A catalyst for cold plasma synergistic conversion of carbon dioxide and its preparation method

Abstract

The present invention discloses a catalyst and preparation method for the synergistic conversion of carbon dioxide by cold plasma, and relates to the field of low-temperature and normal-pressure gas conversion. The present invention prepares an OVs-In2O3 / ZnO catalyst with oxygen vacancies by resin adsorption. The preparation process is simple, and large-scale preparation can be achieved, which is convenient for production. Cold plasma and OVs-In2O3 / ZnO catalyst are combined. Under the conditions of low temperature and normal pressure, high-energy electrons generated in the entire space of the DBD coaxial reactor and H species dissociated from the catalyst surface synergistically assist in the hydrogenation activation of CO2. The OVs-In2O3 / ZnO catalyst with oxygen vacancies develops a new CO2 activation path in a plasma atmosphere, which extends the CO2 hydrogenation behavior that is limited to the catalyst surface to the gas phase, reduces the hydrogenation activation energy barrier of CO2, and significantly improves the performance of converting CO2 into CO with high added value. The problem of difficult activation of existing CO2, low product selectivity, low yield and high energy consumption is solved.

Description

Technical Field

[0001] The present invention relates to the field of low-temperature, normal-pressure gas conversion, and in particular to a catalyst for the synergistic conversion of carbon dioxide by cold plasma and a preparation method thereof. Background Art

[0002] Rapid industrial and economic development inevitably requires a vast supply of fossil fuels, but this also leads to excessive CO2 emissions. Over the past 30 years, the combustion of fossil fuels such as coal, oil, and natural gas has released approximately 5 billion tons of CO2 annually. As a result, the Earth's biosphere is no longer able to recycle carbon through photosynthesis or other pathways. The sharp rise in atmospheric CO2 concentrations has severely impacted the environment and climate. Adhering to the concept of green development, clean carbon dioxide conversion technologies, which convert CO2 into high-value-added chemical products, are considered promising.

[0003] To develop this green chemical route, thermal catalysis, electrocatalysis, photocatalysis, and plasma catalysis technologies have been developed to activate CO2. However, thermal catalysis requires high temperatures to activate CO2 molecules, and since CO2 is a thermodynamically stable non-polar molecule, it is not easy to adsorb on the catalyst surface, especially in an environment with a solution (such as electrocatalysis and photocatalysis), CO2 will be even more difficult to adsorb. In addition, in thermal catalysis, electrocatalysis, and photocatalysis technologies, the multi-species reaction on the catalyst surface involves competitive adsorption of CO2 and co-reactants, and the multi-proton transfer process of CO2 on the surface ultimately makes the reaction energy barrier of the catalytic activation path of CO2 high, resulting in more limitations on the application of these technologies in large-scale CO2 conversion process. Summary of the Invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a catalyst for the synergistic conversion of carbon dioxide by cold plasma at low temperature and normal pressure and a preparation method thereof.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0006] A method for preparing a catalyst for cold plasma synergistic conversion of carbon dioxide is provided, comprising the following steps:

[0007] S1: pre-treating CER resin to obtain CER powder;

[0008] S2: Zn(NO3)3·6H2O and In(NO3)3·xH2O were mixed in a molar ratio of 3:1 to obtain a mixed solution;

[0009] S3: adding the mixed solution dropwise into the CER powder, and continuously grinding and mixing during the adding process, and drying after mixing to obtain a mixed powder;

[0010] S4: calcining the mixed powder at 350°C for 8 hours to obtain a catalyst.

[0011] Furthermore, step S1 includes the following specific steps:

[0012] A1: Prepare 1 mol / L HCl solution and 1 mol / L NaOH solution;

[0013] A2: NaOH solution, HCl solution, and deionized water were injected into the ion exchange column containing CER resin in sequence;

[0014] A3: Use deionized water to rinse the ion exchange column containing CER resin until the pH is neutral;

[0015] A4: Take out the cleaned CER resin and dry it at 40°C for 24 hours;

[0016] A5: Grind the dried CER resin at 600 r / min for 2 h to obtain CER powder.

