Nickel-cobalt-based photo-thermal catalyst, preparation method and application

Abstract

The invention discloses a preparation method and application of a nickel-cobalt-based photo-thermal catalyst, NiCo alloy nanoparticles of the catalyst are uniformly loaded on amorphous Al2O3 nanosheets, metal elements in the catalyst comprise three metal elements of Ni, Co and Al, and the molar ratio of Ni to Co to Al is 1: 1: 1-3: 1: 1. The NiCo alloy catalyst shows excellent activity in photo-thermal methane cracking and photo-thermal methane dry reforming reaction; compared with traditional thermocatalysis, the catalyst provided by the invention utilizes light as energy input to drive the methane conversion reaction, and reduces energy input required by the reaction, so that the photo-thermal methane conversion utilization reaction adopted by the invention is more environment-friendly and energy-saving than a system in the prior art; the high-added-value carbon nanofibers are prepared through photo-thermal methane cracking for the first time, the diameter of the carbon nanofibers is about 30 nm, the length of the carbon nanofibers can reach micron, and the method is expected to be amplified in industry and applied practically.

Description

Technical Field

[0001] The present invention relates to a catalyst for methane conversion and utilization, and in particular to a nickel-cobalt-based photothermal catalyst, a preparation method and an application thereof. Background Art

[0002] The main purpose of methane conversion and utilization is to convert methane into hydrogen and other products. The main methods include methane dry reforming, methane cracking and methane wet reforming. Among them, methane dry reforming is the reaction of methane and carbon dioxide to generate hydrogen and carbon monoxide. The product can be separated to obtain hydrogen or directly used as the raw material of the Fischer-Tropsch reaction; methane cracking is a thermochemical process that decomposes methane into hydrogen and solid carbon at high temperature; methane wet reforming is the chemical reaction between methane and water vapor under certain conditions to generate hydrogen and carbon monoxide. The above three methane conversion and utilization methods all need to be carried out at relatively high temperatures (700℃-1100℃). When providing the required high temperature environment, a large amount of fossil energy will inevitably be consumed, causing secondary pollution and other problems. Therefore, it is of great significance to find a cleaner way to drive the methane conversion reaction. Summary of the invention

[0003] The technical purpose of the present invention is to provide a method for preparing a photothermal methane conversion and utilization catalyst. The catalyst uses hydrotalcite as a precursor and utilizes the adjustable composition of the hydrotalcite precursor to form an alloy photothermal catalyst with an adjustable NiCo ratio. The specific structure is that NiCo alloy nanoparticles are loaded on amorphous Al2O3 nanosheets. The above catalyst can be used to achieve photothermal methane dry reforming and methane cracking reactions. The catalyst uses light as energy input to drive the methane conversion and utilization reaction, thereby reducing the energy input required for the reaction.

[0004] In order to achieve the above technical objectives, the technical solution provided by the present invention is:

[0005] A nickel-cobalt-based photothermal catalyst, wherein NiCo alloy nanoparticles are uniformly loaded on amorphous Al2O3 nanosheets, wherein the molar ratio of the metal elements Ni, Co and Al is 1:1:1 to 3:1:1.

[0006] Furthermore, the molar ratio of the metal elements Ni, Co and Al is 2:1:1.

[0007] Another aspect of the present invention provides a method for preparing a nickel-cobalt-based photothermal catalyst, comprising the following steps:

[0008] Step 1: dissolving nickel salt, cobalt salt and aluminum salt, adding a precipitant for reaction, washing, drying and grinding to obtain a NiCoAl hydrotalcite precursor;

[0009] Step 2: The NiCoAl hydrotalcite precursor in step 1 is reacted in a hydrogen and argon atmosphere to obtain a nickel-cobalt-based photothermal catalyst.

[0010] Furthermore, the reaction temperature of step 1 is 110-130° C., and the reaction time is 12-24 hours.

