A hydrogen production and product purification method, system and application based on ethanol-carbon dioxide reforming

Abstract

The application discloses a hydrogen production and product purification method and system based on ethanol-carbon dioxide reforming and application, and the method comprises the following steps: continuously adding and mixing gasified ethanol and carbon dioxide gas to obtain a raw material mixed gas; performing heat exchange on the raw material mixed gas and a heat exchange medium to obtain the raw material mixed gas after heat exchange; preheating the raw material mixed gas after heat exchange; performing a reforming hydrogen production reaction on the raw material mixed gas after preheating under the action of a Co@SiO2 eggshell type nanoparticle catalyst with a combined oxidation state to obtain product synthesis gas; using the product synthesis gas as a heat exchange medium to perform heat exchange with the raw material mixed gas; sequentially performing ethanol separation and carbon dioxide separation on the product synthesis gas after heat exchange to obtain target synthesis gas; and recycling the separated ethanol and carbon dioxide as raw materials.

Description

Technical Field

[0001] This invention relates to the field of hydrogen production technology from ethanol / carbon dioxide reforming, and more specifically, to a method, system, and application for hydrogen production and product purification based on ethanol-carbon dioxide reforming. Background Technology

[0002] Hydrogen energy is a green and efficient secondary energy source. Although it is not as well-known as electricity because it has not yet been widely used, it has characteristics that are unmatched by any other known energy source. It will soon become an inevitable choice for solving the energy problems of future human society, a rising star in the energy field, and is even called the "ultimate energy" by industry experts.

[0003] Currently, most hydrogen globally is produced from fossil fuels, with methane steam reforming being the mainstream method. In this process, methane reacts with steam at high temperatures to produce hydrogen, carbon monoxide, and carbon dioxide. This is a widely used industrial method for hydrogen production. However, this process generates carbon dioxide, resulting in the underutilization of carbon and the generation of greenhouse gases. Another method is methanol steam reforming, which is based on the conversion of methanol into hydrogen and carbon dioxide under specific conditions (such as high temperature and pressure). Again, carbon is not fully utilized in this process. Therefore, finding more environmentally friendly and sustainable methods for hydrogen production and carbon utilization is crucial.

[0004] Through ongoing research, it has been discovered that hydrogen production from ethanol and carbon dioxide can solve the aforementioned problems. Firstly, ethanol has a wide range of sources and can be produced through green and sustainable fermentation. The raw materials for fermentation can be starchy agricultural products such as grains, potatoes, or wild plant fruits, as well as molasses waste from sugar factories, or cellulose-containing materials such as sawdust and plant stems. After certain pretreatment, these substances can be hydrolyzed and fermented to produce crude ethanol, which can then be distilled to obtain 95% industrial ethanol. Furthermore, this reaction process can utilize CO2, one of the major greenhouse gases and also the most abundant and cheapest form of carbon dioxide in the world. This reaction not only uses carbon dioxide as a raw material to produce carbon monoxide, which has great industrial potential, but also objectively reduces carbon dioxide emissions, which is of multiple significance in terms of environment, energy and carbon neutrality. Finally, the ratio of CO to H2 produced by this reaction is close to 1:1. This ratio is conducive to the FT reaction. The FT reaction is a process of synthesizing hydrocarbons from syngas (a mixture of carbon monoxide and hydrogen) under the conditions of a catalyst and appropriate conditions. The catalyst is usually iron-based or cobalt-based. It is a key step in the conversion of non-petroleum-based carbon resources into liquid fuels. In other words, through this reaction, ethanol and carbon dioxide obtained in the green process can be converted into liquid fuels, thereby achieving a green substitution of fossil fuels.

[0005] This reaction is endothermic, and high temperatures are more conducive to its progress. However, it is also a complex reaction system, and various side reactions often occur during the actual reaction process, leading to a decrease in syngas yield. There are many common side reactions, so the catalyst's conversion rate, selectivity, thermal stability, and surface carbonization degree are important factors in evaluating the catalyst's effectiveness.

[0006] CH3CH2OH + CO2 → 3CO + 3H2 (Main reaction)

[0007] CH3CH2OH——3CO + CH4 + H2 (side reaction of ethanol decomposition) CH3CH2OH → CH3CHO + H2 (side reaction of ethanol dehydrogenation) CH3CH2OH——C2H4+ H2O (side reaction of ethanol dehydration) CO + H2O → CO2 + H2 (water-gas side reaction) CH4 + CO2 → 2CO + 2H2 (side reaction of methane dry reforming) CO2 + H2 → CO + H2O (reverse side reaction of water gas) Since the ethanol / carbon dioxide reforming reaction is a high-temperature reaction, the theoretical minimum initial reaction temperature is 318℃, and the normal reaction temperature is 500-800℃. Therefore, the thermal stability of the catalyst at the reaction temperature is particularly important. We use a method of encapsulating nanocomposite materials with mesoporous silica to improve the stability of cobalt catalysts. This method has advantages in terms of catalytic transport and diffusion. This structure involves embedding nanoparticles into a silica encapsulation layer to form core-shell nanoparticles. The porous silica shell encapsulating the nanoparticles can effectively prevent the aggregation of active metal Ni at high reaction temperatures and also ensure that the nanoparticles separated within the shell are relatively uniform.

