阅读说明：本技术 一种可再生能源驱动的二氧化碳加氢合成甲酸的系统及方法 (System and method for synthesizing formic acid by hydrogenation of carbon dioxide driven by renewable energy ) 是由 王焕君 刘蓉 郭东方 刘练波 范金航 赵磊 于 2021-09-10 设计创作，主要内容包括：本发明属于可再生能源利用以及温室气体减排技术领域,具体涉及一种可再生能源驱动的二氧化碳加氢合成甲酸的系统及方法。该系统包括二氧化碳捕集装置、制氢装置、甲酸合成装置和可再生能源发电装置,该系统通过各个装置间的配合作用可以直接利用空气中的二氧化碳和可再生能源发电装置过剩的电能合成高能量甲酸,既减少了可再生能源在用电低谷浪费严重的现象,解决了可再生能源的弃电问题,又降低了空气中温室气体二氧化碳的含量,同时还实现了二氧化碳气体的资源化利用,得到了高能量化合物甲酸,节省了原料的运输成本。(The invention belongs to the technical field of renewable energy utilization and greenhouse gas emission reduction, and particularly relates to a system and a method for synthesizing formic acid by hydrogenation of carbon dioxide driven by renewable energy. The system comprises a carbon dioxide capture device, a hydrogen production device, a formic acid synthesis device and a renewable energy power generation device, the system can directly utilize carbon dioxide in the air and surplus electric energy of the renewable energy power generation device to synthesize high-energy formic acid through the cooperation among the devices, the phenomenon that renewable energy is seriously wasted in power utilization valleys is reduced, the problem of electricity abandonment of renewable energy is solved, the content of greenhouse gas carbon dioxide in the air is reduced, the resource utilization of carbon dioxide is realized, high-energy compound formic acid is obtained, and the transportation cost of raw materials is saved.)

1. A system for synthesizing formic acid by hydrogenation of carbon dioxide driven by renewable energy sources is characterized by comprising,

a renewable energy power generation device;

a carbon dioxide capture device for directly capturing carbon dioxide in the air;

the hydrogen production device is used for electrolyzing water to produce hydrogen and oxygen;

and the formic acid synthesis device is respectively communicated with the carbon dioxide capture device and the hydrogen production device, and synthesizes formic acid by using the electric energy produced by the renewable energy power generation device, the carbon dioxide captured by the carbon dioxide capture device and the hydrogen produced by the hydrogen production device.

2. The system of claim 1, wherein the renewable energy power generation device is in communication with the carbon dioxide capture device to provide electrical energy to the carbon dioxide capture device; and/or the presence of a gas in the gas,

the renewable energy power generation device is communicated with the hydrogen production device to provide electric energy for the hydrogen production device.

3. The system of claim 1 or 2, wherein the formic acid synthesis device comprises a gas mixing unit, wherein carbon dioxide from the carbon dioxide capture device and hydrogen from the hydrogen production device are uniformly mixed to form a mixed gas;

the formic acid synthesis unit is communicated with the gas mixing unit, and mixed gas of carbon dioxide and hydrogen enters the formic acid synthesis unit to react to obtain mixed liquid of formic acid and water;

and the formic acid separation unit is communicated with the formic acid synthesis unit and is used for separating mixed liquid of formic acid and water to obtain formic acid.

4. The system of any one of claims 1 to 3, wherein the carbon dioxide capture device comprises CO₂The absorption unit is internally provided with a porous liquid spraying port which is used for spraying porous liquid and capturing carbon dioxide in the air;

CO₂a regeneration unit with said CO₂The absorption units are communicated and come from CO₂Rich liquid from the absorption unit with CO₂The barren solution of the regeneration unit exchanges heat, and the barren solution after heat exchange enters CO₂The absorption unit captures carbon dioxide in the air, and the rich solution after heat exchange enters CO₂Regenerating in a regeneration unit to obtain barren solution and carbon dioxide, and recycling the barren solution to CO₂Reuse in an absorption unit, carbon dioxide into CO₂The storage unit stores for later use;

CO₂storage units respectively associated with the CO₂The regeneration unit is communicated with the formic acid synthesis device and is used for storing CO₂The carbon dioxide regenerated by the regeneration unit provides carbon dioxide for the formic acid synthesis unit.

