Process for the production of green methanol by fermentation of biomass

Abstract

The application discloses a biomass fermentation process for preparing green methanol, which comprises the following steps: providing a biomass raw material, and fermenting to obtain biogas; obtaining rich-methane gas after crude purification of the biogas; obtaining qualified rich-methane gas after super-precision detoxification of the rich-methane gas; adding medium-pressure steam into the qualified rich-methane gas, and performing a methane steam reforming reaction to obtain a mixed gas; performing PSA treatment on the mixed gas to obtain a resolved gas and a raw material gas; and feeding the resolved gas into a normal-temperature catalytic heat exchange system, and taking the raw material gas as one of raw materials for methanol synthesis to prepare refined methanol. The application realizes full-chain coupling and efficient utilization, combines biomass fermentation, biogas purification and methane steam reforming, and adopts a CO2 circulation technology. The application realizes full-process energy integration: the waste heat in the fermentation process, the waste heat of the PSA resolved gas and the waste water of rectification are utilized to drive the methane steam reforming reaction, the system energy consumption is reduced, and the economic efficiency and sustainability of the system are further improved.

Description

Technical Field

[0001] This application relates to the field of biomass energy conversion technology, and in particular to a process for producing green methanol from biomass fermentation. Background Technology

[0002] Biomass energy, as the only renewable carbon source, plays a crucial role in replacing fossil fuels and achieving a closed carbon cycle through its efficient conversion and high-value utilization. Biomass biogas, an important biomass energy source, is currently mainly utilized for power generation or purification to produce biomethane. However, both pathways have significant bottlenecks: the energy conversion efficiency of power generation is typically below 40%, resulting in poor economic viability; and the complex impurities in biogas, such as hydrogen sulfide, chlorine, arsenic, and phosphorus, are difficult to treat, easily leading to catalyst poisoning and deactivation in subsequent hydrocarbon conversion and synthesis processes, severely impacting process stability and product purity.

[0003] Under current technological conditions, the potential of biogas as a chemical feedstock has not been fully realized, neither in terms of energy utilization efficiency nor material conversion value. In particular, the high cost and unsatisfactory results of impurity removal have become a key technological bottleneck restricting its high-value utilization. Green methanol, as an ideal liquid energy carrier and basic chemical feedstock, is easy to store and transport, and can be widely used in the synthesis of clean fuels, hydrogen energy carriers, and fine chemicals, offering significant carbon reduction benefits and market prospects. Therefore, developing a new process that can efficiently and cleanly convert biogas into green methanol, achieving synergistic impurity removal, long-term catalyst stability, and low-carbon operation throughout the entire process, has become an urgent need and an important research direction for promoting the upgrading and utilization of biomass resources and facilitating the green transformation of the energy and chemical industry. Summary of the Invention

[0004] In view of this, this application provides a process for producing green methanol from biomass fermentation, which aims to solve the problem that there is no efficient and pollution-free way to convert biogas into green methanol in the existing technology.

[0005] The embodiments of this application are implemented as follows: This invention provides a green methanol production process from biomass fermentation, comprising the following steps: S01. Provide biomass raw materials and ferment them to obtain biogas; SO2, methane-rich gas is obtained after the initial purification of biogas; SO3, ultra-fine detoxification of methane-rich gas to obtain qualified methane-rich gas; S04, qualified methane-rich gas, is then added with medium-pressure steam to carry out methane steam reforming reaction to obtain a mixed gas of hydrogen, carbon monoxide, carbon dioxide and methane. S05. Perform PSA treatment on the mixed gas to obtain desorbed gas and feed gas; S06. The desorbed gas enters the ambient temperature catalytic heat exchange system, and the feed gas is used as one of the raw materials for methanol synthesis to produce refined methanol.

[0006] In some embodiments, biomass feedstocks include agricultural biomass, forestry biomass, or human and animal excrement; and / or Biomass feedstock pretreatment, said pretreatment including adjusting the carbon-to-nitrogen ratio and pH value of the biomass feedstock; and / or The fermentation is a two-stage anaerobic fermentation, which includes a hydrolysis-acidification stage and a methanogenesis stage; and / or Biogas, by volume percentage, includes 60%~70% CH4, 25%~30% CO2, 0.1%~1% CO, total sulfur ≤200ppm, total chlorine ≤100ppm, total arsenic ≤20ppm, total phosphorus ≤20ppm, and the balance is N2.

