Regional reactor for preparing methanol through reinforced carbon dioxide hydrogenation

Abstract

The invention discloses a regional reactor for preparing methanol by reinforcing carbon dioxide hydrogenation, which is characterized in that a reaction region of the reactor is divided into a gas-solid phase reaction region and a liquid phase reaction region through a porous material to form a unique partitioned reaction environment; mixed gas of hydrogen and carbon dioxide is introduced into the gas-phase reaction zone, and methanol and water are generated through reaction under the action of a catalyst filled in the fixed reaction bed; liquid which is selective to methanol or water or methanol and water and stable in property is introduced into the liquid phase area, methanol or water or methanol and water generated through reaction is continuously dissolved, reaction balance is broken, and the balance moves in the direction beneficial to methanol generation. Regional reactors are used for removing reaction products to help overcome reaction equilibrium limitation, the effects of improving the one-way carbon conversion rate, reducing the circulation amount of reaction outlet gas and reducing the size of the reactor are achieved, and the method has very high economic benefits.

Description

Technical Field

[0001] This invention relates to the field of chemical process technology, specifically to a zone reactor for enhanced carbon dioxide hydrogenation to methanol production. This reactor is used to improve the conversion rate of carbon dioxide and the selectivity of methanol, falling under the category of carbon dioxide resource conversion and utilization and green chemical technology. Background Technology

[0002] Methanol, as an important industrial raw material, plays a crucial role in today's chemical industry. It is a key starting material for the production of many important chemicals, such as formaldehyde, dimethyl ether, and acetic acid. Formaldehyde is widely used in the production of adhesives and preservatives in industries such as wood processing, textiles, and plastics; dimethyl ether can be used as an aerosol, refrigerant, and clean fuel; and acetic acid is an important intermediate in many organic synthesis reactions, with wide applications in food, pharmaceuticals, and chemicals. Furthermore, with the increasing global demand for clean energy, methanol also shows great potential as an alternative fuel. Its combustion is relatively clean, which can reduce the environmental pollution caused by the combustion of traditional fossil fuels to a certain extent, further highlighting the importance of methanol as a multifunctional chemical.

[0003] In recent years, with the deepening of the concept of green chemistry, carbon capture technology and water electrolysis technology have made significant progress. Carbon capture technology can effectively capture carbon dioxide from industrial emission sources or the atmosphere, reducing its emissions; water electrolysis technology can produce high-purity "green hydrogen" driven by renewable energy. These technological advancements have led to increasing attention being paid to the process of producing methanol using "green hydrogen" and captured carbon dioxide. This process not only enables the resource utilization of carbon dioxide, converting it into valuable chemicals, but also helps alleviate environmental problems such as the greenhouse effect caused by excessive carbon dioxide emissions.

[0004] However, traditional carbon dioxide hydrogenation processes face numerous technical obstacles in directly converting carbon dioxide into methanol. Firstly, in terms of catalysis, traditional catalysts suffer from slow kinetics, resulting in low reaction rates that cannot meet the demands of large-scale industrial production. Secondly, many traditional catalytic reactions are sensitive to water; the generated water may negatively impact the activity and stability of the catalyst, thereby affecting the continuation of the reaction and the yield of methanol.

[0005] CN119306572A proposes a technology for controlling the carbon dioxide hydrogenation to methanol reaction process using an eluent spraying method. This process achieves eluent spraying through a multi-stage liquid distributor; however, this leads to complex equipment structure and increased investment costs. At the same time, the direct wetting of the catalyst bed by the liquid solvent not only limits the range of solvent system choices but also requires anti-wetting modification of the catalyst to avoid reduced activity. Furthermore, the coexistence of gas and liquid phases in the same reaction area inhibits the forward progress of the reversible reaction, making it difficult to effectively improve the single-pass conversion rate of carbon dioxide and the selectivity of methanol. Summary of the Invention

[0006] The purpose of this invention is to overcome the limitations of existing technologies and provide a zone reactor for enhanced carbon dioxide hydrogenation to methanol production. By introducing porous materials, specific reaction methods, and complementary selective solvents and suitable catalysts, this invention effectively alters the reaction equilibrium, overcomes thermodynamic limitations, and significantly improves the conversion rate of carbon dioxide and the selectivity of methanol, thereby achieving high efficiency and sustainable development of the carbon dioxide hydrogenation to methanol process.

[0007] This invention first provides a zoned reactor for enhanced carbon dioxide hydrogenation to methanol production. The zoned reactor has a gas-solid phase reaction zone and a liquid phase absorption zone, which are separated by a porous material. A catalyst is placed in the gas-solid phase reaction zone, and carbon dioxide and hydrogen are introduced to produce the carbon dioxide hydrogenation to methanol reaction. A solvent is introduced into the liquid phase absorption zone. The methanol and / or water produced in the gas-solid phase reaction zone are absorbed and carried away by the solvent within the pores of the porous material.