5. The system according to any one of claims 1 to 4, wherein the hydrogen production device comprises a water electrolysis hydrogen production unit for electrolyzing water to obtain hydrogen and oxygen;

and the hydrogen storage unit is communicated with the water electrolysis hydrogen production unit and is used for storing hydrogen and providing hydrogen for the formic acid synthesis device.

6. The system of any one of claims 1-5, further comprising a PLC programmable controller;

the PLC is connected with the carbon dioxide capture device to adjust the capture rate and the regeneration rate of the carbon dioxide; and/or the presence of a gas in the gas,

the PLC is connected with the hydrogen production device to adjust the rate of producing hydrogen by electrolyzing water; and/or the presence of a gas in the gas,

the PLC is connected with the formic acid synthesis device to adjust the rate of synthesizing formic acid.

7. A method for synthesizing formic acid by hydrogenation of carbon dioxide driven by renewable energy, which is characterized by adopting the system of any one of claims 1-6 and comprising the specific steps of synthesizing the formic acid by the carbon dioxide and the hydrogen under the action of a catalyst and an alkaline solution.

8. The method of claim 7, wherein the catalyst is a supported catalyst comprising a support and an active site; the loading amount of the active center in the supported catalyst is less than 0.5 wt%;

the carrier is at least one of silicon dioxide, carbon materials, molecular sieves, hydrotalcite and mesoporous alumina;

the active center is a noble metal monoatomic atom; the noble metal nitrogen atom is at least one of Au, Pd, Ru and Rh.

9. The method according to claim 7 or 8, wherein the alkaline solution is an aqueous sodium bicarbonate solution having a concentration of 1-1.5 mol/L;

the ratio of the mass of the catalyst to the volume of the alkaline solution is 1-1.5g to 100 ml.

10. The method of any of claims 7-9, wherein the porous liquid comprises ZIF-8, and further comprises at least one of ethylene glycol, 2-methylimidazole, and polydimethylsiloxane;

preferably, the porous liquid comprises ZIF-8, ethylene glycol, and 2-methylimidazole; or, the porous liquid comprises ZIF-8 and polydimethylsiloxane;

more preferably, the mass fraction of ZIF-8 in the porous liquid is 10-20%.

Technical Field

The invention belongs to the technical field of renewable energy utilization and greenhouse gas emission reduction, and particularly relates to a system and a method for synthesizing formic acid by hydrogenation of carbon dioxide driven by renewable energy.

Background

The thermal power plant is an important power production place in China, and contributes more than 70% of generated energy every year. While producing electricity, the combustion of fossil fuels produces large quantities of carbon dioxide, accelerating the global warming process and bringing significant impact on the global ecological environment. On the one hand, in order to reduce the emission of carbon dioxide and optimize an energy structure, renewable new energy power generation engineering practices such as photovoltaic and wind power are developed by the people in the industry. However, intermittent renewable energy sources such as wind power or photovoltaic power generation have strong uncertainty and volatility, and have the problems of difficult peak shaving and difficult grid connection. Taking wind power as an example, the wind power generation amount is larger in the valley period of the used charge, and the phenomenon of 'wind abandon' is prominent, so that the wind resource waste is caused; in the peak period of the electric load, the phenomenon of insufficient power supply exists.

On the other hand, the power generation industry and the fossil fuel combustion field cause CO in the air₂Increasingly, the content of (A) is increasing. CO 2₂Is a renewable carbon resource with rich and safe reserves, and can realize CO through chemical conversion₂Resource utilization of (3) CO₂Changes waste into valuable, realizes high-value utilization, can fix carbon dioxide and reduce air CO₂And (4) obtaining energy and materials with high added values. Therefore, how to convert CO₂This greenhouse gas is converted into valuable clean waterClean energy becomes one of the research hotspots. Except the CO discharged by fixed point sources in the power industry and the industry of thermal power plants₂In addition, there is approximately 50% of the distributed source emission of CO₂Of these CO₂The carbon dioxide is widely dispersed in the air, the storage amount is high, and how to realize the recovery of the carbon dioxide in the air and relieve the greenhouse effect also becomes one of the difficulties which are urgently needed to be solved by the industry personnel.

