiently in the temperature range of 500 °C to 650 °C, improving the selective yield of styrene. The two-stage cooling system ensures the stability of styrene during the cooling process and avoids styrene degradation. The composite material molecular sieve fractionating tower and nanoscale membrane separation technology effectively separate styrene and by-products, improve the styrene purity, and reduce the formation of by-products at the same time. The gas recovery device recovers gas through filtration and purification, reduces waste gas emissions, and improves energy utilization efficiency. The by-product treatment adopts a combination of biocatalysis and chemical catalysis to convert harmful by-products into recyclable chemicals, further improving the resource utilization rate and reducing environmental pollution. The overall technical solution solves the problems of poor reaction selectivity, low energy efficiency, and high waste gas emissions in the prior art by optimizing reaction conditions and resource recovery, improving production efficiency, and reducing environmental impact.

[0007] In addition, the raw material gasification method for dehydrogenating ethylbenzene to produce styrene proposed above according to the present invention may also have the following additional technical features: Specifically, the catalyst is a material composed of a composite of silica and bauxite, and the mass ratio of sodium molybdate and sodium tungstate in the catalyst is 3:2, which can maintain high dehydrogenation activity and selectivity in the temperature range of 500 °C to 600 °C.

[0008] Specifically, the staged heating technology precisely controls the heating rate in stages. The heating rate in the first stage is 5°C / min, the heating rate in the second stage is 3°C / min, and the heating rate in the third stage is 2°C / min, so as to avoid excessive thermal decomposition of ethylbenzene molecules and ensure gasification efficiency.

[0009] Specifically, the two-stage cooling system includes a first stage of using coolant spray to quickly cool down to 300°C, and a second stage of further cooling the reaction gas to below 100°C through a heat exchange system combined with a condensing device to achieve an efficient and uniform cooling process.

[0010] Specifically, the composite molecular sieve distillation tower uses a composite material of ZSM-5 molecular sieve and activated carbon. The pore size of the molecular sieve is 0.5 to 0.6 nm. It can selectively separate styrene based on the molecular size difference between styrene and by-products, thereby improving separation efficiency, and the solvent-free separation process can reduce energy consumption.

[0011] Specifically, the membrane separation technology is nano-scale membrane filtration, which uses ceramic membrane materials with a pore size of 1 to 5 nm. It can effectively separate unreacted ethylbenzene and by-products, and improve its selectivity through membrane surface modification technology, thereby reducing membrane pollution and maintenance costs.

[0012] Specifically, the gas recovery device includes a multi-layer fine filtration system that can remove moisture, chlorides and other impurities in the reaction gas. The purified gas is returned to the reaction system in proportion, reducing exhaust gas emissions and improving energy utilization.

[0013] Specifically, by-product treatment adopts a combination of biocatalysis and chemical catalysis. In the biocatalytic step, enzymes are used to decompose harmful by-products, and in the chemical catalytic step, acid catalysts are used to convert by-products into recyclable organic chemicals, thereby improving resource utilization and reducing environmental pollution.

[0014] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which: Figure 1 This is a schematic diagram of the raw material gasification method for preparing styrene by dehydrogenating ethylbenzene according to the present invention; Figure 2 It is a schematic diagram of experimental data of ethylbenzene dehydrogenation experiment using standard catalyst of the present invention; Figure 3 A schematic diagram of experimental data of an ethylbenzene dehydrogenation experiment using an optimized catalyst according to the present invention; Figure 4 Schematic diagram of experimental data for the by - product treatment and reflux of ethylbenzene dehydrogenation experiment of the present invention; Figure 5 Schematic diagram of experimental data for the ethylbenzene dehydrogenation experiment using the modified catalyst of the present invention; Figure 6 Schematic diagram of experimental data for the by - product treatment and reflux of ethylbenzene dehydrogenation experiment of the present invention. Detailed implementation manners

[0016] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are intended to explain the present invention, and should not be construed as limiting the present invention. On the contrary, the embodiments of the present invention include all changes, modifications and equivalents falling within the spirit and scope of the appended claims.

