CN117658753A - Method for producing multi-carbon hydrocarbons by reducing carbon dioxide - Google Patents

Abstract

The invention provides a method for reducing carbon dioxide to produce multi-carbon hydrocarbons, which includes providing a reduction reaction and separation and purification system, performing an absorption step, performing a photocatalytic step, performing a separation step, performing a liquid phase purification step and performing a gas phase purification step. . The absorption step uses an absorbent to absorb carbon dioxide gas. The photocatalytic step reacts carbon dioxide with a photocatalyst to form a carbon-based compound. The separation step produces a liquid phase mixture and a gas phase mixture from the carbon-based compound. The liquid phase purification step is to filter and dry the liquid phase mixture, and the gas phase purification step is to form multi-carbon hydrocarbons from the gas phase mixture through pressure swing adsorption. In this way, carbon dioxide can be reduced and separated and purified into multi-carbon hydrocarbons through the designed system and appropriate photocatalysts.

Description

Method for producing multi-carbon hydrocarbons by reducing carbon dioxide

Technical field

The present invention relates to a method for reducing carbon dioxide, and in particular to a method for reducing carbon dioxide to produce multi-carbon hydrocarbons.

Background technique

Petrochemical fuels are currently the most common source of power and play an important role in industrial development, transportation and agricultural development. However, during the use of fossil fuels, they will emit a large amount of carbon dioxide, causing the greenhouse effect, air pollution and other environmental problems. Question, in order to enable the sustainable development of the environment, how to reduce carbon dioxide emissions and energy regeneration have become issues of current importance.

The current method to reduce carbon dioxide emissions is to use a high-efficiency power generation system, but it consumes a lot of energy and requires high operating costs, which is not economical. In order to save costs, reduce energy consumption and protect the environment, photocatalytic reduction of carbon dioxide is the main method. This research technology uses sunlight as the energy source and does not produce additional carbon dioxide when using photocatalysts for reactions. However, this method of reducing carbon dioxide will produce a variety of organic compounds with different properties.

In view of this, how to design a process for reducing carbon dioxide and separate and purify the generated organic matter to meet economic benefits has become the goal of relevant industry players.

Contents of the invention

An object of the present invention is to provide a method for reducing carbon dioxide to produce multi-carbon hydrocarbons, using a suitable photocatalyst to carry out a photocatalytic reaction on carbon dioxide, and by designing a reduction reaction and separation and purification system, so that it can effectively Separate and purify the organic matter produced by the photocatalytic reaction.

One embodiment of the present invention provides a method for reducing carbon dioxide to produce multi-carbon hydrocarbons, which includes providing a reduction reaction and separation and purification system, performing an absorption step, performing a photocatalytic step, performing a separation step, and performing a liquid phase purification step and a gas phase purification step. The reduction reaction and separation and purification system includes a carbon dioxide absorption tower, a reactor, a gas-liquid separation device, a liquid phase purification device and a gas phase purification device. The carbon dioxide absorption tower contains an absorbent, and the reactor is connected to a liquid in the carbon dioxide absorption tower. outlet and contains a photocatalyst. The gas-liquid separation device is connected to the reactor, and the gas-liquid separation device is connected to a liquid phase tank and a gas phase tank through a first flow path and a second flow path respectively. The liquid phase purification device is connected to the liquid phase tank. The gas phase purification device includes a washing tower and at least one set of separation columns. The washing tower is connected to the gas phase tank, and the separation column is connected to the washing tower. The absorption step is in a carbon dioxide absorption tower, using an absorbent to perform carbon dioxide absorption treatment on a carbon dioxide gas to form a mixed solution. The photocatalytic step is in a reactor, where the mixed solution and the photocatalyst are reacted under the irradiation of a light source to form a carbon-based compound. The separation step is to separate the carbon-based compound through a gas-liquid separation device to generate a liquid phase mixture and a gas phase mixture, and store them in a liquid phase tank and a gas phase tank respectively. The liquid phase purification step involves filtering and drying the liquid phase mixture in a liquid phase purification device to purify the liquid phase mixture. The gas phase purification step involves washing the gas phase mixture through a scrubber in a gas phase purification device, and separating and purifying the gas phase mixture in a separation column using a pressure swing adsorption method to form a multi-carbon hydrocarbon.