[0008] The sub-regional reactor is a batch reactor, a tubular reactor, or a plate reactor; when it is a batch reactor, the upper part of the reactor is a gas-solid phase reaction zone, in which a catalyst cage is fixed, and the lower part is a liquid phase absorption zone; the two zones are separated in the middle by a porous material.

[0009] When it is a tubular reactor, the porous material is used as the tube wall material; the tubes are arranged sequentially and at intervals inside the tubular reactor, with one side of the tubes being the gas-solid phase reaction zone and the other side being the liquid phase absorption zone; when it is a plate reactor, the porous material is used as porous baffles, and multiple porous baffles divide the plate reactor into multiple regions composed of alternating gas-solid phase reaction zones and liquid phase absorption zones.

[0010] According to a preferred embodiment of the present invention, the solvent has a boiling point of 250°C or higher; the solvent has high solubility in water or methanol or both, let the solubility of the solvent in methanol or water or in methanol and water be S1, and the solubility in carbon dioxide, hydrogen and carbon monoxide be S2, satisfying S1 / S2≥50.

[0011] According to a preferred embodiment of the present invention, when the sub-zone reactor is a batch reactor, the catalyst is raised by a catalyst cage to avoid direct contact between the catalyst and the solvent. The solvent in the liquid phase absorption zone is stirred by a stirring paddle to accelerate the absorption of methanol or water by the solvent. The gas-solid phase reaction zone is adjusted to a single gas phase zone or multiple gas phase zones according to the reaction rate and time.

[0012] According to a preferred embodiment of the present invention, the porous material has gas channels and liquid channels arranged alternately. The pore size of the porous material is below 200 nm (preferably in the range of 50 to 200 nm), and it can maintain its mechanical structure at room temperature to 300°C and at atmospheric pressure to 10 MPa. This ensures that the methanol and / or water generated in the reaction can dissolve in the solvent under different reaction conditions and enter the pores but do not pass through them, so that methanol and / or water dissolve in the solvent in the porous material.

[0013] According to a preferred embodiment of the present invention, the solvent is mainly an organic solvent or an ionic liquid. The organic solvent is a higher alcohol, tetraethylene glycol dimethyl ether, or ethylene glycol oligomer. The ionic liquid is one or more of 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]), 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIM][PF6]), 1-butyl-3-methylimidazolium nitrate ([BMIM][NO3]), or 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]).

[0014] According to a preferred embodiment of the present invention, the porous material provides a site for methanol and / or water to dissolve in the solvent, and the porous material is one of silica porous material, alumina porous material, molecular sieve composite porous material, multilayer ceramic porous material, polymer porous material, hydroxyl sodalite (H-SOD) porous material, and graphene oxide (GO) porous material.

[0015] According to a preferred embodiment of the present invention, the gas-solid phase reaction zone is filled with a catalyst for catalyzing the hydrogenation reaction of carbon dioxide and hydrogen, wherein the catalyst is one or more of copper-based catalysts, noble metal supported catalysts, cobalt-based catalysts, iron-based catalysts, molybdenum-based catalysts, tungsten-based catalysts, or tin-based catalysts.

[0016] This invention also provides a method for producing methanol by carbon dioxide hydrogenation based on the aforementioned zoned reactor. The method includes: mixing carbon dioxide and hydrogen into a feed gas, pressurizing it, and preheating it to 200°C–280°C; introducing the feed gas into the gas-solid phase reaction zone; preheating the solvent to 140°C–280°C and introducing it into the liquid phase absorption zone; establishing a pressure gradient on both sides of the porous material, so that the pressure on the liquid phase absorption zone side is higher than that on the gas-solid phase reaction zone side, controlling the pressure difference range to be 1–10 MPa, and utilizing the capillary resistance and pressure balance principle of the porous medium to ensure effective isolation between the gas and liquid phases and ensure the stable operation of the zoned reaction system.

[0017] In the gas-solid phase reaction zone, carbon dioxide and hydrogen are converted into methanol and water under the action of a catalyst. As the concentration of the products increases with continuous reaction, while the concentration of the solvent on the liquid solvent side is low, the reaction products water, methanol, or water and methanol diffuse from the high concentration to the low concentration into the pores but do not pass through the pores. This allows water, methanol, or water and methanol to dissolve in the solvent in the porous material and be carried away by the solvent, thereby effectively changing the reaction equilibrium in the gas-solid phase reaction zone, breaking the thermodynamic limitation, and improving the conversion rate of carbon dioxide and the selectivity of methanol.