[0017] The raw material gasification method for the dehydrogenation of ethylbenzene to styrene according to the embodiments of the present invention will be described below with reference to the accompanying drawings.

[0018] As Figures 1-6 shown, the raw material gasification method for the dehydrogenation of ethylbenzene to styrene according to the embodiments of the present invention may include the following steps: S1. Select ethylbenzene as the raw material and heat ethylbenzene in three segments through the "step - by - step heating" technology. The first segment is from 250°C to 300°C, the second segment is from 400°C to 450°C, and the third segment is from 450°C to 500°C, to avoid sudden temperature changes and promote the gasification of ethylbenzene.

[0019] It should be noted that in step S1 described in this embodiment, ethylbenzene is selected as the raw material and the "step - by - step heating" technology is adopted to heat ethylbenzene in three segments to avoid the negative impact of sudden temperature changes on the reaction. In the first segment, the temperature is raised to 250°C to 300°C to promote the preliminary gasification of ethylbenzene; in the second segment, it is heated to 400°C to 450°C to further activate ethylbenzene molecules and improve its gasification efficiency; in the third segment, it is heated to 450°C to 500°C to completely gasify ethylbenzene, providing sufficient gaseous raw materials for the subsequent dehydrogenation reaction, ensuring the efficient progress of the reaction and increasing the yield of styrene.

[0020] S2. Use a catalyst composed of a composite of silica and bauxite, and the catalyst contains 5% to 15% sodium molybdate and sodium tungstate. Dehydrogenate ethylbenzene at a temperature range of 500°C to 650°C to increase the yield of styrene.

[0021] It should be noted that in step S2 of this embodiment, a catalyst composed of silica and bauxite is used, in which the mass ratio of sodium molybdate to sodium tungstate is 3:2, and the content is 5% to 15% of the catalyst mass. This catalyst has excellent dehydrogenation activity and selectivity and can efficiently catalyze the dehydrogenation reaction of ethylbenzene in the temperature range of 500°C to 650°C. The pore structure and surface characteristics of this composite catalyst are carefully designed, which not only improve the reaction activity of ethylbenzene but also reduce the generation of by-products, thus significantly increasing the yield of styrene and improving the selectivity and stability of the reaction.

[0022] S3. Control the hydrogen concentration in the reaction atmosphere to be 5% to 20% to promote hydrogen removal, improve the selectivity of styrene, and reduce by-products.

[0023] It should be noted that in step S3 of this embodiment, by precisely controlling the hydrogen concentration in the reaction atmosphere to be 5% to 20%, it is ensured that the dehydrogenation reaction proceeds under the optimal conditions, thereby promoting the effective removal of hydrogen in the ethylbenzene molecule. By controlling the hydrogen concentration, the reaction rate can be adjusted and the generation of by-products can be reduced, further improving the selective yield of styrene. At the same time, unnecessary side reactions, such as the formation of coke and other low-value by-products, are maximally inhibited to ensure the reaction efficiency and product purity.

[0024] S4. Through a two-stage cooling system, spray cooling in the first stage to 300°C and heat exchange cooling in the second stage to below 100°C to prevent the degradation of styrene.

[0025] It should be noted that in this embodiment, a two-stage cooling system is used to ensure that the reaction gas remains stable during the cooling process and prevent the degradation of styrene. In the first stage, the gas is rapidly cooled to 300°C by spray cooling to effectively remove the heat generated during the reaction and prevent the decomposition of styrene at high temperatures; in the second stage, the gas is further cooled to below 100°C through a heat exchange device to ensure that styrene is not affected by pyrolysis during the cooling process, and at the same time, it prepares for the subsequent separation and recovery steps, improving the product quality and recovery efficiency of styrene.

[0026] S5. Use a composite material molecular sieve fractionating tower, adopting a composite material of ZSM-5 molecular sieve and activated carbon, to separate styrene from by-products and ensure that the purity of styrene reaches more than 98%.

