A preparation method of a catalyst for the photocatalytic dry reforming reaction of methane, its product and application

Abstract

The present invention discloses a method for preparing a catalyst for photothermal catalytic methane dry reforming reaction, as well as its product and application. Nickel nitrate hexahydrate and molybdenum chloride are used as metal sources, 2-methylimidazole is used as an organic ligand, and a MOF precursor is synthesized in the presence of aluminum oxide. The precursor is then pyrolyzed at high temperature under an H2 / Ar atmosphere to obtain a Ni-Mo@C / Al2O3 photothermal catalyst. The C species generated in situ after pyrolysis have excellent photothermal conversion effects, and the Ni and Mo bimetallics in the resulting catalyst act synergistically to match the reaction rates of methane and carbon dioxide, exhibiting good catalytic performance under full-spectrum illumination. This catalyst preparation method is simple and inexpensive, and has great application potential in alleviating the greenhouse effect and energy depletion problems.

Description

Technical Field

[0001] The present invention belongs to the technical field of photothermal coupled catalytic methane dry reforming, and specifically relates to a method for preparing a catalyst for photothermal catalytic methane dry reforming reaction, as well as its product and application. Background Art

[0002] Carbon dioxide and methane, as major greenhouse gases, have a serious impact on the human living environment and sustainable economic and social development. The "dual carbon" issue has garnered worldwide attention. Dry reforming, which converts carbon dioxide and methane into higher-quality synthesis gas (hydrogen and carbon monoxide), is an ideal solution. However, because this reaction is a highly endothermic process, traditional thermal catalysis requires large amounts of heat, resulting in significant energy consumption. Using green, renewable solar energy instead of thermal energy to drive the methane dry reforming process offers significant advantages in both energy conservation and environmental improvement, making it a highly attractive approach. Summary of the Invention

[0003] The purpose of this section is to summarize some aspects of embodiments of the present invention and to briefly introduce some preferred embodiments.

[0004] As one aspect of the present invention, the present invention provides a method for preparing a catalyst for photothermal catalytic methane dry reforming reaction, which comprises the following steps:

[0005] Preparation of NiMo-MOF / Al2O3: nickel nitrate and molybdenum chloride are dissolved in an organic solvent to obtain solution A, and the solution is stirred and mixed; 2-methylimidazole and aluminum oxide are added to the organic solvent to obtain solution B, and the solution is stirred and mixed; solution A is added to solution B, the mixture is stirred and mixed, and the mixture is heated to 120-160°C for reaction, cooled, centrifuged, washed, and the solid is collected and dried to obtain NiMo-MOF / Al2O3, wherein the molar ratio of nickel nitrate to molybdenum chloride is 2-4:1;

[0006] Preparation of NiMo@C / Al2O3: The NiMo-MOF / Al2O3 was heated to 600-700°C and calcined in a mixed atmosphere of H2 and Ar at a constant flow rate to obtain a NiMo@C / Al2O3 catalyst.

[0007] As a preferred embodiment of the method for preparing a catalyst for photothermal catalytic methane dry reforming reaction according to the present invention: nickel nitrate and molybdenum chloride are dissolved in an organic solvent, and the organic solvent includes methanol; 2-methylimidazole and aluminum oxide are added to the organic solvent, and the organic solvent includes methanol.

[0008] As a preferred embodiment of the method for preparing a catalyst for photothermal catalytic methane dry reforming reaction of the present invention: the solution A is obtained and stirred and mixed; the stirring and mixing is performed at room temperature for 15 to 30 minutes.

[0009] As a preferred solution of the method for preparing a catalyst for photothermal catalytic methane dry reforming reaction according to the present invention: the insulation reaction is carried out at a temperature of 140° C. for 12 hours.

[0010] As a preferred embodiment of the method for preparing a catalyst for photothermal catalytic methane dry reforming reaction of the present invention: the constant flow rate is 200 ml min -1 In the mixed atmosphere, the volume percentage of H2 is 5%.

[0011] As a preferred embodiment of the method for preparing the catalyst for photothermal catalytic methane dry reforming reaction of the present invention: the calcination at 600-700°C is carried out at a temperature of 5°C min -1 The mixture was heated to 650 °C at a constant heating rate for 3 h.

[0012] As a preferred embodiment of the method for preparing a catalyst for photothermal catalytic methane dry reforming reaction of the present invention: the concentration of nickel nitrate in the solution A is 0.005-0.075 mmol ml -1 , the concentration of molybdenum chloride is 0.005~0.075mmol ml -1 .