[0007] In some embodiments, agricultural biomass includes one or more of straw, rice husks, corn cobs, sugarcane bagasse, and peanut shells; and / or Forestry biomass includes one or more of the following: branches, roots, sawdust, shavings, and wood chips; and / or Adjust the carbon-to-nitrogen ratio of the biomass feedstock to 25-30:1; and / or pH value is 6.8~7.5; and / or The temperature during the hydrolysis and acidification stage is 35℃~40℃; and / or The temperature for the methanogenesis stage is 55℃~60℃.

[0008] In some embodiments, biogas pre-purification includes wet decarbonization, pre-detoxification, and hydrorefining detoxification; and / or Ultra-precipitation of methane-rich gas reduced the levels of total sulfur, total chlorine, total arsenic, and total phosphorus to below 0.1 ppm; and / or The pressure of medium-pressure steam is 2.8 MPa to 3.8 MPa; and / or The temperature of medium-pressure steam is 229℃~248℃; and / or The qualified methane-rich gas is then mixed with medium-pressure steam and fed into the reformer, where it undergoes a methane steam reforming reaction under the action of catalyst a.

[0009] In some embodiments, wet decarbonization reduces CO2 in biogas to 1%–3%; and / or Crude detoxification and hydrogenation detoxification reduce the total sulfur, total chlorine, total arsenic and total phosphorus to 5 ppm to 10 ppm; and / or The catalyst a, by mass percentage, comprises 16%~17% NiO, 0.1%~0.2% CeO2, 82.4%~83.4% Al2O3, with the balance being MgO.

[0010] In some embodiments, the pressure of PSA processing is 2.0 MPa to 3.0 MPa; and / or The PSA treatment temperature is 30℃~50℃.

[0011] In some embodiments, the desorption gas, by volume percentage, comprises 38%–41% H2, 5%–10% CH4, 11%–13% CO, 35%–40% CO2, and the balance being N2; and / or The raw material gas, by volume percentage, includes a mixture of 81.3%~83.7% H2, 9.6%~12% CO and 4.3%~6.7% CO2, and the H:C ratio of the mixture is adjusted to 4.3:1~6:1.

[0012] In some embodiments, the desorbed gas enters a room-temperature catalytic heat exchange system, and boiler water is added to the system to generate low-pressure steam and compliant emission gas; and / or The feed gas undergoes a methanol synthesis reaction, producing medium-pressure steam and crude alcohol as products. Other alcohols, ethers, and methane are produced as byproducts, along with unreacted hydrogen and carbon monoxide. The crude alcohol is separated into methanol through a three-stage distillation process with a purity ≥99.5%. The unreacted gas is purge gas, one-third of which is used as one of the feedstocks for the methane steam reforming reaction. The distillation wastewater from the three-stage distillation process enters an ambient temperature catalytic heat exchange system. The remaining purge gas is directly combusted in the furnace to provide heat for the methane steam reforming.

[0013] In some embodiments, the purge gas, by volume percentage, comprises 1%–3% CH4, 88%–90% H2, 6%–8% CO, with the balance being CO2; and / or Distillation wastewater includes water, other alcohols, and ethers.

[0014] In some embodiments, crude alcohol comprises methanol and water; and / or Other alcohols include ethanol, propanol, butanol, and pentanol.

[0015] Beneficial effects: This application achieves full-chain coupling and efficient utilization: combining biomass fermentation, biogas purification and methane steam reforming, and adopting CO2 recycling technology (carbon conversion rate >90%). Specifically, 1 / 3 of the total purge gas volume is subjected to methane steam reforming reaction, and finally goes to methanol synthesis, realizing partial CO2 recycling, effectively achieving carbon neutrality, and improving energy conversion efficiency and economy.

[0016] This application achieves full-process energy integration: by utilizing the waste heat from the fermentation process, PSA desorption gas, and distillation wastewater, the methane steam reforming reaction is driven, reducing system energy consumption and further improving the system's economy and sustainability.

[0017] This application utilizes an innovative ultra-precise detoxification and decarbonization process to remove harmful impurities during biogas purification, significantly improving the stability of the catalytic reaction and the lifespan of the catalyst.

