A photothermal catalyst for concentrating photocatalytic CO2 reduction, its preparation method and application

Abstract

The present invention discloses a photothermal catalyst for concentrating photocatalytic CO2 reduction, its preparation method and application. In the present invention, nickel foam is used as the carrier and nickel source, and NiFe2O4 nanosheets are in-situ grown on the surface of nickel foam by hydrothermal method, and then NiFe2O4@Ni-M x / CeO2-MgO-Al2O3, where M is Cu, Co, Pt, Pd or Ru, and the range of X is 1-3. This photocatalyst has abundant oxygen vacancies, which can inhibit the influence of carbon deposition on catalytic activity, and has abundant acid-base sites, enhancing the adsorption and activation of CO2 and H2O. After calcination reduction, highly dispersed and highly active metal alloy Ni-M is obtained due to the metal-support interaction, further improving the CO2 conversion rate and the selectivity of CH4. Therefore, this catalyst exhibits high catalytic activity and excellent cycle stability in the concentrating photothermal catalytic CO2 reduction reaction.

Description

Technical Field

[0001] The present invention relates to a photothermal catalyst for concentrating photocatalytic CO2 reduction, a preparation method thereof, and an application thereof, belonging to the field. Background Art

[0002] With the development of industrial society, the excessive consumption of fossil fuels has led to a large amount of CO2 greenhouse gas emissions into the atmosphere, causing serious greenhouse effects. Converting CO2 into chemical fuels using solar energy is considered one of the most promising methods to reduce CO2 emissions and alleviate energy consumption. However, due to the huge thermodynamic barrier of CO2 molecules and the slow kinetics of multi-electron reaction steps, the reduction product selectivity is low and the photocatalytic activity is poor, severely limiting the application of photocatalytic CO2 reduction. In recent years, photothermal catalysis has been proven to be far superior to single photocatalysis or thermal catalysis in terms of conversion efficiency and product selectivity; light energy excites carriers and high-energy hot electrons, promoting the reduction of reaction activation energy, which can solve the disadvantage of high energy consumption in thermal catalysis; thermal energy accelerates the transmission, adsorption, and charge migration speed of reaction gas molecules, overcomes kinetic limitations, and provides the power required to cross the activation energy. The synergistic effect of light and heat can effectively improve the utilization rate of solar energy.

[0003] However, the current photothermal catalytic CO2 reduction technology is not yet mature. The photothermal catalysis in the reported literature still requires external heating to achieve, which goes against the original intention of energy conservation and emission reduction. In addition, the current reported photothermal catalytic CO2 reduction reaction also has problems such as low reaction rate and catalyst instability. Summary of the Invention

[0004] Object of the Invention: To overcome the problems of low reaction rate, catalyst instability, and inability to fully utilize the photothermal effect existing in the existing photothermal catalytic CO2 reduction reaction, the first object of the present invention is to provide a photothermal catalyst NiFe2O4@Ni-M X / CeO2-MgO-Al2O3 (M = Cu, Co, Pt, Pd, Ru, X = 1 - 3) for concentrating photocatalytic CO2 reduction. The second object of the present invention is to provide a preparation method of the photothermal catalyst for concentrating photocatalytic CO2 reduction. The third object of the present invention is the application of the photothermal catalyst for concentrating photocatalytic CO2 reduction in photocatalytic CO2 reduction.

[0005] Technical Solution: A photothermal catalyst for concentrating photocatalytic CO2 reduction according to the present invention, wherein the photothermal catalyst uses nickel foam as a carrier and nickel source, and NiFe2O4 nanosheets are in-situ grown on the surface of nickel foam by a hydrothermal method, and then NiFe2O4@Ni-M x / CeO2-MgO-Al2O3 is obtained by coprecipitation and calcination reduction, wherein the range of X is 1 - 3, and the M is Cu, Co, Pt, Pd or Ru.

[0006] The preparation method of the photothermal catalyst for concentrating light catalytic CO2 reduction according to the present invention includes the following steps:

[0007] (1) Pretreat the nickel foam. Dissolve ferric nitrate nonahydrate in deionized water and methanol, and while stirring, dropwise add an alkali solution to adjust the pH of the solution, and mix well to obtain a mixed solution;

[0008] (2) Mix the treated nickel foam with the mixed solution obtained in step (1), carry out a constant-temperature hydrothermal reaction, take out the nickel foam, wash it, dry it, and anneal it at a high temperature to obtain nickel foam with NiFe2O4 nanosheets grown on its surface;

[0009] (3) Dissolve nickel nitrate hexahydrate, cerium nitrate hexahydrate, magnesium nitrate hexahydrate, aluminum nitrate nonahydrate and urea in deionized water to prepare a first solution. Dropwise add a precursor solution containing M to the first solution, stir evenly, put in the nickel foam with NiFe2O4 nanosheets grown on its surface, and carry out an oil bath heating reaction. Take out the nickel foam, wash it, and dry it;

[0010] (4) Calcinate the nickel foam obtained in step (3), put it into a tubular furnace for reduction, and finally obtain a NiFe2O4@Ni-M / CeO2-MgO-Al2O3 monolithic catalyst.