[0013] As a preferred embodiment of the method for preparing a catalyst for photothermal catalytic methane dry reforming reaction of the present invention: in the solution B, the concentration of 2-methylimidazole is 0.25-0.5 mmol ml -1 , the concentration of aluminum oxide is 5-10 mg / ml -1 .

[0014] Beneficial effects of the present invention: The photothermal reaction catalyst prepared by the present invention has high-efficiency photothermal conversion capability, good stability and excellent catalytic reaction performance. The catalyst exhibits excellent light absorption capability for the sunlight spectrum and can efficiently utilize the energy of sunlight. Moreover, the catalyst derived by high-temperature pyrolysis of MOF has good high-temperature stability. The synergistic effect of the two components of nickel and molybdenum in the catalyst can effectively activate methane and carbon dioxide molecules, improve the photothermal conversion capability of the photothermal catalyst, and solve the problem of carbon deposition prone to occur under high-temperature conditions in methane dry reforming catalysts. The present invention uses a mixture of MOF and alumina as a template precursor. The NiMo@C / Al2O3 material obtained by high-temperature pyrolysis can retain the advantages of the precursor structure, has the characteristics of high specific surface area and highly dispersed metal components, which is beneficial to the conversion of reactant molecules.

[0015] The active component Ni in the catalyst obtained by the present invention can effectively activate methane molecules. After the introduction of the Mo component, the methane-carbon dioxide activation rate can be matched, thereby having resistance to carbon deposition and better catalytic activity. At the same time, the presence of the C component can improve the efficiency of the photothermal effect of converting infrared spectra, providing temperature conditions for the reaction; at the same time, the sintering and aggregation of metal sites at high temperatures are inhibited, thereby improving the stability and life of the catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort. Among them:

[0017] Figure 1 X-ray diffraction (XRD) patterns of the products obtained in Examples 1, 2, 3, 4, and 5;

[0018] Figure 2 The UV-Vis-IR absorption spectra of the products obtained in Examples 1, 2, 3, 4, and 5 are shown in FIG.

[0019] Figure 3 N2 adsorption-desorption isotherm (BET) curves of the products obtained in Examples 1, 2, 3, 4, and 5;

[0020] Figure 4 This is a scanning electron microscope (SEM) image of the product obtained in Example 3;

[0021] Figure 5 Transmission electron microscopy (TEM) images and EDS mapping images of the product obtained in Example 3;

[0022] Figure 6 This is a curve showing the change in surface temperature of the product prepared in Example 3 as light power increases during the photothermal catalytic methane dry reforming reaction;

[0023] Figure 7 is the product formation rate of the photothermal catalytic methane dry reforming reaction of the product prepared in Example 3;

[0024] Figure 8 The conversion rate of reactants in the photothermal catalytic methane dry reforming reaction of the product prepared in Example 3;

[0025] Figure 9 The conversion efficiency of light energy into fuel in the photothermal catalytic methane dry reforming reaction of the product prepared in Example 3. DETAILED DESCRIPTION

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with specific embodiments.

[0027] Example 1:

[0028] Preparation of Ni-MOF / Al2O3:

[0029] 3 mmol of nickel nitrate hexahydrate was dissolved in 40 ml of methanol to obtain solution A, which was stirred at 500 rpm at room temperature for 15 minutes. 10 mmol of 2-methylimidazole and 200 mg of aluminum oxide were then placed in 40 ml of methanol to obtain solution B, which was stirred at 500 rpm at room temperature for 15 minutes. Solution A was then added to solution B to obtain solution C, which was transferred to the reactor liner and stirred at 500 rpm at room temperature for 30 minutes. The reactor liner was then placed in a stainless steel cylinder, heated to 140°C, and kept warm for 12 hours. After cooling to room temperature, the solid was collected by centrifugal washing and dried to obtain Ni-MOF / Al2O3.

[0030] Preparation of Ni@C / Al2O3:

[0031] The prepared Ni-MOF / Al2O3 was placed in a tube furnace at 200 ml min -1 The temperature was set at 5 °C min under a constant flow rate of 5 vol% H2 / Ar mixed atmosphere. -1 The temperature was raised to 650°C at a constant rate and calcined for 3 h, and then naturally cooled to room temperature to obtain a Ni@C / Al2O3 catalyst.

[0032] Example 2:

[0033] Preparation of Ni4Mo1-MOF / Al2O3:

[0034] 2.4 mmol of nickel nitrate hexahydrate and 0.6 mmol of molybdenum chloride were dissolved in 40 ml of methanol to obtain solution A, which was stirred at 500 rpm at room temperature for 15 minutes. 10 mmol of 2-methylimidazole and 200 mg of aluminum oxide were then placed in 40 ml of methanol to obtain solution B, which was stirred at room temperature for 15 minutes. Solution A was then added to solution B to obtain solution C, which was transferred to the reactor liner and stirred at room temperature for 30 minutes. The reactor liner was then placed in a stainless steel cylinder, heated to 140°C, and kept warm for 12 hours. After cooling to room temperature, the solid was collected by centrifugal washing and dried to obtain Ni4Mo1-MOF / Al2O3 / Al2O3.