[0008] Due to the introduction of the novel catalyst, the entire reaction system needs to be reconstructed, and the relevant catalytic process also needs to be adjusted accordingly. At the same time, the products after the reaction are also quite complex. In addition to the main components CO, H2, and CO2, there may also be small amounts of CH3CH2OH, CH4, CH3CHO, C2H4, etc., which require further separation of the main target products CO and H2.

[0009] Previous ethanol / carbon dioxide reforming processes for hydrogen production largely referenced methanol reforming processes, employing multi-stage pressure swing adsorption after the reaction to generate relatively pure hydrogen. However, since the main products of ethanol / carbon dioxide reforming for hydrogen production are hydrogen and carbon monoxide, which can be used as syngas in the Fischer-Tropsch reaction, and the byproducts are mainly CH4, CH3CHO, C2H4, as well as the raw materials ethanol and carbon dioxide, the separation process required for methanol reforming for hydrogen production is not as complex. Summary of the Invention

[0010] The purpose of this invention is to overcome the above-mentioned defects in the prior art and provide a method, system and application for hydrogen production and product purification based on ethanol-carbon dioxide reforming.

[0011] To achieve the above objectives, the technical solution of the present invention is as follows: A method for hydrogen production and product purification based on ethanol-carbon dioxide reforming, the method comprising the following steps: S1. Continuously add vaporized ethanol and carbon dioxide gas and mix them to obtain raw material mixture gas; S2. The raw material mixture is heated with the heat exchange medium to obtain the heated raw material mixture. S3. Preheat the heat-exchanged raw material mixture to obtain a preheated raw material mixture; S4. The preheated raw material mixture is reformed to produce hydrogen under the action of a combined oxidized Co@SiO2 eggshell nanoparticle catalyst to obtain product syngas. S5. The product synthesis gas obtained in step S4 is used as the heat exchange medium and introduced into step S2 to exchange heat with the raw material mixture gas, so as to obtain the product synthesis gas after heat exchange and the raw material mixture gas after heat exchange. S6. The heat-exchanged product synthesis gas is sequentially subjected to ethanol separation and carbon dioxide separation to obtain the target synthesis gas, and the separated ethanol and carbon dioxide are used as raw materials to be recycled in step S1. In the case where no product synthesis gas is obtained in step S4, step S2 is omitted, and the raw material mixture obtained in step S1 is preheated in step S3; after step S4 is performed for the first time and product synthesis gas is obtained, the heat exchange medium is the product synthesis gas obtained in step S4.

[0012] The present invention also discloses a hydrogen production and product purification system based on ethanol-carbon dioxide reforming for implementing the method described above, the system comprising a continuous feeding unit, a heat exchange unit, a preheating unit, a reforming reaction unit and a product separation unit. The continuous feeding unit is used to prepare the raw material mixture gas, including a first gasifier, a second gasifier, and a mixing device; the first gasifier is used to gasify liquid ethanol, and the second gasifier is used to gasify carbon dioxide; the outlets of the first gasifier and the second gasifier are both connected to the inlet of the mixing device, and the gasified ethanol and carbon dioxide gas are continuously fed into the mixing device for mixing to prepare the raw material mixture gas; The heat exchange unit is used to recover reaction heat energy and is provided with a first flow channel and a second flow channel; the inlet of the first flow channel is connected to the outlet of the mixing device for continuous introduction of raw material mixed gas; the outlet of the first flow channel is connected to the inlet of the preheating unit; the inlet of the second flow channel is connected to the outlet of the reforming reaction unit for continuous introduction of product synthesis gas; the outlet of the second flow channel is connected to the inlet of the product separation unit. The inlet of the preheating unit is connected to the outlet of the first flow channel of the heat exchange unit, and the outlet is connected to the inlet of the reforming reaction unit, for preheating the continuously introduced heat-exchanged raw material mixture. The reforming reaction unit is filled with a combined oxidized Co@SiO2 eggshell-shaped nanoparticle catalyst, which is used to reform the continuously introduced preheated raw material mixture into hydrogen through ethanol and carbon dioxide reforming. The inlet is used to continuously receive the raw material mixture from the preheating unit, and the outlet continuously sends the product synthesis gas generated by the reaction to the second flow channel inlet of the heat exchange unit. The product separation unit is used to separate and recover unreacted raw materials, including an ethanol separation unit and a carbon dioxide separation unit connected in sequence; the inlet of the ethanol separation unit is connected to the outlet of the second flow channel of the heat exchange unit, and is used to condense and separate unreacted ethanol; the carbon dioxide separation unit is used to separate unreacted carbon dioxide from the gas flow; the outlets of the ethanol separation unit and the carbon dioxide separation unit are respectively connected to the inlets of the first gasifier and the second gasifier; the separated ethanol and carbon dioxide can be reused as raw materials; The system is configured to operate in two modes: Start-up mode: When there is no product synthesis gas in the system, the raw material mixed gas flows out from the mixing device and enters the preheating unit through the first flow channel of the heat exchange unit; Normal operating mode: When the system generates product synthesis gas, the raw material mixed gas flows out of the mixing device and exchanges heat with the product synthesis gas from the second channel in the first channel of the heat exchange unit, and then is preheated by the preheating unit.