[0011] Further, in step (1), the volume ratio of the deionized water to methanol is 1:1 to 2.

[0012] Further, in step (1), the concentration of ferric nitrate nonahydrate dissolved in deionized water and methanol is 0.1 to 0.15 mol / L.

[0013] Further, in step (1), the alkali solution is sodium hydroxide or potassium hydroxide.

[0014] Further, in step (1), the concentration of the alkali solution is 0.2 to 0.5 mol / L.

[0015] Further, in step (1), the pH is 9 to 12.

[0016] Further, in step (2), the temperature of the constant-temperature hydrothermal reaction is 120 to 180 °C, and the time of the constant-temperature hydrothermal reaction is 12 to 24 h.

[0017] Further, in step (2), the temperature of the high-temperature annealing is 300 to 500 °C, and the time of the high-temperature annealing is 3 to 6 h.

[0018] Further, in step (3), the molar ratio of the divalent metal ions to the trivalent metal ions in the first solution is 1 to 2:1.

[0019] Further, in step (3), the total concentration of nickel nitrate hexahydrate, cerium nitrate hexahydrate, magnesium nitrate hexahydrate, and aluminum nitrate nonahydrate in the first solution is 0.1 - 0.5 mol / L.

[0020] Further, in step (3), the molar ratio of the total moles of nickel nitrate hexahydrate, cerium nitrate hexahydrate, magnesium nitrate hexahydrate, and aluminum nitrate nonahydrate to the moles of urea is 1:10 - 30.

[0021] Further, in step (3), the precursor solution containing M is any one of copper nitrate solution, cobalt nitrate solution, chloroplatinic acid solution, palladium chloride solution, and ruthenium chloride solution.

[0022] Further, in step (3), the molar ratio of M to nickel nitrate hexahydrate is 1 - 3:1.

[0023] Further, in step (3), the temperature of the oil bath heating reaction is 100 - 160 °C, and the time of the oil bath heating reaction is 18 - 24 h.

[0024] Further, in step (4), the calcination temperature is 350 - 500 °C, and the calcination time is 6 - 10 h.

[0025] Further, in step (4), the reducing gas used for reduction is a H2 - Ar mixed gas with a volume ratio of 5:95 - 10:90, the reduction temperature is 100 - 150 °C, and the reduction time is 15 - 30 min.

[0026] Application of the photothermal catalyst for concentrating photocatalytic CO2 reduction according to the present invention in photocatalytic CO2 reduction.

[0027] Further, place the photothermal catalyst of the present invention on 0.3 - 0.5 g of quartz wool, use two Fresnel lenses to focus simulated sunlight on the surface of the catalyst, adjust the light intensity by adjusting the distance between the photocatalyst and the lens, and the light intensity is 400 - 4500 mW / cm 2 , the reaction gas is a CO2 - N2 mixed gas with a volume ratio of 10:90 - 15:85, and the time for the photocatalytic reduction reaction is 0.5 - 3 h.

[0028] Beneficial effects: Compared with the prior art, the present invention has the following remarkable advantages:

[0029] (1) The preparation method of the present invention is simple, has high repeatability, and is suitable for large-scale production.

[0030] (2) The NiFe2O4 nanosheets in-situ grown with nickel foam as the carrier and nickel source in the present invention have excellent light absorption ability under ultraviolet-visible light, and the photoinduced thermal effect promotes the improvement of the CO2 reaction rate.

[0031] (3) Ni-M / CeO2-MgO-Al2O3 (M = Cu, Co, Pt, Pd, Ru) nanosheets are loaded on the surface of NiFe2O4 to add more reactive sites; the finally constructed monolithic catalyst not only has abundant oxygen vacancies to inhibit the influence of carbon deposition on the catalytic activity, but also has abundant acid-base sites to enhance the adsorption and activation of CO2 and H2O.

[0032] (4) After calcination and reduction, due to the metal-support interaction, highly dispersed and highly active metal alloy Ni-M can be obtained, further improving the conversion rate of CO2 and the selectivity of CH4.

[0033] (5) CeO2 in the present invention has both the characteristics of photocatalysis and thermocatalysis. Its abundant oxygen vacancies can timely eliminate the deposited carbon at high temperatures. Therefore, this photocatalyst can maintain good anti-coking property and chemical stability under concentrated high temperature.

[0034] (6) The photocatalyst prepared in the present invention has abundant acid-base sites, enhancing the adsorption and activation of CO2 and H2O, and realizing a high-performance photothermal-driven CO2 reduction reaction. Therefore, this photocatalyst exhibits high catalytic activity in the concentrated photothermal catalytic CO2 reduction reaction. Description of the Drawings

[0035] Figure 1 is the operation flow chart of the present invention;

[0036] Figure 2 is the electron microscope image of the monolithic photocatalyst NiFe2O4@Ni-Cu2 / CeO2-MgO-Al2O3 prepared in Example 6. Detailed Embodiments

[0037] The technical solutions of the present invention will be further described below with reference to the drawings.