[0017] Furthermore, in step A2, the solid-liquid ratio of the CER resin to deionized water is 0.2 g / mL; the solid-liquid ratio of the CER resin to the HCl solution or the NaOH solution is 0.05 g / mL.

[0018] Furthermore, in step S3, the solid-liquid ratio of the CER powder to the mixed liquid is 0.5 g / mL.

[0019] A catalyst prepared by the above preparation method.

[0020] A method for converting carbon dioxide using the above catalyst in conjunction with cold plasma comprises the following steps:

[0021] B1: Distribute the catalyst evenly in the quartz wool and place the quartz wool mixed with the catalyst in a plasma generator;

[0022] B2: Introduce H2 into the plasma generator to convert the plasma generator into a hydrogen atmosphere;

[0023] B3: Continuously introduce a mixed gas of CO2:H2 in a ratio of 1:3 into the plasma generator to convert carbon dioxide into CO through the plasma generator.

[0024] Furthermore, the pressure in the plasma generator is maintained at 1 atm.

[0025] Furthermore, the input power of the plasma generator is 160W.

[0026] The beneficial effects of the present invention are:

[0027] The present invention prepares an OVs-In2O3 / ZnO catalyst with oxygen vacancies by resin adsorption. The preparation process is simple, can achieve large-scale preparation, and is easy to produce. Cold plasma and OVs-In2O3 / ZnO catalyst are combined. Under low temperature and normal pressure conditions, high-energy electrons generated in the entire space of the DBD coaxial reactor and H species dissociated from the catalyst surface synergistically assist in the hydrogenation activation of CO2. The OVs-In2O3 / ZnO catalyst with oxygen vacancies develops a new CO2 activation pathway in a plasma atmosphere, extending the CO2 hydrogenation behavior that is limited to the catalyst surface to the gas phase, reducing the CO2 hydrogenation activation energy barrier, and significantly improving the performance of converting CO2 into CO with high added value. It solves the problems of difficult activation of existing CO2, low product selectivity, low yield, and high energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the process for preparing the catalyst of the present invention;

[0029] Figure 2 This is the XRD test result diagram of the catalyst prepared in Example 1;

[0030] Figure 3 : The resonance wave spectrum of OVs-In2O3 / ZnO powder and In2O3 / ZnO powder in Example 2;

[0031] Figure 4 This is a comparison chart of the CO2 conversion effect in Example 3. DETAILED DESCRIPTION

[0032] The specific embodiments of the present invention are described below to facilitate understanding of the present invention by those skilled in the art. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations utilizing the concepts of the present invention are protected.

[0033] Example 1 Preparation of catalyst

[0034] Prepare 1L of 1mol / L HCl solution and 1L of 1mol / L NaOH solution. Figure 1In the preparation process shown, 1L of NaOH solution, 1L of HCl solution, and 250mL of deionized water are sequentially injected into an ion exchange column containing 50g of CER resin. After no solution is filtered out of the column, the CER resin in the ion exchange column is rinsed with deionized water until the pH of the CER resin is neutral. The rinsed CER resin is transferred to a drying oven and heated to 40°C for approximately 24 hours. At this point, the CER is not completely dry and still retains some moisture. The CER resin is then ground using a high-speed ball mill at 600 rpm for 2 hours to pulverize it. The pulverized CER powder is then placed in a constant temperature and humidity chamber for later use.

[0035] Zn(NO3)3·6H2O and In(NO3)3·xH2O were mixed in a molar ratio of 3:1 to obtain a mixed solution. 2 ml of the mixed solution was added dropwise to 1 g of CER powder while grinding. Finally, the mixed and ground CER powder was transferred to a 60°C oven for drying and then calcined in a muffle furnace at 350°C for 8 hours to obtain the catalyst OVs-In2O3 / ZnO powder. XRD analysis of the catalyst OVs-In2O3 / ZnO powder was performed, and the results were as follows: Figure 2 shown.