[0018] According to a preferred embodiment of the present invention, the gas after reaction is fed into a condenser, the condensed gas phase is used as a circulating gas, pressurized and then mixed with the raw material gas, preheated and then fed into the reactor; the liquid phase obtained by condensation is fed into a methanol purification unit.

[0019] The solvent is drawn from the reactor into the flash tank. The liquid phase obtained after flash evaporation is recycled as solvent and, after preheating, re-enters the liquid phase absorption zone.

[0020] The present invention also provides a process system comprising the aforementioned zoned reactor, the process system further comprising:

[0021] The condenser is connected to the gas phase outlet of the receiving sub-reactor to receive gaseous products and perform gas-liquid separation.

[0022] The compressor is connected to the gas phase outlet of the condenser to pressurize the gas and input it into the gas feed line to mix with the fresh raw material gas;

[0023] A gas preheater is installed on the gas feed line to preheat the raw gas.

[0024] Flash tank, which receives the liquid-phase products from the zone reactor.

[0025] The methanol purification unit is connected to the liquid phase outlet of the receiving sub-reactor, and receives the liquid phase solvent for flash evaporation separation.

[0026] Solvent preheater is used to preheat solvents.

[0027] Compared with existing technologies, this invention proposes a regional reaction system that constructs a gas-liquid isolated reaction interface using porous materials. On one hand, the reaction process is decomposed into an independently controllable gas-solid catalytic zone and a liquid-phase mass transfer zone. Regional control optimizes thermodynamic equilibrium, increasing the carbon dioxide conversion rate to over 25%. On the other hand, the pore size sieving effect (pore size range 50–200 nm) of the porous matrix achieves physical isolation between the solvent and catalyst, eliminating solvent interference with catalyst activity and improving methanol selectivity to over 85%. This system uses structurally stable porous materials (including but not limited to metals and ceramics), offering significant advantages such as simple preparation processes and reduced equipment costs. It overcomes the technical limitations of traditional gas-liquid-solid three-phase coupling and achieves large-scale capacity expansion through modular design, demonstrating significant application value in the field of carbon dioxide hydrogenation to methanol. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 A framework diagram of the carbon dioxide hydrogenation process using the zone reactor of this invention;

[0030] Figure 2 This is a reaction flow diagram of the carbon dioxide hydrogenation process using the zone reactor of the present invention;

[0031] Figure 3 This is a schematic plan view of the multi-region porous material reactor involved in this invention;

[0032] Figure 4 This is a schematic diagram of a batch reactor for regional porous materials involved in this invention;

[0033] Figure 5 This is a schematic diagram of a tubular reactor of the same specification with regional porous materials involved in this invention;

[0034] Figure 6 This is a plan view of the tubular reactors of different specifications of regional porous materials involved in this invention;

[0035] Figure 7 This is a schematic diagram of a tubular reactor with different specifications of regional porous materials involved in this invention; Figure 8 This is a schematic diagram of the plate reactor with regional porous materials involved in this invention;

[0036] Figure 9This is a schematic cross-sectional view of the plate reactor with segmented porous materials involved in this invention.

[0037] Figure 2 The system comprises: 1. Carbon dioxide capture system; 2. Gas compression device; 3. Water source; 4. Hydrogen generator; 5. Gas compression device; 6. Selective liquid device; 7. Gas mixing device; 8. Selective porous material zoned reaction tank; 9. Tail gas collection and purification device; 10. Selective liquid solvent collection and purification device; 11. Product purification device. Detailed Implementation

[0038] The present invention will be further described and illustrated below with reference to specific embodiments. The technical features of each embodiment of the present invention can be combined accordingly, provided that there is no mutual conflict.

[0039] The core of this invention lies in providing a partitioned reactor for enhanced carbon dioxide hydrogenation to methanol production. This reactor uses porous materials to divide the reaction zone into a gas-solid phase reaction zone and a liquid phase reaction zone, forming a unique partitioned reaction environment. A mixture of hydrogen and carbon dioxide is introduced into the gas phase reaction zone, where it reacts to produce methanol and water under the action of a catalyst packed in a fixed reaction bed. A stable liquid solvent selectively reacts with methanol or water or methanol and water into the liquid phase zone, continuously dissolving and carrying away the methanol or water or methanol and water produced in the reaction, disrupting the reaction equilibrium and shifting the equilibrium in a direction favorable to methanol production.

