Method and system for preparing green methanol from biomass
The synthesis of methanol from carbon monoxide and hydrogen through biomass fermentation and plasma catalytic conversion solves the problems of high energy consumption and low utilization rate in existing green methanol production, achieving efficient and low-cost green methanol production and promoting the full carbon utilization and economic benefits of biomass resources.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA ENERGY INVESTMENT CORP LTD
- Filing Date
- 2024-10-18
- Publication Date
- 2026-04-21
AI Technical Summary
Existing green methanol production technologies suffer from problems such as high energy consumption, low utilization of biomass fermentation products, and high costs, making industrialization difficult.
Biogas and biogas residue are produced by biomass fermentation. The biogas residue and carbon dioxide are converted into carbon monoxide through plasma catalytic conversion reaction. After being mixed with externally supplied hydrogen, methanol is synthesized under the action of a methanol synthesis catalyst. Plasma catalysts such as cerium oxide and zirconium oxide are used for catalysis. Hydrogen is produced by electrolysis of water using renewable energy power generation.
This approach achieves efficient utilization of carbon dioxide, avoids emissions, reduces energy consumption, and improves economic efficiency. The synthesized methanol can be used in the production of chemical products, reducing waste and increasing the utilization rate of biomass resources.
Smart Images
Figure CN121895119A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the fields of comprehensive utilization of biomass and methanol production technology, specifically, to a method and system for producing green methanol from biomass. Background Technology
[0002] In recent years, biomass liquid fuels, with their excellent carbon reduction properties, have attracted much attention. In particular, green methanol fuel has suddenly become a hot topic, igniting the global investment market, and the development prospects of green methanol production capacity are promising.
[0003] Biomass resources are abundant, and developing biomass-to-methanol liquid fuel technology is not only beneficial to the environment but also an important way to ensure sustainable development. Currently, there are three main technological routes for green methanol production: biomass-to-methane, biogasification, and electro-methanol. Constrained by factors such as storage radius and business models, the large-scale supply of biomass raw materials is unsustainable. Given the relatively low demand for green methanol, the biomass-to-methane and biomass gasification routes have a significant cost advantage and lower industry barriers compared to electro-methanol. The biomass-to-methane route faces the problem of difficult waste disposal, while the biomass gasification route still has unresolved bottleneck technologies and lacks a mature methanol production process. Although the electro-methanol route has relatively mature technology, its cost is high due to the limited costs of carbon and hydrogen sources.
[0004] In 2023, the global annual methanol production capacity was approximately 180 million tons, of which green methanol production capacity was only 500,000 tons, accounting for less than 1%. However, due to factors such as raw materials, technological routes, production capacity, and product purity, the production cost of green methanol varies significantly. Statistics from publicly available project data show that the current average production cost of green methanol is far higher than that of fossil-based methanol, exceeding six times, and it lacks any price competitiveness. Therefore, existing technologies for producing green methanol still suffer from high energy consumption and low utilization of biomass fermentation products. Summary of the Invention
[0005] To address the problems existing in the prior art, this disclosure provides a method and system for producing green methanol from biomass. This method can utilize biomass fermentation products (carbon dioxide) and biogas residue, reduce greenhouse gas emissions, effectively reduce energy consumption, and has high economic benefits.
[0006] To achieve the above objectives, the first aspect of this disclosure provides a method for producing green methanol from biomass, the method comprising the following steps: S1. Anaerobic fermentation of biomass raw materials to obtain biogas and biogas residue; S2. The biogas is separated to obtain a first component containing methane and a second component containing carbon dioxide. S3. The biogas residue is fed into a plasma reactor, and the second component and / or externally supplied carbon dioxide are introduced to carry out a plasma catalytic conversion reaction. The reaction products are then subjected to gas-liquid separation treatment to obtain a third component containing carbon monoxide. S4. The third component is mixed with external hydrogen and then contacted with the methanol synthesis catalyst in the methanol synthesis device to carry out the methanol synthesis reaction.
[0007] Optionally, in step S1, the temperature of the anaerobic fermentation is 10-60℃; and the moisture content of the biogas residue is 0-10%.