[0011] Furthermore, in step 1, the concentration of the nickel salt is 0.05 to 0.3 mol·L -1 ; The concentration of the cobalt salt is 0.05 to 0.1 mol·L -1 ; The aluminum salt concentration is 0.05 to 0.1 mol·L -1 .

[0012] Furthermore, in step 1, the nickel salt is any one of nickel nitrate, nickel chloride or nickel sulfate; the cobalt salt is any one of cobalt nitrate, cobalt chloride or cobalt sulfate; and the aluminum salt is any one of aluminum nitrate, aluminum chloride or aluminum sulfate.

[0013] Furthermore, in step 1, the precipitant is urea or hexamethylenetetramine, and the concentration is 0.5 to 3 mol·L -1 .

[0014] Furthermore, in step 2, the temperature is first raised to 600-800° C. for reduction, the reduction heating rate is 2-5° C. / min and maintained for 2 hours, and then the temperature is lowered to room temperature.

[0015] Furthermore, in step 2, the ratio of hydrogen to argon atmosphere is hydrogen:argon=10%:90%.

[0016] The application of the nickel-cobalt-based photothermal catalyst in the photothermal methane cracking reaction of the present invention comprises the following steps: adding the nickel-cobalt-based photothermal catalyst into a photothermal reactor, introducing methane gas, irradiating with xenon lamp light, and detecting gas products by gas chromatography.

[0017] The application of the nickel-cobalt-based photothermal catalyst in the methane dry reforming reaction of the present invention comprises the following steps: adding the nickel-cobalt-based photothermal catalyst into a photothermal reactor, introducing methane / CO2 gas, irradiating with xenon lamp light, and detecting gas products by gas chromatography.

[0018] The present invention has the following beneficial effects:

[0019] The NiCo alloy catalyst prepared by the present invention shows excellent activity in photothermal methane cracking and photothermal methane dry reforming reactions. Compared with traditional thermal catalysis, the catalyst of the present invention uses light as energy input to drive the methane conversion and utilization reaction, reducing the energy input required for the reaction. Therefore, the photothermal methane conversion and utilization reaction adopted by the present invention is not only more environmentally friendly and energy-saving than the existing technology system, but also realizes the photothermal methane cracking to prepare high-value-added carbon materials for the first time. The carbon nanofiber has a diameter of about 30nm and a length of up to microns. The present invention is expected to be scaled up in industry and put into practical application. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 XRD spectra of the NiCo alloy catalysts obtained in Examples 1-3 of the present invention and the Ni and Co single metal catalysts of the comparative example;

[0021] Figure 2 TEM images of the NiCo alloy catalysts obtained in Examples 1-3 of the present invention, wherein A is the TEM image of NiCo / Al2O3-1 obtained in Example 1; B is the TEM image of NiCo / Al2O3-2 obtained in Example 2; and C is the TEM image of NiCo / Al2O3-3 obtained in Example 3;

[0022] Figure 3 The photothermal methane cracking performance diagram of the NiCo alloy catalyst obtained in Examples 1-3 of the present invention and the Ni and Co single metal catalysts of the comparative example;

[0023] Figure 4 TEM images of carbon products of photothermal methane cracking of NiCo alloy catalysts obtained in Examples 1-3 of the present invention, wherein AB is the TEM image of carbon products of photothermal methane cracking of NiCo / Al2O3-1 obtained in Example 1; CD is the TEM image of carbon products of photothermal methane cracking of NiCo / Al2O3-2 obtained in Example 2; EF is the TEM image of carbon products of photothermal methane cracking of NiCo / Al2O3-3 obtained in Example 3;

[0024] Figure 5 The graph shows the conversion rates of CO2 and CH4 and the generation rates of CO and H2 for photothermal methane dry reforming using the NiCo alloy catalysts obtained in Examples 1-3 of the present invention and the Co single metal catalyst of the comparative example. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is described clearly and completely below in conjunction with the accompanying drawings. 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 addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0027] A nickel-cobalt-based photothermal catalyst, wherein NiCo alloy nanoparticles are uniformly loaded on amorphous Al2O3 nanosheets, wherein the molar ratio of the metal elements Ni, Co and Al is 1:1:1 to 3:1:1.