[0036] In order to confirm that the obtained powder is OVs-In2O3 / ZnO powder with oxygen vacancies, a portion of the OVs-In2O3 / ZnO powder was placed in a tube furnace under an oxygen environment and calcined at 350°C for 8 hours to obtain In2O3 / ZnO powder with oxygen vacancies filled. The OVs-In2O3 / ZnO powder and In2O3 / ZnO powder were tested using an electron paramagnetic resonance spectrometer, and the following results were obtained: Figure 3 The comparison chart shown is by Figure 2 and Figure 3 It can be seen that the above-mentioned preparation method of the present invention can successfully prepare OVs-In2O3 / ZnO powder with vacant oxygen sites.

[0037] Example 2 Catalytic performance test of catalyst

[0038] The experimental group (NTP-OVs-In2O3 / ZnO) was set up: the OVs-In2O3 / ZnO powder prepared in Example 1 was used as a catalyst; the comparative group 1 (NTP-In2O3 / ZnO): the In2O3 / ZnO powder prepared in Example 1 was used as a catalyst; the comparative group 2 (NTP-ZnO): 0.2g ZnO powder was used as a catalyst; and the blank control group (NTP): no catalyst.

[0039] All four groups were tested using the following experimental conditions: 0.2g of catalyst was evenly distributed within quartz wool (a blank control group contained no catalyst), which was then placed within a coaxial DBD plasma generator. After the plasma generator was installed, hydrogen was introduced at a flow rate of 60mL / min for 10 minutes to create a hydrogen atmosphere within the plasma generator, maintaining a pressure of 1atm. A CO2:H2 mixture with a 1:3 ratio was then continuously introduced, with CO2 and H2 flowing at a flow rate of 20mL / min and 60mL / min, respectively.

[0040] Start the tube furnace and monitor the coaxial reactor temperature in real time. Then, turn on the oscilloscope and CTP-2000K plasma power supply, modulating the input power to 160W. The oscilloscope monitors the voltage and current within the DBD plasma generator in real time. Connect a gas analyzer to the plasma generator outlet for real-time analysis. Perform three tests under the same conditions and average the results.

[0041] The evaluation method is: detect the tail gas coming out of the reactor, analyze the gas composition, the ratio of the converted CO2 content to the CO2 content introduced into the reaction is the conversion rate, and the ratio of the generated CO content to the converted CO2 is the CO selectivity.

[0042] The results are as follows Figure 4 shown by Figure 4 It can be seen that there is no obvious difference in the selectivity of CO in the four groups of conversion reactions, all of which are close to 100%; and using the OVs-In2O3 / ZnO powder prepared by the present invention as a catalyst, using a plasma reactor at low temperature and normal pressure, the conversion rate of CO2 is 60.31%, which is significantly higher than the comparison group 1 (43.65%), comparison group 2 (38.40%) and blank control group (36.87%). OVs-In2O3 / ZnO powder can significantly improve the conversion rate of CO2, solving the problems of difficult activation of CO2, low product selectivity, low yield and high energy consumption.

[0043] Example 3: Effect of the ratio of CO2 to H2 on CO2 conversion

[0044] The comparison group 1 was set up: a mixed gas with a CO2:H2 ratio of 1:1 was introduced, specifically, the CO2 flow rate was 20 mL / min and the H2 flow rate was 20 mL / min; the comparison group 2 was set up: a mixed gas with a CO2:H2 ratio of 1:2 was introduced, specifically, the CO2 flow rate was 20 mL / min and the H2 flow rate was 40 mL / min; the comparison group 3 was set up: a mixed gas with a CO2:H2 ratio of 1:3 was introduced, specifically, the CO2 flow rate was 20 mL / min and the H2 flow rate was 60 mL / min; the comparison group 4 was set up: a mixed gas with a CO2:H2 ratio of 1:4 was introduced, specifically, the CO2 flow rate was 20 mL / min and the H2 flow rate was 80 mL / min; the other conditions remained unchanged.

