Ni-doped rare earth metal type nano oxide as well as preparation method and application thereof

Abstract

The invention provides a Ni-doped rare earth metal type nano oxide as well as a preparation method and application thereof. According to the preparation method, the rare earth metal source and the Ni source are directly mixed, then the precursor is prepared, reduction is carried out, in the obtained nano oxide, Ni shows atomic-scale dispersion and mainly shows Ni < 2 + >, and rich, evenly-distributed and stable Ni-O active sites can be constructed. Besides, by the adoption of the method, the content of the Ni element in the Ni-doped rare earth metal type nano oxide can reach about 10 wt% and is far higher than the level in the prior art. In addition, according to the preparation method, synthesis raw materials are easy to obtain, the method is simple, convenient and short in time consumption, and large-scale production is easy to achieve. Tests show that the Ni-doped rare earth metal type nano oxide has excellent photo-thermal catalytic activity.

Description

Technical Field

[0001] The present invention belongs to the field of nano material synthesis, and specifically relates to a Ni-doped rare earth metal nano oxide and a preparation method and application thereof, and in particular to a Ni / CeO x Nano oxides and their preparation methods and applications. Background Art

[0002] Dry reforming of methane (DRM) can simultaneously utilize CO 2 and CH 4 These two main greenhouse gases produce valuable syngas (CO+H 2 ), so it was proposed and studied (Chem Rev. 2017,117(13), 8497-8520). Synthesis gas can be further synthesized into important raw materials for high-value chemicals such as olefins and gasoline through the Fischer-Tropsch synthesis method. Therefore, the DRM reaction can not only effectively mitigate the greenhouse effect, but also provide a viable alternative to traditional fossil fuels, thereby promoting the sustainable development of future energy. In addition, the advancement of this technology makes it possible to effectively exploit natural gas with high carbon dioxide content, paving the way for its wider application, while traditional steam reforming methods are difficult to utilize this resource.

[0003] Due to CO 2 and CH 4 Very stable and difficult to activate, resulting in a DRM energy requirement of up to 247 kJ mol -1 , usually requires a high temperature of 700~1000°C, plus a pressure of 1~30 atmospheres to drive the reaction, resulting in a lot of energy consumption. Therefore, in order to promote the occurrence of low-temperature DRM reactions, clean and sustainable light energy can be introduced as an alternative energy source. To date, various catalysts for light-driven DRM have been developed. Among various catalysts, Ni-based materials exhibit excellent methane cracking ability, with activity comparable to that of precious metal catalysts, and their prices are much lower than those of precious metals. However, Ni-based catalysts are prone to sintering, resulting in a reduction in the number of active sites. In addition, excessive carbon deposition will cause significant deactivation of the catalyst after several cycles. This is because the equilibrium constant of the methane cracking reaction on the Ni surface is higher than that of precious metals, which promotes the formation and growth of inactive carbon nanotubes and graphitic carbon layers, blocking the catalyst active sites.

[0004] Based on the above problems, Akri et al. prepared a single-atom catalyst Ni / HAP-Ce catalyst to inhibit carbon deposition caused by excessive cracking of methane, but when the Ni loading was increased to 10 wt%, Ni particles were still formed (Nat Commun. 2019, 10, 5181). Tavasoli et al. selectively phosphated CeO 2 Nanorod support surface to adjust Ni-CeO 2 Photocatalytic performance, but its activity is still low (Nat Commun. 2023, 14, 1435). Therefore, how to further improve the stability of Ni-based catalysts while retaining their high activity through simple and effective methods is still an urgent requirement for their practical application. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a Ni-doped rare earth metal nano-oxide and a preparation method and application thereof. The Ni-doped rare earth metal nano-oxide has excellent stability and high activity for photothermal catalytic methane dry reforming reaction.

[0006] To achieve this object, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a Ni-doped rare earth metal nano-oxide, which is prepared by heating a mixture of a rare earth metal source and a Ni source to form a precursor, followed by reduction.

[0007] Preferably, the mass content of Ni element in the rare earth metal nano-oxide is 8.5-10 wt%.

[0008] Preferably, the rare earth metal in the rare earth metal source is selected from any one or more of Ce, La, Sm or Nd, preferably Ce.