[0013] The present invention also discloses the application of a target syngas prepared by the method described above, or a target syngas obtained by the system described above, as a feedstock gas in a Fischer-Tropsch reaction.

[0014] Implementing the embodiments of the present invention will have the following beneficial effects: The ethanol-carbon dioxide reforming hydrogen production and product purification method and system provided by this invention utilizes a combined oxidized Co@SiO2 eggshell-type nanoparticle catalyst with a unique porous structure and high specific surface area. This catalyst exhibits excellent catalytic activity and stability during the reaction, enabling near-complete ethanol conversion under mild conditions and maintaining a stable hydrogen-to-carbon monoxide volume ratio in the product syngas between 1.0 and 1.2, making it suitable as feedstock for Fischer-Tropsch reactions to synthesize olefins and alkanes. Furthermore, the process flow incorporates an internal heat integration design, using the product syngas from the reforming reaction as a heat exchange medium to heat the feedstock mixture, saving energy and improving overall energy efficiency and economy. Simultaneously, an ethanol and carbon dioxide separation and reuse unit is included, effectively recovering unreacted feedstock and recycling it into the system, improving feedstock utilization, reducing operating costs, and embodying the principle of green recycling. Attached Figure Description

[0015] Figure 1 This is a comparison chart showing the conversion rates of different reactants in the ethanol / carbon dioxide reforming reaction of Co@SiO2-1, Co@SiO2-1.5, and Co@SiO2-2.5, which are embodiments of the present invention.

[0016] Figure 2 This is a comparison chart showing the yields of different products from Co@SiO2-1, Co@SiO2-1.5, and Co@SiO2-2.5 applied to the ethanol / carbon dioxide reforming reaction, as described in this embodiment of the invention.

[0017] Figure 3 This is a flowchart of a hydrogen production and product purification method based on ethanol-carbon dioxide reforming according to an embodiment of the present invention. Detailed Implementation

[0018] The present invention will be further described below with reference to specific embodiments, but this does not limit the present invention in any way.

[0019] The combined oxidized Co@SiO2 eggshell-type nanoparticle catalyst used in this invention includes cobalt oxide nanoparticles and a mesoporous silica coating layer on the surface of the cobalt oxide nanoparticles; the cobalt ions in the cobalt oxide nanoparticles exist in the form of divalent cobalt and trivalent cobalt.

[0020] In one specific embodiment, the combined oxidized Co@SiO2 eggshell-shaped nanoparticle catalyst can be prepared according to the method described in publication number CN118513035A.

[0021] In one specific embodiment, the combined oxidized Co@SiO2 eggshell-shaped nanoparticle catalyst possesses a porous structure, high specific surface area and pore volume, providing numerous attachment sites and endowing it with strong adsorption capacity, achieving efficient adsorption and improving reaction time. Furthermore, its particle size, specific surface area, pore size distribution, and pore structure are controllable, demonstrating good performance in the ethanol / carbon dioxide reforming reaction. The prepared catalyst was applied to the ethanol / carbon dioxide reforming reaction to investigate its effects on catalytic activity and stability during the reaction.

[0022] Figure 1 The catalytic activities of different catalysts in the ethanol / carbon dioxide reforming reaction were compared (reaction temperature 550℃, ethanol / carbon dioxide / nitrogen volume ratio 1 / 1 / 2, GHSVw 65Lg). -1 L -1 The study found that Co@SiO2-1.5 exhibited the highest ethanol conversion rate of 100%, significantly higher than both Co@SiO2-1 (92%) and Co@SiO2-2.5 (87%). CO2 conversion rates followed a similar trend: Co@SiO2-1.5 (30.7%) > Co@SiO2-1 (25%) > Co@SiO2-2.5 (17.2%). Furthermore, as... Figure 1 As shown, a comparison of the H2 / CO values ​​of the products reveals that, compared with Co@SiO2-1 (1.13) and Co@SiO2-2.5 (2.32), the target H2 / CO ratio of Co@SiO2-1.5 (1.02) is closer to 1.0, which is beneficial to the downstream FT process.

[0023] The stability of the catalyst in the ethanol / carbon dioxide reforming reaction was also investigated under the above conditions. Figure 2 As shown, the ethanol and CO2 conversion rates of Co@SiO2-1.5 remained relatively stable throughout the testing period under all conditions. In contrast, the target H2 / CO molar ratio of the Co@SiO2-2.5 catalyst decreased significantly in the first 10 hours and slightly after 35 hours of operation. This indicates that Co@SiO2-1.5 exhibits a relatively stable degradation rate compared to other materials, demonstrating high application potential.