According to the method of reducing carbon dioxide to produce multi-carbon hydrocarbons according to the aforementioned embodiment, the absorbent may be sodium hydroxide.

According to the method of reducing carbon dioxide to produce multi-carbon hydrocarbons according to the aforementioned embodiment, the photocatalyst may include a selenium-based compound, a tellurium-based compound, an arsenic-based compound or the following formula (i), formula (ii), A compound represented by formula (iii), formula (iv) or formula (v):

M ¹ A ¹ X Formula (i),

M ² BiO ₂ X formula (ii),

BiOX/BiOY formula (iii),

BiOX/BiOY/BiOZ formula (iv),

M ³ A ² O formula (v),

Among them, M ¹ is bismuth, antimony, gallium or indium, M ² is lead, calcium, strontium, barium, copper or iron, and M ³ is lithium, sodium or potassium. A ¹ is oxygen, sulfur, selenium or tellurium, and A ² is titanium, vanadium, chromium, manganese, iron, cobalt, nickel, zirconium, niobium, tantalum, molybdenum or tungsten. X, Y, Z are fluorine, chlorine, bromine or iodine.

According to the method of reducing carbon dioxide to produce multi-carbon hydrocarbons according to the aforementioned embodiment, the photocatalyst may further include a selenium-based compound, a tellurium-based compound, an arsenic-based compound or formula (i), formula (ii), or formula (iii) , a composite of a compound represented by formula (iv) or formula (v) and a two-dimensional structural material.

According to the method of reducing carbon dioxide to produce multi-carbon hydrocarbons according to the aforementioned embodiment, the two-dimensional structural material may be graphite phase carbonitride, graphene oxide, bismuth oxyhalide compound, sulfur-doped graphite phase carbonitride, Carbon nanotubes or graphene.

According to the method for reducing carbon dioxide to produce multi-carbon hydrocarbons in the foregoing embodiment, the number of at least one set of separation columns may be three.

According to the method for reducing carbon dioxide to produce multi-carbon hydrocarbons according to the above embodiment, an adsorbent material contained in at least one set of separation columns can be zeolite, silica gel, activated carbon, activated alumina or Molecular sieves.

According to the method of reducing carbon dioxide to produce multi-carbon hydrocarbons in the foregoing embodiment, at least one set of separation columns may include an adsorption column and a desorption column.

The method of reducing carbon dioxide to produce multi-carbon hydrocarbons according to the aforementioned embodiment may further include a detection step, which uses a detection device connected to the gas phase purification device to measure the production of multi-carbon hydrocarbons. In addition, the detection device may be a gas chromatograph.

Thus, the method of reducing carbon dioxide to produce multi-carbon hydrocarbons of the present invention uses carbon dioxide gas as raw material, catalytically reduces carbon dioxide gas to carbon compounds on a photocatalyst carrier through a photocatalytic reduction process, and conducts the carbon compounds to Separate and purify to obtain multi-carbon hydrocarbons.

Description of drawings

In order to make the above and other objects, features, advantages and embodiments of the present invention more apparent and understandable, the accompanying drawings are described as follows:

Figure 1 is a flow chart illustrating a method for reducing carbon dioxide to produce multi-carbon hydrocarbons according to an embodiment of the present invention;

Figure 2 is a schematic diagram illustrating the reduction reaction and separation and purification system in the method of reducing carbon dioxide to produce multi-carbon hydrocarbons according to the embodiment of Figure 1;

Figure 3 is a schematic diagram illustrating the liquid phase purification device in the reduction reaction and separation and purification system of the embodiment of Figure 2; and

FIG. 4 is a schematic diagram of the gas phase purification device in the reduction reaction and separation and purification system of the embodiment of FIG. 2 .

Detailed ways

Embodiments of the present invention will be described below with reference to the drawings. For the sake of clarity, many practical details will be explained together in the following narrative. The reader should understand, however, that these practical details should not be construed as limiting the invention. That is to say, in some embodiments of the present invention, these practical details are not necessary. In addition, for the sake of simplifying the drawings, some commonly used structures and components are simply illustrated in the drawings; and repeated components may be represented by the same numbers.