[0038] As Figure 1 shown, a preparation method of a photothermal catalyst for concentrated catalytic CO2 reduction in the present invention uses nickel foam as the carrier and nickel source, and hydrothermal method is used to in-situ grow NiFe2O4 nanosheets on the surface of nickel foam, and then a monolithic catalyst NiFe2O4@Ni-M / CeO2-MgO-Al2O3 is formed through coprecipitation method and calcination reduction; wherein, the range of X is 1-3, and M = Cu, Co, Pt, Pd, Ru.

[0039] Example 1

[0040] (1) Using 1 cm × 1.5 cm nickel foam as the substrate, the nickel foam was pretreated. 1 mol / L hydrochloric acid was used to remove the surface oxides, and then deionized water was used to rinse the residual hydrochloric acid and other impurities. Finally, it was placed in an oven and dried for 12 h for standby. Weigh 2.42 g of ferric nitrate nonahydrate and dissolve it in 30 mL of deionized water and

[0041] 30 mL of methanol to form a yellowish-brown solution. While stirring, 0.2 mol / L sodium hydroxide solution was added dropwise to the above yellowish-brown solution to adjust the solution pH = 11, and the mixture was fully mixed to obtain a mixed solution.

[0042] (2) The pretreated nickel foam and the above mixed solution were transferred to a high-pressure reactor and reacted at 180 °C for 12 h. After the reaction, the nickel foam was taken out, washed, and dried, and then placed in a muffle furnace and heated to 500 °C at a heating rate of 5 °C / min and held for 3 h to obtain nickel foam with NiFe2O4 nanosheets grown on its surface.

[0043] (3) Weigh 0.58 g of nickel nitrate hexahydrate, 0.43 g of cerium nitrate hexahydrate, 0.51 g of magnesium nitrate hexahydrate, 0.38 g of aluminum nitrate nonahydrate, and 3.6 g of urea and dissolve them in 60 mL of deionized water to prepare a first solution. 100 mL of 0.35 mol / L copper nitrate solution was added dropwise to the first solution, and after stirring evenly, it was transferred to a round-bottom flask. The nickel foam with NiFe2O4 nanosheets grown on its surface was placed in the round-bottom flask, and the mixture was heated in an oil bath at 100 °C for 24 h. After the reaction, the nickel foam was washed and dried. Subsequently, the nickel foam was placed in a muffle furnace and heated to 400 °C at a heating rate of 5 °C / min and held for 8 h, and then placed in a tubular furnace with a 10% H2 and 90% Ar atmosphere and heated to 125 °C at a heating rate of 2 °C / min and held for 20 min for reduction, finally obtaining the NiFe2O4@Ni-Cu1 / CeO2-MgO-Al2O3 monolithic photocatalyst.

[0044] Example 2

[0045] (1) Using 1 cm × 1.5 cm nickel foam as the substrate, the nickel foam was pretreated. 1 mol / L hydrochloric acid was used to remove the surface oxides, and then deionized water was used to rinse the residual hydrochloric acid and other impurities. Finally, it was placed in an oven and dried for 12 h for standby. Weigh 2.42 g of ferric nitrate nonahydrate and dissolve it in 30 mL of deionized water and 30 mL of methanol to form a yellowish-brown solution. While stirring, 0.2 mol / L sodium hydroxide solution was added dropwise to the above yellowish-brown solution to adjust the solution pH = 11, and the mixture was fully mixed to obtain a mixed solution.

[0046] (2) Transfer the pretreated nickel foam and the above mixed solution into a high-pressure reactor and react at 180 °C for 12 h. After the reaction, take out the nickel foam, wash and dry it. Then place it in a muffle furnace and heat it to 500 °C at a heating rate of 5 °C / min and hold for 3 h to obtain nickel foam with NiFe2O4 nanosheets grown on its surface.

[0047] (3) Weigh 0.58 g of nickel nitrate hexahydrate, 0.43 g of cerium nitrate hexahydrate, 0.51 g of magnesium nitrate hexahydrate, 0.38 g of aluminum nitrate nonahydrate and 3.6 g of urea and dissolve them in 60 mL of deionized water to prepare a first solution. Add 100 mL of 0.35 mol / L cobalt nitrate solution dropwise to the first solution, stir evenly and transfer it to a round-bottom flask. Place the nickel foam with NiFe2O4 nanosheets grown on its surface in the round-bottom flask and heat it in an oil bath at 100 °C for 24 h. After the reaction, wash and dry the nickel foam. Subsequently, place the nickel foam in a muffle furnace, heat it to 400 °C at a heating rate of 5 °C / min and hold for 8 h, then place it in a tubular furnace with an atmosphere of 10% H2 and 90% Ar, heat it to 125 °C at a heating rate of 2 °C / min and hold for 20 min for reduction, and finally obtain the NiFe2O4@Ni-Co1 / CeO2-MgO-Al2O3 monolithic photocatalyst.

[0048] Example 3

[0049] (1) Using 1 cm × 1.5 cm nickel foam as the substrate, pretreat the nickel foam. Use 1 mol / L hydrochloric acid to remove the surface oxides, then use deionized water to rinse the residual hydrochloric acid and other impurities, and finally place it in an oven and dry it for 12 h for standby. Weigh 2.42 g of ferric nitrate nonahydrate and dissolve it in 30 mL of deionized water and 30 mL of methanol to form a yellowish-brown solution. While stirring, add 0.2 mol / L sodium hydroxide solution dropwise to the above yellowish-brown solution to adjust the solution pH = 11, and mix well to obtain a mixed solution.