[0024] Based on the advantages of combined oxidation states of Co@SiO2 eggshell-shaped nanoparticle catalysts in ethanol / carbon dioxide reforming hydrogen production catalysts, this invention discloses a method for hydrogen production and product purification based on ethanol-carbon dioxide reforming, the method comprising the following steps: S1. Continuously add vaporized ethanol and carbon dioxide gas and mix them to obtain raw material mixture gas.

[0025] In one specific embodiment, in step S1, the molar ratio of vaporized ethanol to carbon dioxide gas in the raw material mixture is (0.01~100):1; preferably (0.5~2):1.

[0026] In one specific embodiment, in step S1, the mixing temperature is 80~850℃ and the pressure is 0.01~10MPa; however, since the reforming hydrogen production reaction is a high-temperature and atmospheric-pressure reaction process, the pressure and temperature of this process do not need to be too high. Preferably, the temperature is 100~200℃ and the pressure is 0.1~0.3MPa.

[0027] In one specific embodiment, ethanol and carbon dioxide are selected as raw materials. Carbon dioxide is generally stored in gas cylinders and can be directly vaporized into a gaseous state through a vaporizer. Ethanol is liquid at room temperature and has a boiling point of 78°C. It needs to be pumped into a vaporizer to vaporize the liquid ethanol into a gas. The preparation conditions for the vaporized ethanol are: vaporization temperature of 80~120°C and vaporization pressure of 0.1~1.0 MPa. Preferably, the vaporization temperature is 80~100°C and the vaporization pressure is 0.3~0.5 MPa.

[0028] S2. The raw material mixture is heated with the heat exchange medium to obtain the heated raw material mixture.

[0029] In one specific embodiment, in step S2, the heat exchange is gas-to-gas heat exchange.

[0030] In one specific embodiment, in step S2, the temperature of the heat-exchanged raw material mixture is lower than the reforming hydrogen production reaction temperature in step S4.

[0031] S3. Preheat the heat exchanged raw material mixture to obtain a preheated raw material mixture.

[0032] In one specific embodiment, in step S3, the temperature of the preheated feed gas mixture is the same as the temperature of the reforming hydrogen production reaction in step S4.

[0033] S4. The preheated raw material mixture is reformed to produce hydrogen under the action of a combined oxidized Co@SiO2 eggshell-type nanoparticle catalyst to obtain the product syngas.

[0034] Furthermore, if no product synthesis gas is obtained in step S4, step S2 is omitted, and the raw material mixture obtained in step S1 is preheated in step S3; after step S4 is performed for the first time and product synthesis gas is obtained, the heat exchange medium is the product synthesis gas obtained in step S4.

[0035] In one specific embodiment, in step S4, the conditions for the reforming hydrogen production reaction are: reaction temperature of 300~1200℃, reaction pressure of 0.01~10MPa, and space velocity of 10~1000 / h; preferably, the reaction temperature is 500~800℃, the reaction pressure is 0.1~0.3MPa, and the space velocity is 100~200 / h. The conditions are fine-tuned according to the reaction process and the conversion rate of ethanol to obtain the syngas product of the reforming hydrogen production.

[0036] In one specific embodiment, in step S4, the product synthesis gas mainly consists of hydrogen and carbon monoxide, and also contains byproducts mainly CH4, CH3CHO, C2H4, as well as unreacted carbon dioxide and unreacted ethanol.

[0037] S5. The product synthesis gas obtained in step S4 is used as a heat exchange medium and introduced into step S2 to exchange heat with the raw material mixture gas, so as to obtain the product synthesis gas and the raw material mixture gas after heat exchange.

[0038] Specifically, the feed gas mixture needs to exchange heat with the product syngas to save energy. This heat exchange process requires a gas-to-gas heat exchange reactor. During the heat exchange process, the temperature rise and fall of the feed gas mixture and the product syngas are similar. The feed gas mixture can be heated to a temperature close to that of the product syngas, and the product syngas can be cooled to a temperature close to that of the feed gas mixture. However, considering the heat loss during the heat exchange process, the temperature difference between the two is approximately 50~100℃. Therefore, the temperature of the product syngas after heat exchange is higher than that of the feed gas mixture after heat exchange.

[0039] S6. The heat-exchanged product synthesis gas is sequentially subjected to ethanol separation and carbon dioxide separation to obtain the target synthesis gas, and the separated ethanol and carbon dioxide are fed into step S1 for reuse.

[0040] In one specific embodiment, since unstable operation during industrial applications may lead to waste of raw materials, the separation of ethanol and carbon dioxide is considered in the separation method.

[0041] In one specific embodiment, step S6 involves using an air-cooled tower for air-cooled heat exchange, with a cooling temperature below 80°C. Air is used as the cold source to achieve the transformation of ethanol from a gaseous state to a liquid state. After heat exchange, the ethanol is separated from the air-cooled tower, causing the gaseous ethanol to condense into a liquid state and be separated and reused. The preferred temperature is room temperature to 60°C.