[0028] A method for preparing a nickel-cobalt-based photothermal catalyst comprises the following steps:

[0029] Step 1: dissolving nickel salt, cobalt salt and aluminum salt, adding a precipitant for reaction, washing, drying and grinding to obtain a NiCoAl hydrotalcite precursor.

[0030] Specifically, the reaction conditions include a reaction temperature of 110 to 130° C., a reaction time of 12 to 24 hours, and a nickel salt concentration of 0.05 to 0.3 mol·L -1 The concentration of the cobalt salt is 0.05 to 0.1 mol·L -1 ; The aluminum salt concentration is 0.05 to 0.1 mol·L -1 The nickel salt is any one of nickel nitrate, nickel chloride or nickel sulfate, and they can also be mixed and added; the cobalt salt is any one of cobalt nitrate, cobalt chloride or cobalt sulfate, and they can also be mixed and added; the aluminum salt is any one of aluminum nitrate, aluminum chloride or aluminum sulfate, and they can also be mixed and added; the precipitant is urea or hexamethylenetetramine, and the concentration is 0.5 to 3 mol·L -1 .

[0031] Step 2: The NiCoAl hydrotalcite precursor in step 1 is reacted in a hydrogen and argon atmosphere to obtain a nickel-cobalt-based photothermal catalyst.

[0032] Specifically, in step 2, the reaction conditions include first heating to 600-800°C for reduction, maintaining the reduction heating rate at 2-5°C / min for 2 hours, and then cooling to room temperature; the ratio of hydrogen to argon atmosphere in step 2 is hydrogen:argon = 10%:90%.

[0033] The invention discloses an application of a nickel-cobalt-based photothermal catalyst in a photothermal methane cracking reaction, comprising the following steps: adding a nickel-cobalt-based photothermal catalyst into a photothermal reactor, introducing methane gas, irradiating with xenon lamp light, detecting gas products by gas chromatography, and detecting the activity of the methane cracking reaction.

[0034] The invention discloses an application of a nickel-cobalt-based photothermal catalyst in a methane dry reforming reaction, comprising the following steps: adding a nickel-cobalt-based photothermal catalyst into a photothermal reactor, introducing methane / CO2 gas, irradiating with xenon light, detecting gas products by gas chromatography, and detecting the methane dry reforming reaction activity and product selectivity.

[0035] Example 1

[0036] A method for preparing a nickel-cobalt-based photothermal catalyst and its application in a photothermal methane conversion and utilization reaction, comprising the following steps:

[0037] Step 1: Prepare a solution containing 0.1 mol·L -1 Nickel nitrate, 0.1 mol·L -1 Cobalt nitrate, 0.1 mol·L -1 Aluminum nitrate, 0.6 mol·L -1 100 mL of urea solution was transferred to a hydrothermal reactor and reacted at 120° C. for 12 h. After the reaction, the obtained crude product was washed, dried, and ground to obtain NiCoAl-1 hydrotalcite precursor.

[0038] Step 2: The NiCoAl-1 hydrotalcite precursor obtained in step 1 is heated to 700°C at a rate of 5°C / min in a hydrogen-argon atmosphere (hydrogen / argon = 1:9), maintained for 2 hours, and then cooled to room temperature to obtain a NiCo alloy catalyst with a Ni / Co element ratio of 1:1, marked as NiCo / Al2O3-1.

[0039] The NiCo / Al2O3-1 obtained in step 2 is applied to the photothermal methane cracking reaction. 200 mg NiCo / Al2O3-1 is added to a photothermal reactor, methane gas is introduced, xenon lamp is used for irradiation, gas products are detected by gas chromatography, and the activity of methane cracking reaction is detected.