[0027] It should be noted that in this embodiment, a composite molecular sieve fractionating column is described. This column uses a composite material of ZSM-5 molecular sieve and activated carbon. The microporous structure of the ZSM-5 molecular sieve is used to effectively separate styrene from by-products. By adjusting the proportion and pore size distribution of the composite material, the separation process is optimized, and the molecular size difference between styrene and by-products is precisely utilized, so that the purity of styrene can reach more than 98% under atmospheric pressure, significantly improving the separation efficiency of styrene and reducing the residue of by-products, ensuring the high quality and purity of the final product.

[0028] It should be understood that ZSM-5 molecular sieve is a zeolite-type molecular sieve with a unique pore structure and belongs to aluminosilicate compounds. It is widely used in the fields of catalysis and adsorption. The pore size of ZSM-5 is about 0.5nm, which makes it show excellent selectivity in molecular sieve separation, catalytic reactions and catalytic cracking.

[0029] Its microporous structure enables ZSM-5 to effectively and selectively adsorb and catalyze certain molecules, preventing the entry of larger molecules, and at the same time promoting the occurrence of specific reactions, such as alkylation, cracking, isomerization, etc. ZSM-5 has a significant catalytic effect in chemical reactions such as ethylbenzene dehydrogenation and aromatic hydrocarbon synthesis, which can improve the reaction efficiency and have higher selectivity.

[0030] S6. For unreacted ethylbenzene and by-products, use nanoscale membrane separation technology and conduct a secondary reaction through a reflux technology to improve the raw material utilization rate.

[0031] It should be noted that in step S6 described in this embodiment, for unreacted ethylbenzene and by-products, nanoscale membrane separation technology is adopted. By using a membrane material with precise pore size control (such as ceramic membrane or polymer membrane), unreacted ethylbenzene and by-products are effectively separated from the reaction gas, ensuring high separation efficiency and good selectivity. By combining the reflux technology, these unreacted components are guided back to the reaction system for a secondary reaction, further improving the raw material utilization rate, reducing the generation of waste at the same time, maximizing the conversion rate of reactants, and thus improving the overall economic benefits and reaction efficiency.

[0032] S7. Through a gas recovery device, the condensed gas is filtered and purified and then refluxed to the reaction system. The reflux ratio is precisely controlled to improve energy efficiency and reduce waste gas.

[0033] It should be noted that in this embodiment, an efficient gas recovery device is adopted to cool the gas generated during the reaction through condensation and remove moisture and impurities therein. The condensed gas is further processed through a multi-stage filtration and purification system to ensure that harmful substances in the gas are removed. The purified gas is recycled back to the reaction system according to a precisely controlled reflux ratio, which can not only effectively improve the energy utilization rate of the reaction but also reduce waste gas emissions, ensuring the environmental protection and economy of the whole process.

[0034] S8. Adopt the combination of biocatalysis and chemical catalysis to treat by-products, convert harmful by-products into recyclable chemicals, improve the resource recovery rate, and reduce pollution.

[0035] It should be noted that in the process of by-product treatment described in this embodiment, a method combining biocatalysis and chemical catalysis is adopted. First, harmful by-products are selectively degraded by a biocatalyst (such as enzyme catalysis) to convert them into intermediate products, and then through a chemical catalysis step, an acid catalyst or a metal catalyst is used to further convert these intermediate products into valuable recyclable chemicals. This combined method not only improves the resource recovery rate but also effectively reduces the energy consumption and environmental impact of the by-products during the treatment process, further reducing the emission of waste, and ensuring the environmental protection and sustainability of the process.

[0036] The following is a detailed data description in combination with the experimental steps: Example 1 Ethylbenzene dehydrogenation experiment using a standard catalyst Experimental steps: Raw material selection and treatment: Select ethylbenzene as the raw material with a water content not exceeding 20%. Heat ethylbenzene through a segmented heating technique. The first stage is heated to 270 °C, the second stage is heated to 420 °C, and the third stage is heated to 470 °C, maintaining a heating rate of 4 °C / min for each stage.