[0008] Optionally, in step S3, in the plasma reactor, the volume of the second component or externally supplied carbon dioxide added relative to 1 kg of biogas residue is 5-10 Nm³. 3 The flow rate of the second component or externally supplied carbon dioxide is 30-200 mL / min; the conditions for the plasma catalytic conversion reaction include: controlling the wall temperature of the plasma reactor to 40-90℃ and controlling the pressure inside the plasma reactor to 100-500 kPa.
[0009] Optionally, in the plasma reactor, the power input is 10-100W, the input voltage is 10-24kV, the input current is 0.5-2A, and the discharge frequency is 0.8-20kHz; in the plasma catalytic conversion reaction, the plasma is selected from one or more of dielectric barrier discharge plasma, spark discharge plasma, sliding arc discharge plasma, microwave discharge plasma, and thermal plasma; the catalyst used in the plasma catalytic conversion reaction is selected from one or more of cerium oxide, zirconium oxide, silicon oxide, aluminum oxide, zinc oxide, iron oxide, titanium oxide, calcium oxide, magnesium oxide, barium oxide, strontium oxide, nickel oxide, copper oxide, and molecular sieves.
[0010] Optionally, in step S3, after the reaction products are subjected to gas-liquid separation, the separated gaseous products are further subjected to oxygen separation.
[0011] Optionally, in step S4, the molar ratio of carbon monoxide to externally supplied hydrogen in the third component is 1:(2-2.2).
[0012] Optionally, the conditions for the methanol synthesis reaction include a temperature of 200-300℃ and a pressure of 0.5-10 MPa; the methanol synthesis catalyst is a supported metal catalyst; wherein the support for the supported metal catalyst is selected from one or more of zinc oxide, alumina, zirconium dioxide, chromium trioxide, and indium oxide; and the active metal of the supported metal catalyst is selected from one or more of copper, palladium, ruthenium, and platinum.
[0013] Optionally, in step S4, the externally supplied hydrogen is green hydrogen; optionally, the externally supplied hydrogen comes from water electrolysis; wherein, the electrical energy for water electrolysis comes from renewable energy generation; preferably, the renewable energy generation is photovoltaic power generation or wind power generation.
[0014] The second aspect of this disclosure provides a system applicable to the method described in the first aspect, the system comprising: an anaerobic fermentation apparatus, a separation and processing apparatus, a plasma reactor, a gas-liquid separation apparatus, a syngas mixing apparatus, and a methanol synthesis apparatus; The biogas outlet of the anaerobic fermentation device is connected to the biogas inlet of the first separation and treatment device, the biogas residue outlet of the anaerobic fermentation device is connected to the biogas residue inlet of the plasma reactor, the second component outlet of the separation and treatment device is connected to the second component inlet of the plasma reactor, and the reaction product outlet of the plasma reactor is connected to the reaction product inlet of the gas-liquid separation device. The syngas mixing device includes a third component inlet, a hydrogen inlet, and a syngas outlet; the gas outlet of the gas-liquid separation device is connected to the third component inlet of the syngas mixing device, and the syngas outlet is connected to the syngas inlet of the methanol synthesis device.
[0015] Optionally, the system further includes a water electrolysis device, wherein the external hydrogen outlet of the water electrolysis device is connected to the external hydrogen inlet of the syngas mixing device; optionally, an oxygen separation device is also provided between the gas-liquid separation device and the syngas mixing device.
[0016] Through the above technical solution, this disclosure utilizes the residual residue from biomass fermentation to produce natural gas and a second component containing carbon dioxide as raw materials. Under the action of plasma, the residue and carbon dioxide are decomposed to generate a third component containing carbon monoxide. The carbon monoxide in the third component reacts with hydrogen to synthesize methanol. This method achieves the utilization of carbon dioxide, avoiding the pollution caused by carbon dioxide emissions into the atmosphere. Simultaneously, it can synthesize methanol, which can be used as a raw material to produce other related green chemical products, such as jet fuel, gasoline, diesel, olefins, and plastics, thereby improving economic efficiency. This method not only achieves the utilization of all carbon but also generates no other waste gases or solid waste.