Among the various reaction routes utilizing carbon dioxide, catalytic hydrogenation has received extensive attention and development in the laboratory basic research and chemical industry. Formic acid has wide application, is one of basic organic chemical raw materials, and is widely applied in the industries of medicine, pesticide, tanning, chemistry and the like; in addition, the hydrogen addition of carbon dioxide to prepare formic acid can theoretically achieve 100% of atom utilization rate, and how to prepare formic acid by using electric energy generated by renewable energy sources and carbon dioxide in air becomes a current research difficulty.

Disclosure of Invention

Therefore, the invention aims to overcome the defects of serious waste of renewable energy in electricity utilization valley, high carbon dioxide storage amount in air, greenhouse effect and the like in the prior art, and provides a system and a method for synthesizing formic acid by hydrogenating carbon dioxide driven by renewable energy.

Therefore, the invention provides the following technical scheme,

the invention provides a system for synthesizing formic acid by hydrogenation of carbon dioxide driven by renewable energy sources, which comprises,

a renewable energy power generation device;

a carbon dioxide capture device for directly capturing carbon dioxide in the air;

the hydrogen production device is used for electrolyzing water to produce hydrogen and oxygen;

and the formic acid synthesis device is respectively communicated with the carbon dioxide capture device and the hydrogen production device, and synthesizes formic acid by using the electric energy produced by the renewable energy power generation device, the carbon dioxide captured by the carbon dioxide capture device and the hydrogen produced by the hydrogen production device.

The renewable energy power generation device is communicated with the carbon dioxide capture device and provides electric energy for the carbon dioxide capture device; and/or the presence of a gas in the gas,

the renewable energy power generation device is communicated with the hydrogen production device to provide electric energy for the hydrogen production device.

The formic acid synthesis device comprises a gas mixing unit, a hydrogen production device and a hydrogen collecting unit, wherein carbon dioxide from the carbon dioxide collecting device and hydrogen of the hydrogen production device are uniformly mixed to form mixed gas;

the formic acid synthesis unit is communicated with the gas mixing unit, and mixed gas of carbon dioxide and hydrogen enters the formic acid synthesis unit to react to obtain mixed liquid of formic acid and water;

and the formic acid separation unit is communicated with the formic acid synthesis unit and is used for separating mixed liquid of formic acid and water to obtain formic acid.

The carbon dioxide capture device comprises CO₂The absorption unit is internally provided with a porous liquid spraying port which is used for spraying porous liquid and capturing carbon dioxide in the air;

CO₂a regeneration unit with said CO₂The absorption units are communicated and come from CO₂Rich liquid from the absorption unit with CO₂The barren solution of the regeneration unit exchanges heat, and the barren solution after heat exchange enters CO₂The absorption unit captures carbon dioxide in the air, and the rich solution after heat exchange enters CO₂Regenerating in a regeneration unit to obtain barren solution and carbon dioxide, and recycling the barren solution to CO₂Reuse in an absorption unit, carbon dioxide into CO₂The storage unit stores for later use;

CO₂storage units respectively associated with the CO₂The regeneration unit is communicated with the formic acid synthesis device and is used for storing CO₂The carbon dioxide regenerated by the regeneration unit provides carbon dioxide for the formic acid synthesis unit.

The hydrogen production device comprises a water electrolysis hydrogen production unit for electrolyzing water to obtain hydrogen and oxygen;

and the hydrogen storage unit is communicated with the water electrolysis hydrogen production unit and is used for storing hydrogen and providing hydrogen for the formic acid synthesis device.

The system also comprises a PLC programmable controller;

the PLC is connected with the carbon dioxide capture device to adjust the capture rate and the regeneration rate of the carbon dioxide; and/or the presence of a gas in the gas,

the PLC is connected with the hydrogen production device to adjust the rate of producing hydrogen by electrolyzing water; and/or the presence of a gas in the gas,

the PLC is connected with the formic acid synthesis device to adjust the rate of synthesizing formic acid.