[0050] (2) Transfer the pretreated nickel foam and the above mixed solution into a high-pressure reactor and react at 180 °C for 12 h. After the reaction, take out the nickel foam, wash and dry it. Then place it in a muffle furnace and heat it to 500 °C at a heating rate of 5 °C / min and hold for 3 h to obtain nickel foam with NiFe2O4 nanosheets grown on its surface.

[0051] (3) Weigh 0.58 g of nickel nitrate hexahydrate, 0.43 g of cerium nitrate hexahydrate, 0.51 g of magnesium nitrate hexahydrate, 0.38 g of aluminum nitrate nonahydrate and 3.6 g of urea, dissolve them in 60 mL of deionized water to prepare a first solution. Drop 100 mL of 0.35 mol / L chloroplatinic acid solution into the first solution, stir evenly and transfer it to a round-bottom flask. Put nickel foam with NiFe2O4 nanosheets grown on its surface into the round-bottom flask, heat it in an oil bath to 100 °C and react for 24 h. After the reaction, wash and dry the nickel foam. Then put the nickel foam into a muffle furnace, heat it to 400 °C at a heating rate of 5 °C / min and keep it warm for 8 h, and then put it into a tube furnace with an atmosphere of 10% H2 and 90% Ar, heat it to 125 °C at a heating rate of 2 °C / min and keep it warm for 20 min for reduction, and finally obtain the NiFe2O4@Ni-Pt1 / CeO2-MgO-Al2O3 monolithic photocatalyst.

[0052] Example 4

[0053] (1) Using 1 cm × 1.5 cm nickel foam as the substrate, pretreat the nickel foam. Use 1 mol / L hydrochloric acid to remove the surface oxides, then use deionized water to rinse the residual hydrochloric acid and other impurities, and finally put it into an oven to dry for 12 h for standby. Weigh 2.42 g of ferric nitrate nonahydrate and dissolve it in 30 mL of deionized water and 30 mL of methanol to form a yellowish-brown solution. While stirring, drop 0.2 mol / L sodium hydroxide solution into the above yellowish-brown solution to adjust the solution pH = 11, and mix well to obtain a mixed solution.

[0054] (2) Transfer the pretreated nickel foam and the above mixed solution together to an autoclave and react at 180 °C for 12 h. After the reaction, take out the nickel foam, wash and dry it, and then place it in a muffle furnace and heat it to 500 °C at a heating rate of 5 °C / min and keep it warm for 3 h to obtain nickel foam with NiFe2O4 nanosheets grown on its surface.

[0055] (3) Weigh 0.58 g of nickel nitrate hexahydrate, 0.43 g of cerium nitrate hexahydrate, 0.51 g of magnesium nitrate hexahydrate, 0.38 g of aluminum nitrate nonahydrate and 3.6 g of urea, dissolve them in 60 mL of deionized water to prepare a first solution. Add 100 mL of 0.35 mol / L palladium chloride solution dropwise to the first solution. After stirring evenly, transfer it to a round-bottom flask. Place nickel foam with NiFe2O4 nanosheets grown on its surface in the round-bottom flask, and heat it in an oil bath at 100 °C for 24 h. After the reaction, wash and dry the nickel foam. Then place this nickel foam in a muffle furnace and heat it to 400 °C at a heating rate of 5 °C / min and keep it warm for 8 h. Then put it into a tube furnace with an atmosphere of 10% H2 and 90% Ar, heat it to 125 °C at a heating rate of 2 °C / min and keep it warm for 20 min for reduction, and finally obtain the NiFe2O4@Ni-Pd1 / CeO2-MgO-Al2O3 monolithic photocatalyst.

[0056] Example 5

[0057] (1) Using 1 cm × 1.5 cm nickel foam as the substrate, pretreat the nickel foam. Use 1 mol / L hydrochloric acid to remove the surface oxides, then use deionized water to rinse the residual hydrochloric acid and other impurities, and finally place it in an oven to dry for 12 h for standby. Weigh 2.42 g of ferric nitrate nonahydrate and dissolve it in 30 mL of deionized water and 30 mL of methanol to form a yellowish-brown solution. While stirring, add 0.2 mol / L sodium hydroxide solution dropwise to the above yellowish-brown solution to adjust the solution pH = 11, and mix well to obtain a mixed solution.

[0058] (2) Transfer the pretreated nickel foam and the above mixed solution together to a high-pressure reaction kettle and react at 180 °C for 12 h. After the reaction, take out the nickel foam, wash and dry it, and then place it in a muffle furnace and heat it to 500 °C at a heating rate of 5 °C / min and keep it warm for 3 h to obtain nickel foam with NiFe2O4 nanosheets grown on its surface.

