Preparation method and application of nickel-based catalyst for selectively producing CH4 / CO through photo-thermal catalysis of CO2 hydrogenation
The nickel-based catalyst is prepared by impregnating soluble nickel salts and lanthanum salts in mesoporous silica, which solves the problem of easy sintering of nickel catalysts, and achieves the effect of high selective production of CH4 and CO, which is suitable for industrial applications.
Patent Information
- Application Number
- CN202510426912.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-07
- Publication Date
- 2025-07-18
AI Technical Summary
In the existing photothermal catalytic CO2 hydrogenation reaction, metal catalysts such as nickel are prone to agglomeration and sintering, resulting in a short service life and low economic efficiency, making it difficult to achieve the technical problems of selective production of CH4 and CO.
The mesoporous silica was immersed with aqueous solutions of soluble nickel salts and soluble lanthanum salts to prepare nickel-based catalysts, and the production of CH4 and CO was adjusted by photothermal conditions, including reduction treatment and atmosphere control at different temperatures.
Maintain good activity during long-term reactions, and the selectivity of CH4 and CO both reach more than 95%. The preparation route is simple, the cost is low, and it is suitable for industrial promotion.
Smart Images
Figure CN120325314A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of CO2 catalytic conversion, and particularly to a preparation method and application of a nickel-based catalyst for the selective production of CH4 / CO by photocatalytic hydrogenation of CO2. Background Art
[0002] The extensive consumption of fossil fuels has led to the increasing growth of carbon emissions, bringing a series of environmental problems such as the greenhouse effect. CO2 catalytic conversion is one of the important technologies for reducing the CO2 component in flue gas in industrial scenarios. However, there are still problems such as low catalyst utilization efficiency, unsatisfactory yield, and difficulty in large-scale popularization of technical routes. Using solar energy for photocatalytic conversion of CO2 can effectively reduce the dependence on fossil energy, and using clean energy greatly reduces the negative impact on the environment such as harmful by-products.
[0003] However, in the traditional photocatalytic hydrogenation reaction of CO2, metal catalysts such as nickel are prone to agglomeration and sintering at high temperatures, resulting in short service life and low economic efficiency. Therefore, it is necessary to prepare a catalyst with good activity, stability and economy under long-term photocatalytic hydrogenation reaction of CO2, and selectively produce two widely used chemical raw materials, CH4 and CO, through a simple technical method. Summary of the Invention
[0004] One of the purposes of the present invention is to provide a preparation method of a nickel-based catalyst for the selective production of CH4 / CO by photocatalytic hydrogenation of CO2, which helps to promote the dispersion of metal particles and prevent sintering, has a simple preparation route and low cost, and is suitable for large-scale popularization in industrial production.
[0005] Another purpose of the present invention is to provide an application of a nickel-based catalyst in the selective production of CH4 / CO by photocatalytic hydrogenation of CO2. The selectivities of both CH4 and CO products can reach more than 95% under different photocatalytic conditions, and the adjustment method of photocatalytic conditions is relatively simple, having good application prospects.
[0006] The solution adopted by the present invention to achieve the first purpose is: a preparation method of a nickel-based catalyst for the selective production of CH4 / CO by photocatalytic hydrogenation of CO2, wherein an aqueous solution of a soluble nickel salt, a soluble lanthanum salt or their hydrates is dropped into mesoporous silica, and the solution is fully impregnated into the mesopores, and the obtained solid-liquid mixture is removed of the liquid, dried and calcined to obtain the nickel-based catalyst.
[0007] Preferably, the soluble nickel salt is at least one of Ni(NO3)2, Ni(CH3COO)2, NiCl2, NiSO4 or their hydrates, and the soluble lanthanum salt is at least one of La(NO3)3, LaCl3, LaCO3 or their hydrates.
[0008] Preferably, the mass fraction W1 of nickel in the nickel-based catalyst ranges from 2% ≤ W1 ≤ 30%, and the mass fraction W2 of lanthanum oxide ranges from 0 < W2 ≤ 30%.
[0009] Preferably, the mesoporous silica includes at least one of KIT-6, SBA-16, SBA-15, with a specific surface area greater than 500 m 2 / g and a pore size range of 2 - 50 nm.