The invention also provides a method for synthesizing formic acid by hydrogenation of carbon dioxide driven by renewable energy, which adopts the system and comprises the specific steps that the carbon dioxide and hydrogen are synthesized into the formic acid under the action of a catalyst and an alkaline solution.

The catalyst is a supported catalyst and comprises a carrier and an active center; the loading amount of the active center in the supported catalyst is less than 0.5 wt%;

the carrier is at least one of silicon dioxide, carbon materials, molecular sieves, hydrotalcite and mesoporous alumina;

the active center is a noble metal monoatomic atom; the noble metal nitrogen atom is at least one of Au, Pd, Ru and Rh.

The alkaline solution is sodium bicarbonate water solution, and the concentration of the sodium bicarbonate water solution is 1-1.5 mol/L;

the ratio of the mass of the catalyst to the volume of the alkaline solution is 1-1.5g to 100 ml.

The porous liquid comprises ZIF-8 and also comprises at least one of ethylene glycol, 2-methylimidazole and polydimethylsiloxane;

preferably, the porous liquid comprises ZIF-8, ethylene glycol, and 2-methylimidazole; or, the porous liquid comprises ZIF-8 and polydimethylsiloxane;

more preferably, the mass fraction of ZIF-8 in the porous liquid is 10-20%.

The porous liquid is called pregnant solution after absorbing carbon dioxide; the carbon dioxide is desorbed from the rich liquid and is called lean liquid.

ZIF-8 is a metal organic framework compound (MOFs), which is one of zeolitic imidazolate framework materials.

The technical scheme of the invention has the following advantages:

1. the system for synthesizing the formic acid by the hydrogenation of the carbon dioxide driven by the renewable energy comprises a carbon dioxide capture device, a hydrogen production device, a formic acid synthesis device and a renewable energy power generation device, and can directly utilize the carbon dioxide in the air and the surplus electric energy of the renewable energy power generation device to synthesize the high-energy formic acid by the cooperation of the devices, thereby reducing the phenomenon of serious waste of the renewable energy in the electricity utilization valley, solving the electricity utilization problem of the renewable energy, reducing the content of greenhouse gas carbon dioxide in the air, realizing the resource utilization of the carbon dioxide gas, obtaining the high-energy compound formic acid and saving the transportation cost of the raw materials.

The system can realize flexible operation, can operate when electricity is abandoned, can stop operating when electricity is not abandoned, can adjust the working state in time according to the power supply condition of renewable energy sources, is less restricted by places in installation, and is suitable for various places with renewable energy sources for power generation.

2. According to the system for synthesizing formic acid by hydrogenation of carbon dioxide driven by renewable energy provided by the invention, the carbon dioxide capture device and the hydrogen production device can obtain carbon dioxide and hydrogen by using electric energy generated by renewable energy, so that the problem of electricity abandonment of renewable energy is further solved, the influence on the environment is small in the development and utilization process, additional carbon dioxide is not generated in the carbon capture process, and the greenhouse effect can be effectively relieved.

In the system, the absorption and analysis of the carbon capture, the hydrogen production by electrolysis, the synthesis of formic acid and other links are independently controlled, and the fluctuation receiving capability of the integrated system is improved.

3. According to the system for synthesizing formic acid by hydrogenation of carbon dioxide driven by renewable energy, provided by the invention, the capture rate and the regeneration rate of carbon dioxide, the rate of preparing hydrogen by electrolyzing water and the rate of synthesizing formic acid can be adjusted through the PLC, and the rate of synthesizing formic acid is adjusted in time according to the power condition provided by the renewable energy power generation device so as to assist the power system to keep balance, so that the process of synthesizing formic acid can be well matched with the power fluctuation energy of the renewable energy power generation device within a proper time scale.

