Method for producing ethanol by taking bio-based acetic ether as green hydrogen receptor

Abstract

The invention discloses a method for producing ethanol by taking bio-based acetic ether as a green hydrogen receptor, and relates to the technical field of biomass energy chemical industry. The method provided by the invention at least comprises the following steps: adding green hydrogen and bio-ethyl acetate into a hydrogenation unit according to a molar ratio of (5-12): 1, and carrying out hydrogenation reaction to obtain a product containing bioethanol; adding the bioethanol-containing product into a separation unit, and carrying out gas-liquid separation to obtain a circulating gas component and a bioethanol-containing mixed solution; adding the mixed solution containing the bioethanol into a rectification unit, and rectifying to obtain a circulating liquid component and the bioethanol; and returning the circulating gas component and the circulating liquid component to the hydrogenation unit to participate in the hydrogenation reaction. The ethanol production method provided by the invention is continuous in process, low in consumption and environment-friendly, conforms to the dual-carbon strategy, can synchronously break the green hydrogen application bottleneck and the green ethanol supply demand, and has remarkable benefits.

Description

A method for producing ethanol using bio-based ethyl acetate as a green hydrogen acceptor Technical Field

[0001] This invention relates to the field of biomass energy chemical technology, specifically to a method for producing ethanol using bio-based ethyl acetate as a green hydrogen acceptor. Background Technology

[0002] Against the backdrop of the global "dual-carbon" strategy, green hydrogen, as a clean energy source produced by electrolyzing water from renewable energy sources such as photovoltaics and wind power, has become one of the core directions of energy transformation. However, my country's green hydrogen production capacity is mostly concentrated in regions such as the Northwest, which are rich in wind and solar power but have weak grid absorption capacity. The large-scale application of green hydrogen is limited by severe storage and transportation bottlenecks. Traditional high-pressure tank trucks pose safety hazards such as explosions and leaks when transporting hydrogen, and transportation costs increase significantly with distance. The transportation cost is about 8.9 yuan / kg for 100 kilometers and rises to 23.3 yuan / kg for 500 kilometers, far exceeding the affordability of end users. This makes it difficult to realize the economic value of hydrogen production from surplus wind and solar power. Local consumption of green hydrogen has become a key issue that the industry urgently needs to solve.

[0003] Meanwhile, as an important renewable fuel in the transportation sector, bioethanol is experiencing continuous market demand growth. However, existing bioethanol production processes are constrained by issues such as limited raw material availability and competition with human resources for food, making it difficult to meet market demand. On the other hand, bio-based ethyl acetate is widely available and has low production costs, but its low added value necessitates technological breakthroughs for high-value conversion.

[0004] Currently, there is no technological solution that combines on-site conversion of green hydrogen with high-value utilization of bio-based ethyl acetate. There is also no research on using bio-based ethyl acetate as a green hydrogen acceptor for green hydrogen transport and storage. This results in the inability to address three major industry problems in a coordinated manner: the challenges of green hydrogen storage and transportation, the production capacity gap of bioethanol, and the low added value of bio-based ethyl acetate. Although some technologies have attempted ester hydrogenation to alcohol production, none have been designed for on-site green hydrogen consumption scenarios, nor have they achieved closed-loop recycling and continuous production of raw materials. These technologies suffer from low material utilization, high energy consumption, and insufficient product purity, failing to meet the industrial needs of areas rich in wind and solar energy. Summary of the Invention

[0005] The purpose of this invention is to provide a method for producing ethanol using bio-based ethyl acetate as a green hydrogen acceptor, thereby solving the following technical problems:

[0006] Existing methods for producing bioethanol suffer from problems such as difficulties in storing and transporting green hydrogen, poor utilization of surplus wind / solar power, and low added value of bio-based ethyl acetate.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A method for producing ethanol using bio-based ethyl acetate as a green hydrogen acceptor, comprising at least the following steps:

[0009] Green hydrogen and bio-based ethyl acetate were added to the hydrogenation unit in a molar ratio of 5-12:1. After the hydrogenation reaction, a product containing bioethanol was obtained.

[0010] The bioethanol-containing product is added to the separation unit, and after gas-liquid separation, a circulating gas component and a mixture containing bioethanol are obtained.

[0011] The mixture containing bioethanol is added to a distillation unit, and after distillation, a circulating liquid component and bioethanol are obtained; and

[0012] The circulating gas component and the circulating liquid component are returned to the hydrogenation unit to participate in the hydrogenation reaction.

[0013] As a further aspect of the present invention: the circulating gas component is unreacted green hydrogen, and the circulating liquid component includes 65-75 wt% unreacted bio-based ethyl acetate and 25-35 wt% bioethanol.