[0040] The NiCo / Al2O3-1 obtained in step 2 was applied to the photothermal methane dry reforming reaction. 200 mg NiCo / Al2O3-1 was added to a photothermal reactor, methane / CO2 gas (methane / CO2=1:1) was introduced, xenon lamp was used for irradiation, gas products were detected by gas chromatography, and the methane dry reforming reaction activity and product selectivity were detected.

[0041] Attached Figure 1 The marked curve in the middle is the XRD spectrum of NiCo / Al2O3-1; Figure 2 Figure A in the middle is the TEM image of NiCo / Al2O3-1; Figure 3 The catalyst marked in the figure is NiCo / Al2O3-1 for methane cracking; Figure 4 Figure AB in the middle is the TEM image of the carbon product of NiCo / Al2O3-1; Figure 5 The methane dry reforming activity and product selectivity of the labeled catalyst are NiCo / Al2O3-1.

[0042] Depend on Figure 1 The marked curve shows that the synthesized NiCo / Al2O3-1 is a NiCo alloy catalyst; Figure 2A shows that the obtained NiCo / Al2O3-1 is amorphous Al2O3-loaded NiCo nano-alloy particles; Figure 3 It can be seen that in the NiCo / Al2O3-1 photothermal methane cracking reaction, the methane cracking conversion rate is 4.99%; Figure 4 AB shows that the carbon product of NiCo / Al2O3-1 photothermal methane cracking reaction is high value-added carbon nanofibers; Figure 5 It can be seen that in the methane dry reforming reaction of NiCo / Al2O3-1, the conversion rates of CO2 and CH4 are 1.81% and 2.05%, respectively, and the yields of product selectivity H2 and CO are 419.65 umol g -1 h -1 and 395.75umol g -1 h -1 . It can be seen that the catalyst can realize photothermal methane cracking and dry reforming reactions.

[0043] Example 2

[0044] A method for preparing a nickel-cobalt-based photothermal catalyst and its application in a photothermal methane conversion and utilization reaction, comprising the following steps:

[0045] Step 1: Prepare a solution containing 0.2 mol·L -1 Nickel chloride, 0.1 mol·L -1 Cobalt chloride, 0.1 mol·L -1 Aluminum chloride, 0.6 mol·L -1 100 mL of urea solution was transferred to a hydrothermal reactor and reacted at 110° C. for 24 h. After the reaction, the obtained crude product was washed, dried, and ground to obtain NiCoAl-2 hydrotalcite precursor.

[0046] Step 2: The NiCoAl-2 hydrotalcite precursor obtained in step 1 is placed in a hydrogen and argon atmosphere (hydrogen / argon = 1:9) at a heating rate of 5°C / min to 600°C, maintained for 2 hours, and then cooled to room temperature to obtain a NiCo alloy catalyst with a Ni / Co element ratio of 2:1, marked as NiCo / Al2O3-2.

[0047] The NiCo / Al2O3-2 obtained in step 2 is applied to the photothermal methane cracking reaction. 200 mg NiCo / Al2O3-2 is added to a photothermal reactor, methane gas is introduced, xenon lamp is used for irradiation, gas products are detected by gas chromatography, and the activity of methane cracking reaction is detected.

[0048] The NiCo / Al2O3-2 obtained in step 2 was applied to the photothermal methane dry reforming reaction. 200 mg NiCo / Al2O3-1 was added to a photothermal reactor, and methane / CO2 gas (methane / CO2=1:1) was introduced. Xenon lamp was used for irradiation, and gas products were detected by gas chromatography to detect the activity and product selectivity of the methane dry reforming reaction.

[0049] Attached Figure 1 The marked curve in the middle is the XRD spectrum of NiCo / Al2O3-2; Figure 2 Figure B is the TEM image of NiCo / Al2O3-2; Figure 3 The catalyst marked in the figure is NiCo / Al2O3-2 for methane cracking; Figure 4 The CD images in the middle are TEM images of the carbon products of NiCo / Al2O3-2; Figure 5 The methane dry reforming activity and product selectivity of the labeled catalyst are NiCo / Al2O3-2.