[0035] Preparation of Ni4Mo1@C / Al2O3:

[0036] The prepared Ni4Mo1-MOF / Al2O3 was placed in a tube furnace at 200 ml min -1 The temperature was set at 5 °C min under a constant flow rate of 5 vol% H2 / Ar mixed atmosphere. -1 The temperature was raised to 650°C at a constant rate and calcined for 3 h, and then naturally cooled to room temperature to obtain a Ni4Mo1-MOF / Al2O3 catalyst.

[0037] Example 3:

[0038] Preparation of Ni2Mo1-MOF / Al2O3:

[0039] 2mmol of nickel nitrate hexahydrate and 1mmol of molybdenum chloride were dissolved in 40ml of methanol to obtain solution A, which was stirred at 500rpm for 15min at room temperature. 10mmol of 2-methylimidazole and 200mg of aluminum oxide were then placed in 40ml of methanol to obtain solution B, which was stirred at room temperature for 15min. Solution A was then added to solution B to obtain solution C, which was transferred to the reactor liner and stirred at room temperature for 30min. The reactor liner was then placed in a stainless steel cylinder, heated to 140°C, and kept warm for 12h. After cooling to room temperature, the solid was collected by centrifugal washing and dried to obtain Ni2Mo1-MOF / Al2O3.

[0040] Preparation of Ni2Mo1@C / Al2O3:

[0041] The prepared Ni2Mo1-MOF / Al2O3 was placed in a tube furnace at 200 ml min -1 The temperature was set at 5 °C min under a constant flow rate of 5 vol% H2 / Ar mixed atmosphere. -1 The temperature was raised to 650°C at a constant rate and calcined for 3 h, and then naturally cooled to room temperature to obtain Ni2Mo1@C / Al2O3 catalyst.

[0042] Example 4:

[0043] Preparation of Ni1Mo2-MOF / Al2O3:

[0044] 1mmol of nickel nitrate hexahydrate and 2mmol of molybdenum chloride were dissolved in 40ml of methanol to obtain solution A, which was stirred at 500rpm for 15min at room temperature. 10mmol of 2-methylimidazole and 200mg of aluminum oxide were then placed in 40ml of methanol to obtain solution B, which was stirred at 500rpm for 15min at room temperature. Solution A was then added to solution B to obtain solution C, which was transferred to the reactor liner and stirred at 500rpm for 30min at room temperature. The reactor liner was then placed in a stainless steel cylinder, heated to 140°C, and kept warm for 12h. After cooling to room temperature, the solid was collected by centrifugal washing and dried to obtain Ni1Mo2-MOF / Al2O3.

[0045] Preparation of Ni1Mo2@C / Al2O3:

[0046] The prepared Ni1Mo2-MOF / Al2O3 was placed in a tube furnace at 200 ml min -1 The temperature was set at 5 °C min under a constant flow rate of 5 vol% H2 / Ar mixed atmosphere. -1 The temperature was raised to 650°C at a constant rate and calcined for 3 h, and then naturally cooled to room temperature to obtain a Ni1Mo2-MOF / Al2O3 catalyst.

[0047] Example 5:

[0048] Preparation of Mo-MOF / Al2O3:

[0049] 3 mmol of molybdenum chloride was dissolved in 40 ml of methanol to obtain solution A, which was stirred at 500 rpm at room temperature for 15 minutes. 10 mmol of 2-methylimidazole and 200 mg of aluminum oxide were then placed in 40 ml of methanol to obtain solution B, which was stirred at 500 rpm at room temperature for 15 minutes. Solution A was then added to solution B to obtain solution C, which was transferred to the reactor liner and stirred at 500 rpm at room temperature for 30 minutes. The reactor liner was then placed in a stainless steel cylinder, heated to 140°C, and kept warm for 12 hours. After cooling to room temperature, the solid was collected by centrifugal washing and dried to obtain Mo-MOF / Al2O3.

[0050] Preparation of Mo@C / Al2O3:

[0051] The Mo-MOF / Al2O3 prepared in step (1) was placed in a tube furnace at 200 ml min -1 The temperature was set at 5 °C min under a constant flow rate of 5 vol% H2 / Ar mixed atmosphere. -1 The temperature was raised to 650 °C at a constant rate and calcined for 3 h, and then naturally cooled to room temperature to obtain a Mo@C / Al2O3 catalyst.