[0059] (3) Weigh 0.58 g of nickel nitrate hexahydrate, 0.43 g of cerium nitrate hexahydrate, 0.51 g of magnesium nitrate hexahydrate, 0.38 g of aluminum nitrate nonahydrate and 3.6 g of urea, dissolve them in 60 mL of deionized water to prepare a first solution. Add 100 mL of 0.35 mol / L ruthenium chloride solution dropwise to the first solution. After stirring evenly, transfer it to a round-bottom flask. Place nickel foam with NiFe2O4 nanosheets grown on its surface in the round-bottom flask, and heat it in an oil bath at 100 °C for 24 h. After the reaction, wash and dry the nickel foam. Then put the nickel foam into a muffle furnace, heat it to 400 °C at a heating rate of 5 °C / min and keep it warm for 8 h. Then put it into a tubular furnace with an atmosphere of 10% H2 and 90% Ar, heat it to 125 °C at a heating rate of 2 °C / min and keep it warm for 20 min for reduction, and finally obtain the NiFe2O4@Ni-Ru1 / CeO2-MgO-Al2O3 monolithic photocatalyst.

[0060] Example 6

[0061] (1) Using 1 cm × 1.5 cm nickel foam as the substrate, pretreat the nickel foam. Use 1 mol / L hydrochloric acid to remove the surface oxides, then use deionized water to rinse the residual hydrochloric acid and other impurities, and finally put it into an oven to dry for 12 h for standby. Weigh 2.42 g of ferric nitrate nonahydrate and dissolve it in 30 mL of deionized water and 30 mL of methanol to form a yellow-brown solution. While stirring, add 0.2 mol / L sodium hydroxide solution dropwise to the above yellow-brown solution to adjust the solution pH = 11, and mix well to obtain a mixed solution.

[0062] (2) Transfer the pretreated nickel foam and the above mixed solution to a high-pressure reaction kettle and react at 180 °C for 12 h. After the reaction, take out the nickel foam, wash and dry it. Then place it in a muffle furnace and heat it to 500 °C at a heating rate of 5 °C / min and keep it warm for 3 h to obtain nickel foam with NiFe2O4 nanosheets grown on its surface.

[0063] (3) Weigh 0.58 g of nickel nitrate hexahydrate, 0.43 g of cerium nitrate hexahydrate, 0.51 g of magnesium nitrate hexahydrate, 0.38 g of aluminum nitrate nonahydrate and 3.6 g of urea, dissolve them in 60 mL of deionized water to prepare a first solution. Add 200 mL of 0.35 mol / L copper nitrate solution dropwise to the first solution. After stirring evenly, transfer it to a round-bottom flask. Put nickel foam with NiFe2O4 nanosheets grown on its surface into the round-bottom flask, and heat it in an oil bath at 100 °C for 24 h. After the reaction, wash and dry the nickel foam. Subsequently, put the nickel foam into a muffle furnace, heat it at a heating rate of 5 °C / min to 400 °C and hold for 8 h, then put it into a tube furnace with an atmosphere of 10% H2 and 90% Ar, heat it at a heating rate of 2 °C / min to 125 °C and hold for 20 min for reduction, and finally obtain the NiFe2O4@Ni-Cu2 / CeO2-MgO-Al2O3 monolithic photocatalyst.

[0064] Perform scanning electron microscopy analysis on the NiFe2O4@Ni-Cu2 / CeO2-MgO-Al2O3 monolithic photocatalyst prepared in this example, and the results are as Figure 2 shown. As Figure 2 can be seen, vertically interlaced NiFe2O4 nanosheets grow in-situ on the surface of the nickel foam, and Ni-Cu2 / CeO2-MgO-Al2O3 ultrathin nanosheets are loaded on the surface of the NiFe2O4 nanosheets. Such a catalyst structure is conducive to exposing more catalytic active sites and improving the light utilization efficiency.

[0065] Example 7

[0066] (1) Using a 1 cm × 1.5 cm nickel foam as the substrate, pre-treat the nickel foam. Use 1 mol / L hydrochloric acid to remove the surface oxide, then use deionized water to rinse the residual hydrochloric acid and other impurities, and finally put it into an oven to dry for 12 h for standby. Weigh 2.42 g of ferric nitrate nonahydrate and dissolve it in 30 mL of deionized water and 30 mL of methanol to form a yellow-brown solution. While stirring, add 0.2 mol / L sodium hydroxide solution dropwise to the above yellow-brown solution to adjust the solution pH = 11, and mix well to obtain a mixed solution.

[0067] (2) Transfer the pre-treated nickel foam and the above mixed solution together to a high-pressure reaction kettle and react at 180 °C for 12 h. After the reaction, take out the nickel foam, wash and dry it. Then place it in a muffle furnace and heat it at a heating rate of 5 °C / min to 500 °C and hold for 3 h to obtain nickel foam with NiFe2O4 nanosheets grown on its surface.