[0037] Catalyst preparation: Use a catalyst composed of a composite of silica and bauxite. The catalyst contains 10% sodium molybdate and 10% sodium tungstate, and the catalyst is pre-activated at a temperature of 500 °C to 600 °C.

[0038] Reaction conditions: Carry out the ethylbenzene dehydrogenation reaction under the condition of a temperature of 550 °C, and control the hydrogen concentration in the reaction atmosphere to 10%.

[0039] Cooling and separation: Adopt a two-stage cooling system. The first stage is spray-cooled to 300 °C, and the second stage is cooled to below 100 °C through heat exchange to ensure the stability of styrene.

[0040] Styrene separation and purity detection: Using a molecular sieve fractionating column made of composite materials (a composite of ZSM-5 molecular sieve and activated carbon), the styrene purity was determined to be 98%.

[0041] By-product treatment: Using a method combining biocatalysis and chemical catalysis to treat by-products and convert them into recyclable chemicals.

[0042] Experimental data comparison (as Figure 2 shown) Explanation of experimental results: After using the standard catalyst, the styrene purity and gas recovery rate were significantly improved. Compared with the experiment without catalyst, the styrene purity increased by 13% and the gas recovery rate increased by 15%.

[0043] Example 2 Experiment on ethylbenzene dehydrogenation with optimized catalyst Experimental procedure: Raw material selection and treatment: Select ethylbenzene as the raw material, control the water content at 10%, and use the stepwise heating technique. Heat to 250°C in the first stage, 450°C in the second stage, and 480°C in the third stage, with a heating rate set at 5°C / min.

[0044] Catalyst preparation: Use a catalyst composed of a composite of silica and bauxite, containing 12% sodium molybdate and 8% sodium tungstate, and undergo pre-activation treatment at 500°C.

[0045] Reaction conditions: The reaction temperature is 580°C, and the hydrogen concentration in the reaction atmosphere is controlled at 15%.

[0046] Cooling and separation: Adopt a two-stage cooling system. Cool to 280°C by spraying coolant in the first stage, and further reduce the temperature to 90°C through a heat exchange system in the second stage.

[0047] Styrene separation and purity detection: Use a fractionating column made of a composite of ZSM-5 molecular sieve and activated carbon, and the styrene purity was determined to be 99%.

[0048] By-product treatment: The by-products are refluxed through nanofiltration membrane separation technology for secondary reaction to improve the raw material utilization rate.

[0049] Experimental data comparison (as Figure 3 shown) Explanation of experimental results: Under the optimized catalyst conditions, both the styrene purity and gas recovery rate were improved. Compared with the standard catalyst, the styrene purity increased by 1% and the gas recovery rate increased by 5%. In addition, the use of the optimized catalyst improved the raw material utilization rate to 95%.

[0050] Example 3 By - product Treatment and Ethylbenzene Dehydrogenation Experiment with Recycling Experimental Procedures: Raw Material Selection and Treatment: Select ethylbenzene as the raw material with a water content not exceeding 18%. Adopt a step - by - step heating technique. In the first stage, heat to 280 °C, in the second stage, heat to 420 °C, and in the third stage, heat to 470 °C.

[0051] Catalyst Preparation: Use a catalyst composed of composite silica and bauxite, containing 10% sodium molybdate and 5% sodium tungstate. The catalyst is activated under the condition of 550 °C.

[0052] Reaction Conditions: Control the reaction temperature at 560 °C and the hydrogen concentration at 12%.

[0053] Cooling and Separation: Use a two - stage cooling system. In the first stage, spray - cool to 310 °C, and in the second stage, cool to 110 °C through heat exchange.

[0054] Styrene Separation and Purity Detection: Use a composite molecular sieve fractionating tower, and the styrene purity reaches over 98%.