[0018] This application process generates no wastewater and ensures that the exhaust gas meets emission standards, thus achieving environmental friendliness.

[0019] This application, through efficient technological integration, specifically incorporates ambient temperature catalytic heat exchange technology into methanol synthesis. This improves the reuse of purge gas after three-stage distillation in the steam reforming stage, thereby enhancing methane conversion efficiency and creating technological synergy. This not only effectively improves the energy conversion rate of biomass resources but also solves the high carbon emission problem in traditional methanol production through green methanol synthesis, maximizing resource utilization, meeting sustainable development requirements, and possessing good economic viability and market prospects. Attached Figure Description

[0020] 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.

[0021] Figure 1 This is a flowchart of the biomass fermentation process for producing green methanol provided in the embodiments of this application. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Furthermore, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application.

[0023] In this application, and in the description thereof, the term "comprising" means "including but not limited to". The terms first, second, third, etc., are used merely as illustrative purposes and do not impose numerical requirements or establish an order.

[0024] In this application, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural.

[0025] In this application, "at least one" means one or more, and "more than one" means two or more. "One or more", "at least one of the following", or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0026] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0027] The technical solution of this application is as follows: This application provides a green methanol production process via biomass fermentation, including the following steps: S01. Provide biomass raw materials and ferment them to obtain biogas; SO2, methane-rich gas is obtained after the initial purification of biogas; SO3, ultra-fine detoxification of methane-rich gas to obtain qualified methane-rich gas; S04, qualified methane-rich gas, is then added with medium-pressure steam to carry out methane steam reforming reaction to obtain a mixed gas of hydrogen, carbon monoxide, carbon dioxide and methane. S05. Perform PSA treatment on the mixed gas to obtain desorbed gas and feed gas.

[0028] S06. The desorbed gas enters the ambient temperature catalytic heat exchange system, and the feed gas is used as one of the raw materials for methanol synthesis to produce refined methanol.

[0029] In S01: In some embodiments, the biomass feedstock includes agricultural biomass, forestry biomass, or human and animal excrement.

[0030] Furthermore, agricultural biomass includes one or more of the following: straw, rice husks, corn cobs, sugarcane bagasse, and peanut shells.

[0031] Furthermore, forestry biomass includes one or more of branches, roots, sawdust, shavings, and wood chips.

[0032] Furthermore, the biomass feedstock undergoes pretreatment, which includes adjusting the carbon-to-nitrogen ratio and pH value of the biomass feedstock.

[0033] Furthermore, the carbon-nitrogen ratio of the biomass feedstock can be adjusted to 25-30:1, for example, it can be 25:1, 26:1, 27:1, 28:1, 29:1, 30:1, etc.

[0034] Furthermore, the pH value is 6.8~7.5, for example, it can be 6.8, 6.9, 7, 7.1, 7.2, 7.3, 7.4, 7.5, etc.

[0035] In some embodiments, the fermentation is a two-stage anaerobic fermentation, which includes a hydrolysis-acidification stage and a methanogenesis stage.

[0036] It is understandable that the hydrolysis-acidification stage and the methanogenesis stage occur consecutively.

[0037] Furthermore, the temperature of the hydrolysis and acidification stage is 35℃~40℃, for example, it can be 35℃, 36℃, 37℃, 38℃, 39℃, 40℃, etc.

[0038] Furthermore, the temperature for the methanogenesis stage is 55℃~60℃, for example, it can be 55℃, 56℃, 57℃, 58℃, 59℃, 60℃, etc.

[0039] In some embodiments, the biogas, by volume percentage, comprises 60%~70% CH4, 25%~30% CO2, 0.1%~1% CO, total sulfur ≤200ppm, total chlorine ≤100ppm, total arsenic ≤20ppm, total phosphorus ≤20ppm, and the balance being N2.

[0040] Preferably, the biogas comprises, by volume percentage, 62%~68% CH4, 26%~28% CO2, 0.3%~0.8% CO, total sulfur ≤200ppm, total chlorine ≤100ppm, total arsenic ≤20ppm, total phosphorus ≤20ppm, and the balance being N2.

[0041] More preferably, the biogas, by volume percentage, comprises 65% methane, 28% CO2, 0.1%~1% CO, total sulfur ≤200ppm, total chlorine ≤100ppm, total arsenic ≤20ppm, total phosphorus ≤20ppm, and the balance being N2.