[0040] like Figure 1 The diagram shows a framework of a carbon dioxide hydrogenation process using the zoned reactor of this invention. The methanol generation unit is the zoned reactor of this invention. In the entire carbon dioxide hydrogenation process, the liquid solvent purification unit separates and purifies the products carried out by the liquid solvent dissolution process. The gas collection system provides the reaction feed gas (a mixture of hydrogen and carbon dioxide) to the methanol generation unit, which is the site of the reaction. The product purification unit further purifies the collected methanol, such as by distillation, to remove any impurities and obtain high-purity methanol to meet the purity requirements of different applications.

[0041] Figure 2The diagram illustrates a reaction flow chart. Carbon dioxide collected by the carbon dioxide capture system 1 is compressed by the gas compression device 2 and then enters the gas mixing device 7. Water source 3 supplies water to the hydrogen generator 4 to produce hydrogen, and the generated hydrogen is compressed by the gas compression device 5 and then enters the gas mixing device 7. The gas mixing device 7 mixes the gases to obtain raw material gas, which is then input into the selective porous material regional reaction tank 8 (i.e., the regional reactor of this invention). The selective liquid device 6 injects liquid solvent into the selective porous material regional reaction tank 8. The tail gas generated by the reaction is recovered by the tail gas collection and purification device 9 and then input into the gas mixing device 7 as raw material gas. The liquid solvent generated by the reaction is recovered by the selective liquid solvent collection and purification device 10 and then input into the selective liquid device 6 for storage. The product generated by the reaction is input into the product purification device 11 for purification.

[0042] In the above process, the zoned reactor is the core component of this invention. The following embodiments provide a detailed description of the zoned reactor:

[0043] 1. Preparation of zoned reactors and porous material partitions

[0044] a. Selection and installation of zone reactors

[0045] Based on the predetermined reaction scale and process requirements, select zone reactors of appropriate materials and specifications. For example, for small- to medium-scale laboratory research or pilot-scale stages, glass reactors can be chosen to facilitate observation of the reaction process; while for large-scale industrial production, reactors with higher strength and corrosion resistance, such as stainless steel reactors, are typically selected. When installing the reactor, ensure that it is placed stably, that the connecting pipes are well-sealed, and that all monitoring equipment (such as temperature sensors, pressure sensors, etc.) is accurately positioned and functioning properly.

[0046] The sub-regional reactor can be in the form of a batch reactor, a tubular reactor, or a plate reactor, etc.

[0047] Preferably, when it is a batch reactor, such as Figure 4 As shown, the upper part of the reactor is the gas-solid phase reaction zone, which contains a fixed catalyst cage, while the lower part is the liquid phase absorption zone; the two zones are separated by a porous material. When it is a tubular reactor, as... Figures 5-7 As shown, a porous material is used as the wall material for the tubes; the tubes are arranged sequentially at intervals inside the tubular reactor, with the reactant gas introduced on one side and the solvent introduced on the other side of the tubes. When it is a plate reactor, as... Figure 9 As shown, porous materials are configured as porous baffles, and multiple porous baffles divide the plate reactor into multiple regions consisting of alternating gas-solid phase reaction zones and liquid phase absorption zones.

[0048] b. Preparation and installation of porous material interlayers

[0049] The porous material used in this invention is a selectively permeable porous material, which can be silica porous material, alumina porous material, molecular sieve composite porous material, zeolite porous material, multilayer ceramic porous material, polymer porous material, hydroxyl sodalite (H-SOD) porous material, or graphene oxide (GO) porous material. By carefully selecting these porous materials with specific pore structures and permeability properties, highly efficient separation of generated water and / or methanol can be achieved.

[0050] Selective permeable porous materials can be purchased commercially or prepared using methods disclosed in existing literature. The obtained selective permeable porous materials are then used to produce porous material separators or porous tubes of corresponding shapes using molds of a specific shape.

[0051] The following embodiment illustrates a preparation case: Based on the selectively permeable porous material type (such as silica porous material) selected according to the present invention, a corresponding preparation method is employed. Taking the sol-gel method for preparing silica porous material as an example, firstly, a silicon source (such as tetraethyl orthosilicate), a solvent (such as ethanol), water, and a catalyst (such as hydrochloric acid) are mixed in a certain proportion and reacted under appropriate temperature and stirring conditions. By controlling parameters such as reaction time, temperature, and raw material ratio, a silica porous material layer with suitable porosity, pore size, and mechanical strength is prepared. Similarly, for other types of porous materials, there are also corresponding mature preparation methods, such as alumina porous materials which can be prepared by precipitation. This embodiment can produce porous materials of corresponding shapes using molds of specific shapes, such as annular tubular structures.