[0055] By - product Treatment and Recycling: Adopt nano - scale membrane filtration to separate unreacted ethylbenzene and by - products, and conduct a secondary reaction through the recycling technique to improve the utilization rate and conversion rate of raw materials.

[0056] Comparison of Experimental Data (as Figure 4 shown) Explanation of Experimental Results: Through the treatment of by - product recycling, the purity of styrene and the gas recovery rate are improved. Compared with the control group without recycling, the styrene purity is increased by 6.5% and the gas recovery rate is increased by 8%. In addition, the utilization rate of raw materials is also significantly improved, reaching 97%.

[0057] Summary: Through the above - mentioned multiple examples, the optimization effects of different catalysts, cooling systems, separation techniques, and recycling strategies on the ethylbenzene dehydrogenation reaction process are demonstrated. In all examples, the purity of styrene, the gas recovery rate, and the utilization rate of raw materials are significantly improved, proving the advantages of the technical solutions provided by the present invention in enhancing reaction efficiency, improving product quality, and resource utilization.

[0058] Example 4 Ethylbenzene Dehydrogenation Experiment Using Modified Catalysts Experimental Procedures: Raw Material Selection and Treatment: Select ethylbenzene as the raw material with a water content not exceeding 15%, and heat ethylbenzene using a step - by - step heating technique. In the first stage, heat to 260 °C, in the second stage, heat to 430 °C, and in the third stage, heat to 480 °C. Set the heating rate at 4 °C / min to ensure a smooth gasification process.

[0059] Catalyst Preparation: Use a catalyst composed of silica and bauxite. The catalyst contains 12% sodium molybdate and 8% sodium tungstate, and is prepared by the impregnation method. It is activated at 500 °C. After modification, the dehydrogenation efficiency and selectivity of the catalyst are improved.

[0060] Reaction Conditions: The ethylbenzene dehydrogenation reaction is carried out at a temperature of 570 °C, and the hydrogen concentration in the reaction atmosphere is 10%.

[0061] Cooling and Separation: Adopt a two-stage cooling system. In the first stage, it is spray-cooled to 320 °C, and in the second stage, it is cooled to below 90 °C through a heat exchange system to ensure the stability of styrene.

[0062] Styrene Separation and Purity Detection: Use a fractionating tower composed of ZSM-5 molecular sieve and activated carbon. The purity of styrene reaches over 99%.

[0063] By-Product Treatment: Use a method combining biocatalysis and chemical catalysis to treat by-products, and convert harmful by-products into recyclable organic chemicals.

[0064] Comparison of Experimental Data (as Figure 5 shown) Explanation of Experimental Results: After using the modified catalyst, the purity and gas recovery rate of styrene are significantly improved. Compared with the standard catalyst, the purity of styrene is increased by 2%, and the gas recovery rate is increased by 8%. The raw material utilization rate is increased by 6%, further improving the reaction efficiency.

[0065] Example 5 Ethylbenzene Dehydrogenation Experiment with By-Product Recycling and Membrane Separation Experimental Procedures: Raw Material Selection and Treatment: Select ethylbenzene as the raw material, control the moisture content within 10%, and adopt a stepwise heating technique. In the first stage, it is heated to 275 °C, in the second stage, it is heated to 440 °C, and in the third stage, it is heated to 475 °C, with a heating rate of 3 °C / min.

[0066] Catalyst Preparation: Use a catalyst composed of silica and bauxite. The catalyst contains 10% sodium molybdate and 5% sodium tungstate, and the catalyst is activated at 550 °C to ensure high selectivity and high efficiency of the ethylbenzene dehydrogenation reaction.

[0067] Reaction Conditions: The reaction temperature is set at 560 °C, and the hydrogen concentration is controlled at 12% to maintain a high reaction rate and high selectivity of styrene.

[0068] Cooling and Separation: Adopt a two-stage cooling system. In the first stage, it is spray-cooled to 290 °C, and in the second stage, it is cooled to 100 °C through heat exchange to ensure the stability of styrene.