[0045] The gas was analyzed by a gas analyzer and the results were shown in Table 1.

[0046] Table 1

[0047]

[0048] It can be seen from Table 1 that as the H2 content in the mixed gas increases, the CO2 conversion rate increases accordingly. It can be seen from comparison groups 3 to 4 that after the CO2:H2 ratio increases from 1:3 to 1:4, the CO2 conversion rate does not increase significantly, and the increase in H2 content will lead to an increase in cost. Therefore, as a preference, it is more in line with production interests to use a mixed gas with a CO2:H2 ratio of 1:3 for conversion.

Claims

1. A method for preparing a catalyst for the synergistic conversion of carbon dioxide to carbon monoxide using cold plasma, characterized in that: The steps include: S1: pretreating the cation exchange resin CER to obtain cation exchange resin CER powder; S2: Zn(NO3)3·6H2O and In(NO3)3·xH2O were mixed in a molar ratio of 3:1 to obtain a mixed solution; S3: adding the mixed solution dropwise into the cation exchange resin CER powder, and continuously grinding and mixing during the adding process, and drying after mixing to obtain a mixed powder; S4: calcining the mixed powder at 350°C for 8 hours to obtain a catalyst.

2. The method for preparing a catalyst for preparing carbon monoxide by cold plasma synergistic conversion of carbon dioxide according to claim 1, characterized in that: The step S1 includes the following specific steps: A1: Prepare 1 mol / L HCl solution and 1 mol / L NaOH solution; A2: NaOH solution, HCl solution and deionized water are injected into the ion exchange column containing cation exchange resin CER in sequence; A3: Use deionized water to rinse the ion exchange column containing the cation exchange resin CER until the pH is neutral; A4: Take out the cleaned cation exchange resin CER and dry it at 40°C for 24 hours; A5: Grind the dried cation exchange resin CER at a speed of 600 r / min for 2 h to obtain cation exchange resin CER powder.

3. The method for preparing a catalyst for preparing carbon monoxide by cold plasma synergistic conversion of carbon dioxide according to claim 2, characterized in that: In step A2, the solid-liquid ratio of the cation exchange resin CER to deionized water is 0.2 g / mL; the solid-liquid ratio of the cation exchange resin CER to the HCl solution or the NaOH solution is 0.05 g / mL.

4. The method for preparing a catalyst for preparing carbon monoxide by cold plasma synergistic conversion of carbon dioxide according to claim 1, characterized in that: In step S3, the solid-to-liquid ratio of the cation exchange resin CER powder to the mixed solution is 0.5 g / mL.

5. A catalyst prepared by the preparation method according to any one of claims 1 to 4.

6. A method for producing carbon monoxide by converting carbon dioxide using the catalyst according to claim 5 in conjunction with cold plasma, characterized in that: The steps include: B1: Distribute the catalyst evenly in the quartz wool and place the quartz wool mixed with the catalyst in a plasma generator; B2: Introduce H2 into the plasma generator to convert the plasma generator into a hydrogen atmosphere; B3: Continuously introduce a mixed gas of CO2:H2 with a volume ratio of 1:3 into the plasma generator to convert carbon dioxide into CO through the plasma generator.

7. The method for producing carbon monoxide by converting carbon dioxide using a catalyst in conjunction with cold plasma according to claim 6, characterized in that: The pressure in the plasma generator was maintained at 1 atm.

8. The method for producing carbon monoxide by converting carbon dioxide using a catalyst in conjunction with cold plasma according to claim 6, characterized in that: The input power of the plasma generator is 160W.

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