[0042] In S02: In some embodiments, biogas coarse purification includes wet decarbonization, coarse detoxification, and hydrogenation detoxification.

[0043] Furthermore, wet decarbonization reduces CO2 in biogas to 1%–3%.

[0044] Furthermore, crude detoxification and hydrogenation detoxification reduce the total sulfur, total chlorine, total arsenic and total phosphorus to 5 ppm to 10 ppm, for example, to 4 ppm, 5 ppm, 6 ppm, 7 ppm, 8 ppm, 9 ppm, 10 ppm, etc.

[0045] In S03: In some embodiments, the methane-rich gas is ultrapurely detoxified to reduce the content of total sulfur, total chlorine, total arsenic and total phosphorus to below 0.1 ppm.

[0046] In some embodiments, methane-rich gas passes through an ultra-fine detoxification reactor containing an SCST-304 catalyst. The sulfur, chlorine, arsenic, and phosphorus in the methane-rich gas react with the SCST-304 catalyst to generate copper sulfide, copper chloride, copper arsenide, and copper phosphide, which remain on the SCST-304 catalyst, reducing the total sulfur, total chlorine, total arsenic, and total phosphorus to below 0.1 ppm.

[0047] In S04: In some embodiments, the pressure of the medium-pressure steam is 2.8 MPa to 3.8 MPa, for example, it can be 2.8 MPa, 2.9 MPa, 3.0 MPa, 3.2 MPa, 3.5 MPa, 3.6 MPa, 3.8 MPa, etc.; In some embodiments, the temperature of the medium-pressure steam is 229°C to 248°C, for example, it can be 229°C, 230°C, 232°C, 235°C, 238°C, 240°C, 242°C, 245°C, 246°C, 248°C, etc.

[0048] In some embodiments, qualified methane-rich gas is added with medium-pressure steam and enters a reformer, where a methane steam reforming reaction occurs under the action of catalyst a.

[0049] It is understandable that in qualified methane-rich gas, methane reacts with water vapor as an oxidant to produce a mixture of hydrogen, carbon dioxide, and carbon monoxide. The reaction equation is as follows: CH4 + H2O → CO + 3H2- Q CH4 + 2H2O → CO2 + 4H2- Q CO + H2O → CO2 + H2 + Q It is understandable that the methane in the gas mixture is the methane that was not completely reacted.

[0050] Further, by mass percentage, the catalyst a comprises 16%~17% NiO, 0.1%~0.2% CeO2, 82.4%~83.4% Al2O3, and the balance is MgO.

[0051] It is understood that the preparation method of catalyst a is well known in the art and will not be described in detail here.

[0052] In S05: In some embodiments, the pressure of PSA processing is 2.0 MPa to 3.0 MPa, for example, it can be 2.0 MPa, 2.2 MPa, 2.5 MPa, 2.6 MPa, 2.8 MPa, 3.0 MPa, etc.

[0053] In some embodiments, the temperature for PSA processing is 30°C to 50°C, for example, 30°C, 35°C, 40°C, 45°C, 50°C, etc.

[0054] It is understandable that PSA treatment is divided into decarbonization and hydrogen extraction. Decarbonization is the process of separating CO2 from the gas mixture, while hydrogen extraction is the process of separating CH4 from the decarbonized gas.

[0055] In some embodiments, the desorption gas, by volume percentage, comprises 38%~41% H2, 5%~10% CH4, 11%~13% CO, 35%~40% CO2, and the balance being N2.

[0056] In some embodiments, the feed gas, by volume percentage, comprises a mixture of 81.3% to 83.7% H2, 9.6% to 12% CO, and 4.3% to 6.7% CO2, and the H:C ratio of the mixture is adjusted to 4.3:1 to 6:1.

[0057] In S06: Furthermore, the desorbed gas enters the ambient temperature catalytic heat exchange system, and boiler water is added to the ambient temperature catalytic heat exchange system to generate low-pressure steam and compliant emission gas.