[0014] As a further aspect of the present invention: the temperature of the hydrogenation reaction is 200-300℃, the pressure is 3-6MPa, the liquid hourly space velocity is 0.6-2.2h-1, and the catalyst is a copper-zinc-aluminum composite catalyst.

[0015] As a further aspect of the present invention: the green hydrogen is produced by electrolysis of water driven by photovoltaic power or wind power alone or in combination, and the purity of the green hydrogen is ≥99.9% and the moisture content is ≤10ppm; the bio-based ethyl acetate is produced by green bio-based raw materials through thermochemical conversion, chemical fermentation or electrochemical methods, and the purity of the green bio-based raw materials is ≥99.0%.

[0016] As a further aspect of the present invention: the bio-based ethyl acetate is transported to the water electrolysis hydrogen production site via conventional liquid transportation methods, and the green hydrogen is obtained at the water electrolysis hydrogen production site.

[0017] As a further aspect of the present invention: the pressure of the gas-liquid separation is 1-3 MPa and the temperature is 10-30℃.

[0018] As a further aspect of the present invention: the distillation unit is a distillation column, the top temperature of the distillation column is 71-73℃, the bottom temperature is 77-78℃, and the purity of the bioethanol is ≥99.5%.

[0019] As a further aspect of the present invention: the bioethanol is drawn from the bottom of the distillation column, and the circulating liquid component is drawn from the top of the distillation column.

[0020] As a further aspect of the present invention: the conversion rate of the bio-based ethyl acetate is at least 90%, the utilization rate of the green hydrogen is at least 95%, and the utilization rates of the circulating liquid component and the circulating gas component are at least 95%.

[0021] The beneficial effects of this invention are:

[0022] This invention provides a method for producing green bioethanol using bio-based ethyl acetate as a green hydrogen acceptor. By using bio-based ethyl acetate as a green hydrogen acceptor, liquid bio-based ethyl acetate is transported to the green hydrogen production site for on-site hydrogenation. Green hydrogen does not require long-distance storage and transportation, completely avoiding the safety hazards and high costs of transporting hydrogen by high-pressure tank trucks. This achieves efficient on-site conversion of surplus photovoltaic and wind power into green hydrogen, breaking through the core bottleneck of large-scale application of green hydrogen.

[0023] This invention directionally converts low-value-added bio-based ethyl acetate into high-value-added green ethanol, with low content of reaction byproducts. The product can be directly used as fuel or chemical raw material without complicated post-processing, supplementing the market capacity of green ethanol, alleviating the geographical limitations of raw materials in traditional ethanol production and the problem of "competing with people for food", and meeting the development needs of renewable fuels.

[0024] This invention recycles unreacted green hydrogen and unreacted bio-based ethyl acetate to the hydrogenation unit for hydrogenation reaction, constructing a closed-loop recycling system for green hydrogen and bio-based ethyl acetate. This significantly improves the recycling rate of unreacted materials. The entire process is continuous and uninterrupted, with materials transported between units via pipelines and pumps, resulting in low energy consumption and zero pollutant emissions. Furthermore, the raw material transportation costs are low, reaction conditions are easily controlled, and there is a clear economic premium, making it highly feasible for industrialization.

[0025] This invention organically combines three major areas: clean energy utilization, bio-based chemical conversion, and renewable fuel production. It simultaneously solves three major industrial problems: green hydrogen consumption, high-value utilization of bio-based ethyl acetate, and green ethanol production capacity gap. It achieves triple synergy in wind and solar power consumption, bio-based resource utilization, and renewable fuel supply, which meets the overall needs of the dual-carbon strategy and industrial upgrading. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 is a process flow diagram of the preparation of acetic acid by biothermochemical method in one embodiment. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Referring to Figure 1, this invention proposes a method for producing ethanol using bio-based ethyl acetate as a green hydrogen acceptor. Green hydrogen and bio-based ethyl acetate are added to a hydrogenation unit in a specific ratio to carry out a hydrogenation reaction, yielding a product containing bioethanol. In one embodiment of this invention, the bio-based ethyl acetate is metered out via a pump to ensure that the molar ratio of hydrogen to ethyl acetate is, for example, 5-12:1. The hydrogenation unit is, for example, a fixed-bed reactor, and the temperature of the hydrogenation reaction is set, for example, to 200-300°C, the pressure is set, for example, to 3-6 MPa, and the liquid hourly space velocity is set, for example, to 0.6-2.2 h⁻¹. -1 The catalyst is selected, for example, as a copper-zinc-aluminum composite catalyst. This invention controls the reaction conditions so that the ester bonds of bio-based ethyl acetate break under the action of the catalyst and undergo an addition reaction with green hydrogen, specifically generating bioethanol, with a byproduct content of less than 2%. In one embodiment of this invention, the green hydrogen is produced, for example, by electrolysis of water driven by photovoltaic power or wind power alone or in synergy, and, for example, by preferentially utilizing surplus wind and solar power that cannot be absorbed by the grid. The purity of the green hydrogen is, for example, at least 99.9%, and the water content is, for example, at most 10 ppm. The bio-based ethyl acetate is, for example, produced from green bio-based raw materials through thermochemical conversion, chemical fermentation, or electrochemical methods, and the purity of the green bio-based raw materials is, for example, at least 99.0%, free of mechanical impurities and heavy components. In one embodiment of this invention, the bio-based ethyl acetate is transported to the raw material storage tank at the water electrolysis hydrogen production site for storage and standby using conventional liquid transportation methods. The green hydrogen, obtained at the water electrolysis hydrogen production site, is directly connected to the hydrogenation unit, solving the problems of high cost and difficulty in long-distance storage and transportation of green hydrogen.