[0042] In one specific embodiment, in step S6, carbon dioxide separation employs low-temperature condensation, with a condensation temperature below -70°C. The carbon dioxide is liquefied using the difference in boiling points of the components and then reused as a raw material; preferably, the temperature is -78.5°C to -120.0°C, and the pressure is 0 to 0.1 MPa. During this process, acetaldehyde may also precipitate at 0 to 20°C, which can be separated using staged low-temperature condensation.

[0043] In one specific embodiment, in step S6, the volume ratio of hydrogen to carbon monoxide in the target synthesis gas is 1.0 to 1.2.

[0044] In one specific embodiment, the target synthesis gas mainly contains hydrogen and carbon monoxide.

[0045] In one specific embodiment, the small reaction device is not suitable for low-temperature condensation, and carbon dioxide separation is carried out by polyimide / mixed matrix membrane separation or solid adsorption method for carbon dioxide recovery.

[0046] The present invention also discloses a hydrogen production and product purification system based on ethanol-carbon dioxide reforming for implementing the method described above. The system includes a continuous feeding unit, a heat exchange unit, a preheating unit, a reforming reaction unit, and a product separation unit.

[0047] The continuous feeding unit is used to prepare raw material mixed gas, including a first gasifier, a second gasifier, and a mixing device; the first gasifier is used to gasify liquid ethanol, and the second gasifier is used to gasify carbon dioxide; the outlets of the first gasifier and the second gasifier are both connected to the inlet of the mixing device, and the gasified ethanol and carbon dioxide gas are continuously fed into the mixing device for mixing to prepare raw material mixed gas. The heat exchange unit is used to recover reaction heat energy and is equipped with a first flow channel and a second flow channel. The inlet of the first flow channel is connected to the outlet of the mixing device for continuous introduction of raw material mixed gas. The outlet of the first flow channel is connected to the inlet of the preheating unit. The inlet of the second flow channel is connected to the outlet of the reforming reaction unit for continuous introduction of product synthesis gas. The outlet of the second flow channel is connected to the inlet of the product separation unit. The inlet of the preheating unit is connected to the outlet of the first flow channel of the heat exchange unit, and the outlet is connected to the inlet of the reforming reaction unit, which is used to preheat the continuously introduced heat-exchanged raw material mixture. The reforming reaction unit is filled with a combined oxidized Co@SiO2 eggshell-shaped nanoparticle catalyst, which is used to reform the continuously introduced preheated feed gas mixture into hydrogen through ethanol and carbon dioxide reforming. The inlet is used to continuously receive the feed gas mixture from the preheating unit, and the outlet continuously sends the product synthesis gas generated by the reaction to the inlet of the second flow channel of the heat exchange unit. The product separation unit is used to separate and recover unreacted raw materials, including an ethanol separation unit and a carbon dioxide separation unit connected in sequence; the inlet of the ethanol separation unit is connected to the outlet of the second flow channel of the heat exchange unit, and is used to condense and separate unreacted ethanol; the carbon dioxide separation unit is used to separate unreacted carbon dioxide from the gas flow; the outlets of the ethanol separation unit and the carbon dioxide separation unit are connected to the inlets of the first gasifier and the second gasifier, respectively; the separated ethanol and carbon dioxide can be reused as raw materials. The system is configured to run in two modes: Start-up mode: When there is no product synthesis gas in the system, the raw material mixed gas flows out from the mixing device and enters the preheating unit through the first flow channel of the heat exchange unit; Normal operating mode: When the system generates product synthesis gas, the raw material mixed gas flows out of the mixing device and exchanges heat with the product synthesis gas from the second flow channel in the first flow channel of the heat exchange unit, and then is preheated by the preheating unit.

[0048] In one specific embodiment, the preheating unit is a preheating furnace.

[0049] In one specific embodiment, the heat exchange unit is a heat exchanger; the heat exchanger includes one of shell-and-tube heat exchangers, plate heat exchangers and finned heat exchangers, but considering pressure drop and cost issues, shell-and-tube heat exchangers are more suitable.

[0050] In one specific embodiment, the reforming reaction unit is a reforming hydrogen production reactor, which uses a gas-solid reaction tower and employs the combined oxidized Co@SiO2 eggshell-type nanoparticle catalyst.

[0051] In one specific embodiment, the ethanol separation device is an air-cooled tower.

[0052] In one specific embodiment, the carbon dioxide separation device is one of a cryogenic condenser, a membrane separation device, or an adsorption tower.

[0053] The present invention also discloses the application of a target syngas prepared by the method described above, or a target syngas obtained by the system described above, as a feedstock gas in a Fischer-Tropsch reaction.

[0054] Specifically, the separated product syngas mainly contains hydrogen and carbon monoxide, and can be used as feedstock for the Fischer-Tropsch reaction. When using it, it can be further purified or the syngas ratio adjusted according to the requirements of the Fischer-Tropsch reaction. Impurities in other product syngas can be separated in this process.