[0052] Installation: Accurately install the prepared porous material inside the reaction vessel, using sealing materials (such as rubber sealing rings) to ensure a tight seal against the inner wall of the reaction vessel, preventing gas or liquid leakage. Figure 3 As shown, the porous material divides the interior of the reactor into a gas-solid phase reaction zone and a liquid phase absorption zone. Simultaneously, according to design requirements, the gas inlet and liquid inlet are located on opposite sides of the corresponding porous material partition; that is, the gas inlet is located on the side where carbon dioxide and hydrogen are introduced, and the liquid inlet is located on the side where the selective liquid is introduced. During system operation, to prevent gaseous components from permeating through the porous material into the liquid phase region and causing bubbling interference, a pressure differential control technique is employed: a pressure gradient is established on both sides of the porous material, ensuring that the pressure on the liquid solvent side is higher than that on the gas reaction side, controlling the pressure differential range to 1–10 MPa. This pressure differential design utilizes the capillary resistance and pressure balance principle of the porous medium to ensure effective isolation between the gas and liquid phases while avoiding a decrease in mass transfer efficiency caused by high pressure differential, thus ensuring the stable operation of the zoned reaction system.

[0053] 2. Catalyst loading

[0054] Catalyst selection

[0055] Depending on the specific reaction conditions (such as temperature, pressure, feed ratio, etc.) and the required methanol selectivity, a suitable catalyst can be selected from the types of catalysts mentioned in this invention (such as copper-based catalysts, noble metal supported catalysts, etc.). For example, if a higher reaction rate and methanol selectivity are desired at a relatively low temperature, a copper-based catalyst can be considered, and its specific formulation can be further determined, such as using a copper-based catalyst composed of copper oxide and zinc oxide in a specific ratio.

[0056] Catalyst loading method

[0057] A suitable loading method is used to uniformly pack the selected catalyst into the gas-solid phase reaction zone of the porous material separator. Common loading methods include impregnation and spraying. Taking impregnation as an example, the porous material separator is immersed in a solution containing a catalyst precursor (such as a soluble copper salt solution). After a certain period of immersion, the porous material separator is removed and subjected to drying and calcination treatments, which convert the catalyst precursor into an active catalyst on the surface of the porous material. In this way, it is ensured that the catalyst can be uniformly distributed on the surface of the porous material separator, fully contacting carbon dioxide and hydrogen to exert its catalytic effect.

[0058] 3. Introduction of gas and liquid and setting of reaction conditions

[0059] Gas introduction:

[0060] Carbon dioxide and hydrogen are mixed in a predetermined ratio and then introduced into the gas phase reaction zone of the reactor through a gas inlet. The ratio of carbon dioxide to hydrogen can be adjusted within a certain range according to specific reaction requirements and catalyst characteristics; generally, the common ratio range is between 1:2 and 1:5. For example, when selecting a copper-based catalyst, the ratio of carbon dioxide to hydrogen can be set to 1:3. During gas introduction, the gas flow rate must be monitored in real time using a gas flow monitoring device to ensure accurate and stable flow. Generally, the gas flow rate can be adjusted between 10 and 100 liters per hour depending on the size of the reactor and the predetermined reaction rate.

[0061] Liquid introduction:

[0062] A liquid selective for water or alcohol (such as higher alcohols) is introduced into the liquid phase reaction zone of the reactor through a liquid inlet. The liquid flow rate should be adjusted appropriately based on factors such as the expected rate of water or alcohol formation in the gas phase reaction zone and the permeability of the porous material. Generally, the liquid flow rate can be adjusted between 10 and 100 ml per hour. For example, if the expected amount of water or alcohol to be formed in the gas phase reaction zone is relatively large per hour, and the permeability of the porous material is good, the liquid flow rate can be appropriately increased. During liquid introduction, the liquid flow rate should also be monitored in real time using a liquid flow monitoring device to ensure that the introduced amount meets the requirements.

[0063] Reaction conditions settings:

[0064] The temperature within the zone reactor is set within the range of room temperature to 300°C, and the pressure is set at atmospheric pressure.

[0065] Within the range of ~10 MPa, a suitable combination of temperature and pressure is selected based on the specific reaction requirements and the characteristics of the chosen catalyst. For example, when selecting a copper-based catalyst, the temperature can be set to 200°C and the pressure to 5 MPa. Under these temperature and pressure conditions, the hydrogenation reaction of carbon dioxide and hydrogen is catalyzed using a catalyst packed on the surface of a porous material separator.

[0066] To prevent gaseous components from permeating into the liquid phase region and causing bubbling interference during system operation, a pressure differential control technique is employed: a pressure gradient is established across the porous material, ensuring the pressure on the liquid solvent side is higher than that on the gas reaction side, with the pressure differential controlled within the range of 1–10 MPa. This pressure differential design utilizes the capillary resistance and pressure balance principle of the porous medium to ensure effective isolation between the gas and liquid phases while avoiding a decrease in mass transfer efficiency due to high pressure differential, thus ensuring the stable operation of the zoned reaction system.