[0010] Preferably, the specific steps for removing the liquid and drying are as follows: Stir the obtained solid-liquid mixture at a temperature below 60°C until all the liquid evaporates, and then place the evaporated powder at 80 - 100°C for drying until complete.
[0011] Preferably, the stirring speed is 200 - 600 rpm.
[0012] Preferably, the calcination temperature range is 400 - 550°C, and the calcination time is 3 - 6 h.
[0013] The solution adopted to achieve the second object of the present invention is: the application of a nickel-based catalyst prepared by the described preparation method, applying the nickel-based catalyst to the photothermal catalytic hydrogenation of CO2 for the selective production of CH4 / CO, including the following steps:
[0014] Step 1: Place the nickel-based catalyst in the quartz tube of the photothermal catalytic tubular furnace and conduct sufficient reduction treatment under a certain temperature and reducing atmosphere;
[0015] Step 2: Continuously introduce a mixed atmosphere with a volume ratio of H2 to CO2 of 4:1 and a flow rate of 5 - 100 mL / min into the quartz tube at a certain temperature for the production of CH4 or CO. The specific process is as follows:
[0016] When the temperature is 300 - 375°C and held constant, a product mainly composed of CH4 can be obtained, and the inlet gas flow rate is 5 - 100 mL / min;
[0017] When the temperature is 450 - 600°C and held constant, irradiate with a xenon lamp at 0.1 - 60 W / cm 2 At this time, a product mainly composed of CO can be obtained, and the inlet gas flow rate is 5 - 100 mL / min.
[0018] Preferably, in step 1, the reducing atmosphere is a mixed gas containing hydrogen and an inert atmosphere or high-purity H2. When it is a mixed gas, the H2 content is greater than 4%, the inert gas is N2 or Ar, the reduction temperature is 450 - 600 °C, and the inlet gas flow rate is 10 - 100 mL / min.
[0019] Preferably, in step 2, the mixed atmosphere can be a mixed atmosphere of H2 and CO2, or a mixed atmosphere of H2, CO2 and an inert atmosphere.
[0020] The present invention has the following advantages and beneficial effects:
[0021] The preparation method of the present invention directly impregnates a metal nitrate solution in silica with a good mesoporous structure, which helps to promote the dispersion of metal particles and prevent sintering, thereby maintaining good activity during a long-term reaction.
[0022] The preparation route of the preparation method of the present invention is simple and the cost is low, which is suitable for large-scale promotion in industrial production.
[0023] When the catalyst of the present invention is applied to the selective production of CH4 / CO by photothermal catalytic CO2 hydrogenation, the selectivities of both CH4 and CO products can reach more than 95% under different photothermal conditions, and the adjustment method of photothermal catalytic conditions is relatively simple, having good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 is the XRD pattern of the catalyst prepared by the present invention;
[0025] Figure 2 is the photocurrent response diagram of the catalyst prepared by the present invention;
[0026] Figure 3 is the photoluminescence spectrum diagram of the catalyst prepared by the present invention;
[0027] Figure 4 is the CO2 conversion rate and CH4 selectivity of the catalyst in Example 4 under the condition of producing CH4;
[0028] Figure 5 is the CO2 conversion rate and CO selectivity of the catalyst in Example 4 under the condition of producing CO;
[0029] Figure 6 is the TEM diagram of the catalyst in Example 4 before and after the performance test, where the upper diagram is the TEM diagram of the unreacted catalyst; the lower diagram is the TEM diagram of the catalyst synthesized in Example 1 after reacting for 100 hours under heating at 500 °C and illumination of 2.6 W / cm2. DETAILED DESCRIPTION OF THE INVENTION
[0030] For a better understanding of the present invention, the following embodiments further illustrate the present invention, but the content of the present invention is not limited to the following embodiments only.