[0017] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description
[0018] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings: Figure 1This is a process flow diagram of methanol preparation according to Example 1 of this disclosure.
[0019] Figure 2 This is a process flow diagram of methanol preparation according to Comparative Example 1 of this disclosure. Detailed Implementation
[0020] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.
[0021] The first aspect of this disclosure provides a method for producing green methanol from biomass, the method comprising the following steps: S1. Anaerobic fermentation of biomass raw materials to obtain biogas and biogas residue; S2. The biogas is separated to obtain a first component containing methane and a second component containing carbon dioxide. S3. The biogas residue is fed into a plasma reactor, and the second component and / or externally supplied carbon dioxide are introduced to carry out a plasma catalytic conversion reaction. The reaction products are then subjected to gas-liquid separation treatment to obtain a third component containing carbon monoxide. S4. The third component is mixed with externally supplied hydrogen and then contacted with the methanol synthesis catalyst in the methanol synthesis unit to carry out the methanol synthesis reaction.
[0022] In the process of producing natural gas through anaerobic fermentation of biomass feedstock, biogas containing methane and carbon dioxide is generated, with the first component containing methane serving as a natural gas product. Existing processes often treat the carbon dioxide emissions. In this disclosure, the residual residue from biomass fermentation for natural gas production and the second component containing carbon dioxide are used as raw materials. Under plasma irradiation, the residue and carbon dioxide are decomposed to generate a third component containing carbon monoxide. The carbon monoxide in the third component reacts with hydrogen to synthesize methanol. This method utilizes both carbon dioxide and biogas residue, avoiding the pollution caused by carbon dioxide emissions into the atmosphere. Simultaneously, it can synthesize methanol, which can be used as a raw material to produce other related green chemical products, such as jet fuel, gasoline, diesel, olefins, and plastics, thereby improving economic efficiency. This method not only achieves full carbon utilization but also generates no other waste gases or solid waste.
[0023] In this disclosure, the "separation process" can employ methods conventionally used in the art, such as physicochemical adsorption, pressure swing adsorption, membrane separation, and low-temperature separation.
[0024] In this disclosure, the anaerobic fermentation of biomass feedstock can be carried out using apparatus and methods conventionally employed by those skilled in the art, which will not be elaborated upon here. The biomass feedstock can include naturally occurring biomass, biomass generated during human production activities, and biomass excrement that can be utilized. Examples include forestry biomass (flower and tree pruning materials), agricultural biomass (grain and straw), and aquatic and terrestrial grasses; organic waste from wastewater and sewage; solid waste from domestic (including used clothing and bedding), fisheries, and catering; commercial and service industry waste; and a small amount of construction waste; and livestock and poultry manure.
[0025] In one embodiment of this disclosure, in step S1, the temperature of the anaerobic fermentation is 10-60°C; preferably 20-50°C. When the temperature of the anaerobic fermentation is within the range of the above embodiment, the methane yield can be increased.
[0026] In one embodiment of this disclosure, the moisture content of the biogas residue is 0-10%.
[0027] In one embodiment of this disclosure, in step S3, the volume of the second component or externally supplied carbon dioxide added to the plasma reactor is 5-10 Nm³ relative to 1 kg of biogas residue. 3 The preferred value is 5.76 Nm. 3 To further promote the conversion of biogas residue and carbon dioxide into carbon monoxide, the flow rate of the second component or externally supplied carbon dioxide can be 30-200 mL / min.
[0028] In this disclosure, the amount of the second gas containing carbon dioxide separated from the biogas may not be sufficient to convert all the biogas residue into carbon monoxide. That is, there may be a residue remaining. In this case, external carbon dioxide can be used. The external carbon dioxide can be carbon dioxide separated from other waste gases. The use of external carbon dioxide can further reduce carbon dioxide emissions.
[0029] In one embodiment of this disclosure, the conditions for the plasma catalytic conversion reaction include: controlling the wall temperature of the plasma reactor to 40-90°C, preferably 60°C; and controlling the pressure inside the plasma reactor to 100-500 kPa, preferably 100 kPa. In the above embodiment, the co-conversion of biogas residue and carbon dioxide into carbon monoxide can be further promoted, while simultaneously promoting the reaction of oxygen with carbon and hydrogen in the biogas residue to generate carbon monoxide and water, respectively. Furthermore, if the temperature generated by the plasma is too high, it can be cooled externally using a cooling medium, with the wall temperature of the plasma reactor being 40-90°C; the cooling medium can be tap water.