[0069] Styrene separation and purity detection: Using a composite molecular sieve fractionation tower (ZSM-5 molecular sieve and activated carbon composite material), the styrene purity was determined to be above 98%.

[0070] By-product reflux and membrane separation: Nano-scale membrane separation technology is used to separate unreacted ethylbenzene and by-products, which are then sent into the reaction system for secondary reaction through reflux technology to improve raw material utilization.

[0071] Comparison of experimental data (such as Figure 6 shown) Experimental results: Through reflux and membrane separation technology, the purity of styrene increased by 5%, the gas recovery rate increased by 8%, and the raw material utilization rate increased significantly to 97%, an increase of 9% compared with the control group without reflux.

[0072] It should be understood that the above multiple embodiments demonstrate the optimization effects of different catalysts, cooling systems, separation technologies and reflux strategies on the ethylbenzene dehydrogenation reaction process. In all embodiments, the purity of styrene, gas recovery rate and raw material utilization rate are significantly improved, which proves the advantages of the technical solution provided by the present invention in improving reaction efficiency, improving product quality and resource utilization.

[0073] In one embodiment of the present invention, Figures 1-6 As shown, the catalyst is a composite material of silicon dioxide and bauxite, and the mass ratio of sodium molybdate to sodium tungstate in the catalyst is 3:2. It can maintain high dehydrogenation activity and selectivity in the temperature range of 500°C to 600°C. The staged heating technology accurately controls the heating rate in stages. The heating rate in the first stage is 5°C / min, the heating rate in the second stage is 3°C / min, and the heating rate in the third stage is 2°C / min, so as to avoid excessive thermal decomposition of ethylbenzene molecules and ensure gasification efficiency.

[0074] It should be noted that the catalyst described in this embodiment is composed of a composite of silicon dioxide and bauxite, wherein the mass ratio of sodium molybdate to sodium tungstate is 3:2, and the optimized catalyst surface has abundant active sites and excellent pore structure, which can maintain efficient dehydrogenation reaction and ensure high selectivity yield of styrene in the temperature range of 500°C to 600°C. In order to avoid too fast pyrolysis of ethylbenzene molecules during heating, an accurate staged heating technology is adopted, and the heating rate of the first stage is 5°C / min to ensure uniform heating of the material, and the heating rates of the second stage and the third stage are 3°C / min and 2°C / min, respectively, so as to effectively control the reaction rate, improve the gasification efficiency of ethylbenzene and optimize the stability of subsequent reactions.

[0075] In one embodiment of the present invention, as Figures 1-6 shown, the two-stage cooling system includes rapidly cooling to 300°C using coolant spray in the first stage, and further cooling the reaction gas to below 100°C through a heat exchange system combined with a condensation device in the second stage to achieve an efficient and uniform cooling process.

[0076] It should be noted that the design of the two-stage cooling system described in this embodiment aims to improve the cooling efficiency and protect styrene from pyrolysis. In the first stage, through high-pressure coolant spray technology, the reaction gas is rapidly cooled to 300°C in a short time, effectively removing the heat generated during the reaction and preventing the decomposition of styrene at high temperatures; in the second stage, through the synergistic effect of an efficient heat exchange system and a condensation device, the reaction gas is further cooled to below 100°C, ensuring a uniform and stable cooling process, while facilitating the subsequent gas recovery and separation processes, maximizing the reaction efficiency and product quality.

[0077] In one embodiment of the present invention, as Figures 1-6 shown, the composite molecular sieve fractionating tower uses a composite material of ZSM-5 molecular sieve and activated carbon. The pore size of the molecular sieve is 0.5 to 0.6 nm, which can selectively separate styrene according to the molecular size difference between styrene and by-products, improving the separation efficiency. Moreover, the solvent-free separation process can reduce energy consumption. The membrane separation technology is nanoscale membrane filtration, using ceramic membrane materials with a pore size of 1 to 5 nm, which can effectively separate unreacted ethylbenzene and by-products, and improve its selectivity through membrane surface modification technology, reducing membrane fouling and maintenance costs.