Please refer to Figures 1 and 2. Figure 2 illustrates a step flow chart of a method 100 for reducing carbon dioxide to produce multi-carbon hydrocarbons according to an embodiment of the present invention. Figure 2 illustrates a reduction method according to the embodiment of Figure 1. Schematic diagram of the reduction reaction and separation and purification system 200 in the method 100 for producing multi-carbon hydrocarbons from carbon dioxide. In FIG. 1 , a method 100 for reducing carbon dioxide to produce multi-carbon hydrocarbons includes step 110 , step 120 , step 130 , step 140 , step 150 and step 160 .

Step 110 is to provide a reduction reaction and separation and purification system 200. As shown in Figure 2, the reduction reaction and separation and purification system 200 includes a carbon dioxide absorption tower 210, a reactor 220, a gas-liquid separation device 300, and a liquid phase purification device. 400 and a gas phase purification device 500. The carbon dioxide absorption tower 210 contains an absorbent. The reactor 220 is connected to a liquid outlet 211 of the carbon dioxide absorption tower 210 and contains a photocatalyst. The gas-liquid separation device 300 is connected to the reactor 220, and is connected to a liquid phase tank 330 and a gas phase tank 340 through a first flow path 310 and a second flow path 320 respectively. The liquid phase purification device 400 is connected to the liquid phase tank 330, and the gas phase purification device 500 is connected to the gas phase tank 340.

The following will provide a detailed description of each step of the method 100 for reducing carbon dioxide to produce multi-carbon hydrocarbons, and match the relevant process systems respectively.

Step 120 is an absorption step, which involves using an absorbent to perform carbon dioxide absorption treatment on a carbon dioxide gas in the carbon dioxide absorption tower 210 to form a mixed solution. Specifically, the absorbent of the present invention is sodium hydroxide, and carbon dioxide gas is chemically absorbed in the carbon dioxide absorption tower 210 and stored in the sodium hydroxide alkali solution in the form of carbonate. This step can fully absorb carbon dioxide and avoid unnecessary loss, and can eliminate the pollution of external gases and avoid the interference of unnecessary gases (such as nitrogen) on the reaction.

Step 130 is a photocatalytic step, which involves reacting the mixed solution and the photocatalyst under the irradiation of a light source 221 in the reactor 220 to form a carbon-based compound. Specifically, the mixed solution containing carbon dioxide and sodium hydroxide is sent to the reactor 220, and is irradiated by the light source 221 in the liquid phase to perform a photocatalytic reaction with the photocatalyst. At this time, the carbon dioxide is catalytically reduced to a carbon-based compound.

Specifically, the photocatalyst of the present invention may include but is not limited to a selenium-based compound, a tellurium-based compound, an arsenic-based compound or a compound composed of the following formula (i), formula (ii), formula (iii), formula (iv) or A compound represented by formula (v):

M ¹ A ¹ X Formula (i),

M ² BiO ₂ X formula (ii),

BiOX/BiOY formula (iii),

BiOX/BiOY/BiOZ formula (iv),

M ³ A ² O formula (v),

Among them, M ¹ is bismuth, antimony, gallium or indium, M ² is lead, calcium, strontium, barium, copper or iron, and M ³ is lithium, sodium or potassium. A ¹ is oxygen, sulfur, selenium or tellurium, and A ² is titanium, vanadium, chromium, manganese, iron, cobalt, nickel, zirconium, niobium, tantalum, molybdenum or tungsten. X, Y, Z are fluorine, chlorine, bromine or iodine. In addition, the photocatalyst of the present invention may further include a selenium-based compound, a tellurium-based compound, an arsenic-based compound, or a compound represented by formula (i), formula (ii), formula (iii), formula (iv) or formula (v) A composite with a two-dimensional structural material, wherein the two-dimensional structural material can be but is not limited to graphite phase carbonitride (gC ₃ N ₄ ), graphene oxide (GO), bismuth oxyhalide compound (BiOX), sulfur Doped with graphite phase carbonitride (SC ₃ N ₄ ), carbon nanotubes (CNT) or graphene (GR). Thereby, by synthesizing various photocatalysts or composite photocatalysts, the separation of electrons and holes can be promoted and the efficiency of photocatalytic reduction can be enhanced.