[0030] Referring to Figure 1, the product containing bioethanol obtained after directional hydrogenation in the hydrogenation unit is added to the separation unit for gas-liquid separation, yielding a recycle gas component and a mixture containing bioethanol. In one embodiment of the invention, the recycle gas component is unreacted green hydrogen, and the bioethanol-containing mixture, for example, contains at least ethanol and unreacted bio-based ethyl acetate. In one embodiment of the invention, the pressure for gas-liquid separation is, for example, 1-3 MPa, and the temperature is, for example, 10-30°C. In one embodiment of the invention, the recycle gas component obtained from gas-liquid separation is returned to the hydrogenation unit via a recirculation pipeline after pressurization to participate in the hydrogenation reaction again, achieving efficient recovery and utilization of green hydrogen.

[0031] Referring to Figure 1, the mixture containing bioethanol obtained from the separation unit is added to the distillation unit. After distillation, a circulating liquid component and bioethanol are obtained. In one embodiment of the invention, the distillation unit is, for example, a distillation column, with the top temperature set at, for example, 71-73°C and the bottom temperature set at, for example, 77-78°C. In one embodiment of the invention, bioethanol is collected from the bottom of the column, and the purity of the collected bioethanol is not less than 99.5%, requiring no further separation and purification, and can be used directly as fuel or chemical feedstock. In one embodiment of the invention, the circulating liquid component is collected from the top of the column, and the circulating liquid component is unreacted bio-based ethyl acetate with a small amount of ethanol entrained, wherein the content of unreacted bio-based ethyl acetate is, for example, 65-75 wt%, and the content of bioethanol is, for example, 25-35 wt%. In one embodiment of the invention, the circulating liquid component obtained after distillation is pumped back to the hydrogenation unit via a circulation pipeline to participate in the hydrogenation reaction again, achieving efficient utilization of materials.

[0032] Please refer to Figure 1. In this invention, green hydrogen and bio-based ethyl acetate are introduced into a hydrogenation unit in a specific ratio for a hydrogenation reaction. After the reaction, gas-liquid separation is performed in a separation unit, followed by distillation separation in a distillation unit. This achieves the recycling of unreacted materials, and the products can be directly used as fuel or chemical feedstock without complex post-processing. No dehydrogenation step is required throughout the process, achieving synergy between efficient green hydrogen carrying capacity and high-value utilization of bio-based resources. In one embodiment of this invention, the conversion rate of bio-based ethyl acetate is at least 90%, the utilization rate of green hydrogen is at least 95%, and the utilization rates of the circulating liquid component and the circulating gas component are at least 95%.

[0033] The method for producing ethanol using bio-based ethyl acetate as a green hydrogen acceptor includes the following steps:

[0034] As shown in Figure 1, green hydrogen and bio-based ethyl acetate were used as reaction raw materials. The bio-based ethyl acetate was prepared from corn stalks via a thermochemical method and transported by tank truck to a stainless steel raw material storage tank at the water electrolysis hydrogen production site for storage, with a purity of 99.2%. The green hydrogen was produced by electrolyzing water using surplus photovoltaic power and was directly connected to the hydrogen addition unit at the site, eliminating the need for long-distance transportation. Its purity was 99.93%, and its moisture content was ≤10ppm. The green hydrogen and bio-based ethyl acetate were added to the hydrogen addition unit at a molar ratio of 8:1 using a pump and a hydrogen flow meter for directional hydrogenation. The hydrogen addition unit was a fixed-bed reactor filled with a copper-zinc-aluminum composite catalyst. The reaction temperature was set at 250℃, the pressure at 4MPa, and the liquid hourly space velocity at 1.2h / min. -1 After hydrogenation, a product containing bioethanol is obtained.