[0050] Depend on Figure 1 The marked curve shows that the synthesized NiCo / Al2O3-2 is a NiCo alloy catalyst; Figure 2 B shows that the obtained NiCo / Al2O3-2 is amorphous Al2O3-loaded NiCo nano-alloy particles. Figure 3 It can be seen that in the NiCo / Al2O3-2 photothermal methane cracking reaction, the methane cracking conversion rate is 6.18%; Figure 4 CD shows that the carbon product of NiCo / Al2O3-2 photothermal methane cracking reaction is high value-added carbon nanofibers; Figure 5 It can be seen that in the methane dry reforming reaction of NiCo / Al2O3-2, the conversion rates of CO2 and CH4 are 2.06% and 2.33%, respectively, and the yields of product selectivity H2 and CO are 506.34 umol g -1 h -1 and 449.24 umol g -1 h -1 . It can be seen that the catalyst can realize photothermal methane cracking and dry reforming reactions.

[0051] Example 3

[0052] Step 1: Prepare a solution containing 0.3 mol·L -1 Nickel sulfate, 0.1 mol·L -1 Cobalt sulfate, 0.1 mol·L -1 Aluminum sulfate, 0.6 mol·L -1100 mL of urea solution was transferred to a hydrothermal reactor and reacted at 130° C. for 12 h. After the reaction, the crude product was washed, dried, and ground to obtain a NiCoAl-3 hydrotalcite precursor.

[0053] Step 2: The NiCoAl-3 hydrotalcite precursor obtained in step 1 is placed in a hydrogen-argon atmosphere (hydrogen / argon = 1:9) at a heating rate of 2°C / min to 800°C, maintained for 2 hours, and then cooled to room temperature to obtain a NiCo alloy catalyst with a Ni / Co element ratio of 3:1, marked as NiCo / Al2O3-3.

[0054] The NiCo / Al2O3-3 obtained in step 2 was applied to the photothermal methane cracking reaction. 200 mg NiCo / Al2O3-3 was added to a photothermal reactor, methane gas was introduced, xenon lamp was used for irradiation, gas products were detected by gas chromatography, and the activity of methane cracking reaction was detected.

[0055] The NiCo / Al2O3-3 obtained in step 2 was applied to the photothermal methane dry reforming reaction. 200 mg NiCo / Al2O3-3 was added to a photothermal reactor, methane / CO2 gas (methane / CO2=1:1) was introduced, xenon lamp was used for irradiation, gas products were detected by gas chromatography, and the activity and product selectivity of methane dry reforming reaction were detected.

[0056] Attached Figure 1 The marked curve in the middle is the XRD spectrum of NiCo / Al2O3-3; Figure 2 Figure C in the middle is the TEM image of NiCo / Al2O3-3; Figure 3 The catalyst marked in the middle is NiCo / Al2O3-3 for methane cracking; Figure 4 Figure EF in the middle is the TEM image of the carbon product of NiCo / Al2O3-3; Figure 5 The methane dry reforming activity and product selectivity of the labeled catalyst are NiCo / Al2O3-3.

[0057] Depend on Figure 1 The marked curve shows that the synthesized NiCo / Al2O3-3 is a NiCo alloy catalyst; Figure 2 It can be seen that the obtained NiCo / Al2O3-3 is amorphous Al2O3-loaded NiCo nano-alloy particles. Figure 3 It can be seen that in the NiCo / Al2O3-3 photothermal methane cracking reaction, the methane cracking conversion rate is 5.62%; Figure 4 EF shows that the carbon product of NiCo / Al2O3-3 photothermal methane cracking reaction is high value-added carbon nanofibers; Figure 5It can be seen that in the NiCo / Al2O3-3 methane dry reforming reaction, the conversion rates of CO2 and CH4 are 1.58% and 1.88%, respectively, and the yields of product selectivity H2 and CO are 462.87 umol g -1 h -1 and 375.22 umol g -1 h -1 . It can be seen that the catalyst can achieve efficient photothermal methane cracking and dry reforming reactions.