[0067] 4. Reaction process monitoring and adjustment

[0068] Monitoring parameters

[0069] During the reaction, various monitoring devices installed inside the reaction vessel, such as temperature sensors, pressure sensors, gas composition analyzers, liquid composition analyzers, and product detectors, monitor parameters such as temperature, pressure, gas composition, liquid composition, and product formation in real time. This monitoring data allows for a comprehensive understanding of the reaction's dynamics and timely detection of potential problems, such as excessively high or low temperatures, abnormal pressure, or unsatisfactory product formation rates.

[0070] Adjustment measures

[0071] Based on the monitoring results, corresponding adjustment measures are taken. For example, if the temperature deviates from the set value, the temperature is adjusted in a timely manner using heating or cooling devices; if the pressure is abnormal, it is adjusted using pressure regulating devices; if the gas or liquid flow rate does not meet the requirements, it is adjusted using flow regulating devices; if the product formation is not ideal, such as the carbon dioxide conversion rate or methanol selectivity not meeting expectations, the reaction conditions are adjusted, such as changing the temperature, pressure, and the ratio of gas to liquid, to optimize the reaction process and improve reaction efficiency.

[0072] Product collection and subsequent processing

[0073] Product collection

[0074] After the reaction is complete, the generated methanol, unreacted carbon dioxide, hydrogen, and any other possible byproducts are collected by a product collection device located at the outlet of the reaction vessel. The different products are collected into separate containers for subsequent analysis and processing. For example, methanol is collected in a dedicated methanol collection container, unreacted carbon dioxide and hydrogen are collected in a recyclable container, and other byproducts are collected in appropriate processing containers.

[0075] Follow-up processing

[0076] Methanol purification:

[0077] The collected methanol is further purified, such as by distillation, to remove any impurities and obtain a high-purity methanol product to meet the purity requirements of different applications.

[0078] Raw material recycling: Unreacted carbon dioxide and hydrogen can be recycled and reintroduced into the reaction vessel to improve raw material utilization. Before recycling, necessary treatments are required, such as removing any impurities and adjusting the gas ratio.

[0079] By-product treatment: Other collected by-products will be treated according to their properties and uses. For example, some by-products may have economic value and can be recycled; while others may have an environmental impact and require safe disposal, such as through chemical conversion or physical landfill.

[0080] Based on the above description of the zoned reactor, the present invention further provides a process system including the aforementioned zoned reactor, wherein the process system further includes:

[0081] The condenser is connected to the gas phase outlet of the receiving sub-reactor to receive gaseous products and perform gas-liquid separation.

[0082] The compressor is connected to the gas phase outlet of the condenser to pressurize the gas and input it into the gas feed line to mix with the fresh raw material gas;

[0083] A gas preheater is installed on the gas feed line to preheat the raw gas.

[0084] Flash tank, which receives the liquid-phase products from the zone reactor.

[0085] The methanol purification unit is connected to the liquid phase outlet of the receiving sub-reactor, and receives the liquid phase solvent for flash evaporation separation.

[0086] Solvent preheater is used to preheat solvents.

[0087] In the carbon dioxide-to-methanol process, traditional processes mainly employ reactors such as fixed-bed, slurry-bed, and trickle-bed reactors. From a thermodynamic perspective, this reaction process requires low-temperature and high-pressure conditions to shift the chemical equilibrium towards methanol production.

[0088] Fixed-bed reactors, a typical example of traditional processes, have catalysts that are statically packed inside. In actual operation, due to the limited heat transfer efficiency within the reactor, it is difficult to effectively control the heat generated during the reaction. Temperature runaway can lead to reduced catalyst activity, increased side reactions, and consequently a significant decrease in carbon dioxide conversion rate. To improve this situation, a slurry-bed reactor was adopted as an improvement. In a slurry bed, catalyst particles are suspended in a liquid medium, and the heat generated by the reaction can be removed in a timely manner by introducing heat transfer oil into the catalyst system. However, this process has significant drawbacks. The gas-solid two-phase contact is uneven in the slurry system, easily forming unstable bubbles at the gas-liquid interface. This increases the mass transfer resistance between the gas, liquid, and solid phases, resulting in low mass transfer efficiency and severely restricting the improvement of carbon dioxide conversion rate.

[0089] To address the drawbacks of slurry beds, trickle bed reactors have emerged. Trickle beds incorporate a liquid spraying device above the catalyst bed, continuously spraying liquid to remove reaction products promptly while effectively reducing the reaction temperature. However, this process faces the challenge of precisely controlling the liquid flow rate and velocity in practical operation. Due to the complex characteristics of liquid flow, it is highly susceptible to fluctuations in operating conditions, leading to instability in the reaction system and making it difficult to maintain a highly efficient reaction state.