[0052] Evaluation of photothermal catalytic methane dry reforming activity: The photothermal catalytic methane dry reforming activity evaluation reaction was carried out in a homemade mobile phase reactor. The light source used in the reaction was a MC-PF300C full-spectrum xenon lamp light source from Beijing Magnesium Technology Co., Ltd., and a K9 plano-convex lens was used to focus the light into a circular spot with a diameter of 6 mm. The reaction light rate density was 353.8 W / cm 2 The catalyst dosage was 15 mg, the reaction gas flow rate was 100 sccm, N2 was the balance gas, the CO2 / CH4 / N2 ratio was 40 / 40 / 20, and the reaction products were detected online by gas chromatography with a TCD detector.

[0053] according to Figure 6 The results show that under the irradiation of xenon lamp light source, as the light intensity increases, the temperature of the material surface continues to rise, reaching 789±10℃, indicating that the material has excellent photothermal conversion ability.

[0054] according to Figure 7 The activity test results show that among the catalysts with different Ni / Mo ratios, Ni2Mo1@C / Al2O3 has the highest hydrogen and carbon monoxide generation rates, which can reach 114.2±2.9mmol g -1 min -1 and 124.0 ± 3.1 mmol g -1 min -1 .

[0055] according to Figure 8 The activity test results show that among the catalysts with different Ni / Mo ratios prepared, Ni2Mo1@C / Al2O3 has the highest methane and carbon dioxide conversion rates, which are 48.8±2% and 44.9±1%, respectively.

[0056] according to Figure 9 It can be seen from the active solar energy conversion efficiency that Ni2Mo1@C / Al2O3 has a very high light energy to fuel conversion efficiency: 36.7±0.5%.

[0057] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a catalyst for photothermal catalytic methane dry reforming reaction, characterized in that: The following steps are included: Preparation of NiMo-MOF / Al2O3: Dissolve nickel nitrate and molybdenum chloride in an organic solvent to obtain solution A, and stir to mix; add 2-methylimidazole and aluminum oxide to the organic solvent to obtain solution B, and stir to mix; Solution A is added to solution B, stirred and mixed, heated to 120-160° C. for reaction, cooled, centrifuged, washed, solids collected, and dried to obtain NiMo-MOF / Al2O3, wherein the molar ratio of nickel nitrate to molybdenum chloride is 2-4:1; Preparation of NiMo@C / Al2O3: The NiMo-MOF / Al2O3 was heated to 600-700°C and calcined in a mixed atmosphere of H2 and Ar at a constant flow rate to obtain a NiMo@C / Al2O3 catalyst.

2. The method for preparing a catalyst for photothermal catalytic methane dry reforming reaction according to claim 1, characterized in that: The nickel nitrate and molybdenum chloride are dissolved in an organic solvent, which includes methanol; and the 2-methylimidazole and aluminum oxide are added to the organic solvent, which includes methanol.

3. The method for preparing a catalyst for photothermal catalytic methane dry reforming according to claim 1 or 2, characterized in that: The solution A is obtained and stirred and mixed; the stirring and mixing is performed at room temperature for 15 to 30 minutes.

4. The method for preparing a catalyst for photothermal catalytic methane dry reforming according to claim 1 or 2, characterized in that: The heat preservation reaction was carried out at a temperature of 140° C. for 12 hours.

5. The method for preparing a catalyst for photothermal catalytic methane dry reforming according to claim 1 or 2, characterized in that: The constant flow rate is 200 ml min -1 In the mixed atmosphere, the volume percentage of H2 is 5%.

6. The method for preparing a catalyst for photothermal catalytic methane dry reforming according to claim 1 or 2, characterized in that: The heating to 600-700℃ calcination is carried out at 5℃min -1 The mixture was heated to 650 °C at a constant heating rate for 3 h.

7. The method for preparing a catalyst for photothermal catalytic methane dry reforming according to claim 1 or 2, characterized in that: In the solution A, the concentration of nickel nitrate is 0.005-0.075 mmol ml -1 , the concentration of molybdenum chloride is 0.005~0.075mmol ml -1 .

8. The method for preparing a catalyst for photothermal catalytic methane dry reforming according to claim 1 or 2, characterized in that: In the solution B, the concentration of 2-methylimidazole is 0.25-0.5 mmol ml -1 , the concentration of aluminum oxide is 5-10 mg / ml -1 .

9. The catalyst obtained by the preparation method according to claim 1.

10. Use of the catalyst prepared by the preparation method according to claim 1 in photothermal catalytic methane dry reforming reaction.

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