[0009] In a second aspect, the present invention provides a method for preparing the above-mentioned Ni-doped rare earth metal type nano oxide, comprising the following steps: S1: After mixing a rare earth metal source, a Ni source and a solvent, the obtained mixture is reacted under heating conditions to obtain a precursor; S2: After reducing the precursor, Ni-doped rare earth metal nano-oxide is obtained.

[0010] Preferably, the rare earth metal source is selected from Ce(NO 3 ) 3 6H 2 O、La(NO 3 ) 2 6H 2 O、Sm(NO 3 ) 2 6H 2O、Nd(NO 3 ) 2 6H 2 O、CeCl 3 7H 2 O、LaCl 3 7H 2 O、SmCl 3 6H 2 O or NdCl 3 6H 2 Any one or more of O.

[0011] Preferably, the Ni source is selected from Ni(NO 3 ) 2 6H 2 O and / or NiCl 2 6H 2 O.

[0012] Preferably, the solvent is selected from triethylene glycol and / or ethylene glycol.

[0013] Preferably, the molar ratio of the rare earth metal source to the Ni source is (3.0-3.6):1.

[0014] Preferably, the rare earth metal source is completely dissolved in the solvent and then mixed with the Ni source to obtain a mixture.

[0015] Preferably, the dissolving is carried out under the condition of increasing the temperature from room temperature to 80-100°C.

[0016] Preferably, the temperature of the heating condition is 160-200° C.; and the time for heating to the temperature of the heating condition is 5-10 minutes.

[0017] Preferably, the reaction time is 0.5 to 3 h.

[0018] Preferably, the reduction is carried out in an atmosphere containing hydrogen.

[0019] Preferably, the reduction temperature is 300-400° C. and the time is 1-5 h.

[0020] In a third aspect, the present invention provides an application of the above-mentioned Ni-doped rare earth metal nano-oxide in photothermal catalytic methane dry reforming.

[0021] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a Ni-doped rare earth metal nano-oxide, which is prepared by heating a mixture of a rare earth metal source and a Ni source to form a precursor, and then reducing it. In the present invention, the rare earth metal source and the Ni source are directly mixed, and then the precursor is prepared, and then reduced. In the obtained nano-oxide, N is dispersed at the atomic level, and mainly in the form of Ni 2+ , rich, uniformly distributed and stable Ni-O active sites can be constructed. In addition, by adopting the above method, the content of Ni element in Ni-doped rare earth metal nano-oxide can reach about 10 wt%, which is much higher than the existing technology level. In addition, the preparation method provided by the present invention has easy access to synthetic raw materials, is simple and convenient, and is short in time, and is easy to achieve large-scale production.

[0022] The present invention uses the above-mentioned Ni-doped rare earth metal nano-oxide as a catalyst for the photothermal catalytic methane dry reforming reaction. The Ni-O active sites present therein are conducive to the generation of CH X O* (1≤x≤3) intermediates, avoiding carbon deposition in deep dehydrogenation of methane, thereby reducing catalyst deactivation caused by carbon deposition. In addition, the presence of rare earth metal oxides is conducive to the adsorption and activation of CO 2 , facilitating the catalysis of Ni-O active sites, thereby further promoting CH X Conversion of O* intermediates.

[0023] The test shows that the Ni-doped rare earth metal nano-oxide provided by the present invention is used as a catalyst in the photothermal catalytic methane dry reforming reaction. -2 H under the light intensity 2 The CO yield was as high as 626.5 and 728.5 mmol g cat -1 h -1 , and has good photothermal conversion ability, and can operate stably for 100 h, indicating its good stability and life of photothermal catalytic methane dry reforming. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The Ni / CeO prepared in Example 1 x Precursor and Ni / CeO x -X-ray diffraction pattern of 350 samples; Figure 2 The Ni / CeO prepared in Example 1 x -Element distribution map of 350 samples; Figure 3 The Ni / CeO prepared in Example 1 x -350 as a catalyst for photothermal catalytic methane dry reforming to generate CO and H at different light intensities 2 Yield result diagram of Figure 4 The Ni / CeO prepared in Example 1 x -350 and Ni obtained in Comparative Example 1 NP / CeO 2 As a catalyst for photothermal catalytic methane dry reforming at 4 W cm -2 Graph showing the long cycle stability test results under light intensity of . DETAILED DESCRIPTION

[0025] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In view of the problem that existing Ni-based catalysts have poor coking resistance and are easily deactivated by carbon deposition, the present invention provides a Ni-doped rare earth metal type nano-oxide, which is preferably prepared by heating a mixture of a rare earth metal source and a Ni source to form a precursor, followed by reduction.