[0055] The following are specific embodiments. The Co@SiO2-1.5 used in this embodiment can be prepared according to the method described in Example 1 of Publication No. CN118513035A.

[0056] The hydrogen production and product purification method based on ethanol-carbon dioxide reforming in this embodiment includes the following steps: S1. Continuously add vaporized ethanol and carbon dioxide gas and mix them to obtain raw material mixture gas.

[0057] S2. The raw material mixture is heated with the heat exchange medium to obtain the heated raw material mixture.

[0058] S3. Preheat the heat exchanged raw material mixture to obtain a preheated raw material mixture.

[0059] S4. The preheated raw material mixture is reformed under the action of Co@SiO2-1.5 catalyst to produce hydrogen, and the product syngas is obtained.

[0060] Furthermore, if no product synthesis gas is obtained in step S4, step S2 is omitted, and the raw material mixture obtained in step S1 is preheated in step S3; after step S4 is performed for the first time and product synthesis gas is obtained, the heat exchange medium is the product synthesis gas obtained in step S4.

[0061] S5. The product synthesis gas obtained in step S4 is used as a heat exchange medium and introduced into step S2 to exchange heat with the raw material mixture gas, so as to obtain the product synthesis gas and the raw material mixture gas after heat exchange.

[0062] S6. The heat-exchanged product synthesis gas is sequentially subjected to ethanol separation and carbon dioxide separation to obtain the target synthesis gas, and the separated ethanol and carbon dioxide are fed into step S1 for reuse.

[0063] This embodiment is used to implement the hydrogen production and product purification system based on ethanol-carbon dioxide reforming as described above. The system includes a continuous feeding unit, a heat exchange unit, a preheating unit, a reforming reaction unit, and a product separation unit.

[0064] The continuous feeding unit is used to prepare raw material mixed gas, including a first gasifier, a second gasifier, and a mixing device; the first gasifier is used to gasify liquid ethanol, and the second gasifier is used to gasify carbon dioxide; the outlets of the first gasifier and the second gasifier are both connected to the inlet of the mixing device, and the gasified ethanol and carbon dioxide gas are continuously fed into the mixing device for mixing to prepare raw material mixed gas.

[0065] The heat exchange unit is used to recover reaction heat energy and is equipped with a first flow channel and a second flow channel. The inlet of the first flow channel is connected to the outlet of the mixing device for continuous introduction of raw material mixed gas. The outlet of the first flow channel is connected to the inlet of the preheating unit. The inlet of the second flow channel is connected to the outlet of the reforming reaction unit for continuous introduction of product synthesis gas. The outlet of the second flow channel is connected to the inlet of the product separation unit to control the temperature of the raw material mixed gas after heat exchange to be lower than that of the reforming hydrogen production reaction in step S4. The temperature of the product synthesis gas after heat exchange is higher than that of the raw material mixed gas after heat exchange.

[0066] The inlet of the preheating unit is connected to the outlet of the first flow channel of the heat exchange unit, and the outlet is connected to the inlet of the reforming reaction unit, which is used to preheat the continuously introduced heat-exchanged raw material mixture.

[0067] The reforming reaction unit is filled with Co@SiO2-1.5 catalyst, which is used to reform the continuously introduced preheated feed gas mixture into hydrogen through ethanol and carbon dioxide reforming. The inlet receives the feed gas mixture from the preheating unit, and the outlet sends the product synthesis gas generated by the reaction to the inlet of the second flow channel of the heat exchange unit.

[0068] The product separation unit is used to separate and recover unreacted raw materials, including an ethanol separation unit and a carbon dioxide separation unit connected in sequence; the inlet of the ethanol separation unit is connected to the outlet of the second flow channel of the heat exchange unit, and is used to condense and separate unreacted ethanol; the carbon dioxide separation unit is used to separate unreacted carbon dioxide from the gas flow; the outlets of the ethanol separation unit and the carbon dioxide separation unit are connected to the inlets of the first gasifier and the second gasifier, respectively; the separated ethanol and carbon dioxide can be reused as raw materials.

[0069] The system is configured to run in two modes: Start-up mode: When there is no product synthesis gas in the system, the raw material mixed gas flows out from the mixing device and enters the preheating unit through the first flow channel of the heat exchange unit; Normal operating mode: When the system generates product synthesis gas, the raw material mixed gas flows out of the mixing device and exchanges heat with the product synthesis gas from the second flow channel in the first flow channel of the heat exchange unit, and then is preheated by the preheating unit.

[0070] The preheating unit is a preheating furnace.

[0071] The heat exchange unit is a shell-and-tube heat exchanger.

[0072] The reforming reaction unit is a reforming hydrogen production reactor, which uses a gas-solid reaction tower and a Co@SiO2-1.5 catalyst.

[0073] The ethanol separation unit is an air-cooled tower.