[0058] Furthermore, the feed gas undergoes a methanol synthesis reaction, producing medium-pressure steam and crude alcohol as products. Other alcohols, ethers, and methane are produced as byproducts, along with unreacted hydrogen and carbon monoxide. The crude alcohol is separated into methanol through a three-stage distillation process with a purity ≥99.5%. The unreacted gas is purge gas, of which 1 / 3 is used as one of the feedstocks for the methane steam reforming reaction. The distillation wastewater generated from the three-stage distillation enters an ambient temperature catalytic heat exchange system. The remaining purge gas is directly burned in the furnace to provide heat for the methane steam reforming.

[0059] It is understandable that the remaining purge gas goes to the furnace of the methane steam reforming reactor, where it is burned to provide heat for the methane steam reforming.

[0060] Furthermore, by volume percentage, the purge gas comprises 1%~3% CH4, 88%~90% H2, 6%~8% CO, with the balance being CO2.

[0061] Furthermore, crude alcohols include methanol and water.

[0062] Other alcohols include ethanol, propanol, butanol, and pentanol.

[0063] Distillation wastewater includes water, other alcohols (ethanol, propanol, butanol, pentanol) and ethers.

[0064] Methanol synthesis: Hydrogen, carbon monoxide, and carbon dioxide in the feed gas react with a methanol synthesis catalyst to produce methanol and water, with other alcohols as byproducts. The reaction formula is as follows: CO + 2H₂ → CH₄O₂ + Q CO2 + 3H2 → CH4O + H2O + Q Side reactions: CO + 3H₂ → CH₄ + H₂O + Q CO2 + 4H2 → CH4 + H2O + Q CH3OH + CO + 2H2 → C2H5OH + H2O + Q C2H5OH + CO + 2H2 → C3H7OH + H2O + Q 2CO + 4H2→ CH3OCH3 + H2O + Q In this application, the distillation wastewater generated during methanol synthesis is combined with the desorbed gas generated by PSA and then enters a room-temperature catalytic heat exchange system for reaction. No wastewater is generated after the reaction, and the energy consumption of the entire system can be saved.

[0065] Compared with the traditional one-stage or two-stage natural gas conversion process, this application adopts a one-stage conversion + partial purge gas reuse. Since the CH4 content in the purge gas is relatively high, sending it all to the furnace for combustion would result in a waste of effective CH4. In this application, the purge gas is mixed with the feed gas and then returned to the converter, which not only saves investment (the first stage is lower than the second stage, and only a specially designed pipeline mixer needs to be added), but also solves the problem of high energy consumption in the traditional one-stage furnace.

[0066] The innovative catalyst a (with the content of active component Ni increased by 0.5%~1%) in this application: Hydrogen helps methane dispersion, but dispersed methane reduces the adsorption partial pressure of the reaction. The catalyst contains 0.01~0.05% rare earth cerium, which has an affinity for methane, which improves the methane adsorption efficiency. At the same time, the more dispersed methane has a higher reaction efficiency.

[0067] The ambient temperature catalytic heat exchange system uses SCST-901F / 902F / 903F catalysts specially made by Shutai, which can process methane, hydrogen and CO in PSA decarbonization, generate low-grade heat and produce low-pressure steam.

[0068] Experimental Example 1 After preliminary purification of biogas, the resulting methane-rich gas contains CH4 (90-95%), CO2 (1-3%), CO (0.15-1.5%), N2 (0.15-1.5%), total sulfur (10 ppm), total chlorine (10 ppm), total arsenic (5 ppm), and total phosphorus (5 ppm). The methane-rich gas flow rate is set at 10 Nm³ / h, 15 Nm³ / h, and 20 Nm³ / h, with the inlet temperature controlled at 240-300℃ and the operating pressure set at 1.0 MPa and 2.0 MPa. After the reaction, the outlet gas shows a total sulfur content of 0.05-0.09 ppm, a total chlorine content of 0.06-0.1 ppm, and total arsenic and total phosphorus contents both <0.02 ppm.

[0069] Experimental Example 2 Simulated methane steam reforming reaction: Inlet gas composition: CH4: 22~25%, H2: 2~4%, CO2: 0.5~1%, CO: 0.3~0.6%, H2O: 71~74%, balance N2; flow rate controlled at 10 Nm³ / h, 20 Nm³ / h, 30 Nm³ / h; reaction temperature controlled at 650~900℃; reaction pressure at 2.0~3.0 MPa; dry gas composition after reaction: CH4: 1~3%, H2: 74~76%, CO: 11~13%, CO2: 10~12%, balance N2; methane conversion rate 90~95%.