Step 140 is a separation step, which is to separate the carbon-based compound through the gas-liquid separation device 300 to generate a liquid phase mixture and a gas phase mixture, and store them in the liquid phase tank 330 and the gas phase tank 340 respectively. Specifically, the carbon-based compounds after photocatalytic reduction can include methane, formaldehyde, methanol, formic acid, etc., and are sent to the liquid phase tank 330 and the gas phase tank 340 for collection through simple gas-liquid separation for subsequent processing processes. . In addition, both the liquid phase tank 330 and the gas phase tank 340 can be provided with a reflux device as a tool for adjusting reaction conditions to define the reaction residence time, gas-liquid ratio and catalyst efficiency, but the present invention is not limited to this disclosure.

Step 150 is a liquid phase purification step, which involves filtering and drying the liquid phase mixture in the liquid phase purification device 400 to purify the liquid phase mixture. Please refer to FIG. 3 , which is a schematic diagram of the liquid phase purification device 400 in the reduction reaction and separation and purification system 200 of the embodiment of FIG. 2 . The liquid phase purification device 400 includes a stirring tank 410, a heater 420, a distillation tower 430, a filter 440 and an oven 450.

Specifically, the liquid phase mixture contains incompletely reacted carbon dioxide and reaction by-products such as formaldehyde, methanol, formic acid, moisture, sodium hydroxide and other possible components. Under alkaline conditions, formic acid cannot easily exist independently. It will form sodium formate salts with sodium hydroxide alkali solution and dissolve in the solution. Formaldehyde will easily form sodium formate and methanol under high pH conditions. When the liquid phase mixture is sent from the liquid phase tank 330 to the stirring tank 410, the heater 420 is used for heating, so that methanol, carbon dioxide, water vapor, etc., which are sensitive to temperature conditions, escape and are sent to the distillation chamber located at the top of the stirring tank 410. Tower 430 performs separation, in which methanol can be collected at the top of the tower, and carbon dioxide can be refluxed into the reaction zone to re-carry out the photocatalytic reaction. In addition, after the stirring tank 410 cools down, the solubility of sodium formate will be reduced, causing sodium formate to crystallize and precipitate. After passing through the filter 440, the sodium formate can be separated, and the sodium hydroxide alkali solution that has been reduced by sodium formate can be returned to the reaction zone to participate again. Absorption and photocatalytic reaction of carbon dioxide gas. Furthermore, the filtered sodium formate cake will be sent to the oven 450 for purification. If too much methanol or sodium hydroxide remains on the surface of the sodium formate, ethanol can be used for cleaning.

Step 160 is a gas phase purification step, which is to separate and purify the gas phase mixture in a pressure swing adsorption (PSA) manner in the gas phase purification device 500 to form a multi-carbon hydrocarbon. Please refer to FIG. 4 , which is a schematic diagram of the gas phase purification device 500 in the reduction reaction and separation and purification system 200 of the embodiment of FIG. 2 . The gas phase purification device 500 includes a washing tower 510 and at least one set of separation columns 520. The washing tower 510 is connected to the gas phase tank 340, and the separation column 520 is connected to the washing tower 510.

Specifically, the gas phase mixture may contain components such as methanol, methane, carbon monoxide, formaldehyde, formic acid, unreacted carbon dioxide, and oxygen formed from moisture during the photocatalytic reaction. The gas phase mixture is first sent from the gas phase tank 340 to the washing tower 510, and is washed through the washing tower 510. The washing tower 510 contains sodium hydroxide to remove formic acid and formaldehyde under alkaline conditions, and to remove carbon dioxide that escapes from incomplete reaction. The gas can also be absorbed by the scrubber and recycled to the reaction zone.