4. The peak shaving method for synthesizing the formic acid by the hydrogenation of the carbon dioxide driven by the renewable energy sources, provided by the invention, has the advantages that the formic acid can be prepared by using the system, the method is energy-saving and environment-friendly, the electricity waste generated by a renewable energy source power generation device is consumed, the carbon dioxide in the air can be utilized, and the problem of high carbon dioxide storage in the air is effectively solved.

The invention can directly synthesize formic acid by adopting a specific catalyst and an alkaline solution, and overcomes the defects of difficult synthesis of formic acid due to stable carbon dioxide and high free energy in the prior art. Furthermore, the carbon dioxide in the air can be directly captured by adopting the specific porous liquid, because the porous liquid has the advantages of ordered and regular pore channels of the solid material, liquid fluidity and the like, and the solid material can be used for capturing CO₂The selective physical adsorption of the gas and the chemical absorption of the solution to the gas are coupled, which is favorable for greatly improving the CO content of the porous liquid₂The absorption and separation effect of (2) is not limited by the low concentration of carbon dioxide in the air. Further, the capture of carbon dioxide from air using porous liquids also overcomes the emission of CO from dispersed sources₂The carbon capture device has the advantages of low concentration in air, wide distribution, high capture difficulty and high energy consumption, and the direct carbon capture from the air has the advantages of small restriction on places, good flexibility and the like.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a schematic diagram of a system for the renewable energy driven hydrogenation of carbon dioxide to formic acid in example 1 of the present invention;

FIG. 2 is a system for the renewable energy driven hydrogenation of carbon dioxide to formic acid in a preferred embodiment of the present invention;

reference numerals:

a-a renewable energy power generation device; b-a carbon dioxide capture device; c-a hydrogen production unit; a D-formic acid synthesis device;

1-an air compression unit; 2-CO₂An absorption unit; 3-cold pregnant solution pump; 4-a heat exchange unit; 5-a rich liquid storage unit; 6-hot rich liquid pump; 7-CO₂A regeneration unit; 8-a heating unit; 9-hot barren liquor pump; 10-barren liquor storage unit; 11-a cold barren pump; 12-CO₂A compression unit; 13-CO₂A storage unit; 14-CO₂A valve; 15-a water storage unit; 16-a water pump; 17-a water electrolysis hydrogen production unit; 18-O₂A storage unit; 19-H₂A storage unit; 20-H₂A valve; 21-a gas mixing unit; a 22-formic acid synthesis unit; a 23-formic acid separation unit;

2-1-a first outlet; 2-2-second outlet-1; 2-3-porous liquid spray opening.

Detailed Description

The following examples are provided to further understand the present invention, not to limit the scope of the present invention, but to provide the best mode, not to limit the content and the protection scope of the present invention, and any product similar or similar to the present invention, which is obtained by combining the present invention with other prior art features, falls within the protection scope of the present invention.

In the description of the present invention, it should be noted that unless otherwise explicitly stated or limited, the terms "connected" and "communicating" are to be interpreted broadly, e.g., as meaning directly connected to each other, indirectly connected to each other through an intermediary, and communicating between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

The examples do not show the specific experimental steps or conditions, and can be performed according to the conventional experimental steps described in the literature in the field. The reagents or instruments used are not indicated by manufacturers, and are all conventional reagent products which can be obtained commercially.

Example 1

The embodiment provides a system for synthesizing formic acid by hydrogenation of carbon dioxide driven by renewable energy, which comprises a renewable energy power generation device A, a carbon dioxide capture device B, a hydrogen production device C and a formic acid synthesis device D, as shown in FIG. 1,