[0078] It should be noted that the composite molecular sieve fractionating tower described in this embodiment uses a composite material of ZSM-5 molecular sieve and activated carbon. Through the precisely designed pore size (0.5 to 0.6 nm), it can effectively perform selective separation according to the molecular size difference between styrene and by-products, significantly improving the separation efficiency. Moreover, the solvent-free separation process avoids the environmental pollution and energy consumption problems caused by the use of solvents. In addition, the use of nanoscale ceramic membrane separation technology with a pore size range of 1 to 5 nm can efficiently separate unreacted ethylbenzene and by-products. After the membrane surface is modified, the selectivity and anti-fouling ability of the membrane are improved, reducing the cleaning frequency and maintenance costs of the membrane, thus ensuring the high efficiency and long-term stability of the separation process.

[0079] In one embodiment of the present invention, as Figures 1-6As shown, the gas recovery device includes a multi-layer fine filtration system that can remove moisture, chlorides, and other impurities from the reaction gas. The purified gas is refluxed to the reaction system in proportion, reducing waste gas emissions and improving energy utilization efficiency. By-product treatment adopts a combination of biocatalysis and chemical catalysis. In the biocatalysis step, enzymes are used to catalytically decompose harmful by-products, and in the chemical catalysis step, acid catalysts are used to convert by-products into recyclable organic chemicals, improving resource utilization rate and reducing environmental pollution.

[0080] It should be noted that the gas recovery device described in this embodiment uses a multi-layer fine filtration system to gradually remove moisture, chlorides, and other impurities from the reaction gas, and through an efficient gas purification process, ensures the purity of the recovered gas so as to reflux it to the reaction system in precise proportion, thereby optimizing energy utilization and reducing waste gas emissions. In addition, by-product treatment combines two technologies of biocatalysis and chemical catalysis. In the biocatalysis step, enzymes are used to catalytically decompose harmful by-products efficiently, and in the chemical catalysis step, acid catalysts are used to convert by-products into recyclable organic chemicals, which not only improves the resource recovery rate but also effectively reduces environmental pollution.

[0081] In summary, the raw material gasification method for dehydrogenating ethylbenzene to styrene in the embodiments of the present invention improves the efficiency and product quality of dehydrogenating ethylbenzene to styrene through an optimized reaction process and innovative technical solutions. First, the segmented heating technology is adopted to precisely control the heating process, avoiding sudden temperature changes and improving the gasification efficiency of ethylbenzene. Second, a composite catalyst containing sodium molybdate and sodium tungstate is used to dehydrogenate ethylbenzene efficiently in the temperature range of 500°C to 650°C, improving the selective yield of styrene. The two-stage cooling system ensures the stability of styrene during the cooling process, avoiding styrene degradation. The composite material molecular sieve fractionating tower and nanoscale membrane separation technology effectively separate styrene and by-products, improving the purity of styrene and reducing the formation of by-products at the same time. The gas recovery device purifies and recovers the gas through filtration, reducing waste gas emissions and improving energy utilization efficiency. By-product treatment adopts a combination of biocatalysis and chemical catalysis to convert harmful by-products into recyclable chemicals, further improving resource utilization rate and reducing environmental pollution. The overall technical solution solves the problems of poor reaction selectivity, low energy efficiency, and high waste gas emissions in the prior art by optimizing reaction conditions and resource recovery, improving production efficiency and reducing environmental impact.