Next, the gas washed with sodium hydroxide remains methane, carbon monoxide, methanol, carbon dioxide and a small amount of impurities. The separation column 520 and the pressure swing adsorption technology for separating mixed gases are used to separate and purify different gases. Specifically, the number of separation columns 520 of the present invention can be three groups, but is not limited to this disclosure, and an adsorption material contained in the separation column 520 can be, but is not limited to, zeolite, silica gel, activated carbon, activated alumina or Molecular sieves, each adsorbent material can adsorb different substances, and the required adsorbent material can be selected based on the different characteristics of the gas. In addition, each set of separation columns 520 includes an adsorption column 521 and a desorption column 522, and performs adsorption at normal temperature and high pressure to adsorb a certain gas in the gas phase mixture, and then uses vacuum for desorption. The gas phase mixture can be separated and purified by repeated operations. The pressure swing adsorption technology is well known in the art and will not be described again here.

In addition, after the gas phase purification step, a detection step may be further included, which uses a detection device (not shown) connected to the gas phase purification device 500 to measure the production of multi-carbon hydrocarbons, wherein the detection device may be Gas chromatograph. Specifically, a detection device is used to measure multi-carbon hydrocarbons to obtain chromatogram data of the reaction at each time point, and the types of multi-carbon hydrocarbons and their yields are analyzed.

The present invention is further illustrated by the following specific embodiments, so that those with ordinary skill in the technical field to which the present invention belongs can fully utilize and practice the present invention without over-interpretation, and these embodiments should not be regarded as These are not intended to limit the scope of the invention but are intended to illustrate the materials and methods of practicing the invention.

<Example>

<Reduction of carbon dioxide to produce multi-carbon hydrocarbons>

The present invention is carried out according to the method 100 of reducing carbon dioxide to produce multi-carbon hydrocarbons according to the embodiment of FIG. 1 . Specifically, the carbon dioxide gas is first absorbed through an alkaline solution of sodium hydroxide, then 0.1 g of photocatalyst is added, and the carbon dioxide is reduced to carbon-based compounds under ultraviolet or visible light irradiation. Next, the reduced carbon-based compound is separated into gas and liquid, and the gas phase mixture and the liquid phase mixture are separated and purified respectively. Finally, a gas chromatograph is used to measure the yield of the separated and purified gas phase substance.

Specifically, the photocatalysts used in the present invention are shown in Table 1 below.

<Analysis of multi-carbon hydrocarbons>

In the gas phase purification step, the present invention uses four sets of separation columns to separate and purify various hydrocarbons, in which zeolite is used to separate and purify ethylene, and activated carbon is used to separate and purify methane, ethane, propane, butane and pentane. by Propylene is separated and purified by molecular sieves, acetylene is separated and purified by activated alumina, and the above hydrocarbons are analyzed by gas chromatography, and their time points (hr), concentration (ppm) and yield (μmol/g/ h) are listed in Table 2 below.

It can be seen from the results in Table 2 above that the photocatalysts of Examples 1 to 20 of the present invention can reduce carbon dioxide after photocatalytic reaction, and produce multi-carbon hydrocarbons through a separation and purification process, and the obtained hydrocarbons All compounds were obtained in good yields.

In summary, the method of reducing carbon dioxide to produce multi-carbon hydrocarbons according to the present invention is based on the designed reduction reaction and separation and purification system, reducing carbon dioxide through a photocatalyst to form a variety of products, and utilizing the different properties of the products for separation and purification. Purification is used to produce multi-carbon hydrocarbons, and carbon dioxide can be recovered to form a carbon cycle to achieve the goal of sustainable development.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and modifications without departing from the spirit and scope of the present invention. Therefore, the present invention The scope of protection shall be determined by the appended claims.

Symbol Description

100: Method for producing multi-carbon hydrocarbons by reducing carbon dioxide

110,120,130,140,150,160: steps

200: Reduction reaction and separation and purification system

210:Carbon dioxide absorption tower

211:Liquid outlet

220:Reactor

221:Light source

300: Gas-liquid separation device

310: First flow path

320: Second flow path

330:Liquid phase tank

340:Gas phase tank

400: Liquid phase purification device

410: Stirring tank

420:Heater

430: Distillation tower

440:Filter

450:Oven

500: Gas phase purification device

510: Scrubber

520:Separation column

521:Adsorption column

522: Desorption column

Claims (10)