[0068] (3) Weigh 0.58 g of nickel nitrate hexahydrate, 0.43 g of cerium nitrate hexahydrate, 0.51 g of magnesium nitrate hexahydrate, 0.38 g of aluminum nitrate nonahydrate and 3.6 g of urea, dissolve them in 60 mL of deionized water to prepare a first solution. Add 300 mL of 0.35 mol / L copper nitrate solution dropwise to the first solution, stir evenly and transfer it to a round-bottom flask. Place nickel foam with NiFe2O4 nanosheets grown on its surface in the round-bottom flask, heat it in an oil bath to 100 °C and react for 24 h. After the reaction, wash and dry the nickel foam. Subsequently, put the nickel foam into a muffle furnace, heat it to 400 °C at a heating rate of 5 °C / min and hold for 8 h, then put it into a tubular furnace with a 10% H2 and 90% Ar atmosphere, heat it to 125 °C at a heating rate of 2 °C / min and hold for 20 min for reduction, and finally obtain the NiFe2O4@Ni-Cu3 / CeO2-MgO-Al2O3 monolithic photocatalyst.

[0069] The monolithic photothermal catalysts prepared in Examples 1-7 were used for photocatalytic CO2 reduction reaction under a concentrating reaction device: Place the monolithic photocatalyst on 0.3 g of quartz wool, use two Fresnel lenses to focus the simulated sunlight on the surface of the monolithic photocatalyst, the distance between the monolithic photocatalyst and the lens is 50 mm, and the light intensity is 4500 mW / cm 2 . Use a CO2-N2 mixed gas with a volume ratio of 10:90 as the reaction gas, carry out the photocatalytic reduction reaction for 3 h, and the results are shown in the table.

[0070] Table 1 shows the comparison of the performance of the monolithic catalysts prepared in Examples 1-7 for concentrating catalytic CO2 reduction reaction

[0071]

[0072]

[0073] It can be seen from Table 1 that the monolithic photocatalysts prepared in Examples 1-7 all have good activity for catalytic CO2 reduction, and the monolithic photocatalyst NiFe2O4@Ni-Cu2 / CeO2-MgO-Al2O3 in Example 6 shows the best photocatalytic activity in the concentrating catalytic CO2 reduction reaction and can efficiently reduce the greenhouse gas CO2 into solar fuels (CO\CH4).

[0074] Comparative Example 1

[0075] (1) Using 1 cm × 1.5 cm nickel foam as the substrate, pretreat the nickel foam, use 1 mol / L hydrochloric acid to remove the surface oxides, then use deionized water to rinse the residual hydrochloric acid and other impurities, and finally put it into an oven to dry for 12 h for standby.

[0076] (2) Weigh 0.58 g of nickel nitrate hexahydrate, 0.43 g of cerium nitrate hexahydrate, 0.51 g of magnesium nitrate hexahydrate, 0.38 g of aluminum nitrate nonahydrate and 3.6 g of urea, dissolve them in 60 mL of deionized water to prepare a first solution. Add 200 mL of 0.35 mol / L copper nitrate solution dropwise to the first solution. After stirring evenly, transfer it to a round-bottom flask. Put the pretreated nickel foam into the round-bottom flask, and heat it in an oil bath at 100 °C for 24 h. After the reaction, wash and dry the nickel foam. Then put the nickel foam into a muffle furnace, heat it at a heating rate of 5 °C / min to 400 °C and hold for 8 h, and then put it into a tube furnace with an atmosphere of 10% H2 and 90% Ar, heat it at a heating rate of 2 °C / min to 125 °C and hold for 20 min for reduction, finally obtaining the Ni-Cu2 / CeO2-MgO-Al2O3 monolithic photocatalyst.

[0077] Comparative Example 2

[0078] (1) Using a 1 cm × 1.5 cm nickel foam as the substrate, pretreat the nickel foam. Use 1 mol / L hydrochloric acid to remove the surface oxides, then use deionized water to rinse the residual hydrochloric acid and other impurities, and finally put it into an oven to dry for 12 h for standby. Weigh 2.42 g of iron nitrate nonahydrate and dissolve it in 30 mL of deionized water and 30 mL of methanol to form a yellowish-brown solution. While stirring, add 0.2 mol / L sodium hydroxide solution dropwise to the above yellowish-brown solution to adjust the solution pH = 11, and mix well to obtain a mixed solution.

[0079] (2) Transfer the pretreated nickel foam and the above mixed solution to a high-pressure reactor and react at 180 °C for 12 h. After the reaction, take out the nickel foam, wash and dry it. Then place it in a muffle furnace and heat it at a heating rate of 5 °C / min to 500 °C and hold for 3 h to obtain nickel foam with NiFe2O4 nanosheets grown on its surface.

[0080] (3) Weigh 0.58 g of nickel nitrate hexahydrate, 0.51 g of magnesium nitrate hexahydrate, 0.38 g of aluminum nitrate nonahydrate and 3.6 g of urea, dissolve them in 60 mL of deionized water to prepare a first solution. Add 200 mL of 0.35 mol / L copper nitrate solution dropwise to the first solution. After stirring evenly, transfer it to a round-bottom flask. Put the nickel foam with NiFe2O4 nanosheets grown on its surface into the round-bottom flask, and heat it in an oil bath at 100 °C for 24 h. After the reaction, wash and dry the nickel foam. Then put the nickel foam into a muffle furnace, heat it at a heating rate of 5 °C / min to 400 °C and hold for 8 h, and then put it into a tube furnace with an atmosphere of 10% H2 and 90% Ar, heat it at a heating rate of 2 °C / min to 125 °C and hold for 20 min for reduction, finally obtaining the NiFe2O4@Ni-Cu2 / MgO-Al2O3 monolithic photocatalyst.