the carbon dioxide capturing device B is used for directly capturing carbon dioxide from the air by utilizing the electric energy generated by the renewable energy power generation device; as shown in FIG. 1, an air compression unit 1 is provided inside the carbon dioxide capturing device B, and CO is discharged from the air compression unit₂An absorption unit 2, a cold rich liquid pump 3, a heat exchange unit 4, a rich liquid storage unit 5, a hot rich liquid pump 6, CO₂A regeneration unit 7, a heating unit 8, a hot barren solution pump 9, a barren solution storage unit 10, a cold barren solution pump 11, CO₂Compression unit 12, CO₂A storage unit 13; wherein the air compression unit 1 is connected with CO₂The absorption unit 2 is communicated so that the compressed air enters into the CO₂In the absorption unit 2, CO₂The top of the absorption unit 2 is provided with a porous liquid spraying port 2-3, and porous liquid is sprayed from CO₂The top of the absorption unit 2 sprays downwards to absorb carbon dioxide in the air to realize the capture of the carbon dioxide, the residual air is discharged through a first outlet 2-1, and porous liquid (also called cold rich liquid) after absorbing the carbon dioxide is discharged through a second outlet 2-2; the cold rich liquid enters a rich liquid storage unit 5 to become hot rich liquid after being subjected to heat exchange by a heat exchange unit 4 under the action of a cold rich liquid pump 3, and the hot rich liquid enters CO under the action of a hot rich liquid pump 6₂Regenerated in a regeneration unit 7 to obtain hot barren solution and CO₂Wherein, CO₂The regeneration unit 7 is communicated with a heating unit 8, and the heating unit 8 is CO₂The regeneration unit providing heat, CO₂Separating out from hot rich liquid to realize regeneration, and CO₂By CO₂Compressed by the compression unit 12 and stored in CO₂In the storage unit 13, for standby; hot lean liquid from CO₂Discharge from the regeneration unit 7Enters the heat exchange device 4 under the action of the hot barren liquor pump 9 and comes from CO₂Cold rich solution of the absorption unit 2 exchanges heat, lean solution after heat exchange enters a lean solution storage unit 10 and enters CO under the action of a cold lean solution pump 11₂In the absorption unit 2, carbon dioxide in the air is absorbed, and the porous liquid is recycled. Specifically, the porous liquid used in this example includes ZIF-8, ethylene glycol, and 2-methylimidazole; or, the porous liquid comprises ZIF-8 and polydimethylsiloxane, and the porous liquid is in a slurry state or a suspension state.

The hydrogen production device C is used for electrolyzing water to produce hydrogen and oxygen by utilizing the electric energy produced by the renewable energy power generation device; as shown in fig. 1, a water storage unit 15, a water pump 16, a water electrolysis hydrogen production unit 17, an oxygen storage unit 18, a hydrogen storage unit 19 and a hydrogen valve 20 are arranged in the hydrogen production device; under the action of a water pump 16, water enters a water electrolysis hydrogen production unit 17, hydrogen and oxygen are obtained through electrolysis and enter a hydrogen storage unit 19 and an oxygen storage unit 18 respectively for storage for later use; wherein the hydrogen valve 20 controls the opening and closing of the hydrogen storage device 19.

The formic acid synthesis device D is respectively communicated with the carbon dioxide capture device and the hydrogen production device, and synthesizes formic acid by utilizing the electric energy generated by the renewable energy power generation device, the carbon dioxide produced by the carbon dioxide capture device and the hydrogen produced by the hydrogen production device under the action of a catalyst and an alkaline solution; as shown in FIG. 1, CO₂The valve 14 and the hydrogen valve 20 respectively control the flow of the carbon dioxide and the hydrogen so that the carbon dioxide and the hydrogen enter the formic acid synthesis device; the formic acid synthesis device comprises a gas mixing unit 21, a formic acid synthesis unit 22 and a formic acid separation unit 23 which are communicated, H₂Hydrogen and CO in storage unit 19₂CO in the storage unit 13₂The mixed gas is mixed in a gas mixing unit 21 and enters a formic acid synthesis unit 22, mixed liquid of formic acid and water is synthesized under the action of a catalyst and an alkaline solution, and the mixed liquid of the formic acid and the water is separated by a formic acid separation unit 23 to obtain high-energy compounds of formic acid and water, wherein the formic acid is reserved. Specifically, in the present embodiment, the alkaline solution is an aqueous sodium bicarbonate solution; the catalyst is a supported catalyst, and comprises a carrier andthe loading capacity of the active center in the supported catalyst is less than 0.5 wt%, the carrier is at least one of silicon dioxide, carbon material, molecular sieve, hydrotalcite, magnesium-aluminum hydrotalcite and mesoporous alumina, and the active center is a noble metal single atom; the noble metal nitrogen atom is at least one of Au, Pd, Ru and Rh; the pressure of carbon dioxide is 1-2MPa, the pressure of hydrogen is 2-4MPa, and the reaction temperature is 80-100 ℃; when formic acid and water are obtained by separation, the formic acid and the water are obtained by distillation separation by utilizing the different boiling points of the components, and the water is circulated to a hydrogen production device.