[0027] In the present invention, the mass content of Ni element in the rare earth metal nano-oxide is 8.5-10 wt%.

[0028] In the present invention, the rare earth metal in the rare earth metal source is selected from any one or more of Ce, La, Sm or Nd, preferably Ce.

[0029] In the present invention, the rare earth metal in the rare earth metal source is recorded as M, and the Ni-doped rare earth metal nano-oxide can be recorded as: Ni / MO x , the value of the subscript x is generally between 1 and 2.

[0030] In some embodiments of the present invention, when M is selected from Ce, the Ni-doped rare earth metal nano-oxide can be recorded as: Ni / CeO x (x value is between 1 and 2).

[0031] The present invention also provides a method for preparing the above-mentioned Ni-doped rare earth metal type nano oxide, comprising the following steps: S1: After mixing a rare earth metal source, a Ni source and a solvent, the obtained mixture is reacted under heating conditions to obtain a precursor; S2: After reducing the precursor, Ni-doped rare earth metal nano-oxide is obtained.

[0032] According to the present invention, firstly, a rare earth metal source, a Ni source and a solvent are mixed to obtain a mixture.

[0033] In some embodiments of the present invention, the rare earth metal source is selected from Ce(NO 3 ) 3 6H 2 O、La(NO 3 ) 2 6H 2 O、Sm(NO 3 ) 2 6H 2 O、Nd(NO 3 ) 2 6H 2 O、CeCl 3 7H 2 O、LaCl 3 7H 2 O、SmCl 3 6H 2 O or NdCl 3 6H 2 O, preferably Ce(NO 3 ) 3 6H 2 O and / or CeCl 3 7H 2 O; the Ni source is selected from Ni(NO 3 ) 2 6H 2 O and / or NiCl 2 6H 2 O; the solvent is selected from triethylene glycol or other alcohol reagents, such as ethylene glycol.

[0034] In some specific embodiments of the present invention, the rare earth metal source is selected from Ce(NO 3 ) 3 6H 2 O; the Ni source is selected from Ni(NO 3 ) 2 6H 2 O; the solvent is selected from triethylene glycol to facilitate the formation of CeO with specific exposed (111) and (200) crystal faces 2 .

[0035] In some preferred embodiments of the present invention, in order to ensure that the doped Ni is highly dispersed at the atomic level, the present invention uses Ce(NO 3 ) 3 6H 2 O was added with triethylene glycol, and the mixture was kept at 80-100°C and stirred to fully dissolve. Then Ni(NO 3 ) 2 6H 2O is also kept warm at 80-100°C and stirred to dissolve and mix uniformly to obtain a mixture.

[0036] In the present invention, the molar ratio of the rare earth metal source to the Ni source is (3.0-3.6):1. In some embodiments of the present invention, the Ce(NO 3 ) 3 6H 2 O and Ni (NO 3 ) 2 6H 2 The molar ratio of O is (3.0-3.6):1, preferably (3.0-3.3):1, and more preferably 3.0:1.

[0037] After obtaining the mixture, according to the present invention, the mixture is quickly heated to 160-200°C (specifically 160°C, 170°C, 180°C, 190°C, 200°C), and kept at this temperature for 0.5-3 h, preferably 1-2 h, to obtain a precursor. In the present invention, the heating needs to be carried out quickly, and the heating time is generally controlled at 5-10 min, preferably 5-7 min. The present invention preferably controls the heating time because rapid heating is conducive to the formation of a large number of crystal nuclei, and it is more convenient to shorten the operation time. During the experiment, if the temperature is not raised quickly, some crystal nuclei may grow for too long, which is not conducive to controlling the crystallinity and catalyst size.