[0081] Comparative Example 3

[0082] (1) Using 1 cm × 1.5 cm nickel foam as the substrate, the nickel foam was pretreated. 1 mol / L hydrochloric acid was used to remove the surface oxides, and then deionized water was used to rinse the residual hydrochloric acid and other impurities. Finally, it was placed in an oven and dried for 12 h for standby. Weigh 2.42 g of ferric nitrate nonahydrate and dissolve it in 30 mL of deionized water and 30 mL of methanol to form a yellowish-brown solution. While stirring, 0.2 mol / L sodium hydroxide solution was added dropwise to the above yellowish-brown solution to adjust the solution pH = 11, and the mixture was fully mixed to obtain a mixed solution.

[0083] (2) The pretreated nickel foam and the above mixed solution were transferred to a high-pressure reactor and reacted at 180 °C for 12 h. After the reaction, the nickel foam was taken out, washed and dried. Then it was placed in a muffle furnace and heated to 500 °C at a heating rate of 5 °C / min and held for 3 h to obtain nickel foam with NiFe2O4 nanosheets grown on its surface.

[0084] (3) Weigh 0.58 g of nickel nitrate hexahydrate, 0.43 g of cerium nitrate hexahydrate and 3.6 g of urea and dissolve them in 60 mL of deionized water to prepare a first solution. 200 mL of 0.35 mol / L copper nitrate solution was added dropwise to the first solution. After stirring evenly, it was transferred to a round-bottom flask. The nickel foam with NiFe2O4 nanosheets grown on its surface was placed in the round-bottom flask and heated in an oil bath at 100 °C for 24 h. After the reaction, the nickel foam was washed and dried. Subsequently, the nickel foam was placed in a muffle furnace and heated to 400 °C at a heating rate of 5 °C / min and held for 8 h, and then placed in a tube furnace with a 10% H2 and 90% Ar atmosphere and heated to 125 °C at a heating rate of 2 °C / min and held for 20 min for reduction to finally obtain the NiFe2O4@Ni-Cu2 / CeO2 monolithic photocatalyst.

[0085] Comparative Example 4

[0086] (1) Using 1 cm × 1.5 cm nickel foam as the substrate, the nickel foam was pretreated. 1 mol / L hydrochloric acid was used to remove the surface oxides, and then deionized water was used to rinse the residual hydrochloric acid and other impurities. Finally, it was placed in an oven and dried for 12 h for standby. Weigh 2.42 g of ferric nitrate nonahydrate and dissolve it in 30 mL of deionized water and 30 mL of methanol to form a yellowish-brown solution. While stirring, 0.2 mol / L sodium hydroxide solution was added dropwise to the above yellowish-brown solution to adjust the solution pH = 11, and the mixture was fully mixed to obtain a mixed solution.

[0087] (3) Transfer the pretreated nickel foam and the above mixed solution into a high-pressure reactor and react at 180 °C for 12 h. After the reaction, take out the nickel foam, wash and dry it. Then place it in a muffle furnace and heat it to 500 °C at a heating rate of 5 °C / min and hold for 3 h to obtain nickel foam with NiFe2O4 nanosheets grown on its surface.

[0088] (3) Weigh 0.43 g of cerium nitrate hexahydrate, 0.51 g of magnesium nitrate hexahydrate, 0.38 g of aluminum nitrate nonahydrate and 3.6 g of urea, dissolve them in 60 mL of deionized water to prepare a first solution. After stirring evenly, transfer it to a round-bottom flask. Place the nickel foam with NiFe2O4 nanosheets grown on its surface in the round-bottom flask, and heat it in an oil bath at 100 °C for 24 h. After the reaction, wash and dry the nickel foam. Subsequently, place the nickel foam in a muffle furnace, heat it to 400 °C at a heating rate of 5 °C / min and hold for 8 h, then put it into a tubular furnace with an atmosphere of 10% H2 and 90% Ar, heat it to 125 °C at a heating rate of 2 °C / min and hold for 20 min for reduction, and finally obtain the NiFe2O4@ / CeO2-MgO-Al2O3 monolithic photocatalyst.

[0089] Use the monolithic photocatalysts in Comparative Examples 1, 2, 3, 4 and Example 6 to carry out the photocatalytic CO2 reduction reaction in a concentrating reaction device: Place the monolithic photocatalyst on 0.3 g of quartz wool, use two Fresnel lenses to focus the simulated sunlight on the surface of the catalyst. The monolithic photocatalyst is 50 mm away from the lens, and the light intensity is 4500 mW / cm 2 . Use a CO2-N2 mixed gas with a volume ratio of 10:90 as the reaction gas and carry out the photocatalytic reduction reaction for 3 h. The results are shown in Table 2.

