A multi-sized Ni-based catalyst, its preparation method and application

Abstract

The present invention provides a multi-sized Ni-based catalyst, a preparation method thereof, and an application. The present invention utilizes lanthanum nitrate, nickel nitrate, and citric acid to prepare a Ni@Ni-La2O2CO3 catalyst by instantaneously expanding and annealing a precursor in an argon atmosphere to dope Ni single atoms and Ni particles into La2O2CO3. Using the catalyst prepared by the present invention, hydrogen can be efficiently produced by photocatalytic steam reforming of bioethanol; it shows the high efficiency and sustainability of the Ni@Ni-La2O2CO3 catalyst composed of Ni single atoms and Ni particles doped into La2O2CO3. The preparation method of the Ni-based catalyst provided by the present invention, in which Ni single atoms and Ni particles coexist, has the advantages of low preparation temperature, pertinence, simplicity, simple equipment, and environmental friendliness, providing a new approach for the application of chemical substances with complex compositions in fields such as photocatalytic driving. NP @Ni SA -La2O2CO3 catalyst. NP @Ni SA -La2O2CO3 catalyst.

Description

Technical Field

[0001] The present invention relates to the fields of nanomaterials and catalytic technologies, and particularly to a multi-sized Ni-based catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Currently, fossil fuels remain the main energy source. However, due to their limited reserves and negative environmental impacts, researchers are seeking cleaner and more sustainable energy solutions. In this regard, hydrogen, as an energy carrier with high energy density and zero emissions, has received extensive attention. In particular, second-generation bioethanol produced from lignocellulosic biomass such as agricultural waste has significant potential and prospects as a raw material for hydrogen production. This process is generally divided into two stages: first, the biomass is converted into bioethanol, and then it is converted into hydrogen through a catalytic reforming process.

[0003] The production of bioethanol is a multi-step process, and its specific steps depend on the initial raw material, among which the fermentation of sugar is a key link. Generally, the fermentation process produces a solution containing ethanol, water, and various other components, and the concentration of ethanol is usually between 4% and 12%. To obtain pure ethanol, a series of fractional distillation and separation steps are required, which not only increase the energy consumption but also raise the cost. Directly using bioethanol as a raw material for hydrogen production may be a more economical and efficient method. This can not only reduce costs, but the other oxygenated organic compounds in bioethanol may also help increase the hydrogen production. At the same time, using the existing water can avoid two offsetting steps of removing water from the distillate and adding water to pure ethanol, thus meeting the initial conditions for catalytic steam reforming to produce hydrogen. However, there are also some challenges in directly using bioethanol, mainly due to its complex chemical composition. The impurities in bioethanol are mainly alcohols, accounting for up to 87%, and the presence of higher alcohols may exacerbate carbon deposition. Summary of the Invention

[0004] The purpose of the present invention is to provide a multi-sized Ni-based catalyst, a preparation method thereof, and an application thereof. The multi-sized Ni-based catalyst can be used for catalytic steam reforming of bioethanol to produce hydrogen, and has pertinence, high efficiency, and good stability.

[0005] The present invention is implemented as follows:

[0006] In view of the complex components of bioethanol, the present invention designs a catalyst in which Ni nanoparticles and Ni single atoms coexist and are doped with La2O2CO3, which is used to deal with the complex components in bioethanol and prevent the deactivation of the catalyst caused by the reaction of higher alcohols. The presence of Ni single atoms can have good anti-carbon deposition and anti-sintering capabilities, preventing carbon deposition from causing catalyst deactivation; the presence of Ni particles can ensure high catalytic activity and ensure the stability of the catalytic effect. Doped La2O2CO3 reacts with the generated carbon deposition, effectively avoiding catalyst deactivation caused by carbon deposition (La2O2CO3+C→La2O3+2CO).

[0007] The purpose of the present invention is to propose a new catalyst for preparing hydrogen production from light-driven catalytic bioethanol steam reforming, specifically using citric acid as a template, obtaining a viscous colloid by stirring, heating and drying, and then performing instant expansion annealing on the viscous colloid in an argon atmosphere, and then calcining to obtain a multi-sized Ni-based catalyst. The catalyst can be used for catalytic bioethanol steam reforming hydrogen production, and has pertinence, high efficiency and good stability.

[0008] like Figure 1 As shown, the preparation method of the multi-sized Ni-based catalyst provided by the present invention comprises the following steps:

[0009] (1) Nickel nitrate, lanthanum nitrate and citric acid are mixed and dissolved in deionized water, and stirred to form a mixed solution.

[0010] (2) The mixed solution in step (1) was placed in a multi-head magnetic heating stirrer and stirred, and 1.2 mL of HNO3 and 0.6 mL of C2H8N2 were added dropwise in sequence during the stirring process. After sufficient stirring, NH3·H2O was added dropwise until the solution pH reached 6, and the solution was heated to 80°C and dried to a viscous colloid.

[0011] (3) Place the viscous colloid obtained in step (2) in a blower dryer and dry for 24 hours.

[0012] (4) The dried sample in step (3) is transferred to a quartz tube in a tubular furnace, argon gas is introduced for 1 hour to exhaust the air, the tubular furnace is heated to 400°C, and the quartz tube is placed in the tubular furnace at 400°C. The sample will expand instantly at 400°C, then kept warm for 4 hours, and finally placed in a muffle furnace and calcined at 400°C for 4 hours.