1. A method for reducing carbon dioxide to produce a multi-carbon hydrocarbon comprising:

providing a reduction reaction and separation purification system, comprising:

a carbon dioxide absorber containing an absorbent;

a reactor which is communicated with a liquid outlet of the carbon dioxide absorption tower and contains a photocatalyst;

the gas-liquid separation device is communicated with the reactor and is connected with a liquid phase tank and a gas phase tank through a first flow path and a second flow path respectively;

a liquid phase purifying device which is communicated with the liquid phase tank; and

A gas phase purification device, which comprises a washing tower and at least one group of separation pipe columns, wherein the washing tower is communicated with the gas phase tank, and the at least one group of separation pipe columns are connected with the washing tower;

performing an absorption step of performing carbon dioxide absorption treatment on a carbon dioxide gas in the carbon dioxide absorption tower by using the absorbent to form a mixed solution;

performing a photocatalysis step, wherein the mixed solution and the photocatalyst react under the irradiation of a light source in the reactor to form a carbon-based compound;

a separation step is carried out, wherein the carbon-based compound is separated by the gas-liquid separation device to generate a liquid phase mixture and a gas phase mixture, and the liquid phase mixture and the gas phase mixture are respectively stored in the liquid phase tank and the gas phase tank;

performing a liquid phase purification step of filtering and drying the liquid phase mixture in the liquid phase purification device to purify the liquid phase mixture; and

and performing a gas phase purification step, namely washing the gas phase mixture through the washing tower in the gas phase purification device, and separating and purifying the gas phase mixture in the at least one component separation column in a pressure swing adsorption mode to form a multi-carbon hydrocarbon.

2. The method of reducing carbon dioxide to produce a multi-carbon hydrocarbon according to claim 1, wherein the absorbent is sodium hydroxide.

3. The method of reducing carbon dioxide to produce multi-carbon hydrocarbons according to claim 1, wherein the photocatalyst comprises a selenium-based compound, a tellurium-based compound, an arsenic-based compound, or a compound represented by the following formula (i), formula (ii), formula (iii), formula (iv), or formula (v):

M ¹ A ¹ x-type (i),

M ² BiO ₂ X is of the formula (ii),

BiO X/BiO Y formula (iii),

BiO X/BiO Y/BiO Z type (iv),

M ³ A ² O formula (v);

wherein M1 is bismuth, antimony, gallium or indium, M2 is lead, calcium, strontium, barium, copper or iron, and M3 is lithium, sodium or potassium;

wherein A1 is oxygen, sulfur, selenium or tellurium, A2 is titanium, vanadium, chromium, manganese, iron, cobalt, nickel, zirconium, niobium, tantalum, molybdenum or tungsten;

wherein X, Y, Z is fluorine, chlorine, bromine or iodine.

4. The method of reducing carbon dioxide to produce multi-carbon hydrocarbons according to claim 3, wherein the photocatalyst further comprises the selenium-based compound, the tellurium-based compound, the arsenic-based compound, or a complex of the compound represented by formula (i), formula (ii), formula (iii), formula (iv) or formula (v) and a two-dimensional structural material.

5. The method of reducing carbon dioxide to produce multi-carbon hydrocarbons according to claim 4, wherein the two-dimensional structural material is a graphite-phase carbon-nitrogen compound, graphene oxide, bismuth oxyhalide compound, sulfur-doped graphite-phase carbon-nitrogen compound, carbon nanotubes, or graphene.

6. The method for reducing carbon dioxide to produce a multi-carbon hydrocarbon according to claim 1, wherein the number of said at least one separation column is three.

7. The method for reducing carbon dioxide to produce multi-carbon hydrocarbons according to claim 1, wherein an adsorbent material contained in said at least one separation column is zeolite, silica gel, activated carbon, activated alumina, or a mixture thereofMolecular sieves.

8. The method of reducing carbon dioxide to produce multi-carbon hydrocarbons according to claim 1, wherein the at least one separation column comprises an adsorption column and a desorption column.

9. The method of reducing carbon dioxide to produce multi-carbon hydrocarbons according to claim 1, further comprising a detecting step of measuring the production of the multi-carbon hydrocarbons by connecting a detecting device to the gas phase purifying device.

10. The method of reducing carbon dioxide to produce a multi-carbon hydrocarbon according to claim 9, wherein the detection device is a gas chromatograph.