[0082] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A raw material gasification method for preparing styrene by dehydrogenating ethylbenzene, characterized in that: The following steps are involved: S1, select ethylbenzene as raw material, and heat ethylbenzene in three sections by "stage heating" technology, the first section is 250°C to 300°C, the second section is 400°C to 450°C, and the third section is 450°C to 500°C, avoiding sudden temperature changes and promoting the gasification of ethylbenzene; S2, using a catalyst composed of silicon dioxide and bauxite, the catalyst contains 5% to 15% sodium molybdate and sodium tungstate, and dehydrogenating ethylbenzene at a temperature range of 500°C to 650°C to increase the yield of styrene; S3, controlling the hydrogen concentration in the reaction atmosphere to 5% to 20%, promoting hydrogen removal, improving styrene selectivity, and reducing by-products; S4, through a two-stage cooling system, the first stage is spray cooling to 300°C, and the second stage is heat exchange cooling to below 100°C to prevent styrene degradation; S5. Use composite molecular sieve fractionation tower, adopt ZSM-5 molecular sieve and activated carbon composite material, separate styrene and by-products, and ensure the purity of styrene reaches more than 98%; S6. For unreacted ethylbenzene and by-products, nano-scale membrane separation technology is used and reflux technology is used for secondary reaction to improve the utilization rate of raw materials; S7, through the gas recovery device, the condensed gas is filtered and purified and then returned to the reaction system, accurately controlling the reflux ratio, improving energy efficiency and reducing waste gas; S8. Use a combination of biocatalysis and chemical catalysis to treat by-products, convert harmful by-products into recyclable chemicals, improve resource recovery rates, and reduce pollution.

2. The method for gasifying raw materials for preparing styrene by dehydrogenating ethylbenzene according to claim 1, characterized in that: The catalyst is a composite material of silicon dioxide and bauxite, and the mass ratio of sodium molybdate to sodium tungstate in the catalyst is 3:

2. It can maintain high dehydrogenation activity and selectivity in the temperature range of 500°C to 600°C.

3. The raw material gasification method for preparing styrene by dehydrogenating ethylbenzene according to claim 1, characterized in that: The staged heating technology precisely controls the heating rate in stages. The heating rate in the first stage is 5°C / min, the heating rate in the second stage is 3°C / min, and the heating rate in the third stage is 2°C / min, so as to avoid excessive thermal decomposition of ethylbenzene molecules and ensure gasification efficiency.

4. The method for gasifying raw materials for preparing styrene by dehydrogenating ethylbenzene according to claim 1, characterized in that: The two-stage cooling system includes a first stage using coolant spray to quickly cool down to 300°C, and a second stage using a heat exchange system combined with a condensing device to further cool the reaction gas to below 100°C to achieve an efficient and uniform cooling process.

5. The method for gasifying raw materials for preparing styrene by dehydrogenating ethylbenzene according to claim 1, characterized in that: The composite molecular sieve distillation tower uses a composite material of ZSM-5 molecular sieve and activated carbon. The pore size of the molecular sieve is 0.5 to 0.6 nm. It can selectively separate styrene based on the molecular size difference between styrene and by-products, thereby improving separation efficiency. The solvent-free separation process can reduce energy consumption.

6. The method for gasifying raw materials for preparing styrene by dehydrogenating ethylbenzene according to claim 1, characterized in that: Membrane separation technology is nano-scale membrane filtration, using ceramic membrane materials with a pore size of 1 to 5 nm. It can effectively separate unreacted ethylbenzene and by-products, and improve its selectivity through membrane surface modification technology, thereby reducing membrane pollution and maintenance costs.

7. The method for gasifying raw materials for preparing styrene by dehydrogenating ethylbenzene according to claim 1, characterized in that: The gas recovery device includes a multi-layer fine filtration system that can remove moisture, chlorides and other impurities from the reaction gas. The purified gas is returned to the reaction system in proportion, reducing exhaust emissions and improving energy utilization.

8. The method for gasifying raw materials for preparing styrene by dehydrogenating ethylbenzene according to claim 1, characterized in that: By-product treatment adopts a combination of biocatalysis and chemical catalysis. In the biocatalytic step, enzymes are used to decompose harmful by-products, and in the chemical catalytic step, acid catalysts are used to convert by-products into recyclable organic chemicals, thereby improving resource utilization and reducing environmental pollution.

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