[0090] Based on in-depth research into the problems of the aforementioned traditional processes and reactors, this invention proposes a technical solution. This invention innovatively adopts a zoned reaction design concept, dividing the reactor into two functional zones: a gas phase zone and a liquid phase zone. In the gas phase zone, a precise gas flow control system and pressure regulation device achieve precise control of the proportion and pressure of the reactant gases, creating a stable gas phase environment for the reaction. In the liquid phase zone, an independent liquid flow control system is constructed, optimizing liquid distribution and circulation paths, and simultaneously removing products in situ to achieve precise control of the reaction temperature. This zoned design not only ensures the stability of the reaction temperature and avoids side reactions caused by temperature fluctuations, but also significantly increases the reaction area under the same operating conditions by optimizing the gas-liquid-solid three-phase contact method, effectively improving the carbon dioxide conversion rate and methanol selectivity, providing a new technical path for the efficient development of carbon dioxide to methanol processes. A comparison is made between the methanol processes in existing technical literature and the zoned reactor process of this invention; Tables 1 and 2 compare the relevant operating parameters of these processes with those of the zoned reactor methanol production process of this invention.

[0091] Table 1. Traditional Methanol Production Processes

[0092] project numerical values Carbon dioxide conversion rate % 20～30 methanol selectivity % 50～70

[0093] Table 2. Methanol production process via zoned reaction

[0094] project numerical values Carbon dioxide conversion rate % 40～60 methanol selectivity % 80～90

[0095] As shown in Tables 1 and 2, this invention significantly improves the conversion rate of carbon dioxide and the selectivity of methanol through compartmentalized reaction, almost doubling the conversion rate and selectivity compared to traditional processes. Specifically, by introducing a compartmentalized reactor using selective porous materials, this invention promotes a shift in chemical equilibrium towards methanol formation. The continuous flow of selective solvent removes the water and methanol produced in the reaction, increasing the reaction zone and improving reaction efficiency. Simultaneously, it reduces the required reactor size, thereby lowering equipment costs and demonstrating significant economic value.

[0096] The above descriptions are merely specific embodiments of this application, intended to help those skilled in the art understand or implement this application. It is obvious to those skilled in the art that various modifications can be made to these embodiments, and these general principles can be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application should not be limited to the embodiments shown, but should be considered within the maximum scope that conforms to the principles and novel features of this application.

[0097] Through the above specific embodiments, the regional reactor and process system for enhancing the production of methanol by carbon dioxide hydrogenation of the present invention can effectively realize the resource utilization of carbon dioxide, improve the conversion rate of carbon dioxide and the selectivity of methanol, and provide an innovative and feasible technical solution for the development of green chemical industry.

Claims

1. A compartmentalized reactor for enhanced carbon dioxide hydrogenation to methanol, characterized in that, The sub-regional reactor has a gas-solid phase reaction zone and a liquid phase absorption zone, which are separated by a porous material. The gas-solid phase reaction zone contains a catalyst, and carbon dioxide and hydrogen are introduced to produce methanol via carbon dioxide hydrogenation. The liquid phase absorption zone is introduced with a solvent. The methanol and / or water produced by the reaction in the gas-solid phase reaction zone are absorbed and carried away by the solvent within the pores of the porous material. The sub-regional reactor is a batch reactor, a tubular reactor, or a plate reactor; when it is a batch reactor, the upper part of the reactor is a gas-solid phase reaction zone, in which a catalyst cage is fixed, and the lower part is a liquid phase absorption zone; the two zones are separated in the middle by a porous material. When it is a tubular reactor, the porous material is used as the tube wall material; the tubes are arranged sequentially at intervals inside the tubular reactor, and one side of the inner and outer sides of the tubes is the gas-solid phase reaction zone, and the other side is the liquid phase absorption zone. When it is a plate reactor, porous material is set as porous baffles, and multiple porous baffles divide the plate reactor into multiple regions consisting of alternating gas-solid phase reaction zones and liquid phase absorption zones.

2. The compartmentalized reactor for enhanced carbon dioxide hydrogenation to methanol according to claim 1, characterized in that, The solvent has a boiling point of 250°C or higher; the solvent has high solubility in water or methanol or both; let S1 be the solubility of the solvent in methanol or water or in methanol and water, and S2 be the solubility in carbon dioxide, hydrogen and carbon monoxide, satisfying S1 / S2≥50.