[0070] Experimental Example 3 40%~42% H2, 8%~10% CH4, 10%~12% CO, 35%~38% CO2, and the balance being N2 are introduced into the ambient temperature catalytic heat exchange system at flow rates of 3 Nm / h, 5 Nm / h, and 10 Nm / h. Boiler water is also added to the ambient temperature catalytic heat exchange system, and all 40%~42% H2, 8%~10% CH4, and 10%~12% CO are converted into CO2 and H2O.

[0071] Test Example 4 Simulated full process: The raw material is 300 kg of wood chips, which are mixed with fermentation liquid (pretreatment) and fermented for about 20 days to obtain biogas components of: 64.5% CH4, 28.1% CO2, 0.5% CO, total sulfur 180 ppm, total chlorine 90 ppm, total arsenic 20 ppm, total phosphorus 20 ppm, and 6.869% N2.

[0072] The biogas flow rate is controlled at 10 Nm³ / h before entering the wet decarbonization system, where CO2 and N2 are absorbed to obtain 6.8031 Nm³ / h. Among them, CO2 is reduced to 2.94%, N2 is reduced to 1.47%, and other components are: 94.81% CH4, 0.735% CO, total sulfur 265 ppm, total chlorine 132 ppm, total arsenic 27 ppm, and total phosphorus 26 ppm.

[0073] After decarbonization, the biogas is heated and enters the coarse detoxification system, where it is mixed with 0.05 Nm³ of hydrogen and then undergoes a hydrogenation detoxification reaction. The total sulfur, total chlorine, total arsenic, and total phosphorus levels are reduced to 3.8 ppm, 0.8 ppm, 0.3 ppm, and 0.2 ppm, respectively. The remaining 6.8 Nm³ / h enters the ultra-fine detoxification system, where, under the action of the SCST-304 catalyst, the total sulfur, total chlorine, total arsenic, and total phosphorus react with the catalyst to produce copper sulfide, copper chloride, copper arsenide, and copper phosphide. At the outlet, the total sulfur, total chlorine, total arsenic, and total phosphorus levels are reduced to 0.05 ppm, 0.01 ppm, 0.01 ppm, and 0.01 ppm, respectively.

[0074] The detoxified methane-rich gas is mixed with 1 Nm³ / h of purge gas (2% CH4, 2% CO2, 7% CO, 89% H2) and 7 Nm³ / h of medium-pressure steam before entering the methane steam reforming reactor. The resulting dry gas contains 1.81% CH4, 75.82% H2, 11.06% CO, 10.96% CO2, and 0.35% N2. The gas flow rate at the PSA inlet to the methanol synthesis reactor is adjusted to 28.56 Nm³ / h, with concentrations of 83.76% H2, 10.86% CO, and 5.38% CO2. This gas then enters the methanol synthesis reactor and undergoes three distillations to obtain 3.74 kg / h of methanol (99.99%) and 19.79 Nm³ / h of purge gas (2% CH4, 2% CO2, 7% CO, 89% H2).

[0075] The PSA desorbed gas (9.776% CH4, 11.94% CO, 35.487% CO2, 1.889% N2, 40.907% H2) and the wastewater after distillation are sent to a catalytic heat exchange system, where they are completely converted into CO2 and H2O after reaction.

[0076] The above provides a detailed description of the biomass fermentation process for producing green methanol provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, those skilled in the art will recognize that there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A green methanol production process via biomass fermentation, characterized in that, Includes the following steps: S01. Provide biomass raw materials and ferment them to obtain biogas; SO2, methane-rich gas is obtained after the initial purification of biogas; SO3, ultra-fine detoxification of methane-rich gas to obtain qualified methane-rich gas; S04, qualified methane-rich gas, is then added with medium-pressure steam to carry out methane steam reforming reaction to obtain a mixed gas of hydrogen, carbon monoxide, carbon dioxide and methane. S05. Perform PSA treatment on the mixed gas to obtain desorbed gas and feed gas; S06. The desorbed gas enters the ambient temperature catalytic heat exchange system, and the feed gas is used as one of the raw materials for methanol synthesis to produce refined methanol.