[0074] The carbon dioxide separation device is one of a cryogenic condenser, a membrane separation device, or an adsorption tower.

[0075] Table 1 Summary of reaction conditions for hydrogen production via ethanol / carbon dioxide EDR reforming

[0076] Table 2 Composition of Syngas from Products

[0077] Example 1 The ethanol / carbon dioxide EDR reforming reaction to produce hydrogen was carried out according to the reaction conditions in Table 1. The relevant test results are shown in Table 2. The H2 / CO ratio was approximately 1.11, the total conversion rate of ethanol and CO2 reached 95%, and the content of other gases was 5%.

[0078] Example 2 The ethanol / carbon dioxide EDR reforming reaction to produce hydrogen was carried out according to the reaction conditions in Table 1. The relevant test results are shown in Table 2. The H2 / CO ratio was approximately 1.09, the total conversion rate of ethanol and CO2 reached 98%, and the content of other gases was 2%.

[0079] Example 3 The ethanol / carbon dioxide EDR reforming reaction to produce hydrogen was carried out according to the reaction conditions in Table 1. The relevant test results are shown in Table 2. The H2 / CO ratio was approximately 1.07, the total conversion rate of ethanol and CO2 reached 95%, and the content of other gases was 5%.

[0080] Example 4 The ethanol / carbon dioxide EDR reforming reaction to produce hydrogen was carried out according to the reaction conditions in Table 1. The relevant test results are shown in Table 2. The H2 / CO ratio was approximately 1.07, the total conversion rate of ethanol and CO2 reached 93%, and the content of other gases was 7%.

[0081] Example 5 The ethanol / carbon dioxide EDR reforming reaction to produce hydrogen was carried out according to the reaction conditions in Table 1. The relevant test results are shown in Table 2. The H2 / CO ratio was approximately 1.02, the total conversion rate of ethanol and CO2 reached 89%, and the content of other gases was 11%.

[0082] Example 6 The ethanol / carbon dioxide EDR reforming reaction to produce hydrogen was carried out according to the reaction conditions in Table 1. The relevant test results are shown in Table 2. The H2 / CO ratio was approximately 1.02, the total conversion rate of ethanol and CO2 reached 89%, and the content of other gases was 11%.

[0083] Comparing Example 1 and Example 2, increasing the reaction temperature can improve the conversion rate of the target product, but the H2 / CO ratio decreases slightly.

[0084] Compared with Examples 2 to 4, the increase in space velocity reduced the conversion rate of the target product, but the H2 / CO ratio decreased slightly.

[0085] Comparing Example 1 and Example 5, excessively high reaction temperature reduces the conversion rate of the target product, but the H2 / CO ratio decreases slightly.

[0086] Comparing Examples 5 and 6, changes in other pretreatment conditions had little effect on the reaction.

[0087] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for hydrogen production and product purification based on ethanol-carbon dioxide reforming, characterized in that, The method includes the following steps: S1. Continuously add vaporized ethanol and carbon dioxide gas and mix them to obtain raw material mixture gas; S2. The raw material mixture is heated with the heat exchange medium to obtain the heated raw material mixture. S3. Preheat the heat-exchanged raw material mixture to obtain a preheated raw material mixture; S4. The preheated raw material mixture is reformed to produce hydrogen under the action of a combined oxidized Co@SiO2 eggshell nanoparticle catalyst to obtain product syngas. S5. The product synthesis gas obtained in step S4 is used as the heat exchange medium and introduced into step S2 to exchange heat with the raw material mixture gas, so as to obtain the product synthesis gas after heat exchange and the raw material mixture gas after heat exchange. S6. The heat-exchanged product synthesis gas is sequentially subjected to ethanol separation and carbon dioxide separation to obtain the target synthesis gas, and the separated ethanol and carbon dioxide are used as raw materials to be recycled in step S1. In the case where no product synthesis gas is obtained in step S4, step S2 is omitted, and the raw material mixture obtained in step S1 is preheated in step S3; after step S4 is performed for the first time and product synthesis gas is obtained, the heat exchange medium is the product synthesis gas obtained in step S4.

2. The method for hydrogen production and product purification based on ethanol-carbon dioxide reforming according to claim 1, characterized in that, In step S1, the molar ratio of the vaporized ethanol to carbon dioxide gas in the raw material mixture is (0.01~100):

1. In step S1, the mixing temperature is 80~850℃ and the pressure is 0.01~10MPa; In step S1, the preparation conditions for the vaporized ethanol are: the vaporization temperature is 80~120℃ and the vaporization pressure is 0.1~1.0MPa.

3. The method for hydrogen production and product purification based on ethanol-carbon dioxide reforming according to claim 1, characterized in that, In step S2, the heat exchange is gas-to-gas heat exchange; In step S2, the temperature of the heat-exchanged raw material mixture is lower than the reforming hydrogen production reaction temperature in step S4.