[0030] In this disclosure, the third component containing carbon monoxide can be used in subsequent steps to synthesize methanol. Since carbon monoxide is an important chemical raw material, it can also be collected and sold as a product, or used as a raw material to produce other related green chemical products, such as ethanol, olefins, plastics, jet fuel, gasoline, diesel, and fertilizers. Furthermore, carbon monoxide can be applied in industries such as steelmaking and metal smelting, further improving economic efficiency. In addition, this disclosure avoids the use of existing technologies such as coal gasification and natural gas steam reforming to produce carbon monoxide and hydrogen, effectively reducing energy consumption.
[0031] In one embodiment of this disclosure, the input power of the power source in the plasma reactor is 10-100W, the input voltage is 10-24V, the input current is 0.5-2A, and the discharge frequency is 0.8-20kHz. Under the conditions of the above embodiment, the conversion and synergistic conversion of biogas residue and carbon dioxide can be further promoted.
[0032] In one embodiment of this disclosure, in the plasma catalytic conversion reaction, the plasma may be selected from one or more of dielectric barrier discharge plasma, spark discharge plasma, sliding arc discharge plasma, microwave discharge plasma, and thermal plasma.
[0033] The plasma catalytic conversion reaction disclosed herein requires the use of a catalyst. In one embodiment of this disclosure, the catalyst used in the plasma catalytic conversion reaction is selected from one or more of cerium oxide, zirconium oxide, silicon oxide, aluminum oxide, zinc oxide, iron oxide, titanium oxide, calcium oxide, magnesium oxide, barium oxide, strontium oxide, nickel oxide, copper oxide, and molecular sieves.
[0034] In this disclosure, the gaseous products obtained after the plasma conversion reaction and the separation treatment in the enterprise may still contain oxygen. Therefore, in step S3, after the reaction products are subjected to gas-liquid separation treatment, the separated gaseous products are further subjected to oxygen separation treatment; otherwise, carbon monoxide cannot be used.
[0035] In one embodiment of this disclosure, in step S4, the molar ratio of carbon monoxide to externally supplied hydrogen in the third component is 1:(2-2.2).
[0036] In one embodiment of this disclosure, the conditions for the methanol synthesis reaction include a temperature of 200-300°C and a pressure of 0.5-10 MPa; under the conditions of the above embodiment, the yield of methanol can be further increased.
[0037] In one embodiment of this disclosure, the methanol synthesis catalyst is a supported metal catalyst; wherein the support for the supported metal catalyst is selected from one or more of zinc oxide, alumina, zirconium dioxide, chromium trioxide and indium oxide; and the active metal of the supported metal catalyst is selected from one or more of copper, palladium, ruthenium and platinum.
[0038] The externally supplied hydrogen in this disclosure is green hydrogen. In one embodiment of this disclosure, in step S4, the hydrogen comes from water electrolysis; wherein the electrical energy of the water electrolysis comes from renewable energy power generation; preferably, the renewable energy power generation is photovoltaic power generation or wind power generation. The hydrogen production through water electrolysis can be alkaline water electrolysis, proton exchange membrane water electrolysis, or anion exchange membrane water electrolysis.
[0039] The second aspect of this disclosure provides a system applicable to the method described in the first aspect, the system comprising: an anaerobic fermentation apparatus, a separation and processing apparatus, a plasma reactor, a gas-liquid separation apparatus, a syngas mixing apparatus, and a methanol synthesis apparatus; The biogas outlet of the anaerobic fermentation device is connected to the biogas inlet of the first separation and treatment device, the biogas residue outlet of the anaerobic fermentation device is connected to the biogas residue inlet of the plasma reactor, the second component outlet of the separation and treatment device is connected to the second component inlet of the plasma reactor, and the reaction product outlet of the plasma reactor is connected to the reaction product inlet of the gas-liquid separation device. The syngas mixing device includes a third component inlet, an external hydrogen supply inlet, and a syngas outlet; the gas outlet of the gas-liquid separation device is connected to the third component inlet of the syngas mixing device, and the syngas outlet is connected to the syngas inlet of the methanol synthesis device.