[0038] In the present invention, after the precursor is obtained, it can be reduced. In some embodiments of the present invention, the precursor is preferably treated before reduction.

[0039] The treatment of the precursor preferably includes: adding a certain proportion of a mixed solution of ethanol and ethyl acetate to the obtained precursor solution to obtain a product precipitate, using ethanol to ultrasonically disperse the above sample, and then adding a certain amount of a mixed solution of ethanol and ethyl acetate (ethanol: ethyl acetate is 30:40, volume ratio) for centrifugal separation, repeating the cleaning process, and then drying to obtain a precursor.

[0040] The ultrasonic dispersion can make the precursor dispersed more evenly, clean more fully, and avoid excessive solvent residue. The ratio of ethanol to ethyl acetate can be adjusted according to actual conditions, and ethanol and ethyl acetate can also be other similar reagents, which are not specifically limited in the present invention.

[0041] The drying is preferably vacuum drying, and the temperature of the vacuum drying is 50-70°C, preferably 60°C.

[0042] Finally, according to the present invention, the obtained precursor can be reduced.

[0043] In the present invention, the role of the reduction is to activate the catalyst and further adjust the catalyst surface structure and Ni valence.

[0044] The reduction temperature is 300-400° C., such as 300° C., 310° C., 320° C., 330° C., 340° C., 350° C., 360° C., 370° C., 380° C., 390° C. or 400° C., preferably 350° C. In the present invention, if the reduction temperature is too high, the material will be sintered, Ni will precipitate, and the catalyst structure will be destroyed.

[0045] The reducing gas flow is a gas flow containing hydrogen, preferably a hydrogen-argon mixed gas or a hydrogen-helium mixed gas. To ensure the safety of the experiment, the proportion of hydrogen in the hydrogen-argon mixed gas or the hydrogen-helium mixed gas should not be too high, and can be adjusted as needed, such as: 10% H 2 / 90% Ar.

[0046] In some embodiments of the present invention, the prepared precursor is preferably placed in a tube furnace, and a reducing gas flow is continuously passed for 0.5 to 2 h at room temperature to remove the air in the tube furnace, and then heated at 5 to 10 ° C min -1 The temperature is raised to 300-400° C. for hydrogen reduction for 1-5 h, preferably 2-4 h, and the target product is collected.

[0047] In summary, in some specific embodiments of the present invention, a method for preparing Ni / CeO x The method of nano oxide, the steps are as follows: a) Precursor synthesis: Using triethylene glycol as solvent and surfactant, a polyol-mediated method was used to heat, dissolve and uniformly mix Ce(NO 3 ) 3 6H 2 O and Ni (NO 3 ) 2 6H 2 O, and quickly heated to 170℃ to prepare Ni / CeO x The precursor is ready for use; b) Precursor treatment: adding a certain proportion of a mixed solution of ethanol and ethyl acetate to the precursor solution in step a) to obtain a product precipitate, using ethanol to ultrasonically disperse the sample, then adding a certain amount of a mixed solution of ethanol and ethyl acetate to perform centrifugal separation, repeating the cleaning process, and then vacuum drying to obtain a precursor; c) Sample reduction: The sample prepared in step b) is reduced with hydrogen at a certain temperature to collect Ni / CeO x Series of nano oxides.

[0048] The synthetic raw materials provided by the method are easily available, the method is simple, convenient and time-saving, and it is easy to achieve large-scale production.

[0049] The present invention also provides an application of the Ni-doped rare earth metal type nano-oxide in photothermal catalytic methane dry reforming.

[0050] The test shows that the Ni-doped rare earth metal nano-oxide provided by the present invention is used as a catalyst in the photothermal catalytic methane dry reforming reaction. -2 H under the light intensity 2 The CO yield was as high as 626.5 and 728.5 mmol g cat -1 h -1 , and has good photothermal conversion ability, and can operate stably for 100 h, indicating its good stability and life of photothermal catalytic methane dry reforming.

[0051] It can be seen that the optimized Ni-doped rare earth metal nanooxide has enhanced photothermal catalytic activity, which is at the same level as precious metal catalytic materials. At the same time, the catalytic stability is greatly improved compared with the Ni particle catalyst prepared by the traditional impregnation method.