3. The compartmentalized reactor for enhanced carbon dioxide hydrogenation to methanol according to claim 1, characterized in that, When the sub-zone reactor is a batch reactor, the catalyst is raised to a higher position by a catalyst cage to avoid direct contact between the catalyst and the solvent. The solvent in the liquid phase absorption zone is stirred by a stirring paddle to accelerate the absorption of methanol or water by the solvent. The gas-solid phase reaction zone is adjusted to a single gas phase zone or multiple gas phase zones according to the reaction rate and time.

4. The compartmentalized reactor for enhanced carbon dioxide hydrogenation to methanol according to claim 1, characterized in that, The porous materials used in tubular or plate reactors have pore sizes below 200 nm and can maintain their mechanical structure at temperatures ranging from room temperature to 300°C and at atmospheric pressure to 8 MPa. This ensures that the methanol and / or water generated in the reaction can dissolve in the solvent under different reaction conditions, allowing them to enter the pores but not pass through them, thus enabling the methanol and / or water to dissolve in the solvent within the porous material.

5. The compartmentalized reactor for enhanced carbon dioxide hydrogenation to methanol according to claim 1, characterized in that, The solvent is an organic solvent or an ionic liquid. The organic solvent is a higher alcohol, tetraethylene glycol dimethyl ether, or ethylene glycol oligomer. The ionic liquid is one or more of the following: 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]), 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIM][PF6]), 1-butyl-3-methylimidazolium nitrate ([BMIM][NO3]), or 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]).

6. The compartmentalized reactor for enhanced carbon dioxide hydrogenation to methanol according to claim 1, characterized in that, The porous material provides a site for methanol and / or water to dissolve in the solvent, and the porous material is one of the following: silica porous material, alumina porous material, molecular sieve composite porous material, multilayer ceramic porous material, polymer porous material, hydroxyl sodalite (H-SOD) porous material, and graphene oxide (GO) porous material.

7. The compartmentalized reactor for enhanced carbon dioxide hydrogenation to methanol according to claim 1, characterized in that, The gas-solid phase reaction zone is filled with a catalyst for catalyzing the hydrogenation reaction of carbon dioxide and hydrogen. The catalyst is one or more of the following: copper-based catalyst, noble metal supported catalyst, cobalt-based catalyst, iron-based catalyst, molybdenum-based catalyst, tungsten-based catalyst, or tin-based catalyst.

8. A method for producing methanol by carbon dioxide hydrogenation using a zone reactor according to any one of claims 1-7, characterized in that, Carbon dioxide and hydrogen are mixed to form a feed gas, which is then pressurized and preheated to 200℃~280℃. The feed gas is then introduced into the gas-solid phase reaction zone. The solvent is preheated to 140℃~280℃ and introduced into the liquid phase absorption zone. A pressure gradient is established on both sides of the porous material, so that the pressure on the liquid phase absorption zone side is higher than that on the gas-solid phase reaction zone side. The pressure difference is controlled within the range of 1~10MPa. By utilizing the capillary resistance and pressure balance principle of the porous medium, the effective isolation of the gas and liquid phases is ensured, thus ensuring the stable operation of the zoned reaction system. In the gas-solid phase reaction zone, carbon dioxide and hydrogen are converted into methanol and water under the action of a catalyst. The gas and solvent carrying the reaction products enter the pores but do not pass through the pores. The water or methanol in the gas dissolves in the solvent in the porous material and is carried away with the solvent, thereby effectively changing the reaction equilibrium in the gas-solid phase reaction zone, breaking the thermodynamic limitation, and improving the conversion rate of carbon dioxide and the selectivity of methanol.

9. The method according to claim 8, characterized in that, The gas after the reaction is fed into a condenser. The condensed gas phase is used as a circulating gas, which is pressurized and mixed with the raw material gas. After preheating, it is fed into the reactor. The liquid phase obtained from the condensation is fed into the methanol purification unit. The solvent is drawn from the reactor into the flash tank. The liquid phase obtained after flash evaporation is recycled as solvent and, after preheating, re-enters the liquid phase absorption zone.

10. A process system comprising a zone reactor according to any one of claims 1-7, characterized in that, The process system also includes: The condenser is connected to the gas phase outlet of the receiving sub-reactor to receive gaseous products and perform gas-liquid separation. The compressor is connected to the gas phase outlet of the condenser to pressurize the gas and input it into the gas feed line to mix with the fresh raw material gas; A gas preheater is installed on the gas feed line to preheat the raw gas. Flash tank, which receives the liquid-phase products from the zone reactor. The methanol purification unit is connected to the liquid phase outlet of the receiving sub-reactor, and receives the liquid phase solvent for flash evaporation separation. Solvent preheater is used to preheat solvents.

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