[0040] The methanol synthesis reaction disclosed herein is carried out in a methanol synthesis reactor, which is provided with multiple catalyst beds for loading metal catalysts supported on a carrier.
[0041] In one embodiment of this disclosure, the system further includes a water electrolysis device, wherein the external hydrogen outlet of the water electrolysis device is connected to the external hydrogen inlet of the syngas mixing device.
[0042] In a preferred embodiment of this disclosure, an oxygen separator is further provided between the gas-liquid separator and the syngas mixing device. When the gas at the outlet of the gas-liquid separator does not contain oxygen, the gas product enters the syngas mixing device as a third component. When the gas at the outlet of the gas-liquid separator contains oxygen, the gas product needs to enter the oxygen separator for oxygen separation treatment before the oxygen-separated gas product enters the syngas mixing device as a third component.
[0043] The present disclosure is further described in detail below through examples.
[0044] Example 1 The system settings used in this embodiment are as follows: Figure 1 As shown, the system includes: an anaerobic fermentation unit, a first separation and treatment unit, a plasma reactor, a gas-liquid separation unit, a syngas mixing unit, and a methanol synthesis unit; The biogas outlet of the anaerobic fermentation device is connected to the biogas inlet of the separation and treatment device, the biogas residue outlet of the anaerobic fermentation device is connected to the biogas residue inlet of the plasma reactor, the second component outlet of the separation and treatment device is connected to the second component inlet of the plasma reactor, and the reaction product outlet of the plasma reactor is connected to the reaction product inlet of the gas-liquid separation device. The syngas mixing unit includes a third component inlet, an external hydrogen supply inlet, and a syngas outlet; the gas outlet of the gas-liquid separation unit is connected to the third component inlet of the syngas mixing unit, and the syngas outlet is connected to the syngas inlet of the methanol synthesis unit.
[0045] The system also includes a water electrolysis unit, the hydrogen outlet of which is connected to the hydrogen inlet of the syngas mixing unit.
[0046] The method for preparing coal-to-natural gas using this system includes the following steps: 100 kg of raw material (air-dried straw: cow dung = 1:4.25) was anaerobic fermented at 30℃ for 15 days to produce biogas (2.9 Nm³). 3 ) and biogas residue (14.3 kg, moisture content 0%); The biogas is first separated by a methanol washing method to obtain a first component containing methane and a second component containing carbon dioxide. 0.5 kg of biogas residue was introduced into a plasma reactor (power input of 100 W, input voltage of 24 kV, input current of 1.2 A, discharge frequency of 7.2 kHz; dielectric barrier discharge plasma was used), and 2.88 Nm³ plasma was introduced at a flow rate of 40 mL / min. 3 The second component undergoes a plasma catalytic conversion reaction (wall temperature controlled at 60℃, pressure at 100kPa; catalyst is cerium oxide) to obtain a third component containing carbon monoxide. The third component is mixed with externally supplied hydrogen (the molar ratio of carbon monoxide in the third component to externally supplied hydrogen is 1:2) and then contacted with the methanol synthesis catalyst (a composite support of zinc oxide and aluminum oxide, with copper as the active metal) in the methanol synthesis unit to carry out the methanol synthesis reaction at 250°C and 9 MPa.
[0047] Example 2 The same system and method as in Example 1 are used, except that: 0.5 kg of biogas residue was introduced into a plasma reactor (power input: 100 W; voltage input: 24 kV; current input: 1.2 A; discharge frequency: 7.2 kHz; dielectric barrier discharge plasma was used), and 2.88 Nm³ plasma was introduced at a flow rate of 100 mL / min. 3 The second component undergoes a plasma catalytic conversion reaction (wall temperature controlled at 60℃, pressure at 500kPa; catalyst is cerium oxide) to obtain a third component containing carbon monoxide. The third component is mixed with externally supplied hydrogen (the molar ratio of carbon monoxide in the third component to externally supplied hydrogen is 1:2) and then contacted with the methanol synthesis catalyst (a composite support of zinc oxide and aluminum oxide, with copper as the active metal) in the methanol synthesis unit to carry out the methanol synthesis reaction at 250°C and 9 MPa.