As an alternative embodiment, the carbon dioxide capturing device can be supplied with electric energy by adopting a fossil energy power generation mode, so that the carbon dioxide in the air can be captured.

As an alternative embodiment, the hydrogen production device can be supplied with electric energy by using a fossil energy power generation mode, so that hydrogen and oxygen are produced by electrolyzing water.

In a preferred embodiment, the system for synthesizing formic acid by hydrogenation of carbon dioxide driven by renewable energy source further comprises a PLC (programmable logic controller), as shown in FIG. 2, the PLC is connected with the carbon dioxide capture device, and the input of CO is controlled by a frequency converter₂The flow rate of air of the absorption unit 2 to adjust the capture rate of carbon dioxide; further, the PLC can also control the porous liquid to enter the CO through the frequency converter₂The flow rate of the absorption unit 2 to adjust the capture rate of carbon dioxide; furthermore, the PLC can also control the rich liquid to enter CO through the frequency converter₂The rate of the regeneration unit 7 to adjust the rate of regeneration of carbon dioxide. When the electricity abandon of the renewable energy power generation device is reduced, the capture rate of the carbon dioxide can be adjusted through the PLC so as to keep the power balance.

As another preferred embodiment, the system for synthesizing formic acid by hydrogenation of carbon dioxide driven by renewable energy source further comprises a PLC programmable controller, as shown in fig. 2, the PLC programmable controller is connected with the hydrogen production device, and the frequency converter is used for controlling the rate of hydrogen production by electrolysis of water. When the electricity abandonment of the renewable energy power generation device is reduced, the hydrogen production rate can be adjusted through the PLC so as to keep the power balance.

As another preferred embodiment, the system for synthesizing formic acid by hydrogenation of carbon dioxide driven by renewable energy source further comprises a PLC programmable controller, as shown in fig. 2, the PLC programmable controller is connected with the formic acid synthesizing device, and the rate of synthesizing formic acid is controlled by a frequency converter. When the electricity abandonment of the renewable energy power generation device is reduced, the rate of synthesizing formic acid can be adjusted through the PLC so as to keep the power balance.

Example 2

This example provides a method for preparing formic acid using the system of example 1, comprising the following steps,

under the action of the porous liquid, capturing carbon dioxide by using an electric energy carbon dioxide capturing device generated by a renewable energy power generation device, regenerating to obtain carbon dioxide, and storing for later use; the porous liquid comprises ZIF-8, ethylene glycol and 2-methylimidazole, wherein the mass fraction of the ZIF-8 in the porous liquid is 15 wt%, and the mass ratio of the ethylene glycol to the 2-methylimidazole is 3: 2;

the hydrogen production device electrolyzes water to obtain oxygen and hydrogen for later use by utilizing the electric energy generated by the renewable energy power generation device;

the method comprises the following steps of reacting carbon dioxide and hydrogen under the action of a catalyst and an alkaline solution by utilizing electric energy generated by a renewable energy power generation device to obtain a mixed solution of formic acid and water, and distilling and separating to obtain formic acid and water; wherein the alkaline solution is a 1mol/L sodium bicarbonate aqueous solution; the catalyst is Ru/MgAl-LDHs (magnesium aluminum hydrotalcite), and the load of Ru is 0.3 wt%; the ratio of the mass of catalyst to the volume of aqueous sodium bicarbonate solution was 1.2 g:100 ml; the pressure of carbon dioxide is 1.5 plus or minus 0.1MPa, the pressure of hydrogen is 3 plus or minus 0.1MPa, and the reaction temperature is 90 ℃.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the spirit or scope of the invention.