[0031] Example 1
[0032] A preparation method of a nickel-based catalyst for photocatalytic CO2 hydrogenation to selectively produce CH4 / CO includes the following steps:
[0033] 1. Dissolve 0.49 g of Ni(NO3)2·6H2O and 0.13 g of La(NO3)3·6H2O in 20 mL of distilled water, and stir for 2 minutes to form a homogeneous solution;
[0034] 2. Dropwise add the obtained solution to 0.8 g of dry mesoporous SiO2 powder, and allow the solution to fully impregnate into the mesopores. The mesoporous SiO2 is selected as KIT-6;
[0035] 3. Stir the obtained solid-liquid mixture until all the liquid evaporates. The stirring speed is 200 rpm. Subsequently, place the evaporated powder in an oven at 100 °C and dry for 12 hours;
[0036] 4. Place the dried powder in a muffle furnace, heat it to 500 °C at a rate of 1 degree per minute, and calcine it at 500 °C for 5 hours to obtain the nickel-based catalyst.
[0037] Figure 1 The XRD pattern of the nickel-based catalyst prepared in this example is shown. It can be seen that the main components in the catalyst are Ni and NiO. Since the mesoporous silica exists in an amorphous form, there are no peaks of SiO2 in the diffraction pattern.
[0038] Figure 2 This is the photocurrent response diagram of the catalyst prepared in this example. After 3 on-off (after turning on the light for 30 minutes, turning off the light for 30 minutes, and then repeating) cycles of attenuation, the photocurrent tends to be stable.
[0039] Figure 3 This is the photoluminescence spectrum diagram of the catalyst prepared in this example and the nickel-based catalyst without doping La2O3. It can be seen from the figure that the peak intensity of the Ni-based catalyst after doping La2O3 is lower, indicating that its ability of photo-generated electron-hole recombination is weaker, and thus it has better catalytic activity.
[0040] Example 2
[0041] A preparation method of a nickel-based catalyst for photocatalytic CO2 hydrogenation to selectively produce CH4 / CO includes the following steps:
[0042] 1. Dissolve 0.23 g of NiSO4·6H2O and 0.065 g of LaCl3·7H2O in 20 mL of distilled water, and stir for 2 minutes to form a homogeneous solution;
[0043] 2. Dropwise add the obtained solution to 0.9 g of dry mesoporous SiO2 powder, and allow the solution to fully impregnate into the mesopores. SBA-16 is selected as the mesoporous SiO2;
[0044] 3. Stir the obtained solid-liquid mixture until all the liquid evaporates. The stirring speed is 400 rpm. Subsequently, place the evaporated powder in an oven at 100 °C and dry for 12 hours;
[0045] 4. Place the dried powder in a muffle furnace, heat it to 400 °C at a rate of 1 °C per minute, and calcine it at 400 °C for 5 hours to obtain a nickel-based catalyst.
[0046] Example 3
[0047] A preparation method of a nickel-based catalyst for the selective production of CH4 / CO by photothermal catalytic hydrogenation of CO2 includes the following steps:
[0048] 1. Dissolve 0.63 g of Ni(CH3COO)2·4H2O and 0.2 g of La(NO3)3·6H2O in 20 mL of distilled water, and stir for 2 minutes to form a homogeneous solution;
[0049] 2. Dropwise add the obtained solution to 0.7 g of dry mesoporous SiO2 powder, and allow the solution to fully impregnate into the mesopores. SBA-15 is selected as the mesoporous SiO2;
[0050] 3. Stir the obtained solid-liquid mixture until all the liquid evaporates. The stirring speed is 400 rpm. Subsequently, place the evaporated powder in an oven at 100 °C and dry for 12 hours;
[0051] 4. Place the dried powder in a muffle furnace, heat it to 550 °C at a rate of 1 °C per minute, and calcine it at 550 °C for 5 hours to obtain a nickel-based catalyst.