[0048] Example 3 The same system and method as in Example 1 are used, except that: 0.5 kg of biogas residue was introduced into a plasma reactor (power input: 100 W; voltage input: 24 kV; current input: 1.2 A; discharge frequency: 7.2 kHz; dielectric barrier discharge plasma was used), and 2.88 Nm³ plasma was introduced at a flow rate of 200 mL / min. 3 The second component undergoes a plasma catalytic conversion reaction (wall temperature controlled at 60℃, pressure at 100kPa; catalyst is cerium oxide) to obtain a third component containing carbon monoxide; The third component is mixed with externally supplied hydrogen (the molar ratio of carbon monoxide in the third component to externally supplied hydrogen is 1:2) and then contacted with the methanol synthesis catalyst (a composite support of zinc oxide and aluminum oxide, with copper as the active metal) in the methanol synthesis unit to carry out the methanol synthesis reaction at 250°C and 9 MPa.
[0049] Comparative Example 1 The settings of this comparative system are as follows: Figure 2 As shown, the method for preparing coal-to-methanol using this system includes the following steps: 100 kg of raw material (air-dried straw: cow dung = 1:4.25) was anaerobic fermented at 30℃ for 15 days to obtain (2.9 Nm³). 3 Biogas and biogas residue (14.3 kg, 0% moisture content); The biogas is first separated by a methanol washing method to obtain a first component containing methane and a second component containing carbon dioxide. The second component is mixed with externally supplied hydrogen (the molar ratio of carbon dioxide in the second component to externally supplied hydrogen is 1:3) and then contacted with a methanol synthesis catalyst (a composite support of zinc oxide and aluminum oxide, with copper as the active metal) in a methanol synthesis unit to carry out the methanol synthesis reaction at 260°C and 9 MPa.
[0050] The first component is subjected to a steam reforming reaction to obtain a first syngas containing carbon monoxide and hydrogen. 14.3 kg of biogas residue was subjected to a gasification reaction to obtain a second syngas containing carbon monoxide and hydrogen; The first and second syngas are brought into contact with the methanol synthesis catalyst (a composite support of zinc oxide and alumina, with copper as the active metal) in the methanol synthesis unit, and the methanol synthesis reaction is carried out at 250°C and 9 MPa.
[0051] Compared to Comparative Example 1, Example 1 employed three methods for methanol synthesis: Method 1, methanol synthesis from carbon dioxide (i.e., electrochemical method), producing 4.1 L of methanol; Method 2, methanol synthesis from the first syngas obtained by steam reforming methane (i.e., natural gas reforming method), using 2.9 m³ of... 3 All natural gas products can be used to produce 3.6L of methanol; Method 3: Methanol is synthesized from the second syngas obtained by gasification reaction of biogas residue, also known as residue gasification method, and the methanol content produced is 5.4L.
[0052] Comparative Example 2 The same system and method as in Example 1 are used, except that: 0.5 kg of biogas residue was introduced into a plasma reactor (power input of 150 W, input voltage of 24 kV, input current of 0.8 A, discharge frequency of 7.2 kHz; dielectric barrier discharge plasma was used), and 2.88 Nm³ plasma was introduced at a flow rate of 40 mL / min. 3 The second component undergoes a plasma catalytic conversion reaction (wall temperature controlled at 60℃, pressure at 100kPa; catalyst is cerium oxide) to obtain a third component containing carbon monoxide. The third component is mixed with externally supplied hydrogen (the molar ratio of carbon monoxide in the third component to externally supplied hydrogen is 1:2) and then contacted with the methanol synthesis catalyst (a composite support of zinc oxide and aluminum oxide, with copper as the active metal) in the methanol synthesis unit to carry out the methanol synthesis reaction at 250°C and 9 MPa.