[0052] In order to further illustrate the present invention, the following examples are provided for detailed description. The experimental raw materials used in the following examples of the present invention are all common commercially available products.

[0053] Example 1 1) Ni / CeO x The steps of preparing the nano oxide are as follows: First, 2 mmol Ce(NO 3 ) 3 6H 2 O was added to a 150 mL three-necked flask, and 50 mL of triethylene glycol was added. The mixture was rapidly heated from room temperature to 100°C under strong magnetic stirring and maintained for 30 minutes to allow it to fully dissolve. Then 0.6 mmol Ni(NO 3 ) 2 6H 2 O, stirred for 30 minutes, and the temperature was maintained at 100°C. The resulting solution was rapidly heated from 100°C to 170°C within 7 minutes and stirred for 1 h to obtain Ni / CeO xThe precursor was set aside (the molar ratio of Ni to Ce was 3:10). After the solution was cooled, a mixed solution of an appropriate amount of ethanol and ethyl acetate (volume ratio of 3:40) was added to precipitate the precursor. After centrifugation, an appropriate amount of ethanol was added to ultrasonically disperse the above sample, and then the mixed solution of ethanol and ethyl acetate was centrifuged again. The cleaning process was repeated and finally vacuum dried at 60°C to obtain the precursor. 50 mg of the prepared precursor sample was placed in a tube furnace and a reducing gas flow (10% H 2 / 90% Ar) to remove the air in the tube furnace, and then -1 The temperature was raised to 350 °C for hydrogen reduction for 2 h, and the product Ni / CeO x -350.

[0054] Figure 1 The Ni / CeO prepared in this example x Precursor and Ni / CeO x -350 sample, from which it can be seen that the product prepared in this example has a low crystallinity and shows CeO 2 Crystal form, no diffraction signal of Ni particles was detected. Figure 2 The Ni / CeO prepared in this example x The element distribution map of the -350 sample shows that the prepared sample exhibits a highly dispersed Ni distribution, further indicating that the Ni / CeO with uniform Ni dispersion was successfully synthesized. x Nano oxides.

[0055] 2) Photothermal catalytic methane dry reforming reaction performance test: Take 5 mg Ni / CeO x -350 catalyst, add 400 μL distilled water, disperse by ultrasound and evenly drip on a glass fiber disc to prepare the sample, then place it on a 100°C hot plate to dry. The sample was placed on a quartz holder inside the mobile phase reactor, equipped with a quartz window to allow light irradiation, and a 300 W xenon lamp was used as the light source. CH 4 :CO 2 :Ar (1:1:8) as the raw gas, check the air tightness of the mobile phase device, and adjust the gas flow rate to 20 mL min -1 After fixing the reactor and the xenon lamp, use an optical power meter to adjust the light intensity to 4 W cm -2 The gas components and contents in the outflow phase were detected by online gas chromatograph, and the product yield and feed gas conversion rate were calculated. -2 H under the light intensity 2 The CO yield was as high as 626.5 and 728.5 mmol gcat -1 h -1 .

[0056] Figure 3 The Ni / CeO prepared in Example 1 x -350 as a catalyst for photothermal catalytic methane dry reforming to generate CO and H at different light intensities 2 It can be found that the activity of the material increases with the increase of light intensity.

[0057] 3) Ni / CeO x Photothermal temperature measurement of nano-oxides: Take 5 mg Ni / CeO x -350 catalyst, add 400 μL distilled water, disperse by ultrasound, and evenly drip on a glass fiber disc to prepare a sample, then place it on a 100°C heating plate to dry. Fix the sample on a 200°C heating table, wait for the K-type thin-film thermocouple to measure the sample temperature to stabilize, test the sample temperature with an infrared thermal imager, and calibrate its emissivity to 0.08 based on the thermocouple data. Place the sample at 20 mL min -1 CH 4 :CO 2 :Ar(1:1:8) gas flow, using a calibrated infrared thermal imager to measure 4 W cm -2 The photothermal temperature of the sample surface under light intensity irradiation is 520.2°C, indicating that Ni / CeO x -350 catalyst has good photothermal conversion capability.