[0058] Comparative Example 1

[0059] Step 1: Prepare a solution containing 0.1 mol·L -1 Cobalt nitrate, 0.1 mol·L -1 Aluminum nitrate, 0.6 mol·L -1 100 mL of urea was added, and the liquid was transferred to a hydrothermal reactor and reacted at 120° C. for 12 h. After the reaction, the crude product was washed, dried, and ground to obtain a hydrotalcite precursor.

[0060] Step 2: The hydrotalcite precursor obtained in step 1 was placed in a hydrogen-argon atmosphere (hydrogen / argon = 1:9) at a heating rate of 5°C / min to 700°C and maintained for 2 hours to obtain a Co metal catalyst, which was labeled as Co / Al2O3.

[0061] The Co / Al2O3 obtained in step 2 is applied to the photothermal methane cracking reaction. 200 mg Co / Al2O3 is added to a photothermal reactor, methane gas is introduced, xenon lamp is used for irradiation, gas products are detected by gas chromatography, and the activity of methane cracking reaction is detected.

[0062] The Co / Al2O3 obtained in step 2 was applied to the photothermal methane dry reforming reaction. 200 mg Co / Al2O3 was added to a photothermal reactor, and methane / CO2 gas (methane / CO2=1:1) was introduced. Xenon lamp was used for irradiation, and gas products were detected by gas chromatography to detect the activity and product selectivity of the methane dry reforming reaction.

[0063] Attached Figure 1 The middle is the XRD spectrum of Co / Al2O3 with the marked curve; Figure 3 The catalyst marked in the middle is Co / Al2O3 for methane cracking; Figure 5 The methane dry reforming activity and product selectivity of the Co / Al2O3 catalyst are shown.

[0064] Depend on Figure 1 The marked curve shows that the synthesized Co / Al2O3 is a Co metal catalyst; Figure 3 It can be seen that in the Co / Al2O3 photothermal methane cracking reaction, the methane cracking conversion rate is 1.35%; Figure 5 It can be seen that in the Co / Al2O3 methane dry reforming reaction, the conversion rates of CO2 and CH4 are 0.39% and 0.37%, respectively, and the yields of product selectivity H2 and CO are 74.46 umol g -1 h -1 and 80.27 μmol g -1 h -1 .

[0065] Comparative Example 2

[0066] Step 1: Prepare a solution containing 0.1 mol·L -1 Nickel nitrate, 0.1 mol·L -1 Aluminum nitrate, 0.6 mol·L -1 100 mL of urea was added, and the liquid was transferred to a hydrothermal reactor and reacted at 120° C. for 12 h. After the reaction, the crude product was washed, dried, and ground to obtain a hydrotalcite precursor.

[0067] Step 2: The hydrotalcite precursor obtained in step 1 was placed in a hydrogen-argon atmosphere (hydrogen / argon = 1:9) at a heating rate of 5°C / min to 700°C and maintained for 2 hours to obtain a Ni metal catalyst, which was labeled as Ni / Al2O3.

[0068] The Ni / Al2O3 obtained in step 2 is applied to the photothermal methane cracking reaction. 200 mg Ni / Al2O3 is added to a photothermal reactor, methane gas is introduced, xenon lamp is used for irradiation, gas products are detected by gas chromatography, and the activity of methane cracking reaction is detected.

[0069] Attached Figure 1 The middle is the XRD spectrum of Ni / Al2O3 with the marked curve; Figure 3 The catalyst marked in the figure is Ni / Al2O3 for methane cracking.

[0070] Depend on Figure 1 From the marked curve, it can be seen that the synthesized Ni / Al2O3 is a Ni metal catalyst; Figure 3 It can be seen that in the Ni / Al2O3 photothermal methane cracking reaction, the methane cracking conversion rate is 4.81%.