[0053] Comparative Example 3 The same system and method as in Example 1 are used, except that: 0.5 kg of biogas residue was introduced into a plasma reactor (power input of 100 W, input voltage of 24 kV, input current of 1.2 A, discharge frequency of 7.2 kHz; dielectric barrier discharge plasma was used), and 2.88 Nm³ plasma was introduced at a flow rate of 20 mL / min. 3 The second component undergoes a plasma catalytic conversion reaction (wall temperature controlled at 60℃, pressure at 100kPa; catalyst is cerium oxide) to obtain a third component containing carbon monoxide. The third component is mixed with externally supplied hydrogen (the molar ratio of carbon monoxide in the third component to externally supplied hydrogen is 1:2) and then contacted with the methanol synthesis catalyst (a composite support of zinc oxide and aluminum oxide, with copper as the active metal) in the methanol synthesis unit to carry out the methanol synthesis reaction at 250°C and 9 MPa.
[0054] Comparative Example 4 The same system and method as in Example 1 are used, except that: 0.5 kg of biogas residue was introduced into a plasma reactor (power input of 100 W, input voltage of 24 kV, input current of 1.2 A, discharge frequency of 7.2 kHz; dielectric barrier discharge plasma was used), and 2.88 Nm³ plasma was introduced at a flow rate of 40 mL / min. 3 The second component undergoes a plasma catalytic conversion reaction (wall temperature controlled at 100℃, pressure at 100kPa; catalyst is cerium oxide) to obtain a third component containing carbon monoxide. The third component is mixed with externally supplied hydrogen (the molar ratio of carbon monoxide in the third component to externally supplied hydrogen is 1:2) and then contacted with the methanol synthesis catalyst (a composite support of zinc oxide and aluminum oxide, with copper as the active metal) in the methanol synthesis unit to carry out the methanol synthesis reaction at 250°C and 9 MPa.
[0055] The results of Examples 1-3 and Comparative Examples 1-4 are shown in Table 1.
[0056] Table 1
[0057] As shown in Table 1, the total energy consumption of Comparative Example 1 is greater than that of Example 1. Furthermore, this disclosure uses only 0.5 kg of biogas residue to produce 7.9 L of methanol, which is greater than the methanol yield produced by gasifying 14.3 kg of residue in Comparative Example 1.
[0058] Compared with Comparative Example 2, the input power of the power source in Comparative Example 2 is not within the range of this disclosure. The methanol production of Example 1 is lower than that of Comparative Example 2, but the energy consumption of Example 1 is much lower than that of Comparative Example 2. Based on the above data, the methanol production efficiency is calculated, where the methanol production efficiency (L / Kwh) = methanol production / energy consumption. The methanol production efficiency of Example 1 is 7.9 / 13.3≈0.59L / Kwh, and the methanol production efficiency of Comparative Example 2 is 9.2 / 18.1≈0.51L / Kwh. It can be seen that the methanol production efficiency of Example 1 is higher than that of Comparative Example 2, which means that when the input power of the power source is within the range of this disclosure, the methanol production efficiency is higher.
[0059] Compared with Comparative Example 3, the flow rate of the second component in Comparative Example 3 is not within the range of this disclosure. The energy consumption of Example 1 and Comparative Example 3 is the same, but the methanol production of Example 1 is much higher than that of Comparative Example 3. That is, the methanol production efficiency of Example 1 is higher than that of Comparative Example 3, indicating that when the flow rate of the second component is within the range of this disclosure, the methanol production efficiency is higher.
[0060] Compared with Comparative Example 4, the wall temperature of the plasma reactor in Comparative Example 4 is not within the range of this disclosure. The energy consumption of Example 1 and Comparative Example 4 is similar, but the methanol yield of Example 1 is higher than that of Comparative Example 4, indicating that when the wall temperature of the plasma reactor is within the range of this disclosure, the methanol yield is higher.
[0061] Therefore, the green methanol method of the present invention is more economical.
[0062] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.
[0063] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.
[0064] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.