4. The method for hydrogen production and product purification based on ethanol-carbon dioxide reforming according to claim 1, characterized in that, In step S3, the temperature of the preheated raw material mixture is the same as the temperature of the reforming hydrogen production reaction in step S4.

5. The method for hydrogen production and product purification based on ethanol-carbon dioxide reforming according to claim 1, characterized in that, In step S4, the conditions for the reforming hydrogen production reaction are: reaction temperature of 300~1200℃, reaction pressure of 0.01~10MPa, and space velocity of 10~1000 / h. In step S4, the combined oxidized Co@SiO2 eggshell-shaped nanoparticle catalyst includes cobalt oxide nanoparticles and a mesoporous silica coating layer covering the surface of the cobalt oxide nanoparticles; the cobalt ions in the cobalt oxide nanoparticles exist in the form of divalent cobalt and trivalent cobalt. In step S4, the product synthesis gas is a reforming product synthesis gas containing hydrogen, carbon monoxide, unreacted carbon dioxide, unreacted ethanol, and byproducts.

6. The method for hydrogen production and product purification based on ethanol-carbon dioxide reforming according to claim 1, characterized in that, In step S5, the temperature of the product synthesis gas after heat exchange is higher than the temperature of the raw material mixture gas after heat exchange.

7. The method for hydrogen production and product purification based on ethanol-carbon dioxide reforming according to claim 1, characterized in that, Step S6: The ethanol separation uses an air-cooled tower for air-cooled heat exchange, with a cooling temperature below 80°C, so that the gaseous ethanol is condensed into liquid and separated for reuse. In step S6, the carbon dioxide separation adopts low-temperature condensation, with a condensation temperature below -70°C, so that the carbon dioxide can be liquefied and reused as raw material. In step S6, the volume ratio of hydrogen to carbon monoxide in the target synthesis gas is 1.0 to 1.

2. The target synthesis gas mainly contains hydrogen and carbon monoxide.

8. The method for hydrogen production and product purification based on ethanol-carbon dioxide reforming according to claim 1, characterized in that, In step S6, the carbon dioxide separation is performed using a polyimide / mixed matrix membrane separation method or a solid adsorption method.

9. A hydrogen production and product purification system based on ethanol-carbon dioxide reforming for implementing the method as described in any one of claims 1-8, characterized in that, The system includes a continuous feeding unit, a heat exchange unit, a preheating unit, a reforming reaction unit, and a product separation unit; The continuous feeding unit is used to prepare the raw material mixture gas, including a first gasifier, a second gasifier, and a mixing device; the first gasifier is used to gasify liquid ethanol, and the second gasifier is used to gasify carbon dioxide; the outlets of the first gasifier and the second gasifier are both connected to the inlet of the mixing device, and the gasified ethanol and carbon dioxide gas are continuously fed into the mixing device for mixing to prepare the raw material mixture gas; The heat exchange unit is used to recover reaction heat energy and is provided with a first flow channel and a second flow channel; the inlet of the first flow channel is connected to the outlet of the mixing device for continuous introduction of raw material mixed gas; the outlet of the first flow channel is connected to the inlet of the preheating unit; the inlet of the second flow channel is connected to the outlet of the reforming reaction unit for continuous introduction of product synthesis gas; the outlet of the second flow channel is connected to the inlet of the product separation unit. The inlet of the preheating unit is connected to the outlet of the first flow channel of the heat exchange unit, and the outlet is connected to the inlet of the reforming reaction unit, for preheating the continuously introduced heat-exchanged raw material mixture. The reforming reaction unit is filled with a combined oxidized Co@SiO2 eggshell-shaped nanoparticle catalyst, which is used to reform the continuously introduced preheated raw material mixture into hydrogen through ethanol and carbon dioxide reforming. The inlet is used to continuously receive the raw material mixture from the preheating unit, and the outlet continuously sends the product synthesis gas generated by the reaction to the second flow channel inlet of the heat exchange unit. The product separation unit is used to separate and recover unreacted raw materials, including an ethanol separation unit and a carbon dioxide separation unit connected in sequence; the inlet of the ethanol separation unit is connected to the outlet of the second flow channel of the heat exchange unit, and is used to condense and separate unreacted ethanol; the carbon dioxide separation unit is used to separate unreacted carbon dioxide from the gas flow; the outlets of the ethanol separation unit and the carbon dioxide separation unit are respectively connected to the inlets of the first gasifier and the second gasifier; the separated ethanol and carbon dioxide can be reused as raw materials; The system is configured to operate in two modes: Start-up mode: When there is no product synthesis gas in the system, the raw material mixed gas flows out from the mixing device and enters the preheating unit through the first flow channel of the heat exchange unit; Normal operating mode: When the system generates product synthesis gas, the raw material mixed gas flows out of the mixing device and exchanges heat with the product synthesis gas from the second channel in the first channel of the heat exchange unit, and then is preheated by the preheating unit.

10. The application of a target syngas prepared by the method of any one of claims 1-8, or the target syngas obtained by the system of claim 9, as a feedstock gas in a Fischer-Tropsch reaction.

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