[0071] In summary, in traditional methane conversion reactions such as methane cracking, methane dry reforming, and methane wet reforming, the reaction needs to be carried out at high temperature. A large amount of energy is required to drive the reaction to provide a high temperature environment. In this process, a large amount of fossil energy will inevitably be consumed, which will cause secondary pollution and other problems. The present invention uses sunlight as the energy input for methane conversion, which can reduce the energy input required for the reaction, avoid a large amount of fossil energy consumption, and reduce secondary pollution. In addition, the catalyst for traditional methane cracking is usually a single metal catalyst prepared by an impregnation method. The present invention uses NiCoAl hydrotalcite as a precursor. By regulating the ratio of each raw material in the preparation process of the hydrotalcite precursor, the NiCo alloy catalyst with different active element compositions can be obtained. The different NiCo alloy catalysts show excellent activity in photothermal methane cracking and photothermal methane dry reforming reactions.

[0072] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

[0073] The above specific implementation methods are detailed descriptions of the present invention. It cannot be determined that the specific implementation methods of the present invention are limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions and substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A nickel-cobalt-based photothermal catalyst, characterized in that: NiCo alloy nanoparticles are uniformly loaded on amorphous Al2O3 nanosheets, wherein the molar ratio of metal elements Ni, Co and Al is 1:1:1 to 3:1:

1.

2. A nickel-cobalt-based photothermal catalyst according to claim 1, characterized in that: The molar ratio of the metal elements Ni, Co and Al is preferably 2:1:

1.

3. A method for preparing the nickel-cobalt-based photothermal catalyst as claimed in claim 1, characterized in that: The steps include: Step 1: dissolving nickel salt, cobalt salt and aluminum salt, adding a precipitant for reaction, washing, drying and grinding to obtain a NiCoAl hydrotalcite precursor; Step 2: The NiCoAl hydrotalcite precursor in step 1 is reacted in a hydrogen and argon atmosphere to obtain a nickel-cobalt-based photothermal catalyst.

4. The method for preparing a nickel-cobalt-based photothermal catalyst according to claim 3, characterized in that: In the step 1, the reaction conditions include a reaction temperature of 110 to 130° C. and a reaction time of 12 to 24 hours.

5. The method for preparing a nickel-cobalt-based photothermal catalyst according to claim 3, characterized in that: In step 1, the concentration of the nickel salt is 0.05 to 0.3 mol·L -1 The concentration of the cobalt salt is 0.05 to 0.1 mol·L -1 ; The aluminum salt concentration is 0.05 to 0.1 mol·L -1 .

6. The method for preparing a nickel-cobalt-based photothermal catalyst according to claim 3, characterized in that: In the step 1, the nickel salt is any one of nickel nitrate, nickel chloride or nickel sulfate; the cobalt salt is any one of cobalt nitrate, cobalt chloride or cobalt sulfate; and the aluminum salt is any one of aluminum nitrate, aluminum chloride or aluminum sulfate.

7. The method for preparing a nickel-cobalt-based photothermal catalyst according to claim 3, characterized in that: In step 1, the precipitant is urea or hexamethylenetetramine, and the concentration is 0.5 to 3 mol·L -1 .

8. The method for preparing a nickel-cobalt-based photothermal catalyst according to claim 3, characterized in that: In the step 2, the reaction conditions include first heating to 600-800° C. for reduction, maintaining the reduction temperature at a rate of 2-5° C. / min for 2 hours, and then cooling to room temperature.

9. The method for preparing a nickel-cobalt-based photothermal catalyst according to claim 3, characterized in that: In step 2, the ratio of hydrogen to argon atmosphere is hydrogen:argon=10%:90%.

10. Use of the nickel-cobalt-based photothermal catalyst as claimed in any one of claims 1 or 2 in photothermal methane cracking reaction.

11. Use of the nickel-cobalt-based photothermal catalyst as claimed in any one of claims 1 or 2 in a methane dry reforming reaction.

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