[0058] Example 2 The specific process is the same as that of Example 1, except that in step 1), the obtained solution is rapidly heated from 100°C to 180°C within 7 minutes and stirred for 1 h to obtain Ni / CeO x The subsequent steps are the same. The catalytic activity of the catalyst for methane dry reforming is measured to be comparable to that of the Ni / CeO x -350 close.

[0059] Example 3 The specific process is the same as that of Example 1, except that in step 1), the obtained solution is rapidly heated from 100°C to 190°C within 7 minutes and stirred for 1 h to obtain Ni / CeO x The subsequent steps are the same. The catalytic activity of the catalyst for methane dry reforming is measured to be comparable to that of the Ni / CeO x -350 close.

[0060] Example 4 1) Ni NP / CeO xThe steps of preparing the nano oxide are as follows: First, 2 mmol Ce(NO 3 ) 3 6H 2 O was added to a 150 mL three-necked flask, and 50 mL of triethylene glycol was added. Under strong magnetic stirring, the mixture was rapidly heated from room temperature to 100°C and kept for 30 minutes to allow it to fully dissolve. The mixture was then rapidly heated to 170°C within 7 minutes, stirred for 1 h, and then naturally cooled to 100°C. 0.6 mmol Ni(NO 3 ) 2 6H 2 O, stirred for 30 minutes, and the temperature was maintained at 100°C. The resulting solution was then rapidly heated from 100°C to 170°C within 7 minutes and stirred for 1 h to obtain Ni NP / CeO x The precursor is set aside (the molar ratio of Ni to Ce is 3:10). After the solution is cooled, a mixed solution of an appropriate amount of ethanol and ethyl acetate (volume ratio of 3:40) is added to precipitate the precursor. After centrifugation, an appropriate amount of ethanol is added to ultrasonically disperse the above sample, and then the mixed solution of ethanol and ethyl acetate is centrifuged again. The cleaning process is repeated and finally vacuum dried at 60°C to obtain the precursor. 50 mg of the prepared precursor sample is placed in a tube furnace and a reducing gas flow (10% H) is continuously passed for 0.5 h at room temperature. 2 / 90% Ar) to remove the air in the tube furnace, and then -1 The temperature was raised to 400 °C for hydrogen reduction for 2 h, and the product Ni NP / CeO x (1≤x≤2).

[0061] 2) Photothermal catalytic methane dry reforming reaction performance test: Same as Example 1, but the test results show that Ni NP / CeO x Nano oxides are very inactive.

[0062] Example 5 The specific process is the same as that of Example 1, except that in steps 2) and 3), the xenon lamp intensity is adjusted to 2 W cm using an optical power meter. -2 The photothermal temperature of the sample surface measured by the emissivity-corrected thermal imager is 360.1 °C, and the H 2 The yields of CO were 11.4 and 47.8 mmol g cat -1 h -1 .

[0063] Example 6 The specific process is the same as that of Example 1, except that in steps 2) and 3), the xenon lamp intensity is adjusted to 2.5 W cm using an optical power meter. -2 The photothermal temperature of the sample surface measured by the emissivity-corrected thermal imager is 400.0 °C. 2 The yields of CO were 52.0 and 145.8 mmol g cat -1 h -1 .

[0064] Example 7 The specific process is the same as that of Example 1, except that in steps 2) and 3), the xenon lamp intensity is adjusted to 3 W cm using an optical power meter. -2 The photothermal temperature of the sample surface measured by the emissivity-corrected thermal imager is 430.1 °C, and the H 2 and CO yields were 180.0 and 347.0 mmol g cat -1 h -1 .

[0065] Example 8 The specific process is the same as that of Example 1, except that in steps 2) and 3), the xenon lamp intensity is adjusted to 3.5 W cm using an optical power meter. -2 The photothermal temperature of the sample surface measured by the emissivity-corrected thermal imager is 485.7 °C, and the H 2 The yields of CO were 279.9 and 469.9 mmol g cat -1 h -1 .