[0090] Table 2 Comparison of the performance of the monolithic catalysts in Comparative Examples 1-4 and Example 6 for concentrating catalytic CO2 reduction

[0091]

[0092] It can be seen from Table 2 that the monolithic photocatalyst NiFe2O4@Ni-Cu2 / CeO2-MgO-Al2O3 in Example 6 is far superior to the monolithic photocatalysts in Comparative Examples 1-4 in the concentrating catalytic CO2 reduction reaction, showing the best photocatalytic activity, which benefits from the multiple effects of the oxygen vacancies of CeO2, the acid-base sites of MgO and Al2O3, the Ni-Cu alloy and the light absorption ability of NiFe2O4.

Claims

1. A photothermal catalyst for concentrating photocatalytic CO2 reduction, characterized in that, The photothermal catalyst uses nickel foam as the carrier and nickel source, and NiFe2O4 nanosheets are in-situ grown on the surface of nickel foam by hydrothermal method, and then NiFe2O4@Ni-M x / CeO2-MgO-Al2O3 is obtained by coprecipitation method and calcination reduction, where the range of X is 1-3, and M is Cu, Co, Pt, Pd or Ru.

2. The preparation method of the photothermal catalyst for concentrating light catalytic CO2 reduction according to claim 1, wherein, Including the following steps: (1) Pretreat the nickel foam. Dissolve ferric nitrate nonahydrate in deionized water and methanol, dropwise add an alkali solution while stirring to adjust the pH of the solution, and fully mix to obtain a mixed solution; (2) Mix the treated nickel foam with the mixed solution obtained in step (1), carry out a hydrothermal reaction at a constant temperature, take out the nickel foam, wash it, dry it, and anneal it at a high temperature to obtain nickel foam with NiFe2O4 nanosheets grown on its surface; (3) Dissolve nickel nitrate hexahydrate, cerium nitrate hexahydrate, magnesium nitrate hexahydrate, aluminum nitrate nonahydrate and urea in deionized water to prepare a first solution. Dropwise add a precursor solution containing M to the first solution and stir evenly. Put in the nickel foam with NiFe2O4 nanosheets grown on its surface, carry out an oil bath heating reaction, take out the nickel foam, wash it, and dry it; (4) Calcinate the nickel foam obtained in step (3), put it into a tubular furnace for reduction, and finally obtain the NiFe2O4@Ni-M x / CeO2-MgO-Al2O3 monolithic catalyst.

3. The preparation method according to claim 2, characterized in that, In step (1), the volume ratio of the deionized water to methanol is 1:1 - 2, the concentration of ferric nitrate nonahydrate dissolved in deionized water and methanol is 0.1 - 0.15 mol / L, the alkali solution is sodium hydroxide or potassium hydroxide, the concentration of the alkali solution is 0.2 - 0.5 mol / L, and the pH is 9 - 12.

4. The preparation method according to claim 2, wherein In step (2), the temperature of the hydrothermal reaction at a constant temperature is 120 - 180 °C, the time of the hydrothermal reaction at a constant temperature is 12 - 24 h, the temperature of the high-temperature annealing is 300 - 500 °C, and the time of the high-temperature annealing is 3 - 6 h.

5. The preparation method according to claim 2, characterized in that, In step (3), the molar ratio of the divalent metal ions to the trivalent metal ions in the first solution is 1 - 2:1, the total concentration of nickel nitrate hexahydrate, cerium nitrate hexahydrate, magnesium nitrate hexahydrate, and aluminum nitrate nonahydrate in the first solution is 0.1 - 0.5 mol / L, and the molar ratio of the total moles of nickel nitrate hexahydrate, cerium nitrate hexahydrate, magnesium nitrate hexahydrate, aluminum nitrate nonahydrate to urea is 1:10 - 30.

6. The preparation method according to claim 2, characterized in that In step (3), the precursor solution containing M is any one of copper nitrate solution, cobalt nitrate solution, chloroplatinic acid solution, palladium chloride solution and ruthenium chloride solution. The molar ratio of M to nickel nitrate hexahydrate is 1 - 3:1, the temperature of the oil bath heating reaction is 100 - 160 °C, and the time of the oil bath heating reaction is 18 - 24 h.

7. The preparation method according to claim 2, characterized in that, In step (4), the temperature of the calcination is 350 - 500 °C, and the time of the calcination is 6 - 10 h.

8. The preparation method according to claim 2, characterized in that, In step (4), the reducing gas used for reduction is a H2-Ar mixed gas with a volume ratio of 5:95 - 10:90, the temperature of the reduction is 100 - 150 °C, and the time of the reduction is 15 - 30 min.

9. Application of the photothermal catalyst for concentrating photocatalytic CO2 reduction according to claim 1 in photocatalytic CO2 reduction.

10. The application according to claim 9, wherein Place the photocatalyst described in claim 1 on 0.3 - 0.5 g of quartz wool, and use two Fresnel lenses to focus the simulated sunlight on the surface of the catalyst. Adjust the light intensity by adjusting the distance between the photocatalyst and the lens. The light intensity is 400 - 4500 mW / cm 2 , and the reaction gas is a CO2-N2 mixed gas with a volume ratio of 10:90 - 15:

85. The time for the photocatalytic reduction reaction is 0.5 - 3 h.

Images