[0052] Example 4
[0053] A method for the selective production of CH4 / CO by photothermal catalytic hydrogenation of CO2 using a nickel-based catalyst includes the following steps:
[0054] 1. Take 50 mg of the nickel-based catalyst prepared in Example 1 and place it in a quartz tube of a photothermal catalytic tubular furnace, and fix it with quartz wool;
[0055] 2. Introduce 4% H2 / N2 into the quartz tube, heat it to 500 °C at a rate of 10 °C per minute under this atmosphere, and keep it at 500 °C for 1 hour to fully reduce the catalyst. The inlet gas flow rate is 80 mL / min;
[0056] 3. Subsequently, cool it to 300 °C at a rate of 10 °C per minute. After the temperature stabilizes, switch the atmosphere to 4% H2 / 1% CO2 / 95% Ar, and the inlet gas flow rate is 15 mL / min. At this time, products mainly composed of CH4 can be obtained (CH4 selectivity is greater than 95%); as Figure 4 shown, the CO2 conversion rate and CH4 selectivity of the catalyst in this example under the CH4 production condition are presented;
[0057] 4. Heat it to 500 °C at a rate of 10 °C per minute. After the temperature stabilizes, turn on the 300 W xenon lamp and irradiate it with a power density of 1.0 W / cm 2 The reaction atmosphere is still 4% H2 / 1% CO2 / Ar, and the flow rate is 15 mL / min. At this time, products mainly composed of CO can be obtained (CO selectivity is greater than 99%). As Figure 5 shown, the CO2 conversion rate and CO selectivity of the catalyst in this example under the CO production condition are presented.
[0058] The transmission electron microscope images of the catalyst before and after the performance test are as Figure 4 shown. The upper figure is the TEM image of the unreacted catalyst; the lower figure is the TEM image of the catalyst synthesized in Example 1 after reacting for 100 hours under heating at 500 °C and light irradiation at 2.6 W / cm2. A highly ordered mesoporous structure and dispersed metal particles can be seen in the figure. By comparing the catalysts before and after the reaction at the same magnification, it can be found that only slight agglomeration occurs in the catalyst after the reaction, indicating that the mesoporous silica support used in the present invention has a good dispersion effect.
[0059] Example 5
[0060] A method for the selective production of CH4 / CO by the photothermal catalytic hydrogenation of CO2 using a nickel-based catalyst, comprising the following steps:
[0061] 1. Take 50 mg of the nickel-based catalyst prepared in Example 1 and place it in the quartz tube of the photothermal catalytic tubular furnace, and fix it with quartz wool;
[0062] 2. Introduce 64% H2 / N2 into the quartz tube, heat it to 600 °C at a rate of 10 °C per minute under this atmosphere, and keep it at 600 °C for 1 hour to fully reduce the catalyst. The inlet gas flow rate is 10 mL / min;
[0063] 3. Lower the temperature to 375 °C and keep it at this temperature. Switch the atmosphere to 16% H2 / 4% CO2 / 80% N2 with a flow rate of 20 mL / min. At this time, products mainly composed of CH4 can be obtained (CH4 selectivity is greater than 98%);
[0064] 4. Raise the temperature to 450 °C and keep it at this temperature. Turn on a 300 W xenon lamp and irradiate with a power density of 2.3 W / cm 2 . The reaction atmosphere remains 16% H2 / 4% CO2 / 80% N2 with a flow rate of 100 mL / min. At this time, products mainly composed of CO can be obtained (CO selectivity is greater than 98%).
[0065] Example 6
[0066] A method for the selective production of CH4 / CO by the photothermal catalytic hydrogenation of CO2 over a nickel-based catalyst, comprising the following steps:
[0067] 1. Take 50 mg of the nickel-based catalyst prepared in Example 1 and place it in the quartz tube of a photothermal catalytic tubular furnace, and fix it with quartz wool;
[0068] 2. Introduce 100% H2 into the quartz tube. Under this atmosphere, heat it to 450 °C at a rate of 10 °C per minute and keep it at 450 °C for 1 hour to fully reduce the catalyst. The inlet gas flow rate is 100 mL / min;
[0069] 3. Lower the temperature to 325 °C and keep it at this temperature. Switch the atmosphere to 80% H2 / 20% CO2 with a flow rate of 5 mL / min. At this time, products mainly composed of CH4 can be obtained (CH4 selectivity is greater than 96%);
[0070] 4. Raise the temperature to 500 °C and keep it at this temperature. Turn on a 300 W xenon lamp and irradiate with a power density of 1.8 W / cm 2 . The reaction atmosphere remains 80% H2 / 20% CO2 with a flow rate of 10 mL / min. At this time, products mainly composed of CO can be obtained (CO selectivity is greater than 99%).