2. The biomass fermentation process for producing green methanol according to claim 1, characterized in that, Biomass feedstocks include agricultural biomass, forestry biomass, or human and animal excrement; and / or Biomass feedstock pretreatment, said pretreatment including adjusting the carbon-to-nitrogen ratio and pH value of the biomass feedstock; and / or The fermentation is a two-stage anaerobic fermentation, which includes a hydrolysis-acidification stage and a methanogenesis stage; and / or Biogas, by volume percentage, includes 60%~70% CH4, 25%~30% CO2, 0.1%~1% CO, total sulfur ≤200ppm, total chlorine ≤100ppm, total arsenic ≤20ppm, total phosphorus ≤20ppm, and the balance is N2.

3. The biomass fermentation process for producing green methanol according to claim 2, characterized in that, Agricultural biomass includes one or more of the following: straw, rice husks, corn cobs, sugarcane bagasse, and peanut shells; and / or Forestry biomass includes one or more of the following: branches, roots, sawdust, shavings, and wood chips; and / or Adjust the carbon-to-nitrogen ratio of the biomass feedstock to 25-30:1; and / or pH value is 6.8~7.5; and / or The temperature during the hydrolysis and acidification stage is 35℃~40℃; and / or The temperature for the methanogenesis stage is 55℃~60℃.

4. The biomass fermentation process for producing green methanol according to claim 1, characterized in that, Biogas coarse purification includes wet decarbonization, coarse detoxification, and hydrorefining detoxification; and / or Ultra-precipitation of methane-rich gas reduced the levels of total sulfur, total chlorine, total arsenic, and total phosphorus to below 0.1 ppm; and / or The pressure of medium-pressure steam is 2.8 MPa to 3.8 MPa; and / or The temperature of medium-pressure steam is 229℃~248℃; and / or The qualified methane-rich gas is then mixed with medium-pressure steam and fed into the reformer, where it undergoes a methane steam reforming reaction under the action of catalyst a.

5. The biomass fermentation process for producing green methanol according to claim 4, characterized in that, Wet decarbonization reduces CO2 in biogas to 1%–3%; and / or Crude detoxification and hydrogenation detoxification reduce the total sulfur, total chlorine, total arsenic and total phosphorus to 5 ppm to 10 ppm; and / or The catalyst a, by mass percentage, comprises 16%~17% NiO, 0.1%~0.2% CeO2, 82.4%~83.4% Al2O3, with the balance being MgO.

6. The biomass fermentation process for producing green methanol according to claim 1, characterized in that, The PSA treatment pressure is 2.0 MPa to 3.0 MPa; and / or The PSA treatment temperature is 30℃~50℃.

7. The biomass fermentation process for producing green methanol according to claim 1, characterized in that, The desorption gas, by volume percentage, comprises 38%–41% H2, 5%–10% CH4, 11%–13% CO, 35%–40% CO2, with the balance being N2; and / or The raw material gas, by volume percentage, includes a mixture of 81.3%~83.7% H2, 9.6%~12% CO and 4.3%~6.7% CO2, and the H:C ratio of the mixture is adjusted to 4.3:1~6:

1.

8. The biomass fermentation process for producing green methanol according to claim 1, characterized in that, The desorbed gas enters the ambient temperature catalytic heat exchange system, and boiler water is added to the ambient temperature catalytic heat exchange system to generate low-pressure steam and emission gas that meets the standards. and / or The feed gas undergoes a methanol synthesis reaction, producing medium-pressure steam and crude alcohol as products. Other alcohols, ethers, and methane are produced as byproducts, along with unreacted hydrogen and carbon monoxide. The crude alcohol is separated into methanol through a three-stage distillation process with a purity ≥99.5%. The unreacted gas is purge gas, one-third of which is used as one of the feedstocks for the methane steam reforming reaction. The distillation wastewater from the three-stage distillation process enters an ambient temperature catalytic heat exchange system. The remaining purge gas is directly combusted in the furnace to provide heat for the methane steam reforming.

9. The biomass fermentation process for producing green methanol according to claim 8, characterized in that, By volume percentage, the purge gas comprises 1%–3% CH4, 88%–90% H2, 6%–8% CO, with the balance being CO2; and / or Distillation wastewater includes water, other alcohols, and ethers.

10. The biomass fermentation process for producing green methanol according to claim 8, characterized in that, Crude alcohols include methanol and water; and / or Other alcohols include ethanol, propanol, butanol, and pentanol.

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