Claims
1. A method for producing green methanol from biomass, characterized in that, The method includes the following steps: S1. Anaerobic fermentation of biomass raw materials to obtain biogas and biogas residue; S2. The biogas is separated to obtain a first component containing methane and a second component containing carbon dioxide. S3. The biogas residue is fed into a plasma reactor, and the second component and / or externally supplied carbon dioxide are introduced to carry out a plasma catalytic conversion reaction. The reaction products are then subjected to gas-liquid separation treatment to obtain a third component containing carbon monoxide. S4. The third component is mixed with externally supplied hydrogen and then contacted with the methanol synthesis catalyst in the methanol synthesis unit to carry out the methanol synthesis reaction.
2. The method according to claim 1, wherein, In step S1, the temperature of the anaerobic fermentation is 10-60℃; The moisture content of the biogas residue is 0-10%.
3. The method according to claim 1, wherein, In step S3, in the plasma reactor, the volume of the second component or externally supplied carbon dioxide added relative to 1 kg of biogas residue is 5-10 Nm³. 3 ; The flow rate of the second component or externally supplied carbon dioxide is 30-200 mL / min; The conditions for the plasma catalytic conversion reaction include: controlling the wall temperature of the plasma reactor to 40-90℃ and controlling the pressure inside the plasma reactor to 100-500kPa.
4. The method according to claim 3, wherein, In the plasma reactor, the power supply has an input power of 10-100W, an input voltage of 10-24kV, an input current of 0.5-2A, and a discharge frequency of 0.8-20kHz. In the plasma catalytic conversion reaction, the plasma is selected from one or more of dielectric barrier discharge plasma, spark discharge plasma, sliding arc discharge plasma, microwave discharge plasma, and thermal plasma. The catalyst used in the plasma catalytic conversion reaction is selected from one or more of cerium oxide, zirconium oxide, silicon oxide, aluminum oxide, zinc oxide, iron oxide, titanium oxide, calcium oxide, magnesium oxide, barium oxide, strontium oxide, nickel oxide, copper oxide, and molecular sieves.
5. The method according to claim 1, wherein, In step S3, after the reaction products are subjected to gas-liquid separation, the separated gaseous products are further subjected to oxygen separation.
6. The method according to claim 1, wherein, In step S4, the molar ratio of carbon monoxide to externally supplied hydrogen in the third component is 1:(2-2.2).
7. The method according to claim 6, wherein, The conditions for the methanol synthesis reaction include a temperature of 200-300℃ and a pressure of 0.5-10 MPa. The methanol synthesis catalyst is a supported metal catalyst; wherein the support for the supported metal catalyst is selected from one or more of zinc oxide, alumina, zirconium dioxide, chromium trioxide and indium oxide; and the active metal of the supported metal catalyst is selected from one or more of copper, palladium, ruthenium and platinum.
8. The method according to claim 1, wherein, In step S4, the externally supplied hydrogen is green hydrogen; Optionally, the externally supplied hydrogen comes from water electrolysis; wherein the electricity for water electrolysis comes from renewable energy generation. Preferably, the renewable energy power generation is photovoltaic power generation or wind power generation.
9. A system applicable to the method of any one of claims 1-8, characterized in that, The system includes: an anaerobic fermentation unit, a separation and treatment unit, a plasma reactor, a gas-liquid separation unit, a syngas mixing unit, and a methanol synthesis unit; The biogas outlet of the anaerobic fermentation device is connected to the biogas inlet of the first separation and treatment device, the biogas residue outlet of the anaerobic fermentation device is connected to the biogas residue inlet of the plasma reactor, the second component outlet of the separation and treatment device is connected to the second component inlet of the plasma reactor, and the reaction product outlet of the plasma reactor is connected to the reaction product inlet of the gas-liquid separation device. The syngas mixing device includes a third component inlet, an external hydrogen supply inlet, and a syngas outlet; the gas outlet of the gas-liquid separation device is connected to the third component inlet of the syngas mixing device, and the syngas outlet is connected to the syngas inlet of the methanol synthesis device.
10. The system according to claim 9, wherein, The system also includes a water electrolysis device, wherein the external hydrogen supply outlet of the water electrolysis device is connected to the external hydrogen supply inlet of the syngas mixing device; Optionally, an oxygen separation device is also provided between the gas-liquid separation device and the syngas mixing device.