[0071] The above is the preferred implementation manner of the present invention. Of course, the scope of the rights of the present invention cannot be limited thereby. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and changes can be made, and these improvements and changes are also regarded as the protection scope of the present invention.
Claims
1. A preparation method of a nickel-based catalyst for the selective production of CH4 / CO by photocatalytic CO2 hydrogenation, characterized in that, An aqueous solution of a soluble nickel salt, a soluble lanthanum salt or their hydrates is dropped into mesoporous silica, and the solution is fully impregnated into the mesopores. After removing the liquid, drying and calcining the obtained solid-liquid mixture, the nickel-based catalyst is obtained.
2. The preparation method of the nickel-based catalyst for the selective production of CH4 / CO by photocatalytic CO2 hydrogenation according to claim 1, characterized in that, The soluble nickel salt is at least one of Ni(NO3)2, Ni(CH3COO)2, NiCl2, NiSO4 or their hydrates, and the soluble lanthanum salt is at least one of La(NO3)3, LaCl3, LaCO3 or their hydrates.
3. The preparation method of the nickel-based catalyst for the selective production of CH4 / CO by photocatalytic CO2 hydrogenation according to claim 1, characterized in that, The range of the mass fraction W1 of nickel in the nickel-based catalyst is 2% ≤ W1 ≤ 30%, and the range of the mass fraction W2 of lanthanum oxide is 0 < W2 ≤ 30%.
4. The preparation method of the nickel-based catalyst for the selective production of CH4 / CO by photocatalytic CO2 hydrogenation according to claim 1, characterized in that, The mesoporous silica includes at least one of KIT-6, SBA-16, and SBA-15, and has a specific surface area greater than 500 m 2 / g and a pore diameter ranging from 2 to 50 nm.
5. The preparation method of the nickel-based catalyst for the selective production of CH4 / CO by photocatalytic CO2 hydrogenation according to claim 1, characterized in that, The specific steps for removing the liquid and drying are as follows: The obtained solid-liquid mixture is stirred below 60 °C until all the liquid evaporates, and then the evaporated powder is dried at 80 - 100 °C until complete.
6. The preparation method of the nickel-based catalyst for the selective production of CH4 / CO by photocatalytic CO2 hydrogenation according to claim 5, characterized in that, The stirring speed is 200 - 600 rpm.
7. The preparation method of the nickel-based catalyst for the selective production of CH4 / CO by photocatalytic CO2 hydrogenation according to claim 1, characterized in that, The calcination temperature range is 400 - 550 °C, and the calcination time is 3 - 6 h.
8. Use of a nickel-based catalyst prepared by the preparation method according to any one of claims 1-7, characterized in that, Applying the nickel-based catalyst to the photothermal catalytic hydrogenation of CO2 for the selective production of CH4 / CO includes the following steps: Step 1: Place the nickel-based catalyst in a quartz tube of a photothermal catalytic tubular furnace and conduct sufficient reduction treatment under a certain temperature and reduction atmosphere; Step 2: At a certain temperature, a mixed atmosphere with a volume ratio of H2 to CO2 of 4:1 and a flow rate of 5 - 100 mL / min is continuously introduced into the quartz tube to produce CH4 or CO. The specific process is as follows: When the temperature is 300 - 375 °C and kept warm, a product mainly composed of CH4 can be obtained, and the inlet gas flow rate is 5 - 100 mL / min; When the temperature is 450 - 600 °C and heat preservation is carried out, 0.1 - 60 W / cm 2 xenon lamp irradiation is adopted, and at this time, products mainly composed of CO can be obtained, and the inlet gas flow rate is 5 - 100 mL / min.
9. The application according to claim 8, wherein In Step 1, the reduction atmosphere is a mixed gas containing hydrogen and an inert atmosphere or high-purity H2. When it is a mixed gas, the H2 content is greater than 4%, the inert gas is N2 or Ar, the reduction temperature is 450 - 600 °C, and the inlet gas flow rate is 10 - 100 mL / min.
10. The application according to claim 8, wherein, In Step 2, the mixed atmosphere can be a H2, CO2 mixed atmosphere or a mixed atmosphere of H2, CO2 and an inert atmosphere.