[0066] Comparative Example 1 1) Ni NP / CeO 2 The steps for preparing the impregnation sample are as follows: Take 0.5 g of commercial CeO 2 Put it in a 100 mL beaker, add 20 mL of deionized water, and stir for 30 minutes after ultrasonication to make it evenly dispersed. Take 1.45 g of Ni(NO 3 ) 2 6H 2 O, add 10 mL of deionized water, sonicate until dissolved to prepare a solution with a Ni content of 0.5 M, then take 1.7 mL and add CeO dispersed in deionized water. 2, and continue stirring. After the mixed solution is stirred for 1 h, it is transferred to a hot plate, set the temperature to 70-80 ° C and continue stirring for several hours until the liquid evaporates. The solid is taken out and the precursor is obtained after sufficient grinding. 50 mg of the prepared precursor sample is placed in a tube furnace and a reducing gas flow (10% H) is continuously passed for 0.5 h at room temperature. 2 / 90% Ar) to remove the air in the tube furnace, and then -1 The temperature was raised to 400 °C for hydrogen reduction for 2 h, and the product Ni NP / CeO 2 .

[0067] 2) Photothermal catalytic methane dry reforming reaction performance test: As in Example 1, the initial catalytic activity of the catalyst for methane dry reforming reaction is slightly lower than that of Ni / CeO x -350,4 W cm -2 H under light intensity 2 and CO yields were 522.5 and 651.4 mmol g cat -1 h -1 , and the catalyst deactivates rapidly, and its activity decreases sharply as the reaction proceeds.

[0068] Figure 4 The Ni / CeO prepared in Example 1 x -350 and Ni prepared in Comparative Example 1 NP / CeO 2 As a catalyst for photothermal catalytic methane dry reforming at 4 W cm -2 Long cycle stability test under light intensity of NP / CeO 2 Rapid deactivation occurred within 20 h, and the catalytic activity dropped sharply. x -350 can operate stably for 100 h, indicating its good stability and life of photothermal catalytic methane dry reforming.

[0069] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A Ni-doped rare earth metal nano-oxide, characterized in that: The precursor is formed by heating a mixture of a rare earth metal source and a Ni source, and then reduced to obtain the precursor.

2. The Ni-doped rare earth metal type nano-oxide according to claim 1, characterized in that: The mass content of Ni element in the rare earth metal nano-oxide is 8.5-10 wt %.

3. The Ni-doped rare earth metal type nano-oxide according to claim 1 or 2, characterized in that: The rare earth metal in the rare earth metal source is selected from any one or more of Ce, La, Sm or Nd.

4. A method for preparing Ni-doped rare earth metal nano-oxide according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1: After mixing a rare earth metal source, a Ni source and a solvent, the obtained mixture is reacted under heating conditions to obtain a precursor; S2: After reducing the precursor, Ni-doped rare earth metal nano-oxide is obtained.

5. The preparation method according to claim 4, characterized in that: The rare earth metal source is selected from any one or more of Ce(NO3)3·6H2O, La(NO3)2·6H2O, Sm(NO3)2·6H2O, Nd(NO3)2·6H2O, CeCl3·7H2O, LaCl3·7H2O, SmCl3·6H2O or NdCl3·6H2O; The Ni source is selected from Ni(NO3)2·6H2O and / or NiCl2·6H2O; The solvent is selected from triethylene glycol and / or ethylene glycol.

6. The preparation method according to claim 4 or 5, characterized in that: The molar ratio of the rare earth metal source to the Ni source is (3.0-3.6):

1.

7. The preparation method according to claim 4, characterized in that: After the rare earth metal source is completely dissolved in the solvent, it is mixed with the Ni source to obtain a mixture; The dissolution is carried out under the condition of increasing the temperature from room temperature to 80-100°C.

8. The preparation method according to claim 4, characterized in that: The temperature of the heating condition is 160-200°C; the time of heating to the temperature of the heating condition is 5-10 min; The reaction time is 0.5 to 3 h.

9. The preparation method according to claim 4, characterized in that: The reduction is carried out in an atmosphere containing hydrogen; The reduction temperature is 300-400° C. and the time is 1-5 h.

10. Use of the Ni-doped rare earth metal nano-oxide according to any one of claims 1 to 3 or the Ni-doped rare earth metal nano-oxide prepared by the preparation method according to any one of claims 4 to 9 in photothermal catalytic methane dry reforming.

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