[0035] Referring to Figure 1, the bioethanol-containing product obtained above is added to the separation unit for gas-liquid separation. The gas-liquid separation pressure is set to 2 MPa and the temperature to 20°C. After gas-liquid separation, a circulating gas component and a bioethanol-containing mixture are obtained. The circulating gas component is unreacted green hydrogen, and the bioethanol-containing mixture contains bioethanol and unreacted bio-based ethyl acetate. The circulating gas component obtained from gas-liquid separation is returned to the hydrogenation unit through a circulating pipeline after pressure regulation to participate in the hydrogenation reaction again, achieving efficient recovery and utilization of green hydrogen. The obtained bioethanol-containing mixture is then distilled in the distillation unit.

[0036] Referring to Figure 1, the obtained bioethanol-containing mixture is added to a distillation unit for distillation. The distillation unit is a distillation column with a top temperature of 71°C and a bottom temperature of 78°C. After distillation, a circulating liquid component containing 68.9 wt% bio-based ethyl acetate and 31.1 wt% bioethanol is separated from the top of the distillation column. This circulating liquid component is pumped back to the hydrogenation unit via a circulation pipeline to participate in the hydrogenation reaction again, achieving efficient utilization of the material. Bioethanol with a purity of 99.6% is collected from the bottom of the distillation column, cooled, and sent to a product storage tank.

[0037] The method for producing ethanol using bio-based ethyl acetate as a green hydrogen acceptor, as provided in this embodiment, achieves a bio-based ethyl acetate conversion rate of 92%, an unreacted material recycling rate of 98%, and a green hydrogen utilization rate of 95%. The production process has low energy consumption and no pollutant emissions, and the production cost of bioethanol is 6069 yuan / ton, indicating that the method provided by this invention is feasible and economical.

[0038] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0039] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A method for producing ethanol using bio-based ethyl acetate as a green hydrogen acceptor, characterized in that, The process includes at least the following steps: adding green hydrogen and bio-based ethyl acetate in a molar ratio of 5-12:1 to a hydrogenation unit; after hydrogenation, obtaining a product containing bioethanol; adding the bioethanol-containing product to a separation unit; after gas-liquid separation, obtaining a mixture of a circulating gas component and a bioethanol-containing liquid; adding the bioethanol-containing mixture to a distillation unit; after distillation, obtaining a circulating liquid component and bioethanol; and returning the circulating gas component and the circulating liquid component to the hydrogenation unit to participate in the hydrogenation reaction.

2. The method for producing ethanol using bio-based ethyl acetate as a green hydrogen acceptor according to claim 1, characterized in that, The circulating gas component is unreacted green hydrogen, and the circulating liquid component includes 65-75 wt% unreacted bio-based ethyl acetate and 25-35 wt% bioethanol.

3. The method for producing ethanol using bio-based ethyl acetate as a green hydrogen acceptor according to claim 1, characterized in that, The hydrogenation reaction is carried out at a temperature of 200-300℃, a pressure of 3-6 MPa, and a liquid hourly space velocity of 0.6-2.2 h⁻¹. -1 The catalyst is a copper-zinc-aluminum composite catalyst.

4. The method for producing ethanol using bio-based ethyl acetate as a green hydrogen acceptor according to claim 1, characterized in that, The green hydrogen is produced by electrolyzing water using photovoltaic power or wind power alone or in combination, and the purity of the green hydrogen is ≥99.9% and the moisture content is ≤10ppm. The bio-based ethyl acetate is produced by using green bio-based raw materials through thermochemical conversion, chemical fermentation or electrochemical methods, and the purity of the green bio-based raw materials is ≥99.0%.

5. The method for producing ethanol using bio-based ethyl acetate as a green hydrogen acceptor according to claim 1, characterized in that, The bio-based ethyl acetate is transported to the water electrolysis hydrogen production site via conventional liquid transport methods, and the green hydrogen is obtained at the water electrolysis hydrogen production site.

6. The method for producing ethanol using bio-based ethyl acetate as a green hydrogen acceptor according to claim 1, characterized in that, The pressure for gas-liquid separation is 1-3 MPa, and the temperature is 10-30℃.

7. The method for producing ethanol using bio-based ethyl acetate as a green hydrogen acceptor according to claim 1, characterized in that, The distillation unit is a distillation column, the top temperature of the distillation column is 71-73℃, the bottom temperature is 77-78℃, and the purity of the bioethanol is ≥99.5%.

8. The method for producing ethanol using bio-based ethyl acetate as a green hydrogen acceptor according to claim 7, characterized in that, The bioethanol is drawn from the bottom of the distillation column, and the circulating liquid component is drawn from the top of the distillation column.

9. The method for producing ethanol using bio-based ethyl acetate as a green hydrogen acceptor according to claim 1, characterized in that, The conversion rate of the bio-based ethyl acetate is at least 90%, the utilization rate of the green hydrogen is at least 95%, and the utilization rates of the circulating liquid component and the circulating gas component are at least 95%.

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