[0013] The present invention discloses a method for preparing a multi-sized Ni-based catalyst, wherein the obtained catalyst has a nano-sheet morphology and uniform element distribution. The specific surface area of ​​the multi-sized Ni-based catalyst is 20 to 80 m 2 / g.

[0014] The present invention further discloses NiNP @Ni SA Application of Ni-La2O2CO3 multi-sized Ni-based catalyst in photocatalytic thermocatalytic steam reforming of bioethanol for hydrogen production. Specifically, bioethanol is vaporized and introduced into the reaction device through argon, and the performance of steam reforming of bioethanol for hydrogen production is tested by photocatalytic heating.

[0015] The present invention has the following beneficial effects:

[0016] 1) In the present invention, the Ni-La2O2CO3 multi-sized Ni-based catalyst has Ni existing in the forms of Ni particles and Ni single atoms, which can effectively catalyze various components in view of the complex composition of bioethanol. NP @Ni SA 2) In the present invention, the Ni-La2O2CO3 multi-sized Ni-based catalyst doped with La2O2CO3 effectively addresses the carbon deposition problem during the reaction of bioethanol, improving the stability of the catalyst.

[0017] 3) In the present invention, the preparation process of the Ni-La2O2CO3 multi-sized Ni-based catalyst is simple, the variables are easy to control, it can be mass-produced, does not require water washing, and reduces environmental pollution. NP @Ni SA -La2O2CO3 multi-sized Ni-based catalyst for the problem of carbon deposition caused during the bioethanol reaction process, improving the stability of the catalyst.

[0018] 3) The Ni-La2O2CO3 multi-sized Ni-based catalyst in the present invention has a simple preparation process, the variables are easy to control, it can be mass-produced, does not require water washing, and reduces environmental pollution. NP @Ni SA -La2O2CO3 multi-sized Ni-based catalyst has a simple preparation process, the variables are easy to control, it can be mass-produced, does not require water washing, and reduces environmental pollution. Description of the Drawings

[0019] Figure 1 is the preparation flow chart of the present invention.

[0020] Figure 2 is the XRD pattern of the Ni-La2O2CO3 catalyst obtained in Example 1. NP @Ni SA -La2O2CO3 catalyst.

[0021] Figure 3 is the scanning electron microscope and transmission electron microscope images of the Ni-La2O2CO3 catalyst obtained in Example 1. NP @Ni SA -La2O2CO3 catalyst.

[0022] Figure 4 is the spherical aberration corrected transmission electron microscope image of NiO particles and Ni single atoms in Ni-La2O2CO3 obtained in Example 1. NP @Ni SA -La2O2CO3.

[0023] Figure 5 is the Ni-La2O2CO3 and Ni obtained in Examples 2 and 3. SA -La2O2CO3 and Ni NPXRD pattern of / La2O2CO3.

[0024] Figure 6 is the Ni obtained in Examples 2 and 3 SA -La2O2CO3 and Ni NP Transmission electron micrograph of Ni

[0025] Figure 7 is the Ni obtained in Examples 1, 2, and 3 NP @Ni SA -La2O2CO3, Ni SA -La2O2CO3 and Ni NP Performance graph of thermocatalytic steam reforming of bioethanol to hydrogen over Ni

[0026] Figure 8 is the Ni in Example 1 NP @Ni SA Performance graph of photocatalytic steam reforming of bioethanol to hydrogen over Ni Detailed implementation manners

[0027] This invention was completed with the support of the "General Program of the Natural Science Foundation of Hebei Province B2023204034" and the "Youth Program of Scientific and Technological Research of the Education Department of Hebei Province QN2022059".

[0028] The following describes the detailed implementation manners of this invention with reference to examples.

[0029] Example 1

[0030] Combined with Figure 1 , the preparation method of the multi-sized Ni-based catalyst provided in this example is as follows:

[0031] 1) Add about 5 mL of deionized water to a washed 50 mL graduated beaker at room temperature. Weigh 2.5 g of C6H8O7·H2O, 1 g of La(NO3)3·6H2O, and 0.1 g of Ni(NO3)2·6H2O with a four-digit balance and add them to the beaker to form a mixed solution.

[0032] 2) Place the mixed solution in step 1) on a multi-head magnetic heating stirrer and stir. During the stirring process, sequentially add 1.2 mL of HNO3 and 0.6 mL of C2H8N2 (ethylenediamine). After stirring evenly, add NH3·H2O until the pH reaches 6. Then, raise the temperature of the multi-head magnetic heating stirrer to 80 °C and stir and dry for 1 h until a viscous gel-like substance is obtained.

[0033] 3) Place the gel-like substance in step 2) in a quartz boat and dry and age it at 80 °C in a blast dryer for 24 h.

[0034] 4) Transfer the aged sample in step 3) into a quartz tube, introduce argon gas into the quartz tube for 1 h to expel air, heat the tube furnace to 400 °C at a rate of 5 °C / min, keep it stable for 10 min, and then place the quartz tube containing the sample into the tube furnace at 400 °C. The sample will instantaneously expand and a large amount of gas will be generated at 400 °C. After the gas is stable, keep it warm for 4 h, and the catalyst completes annealing.

[0035] 5) Place the annealed sample in step 4) into a muffle furnace, heat it to 400 °C at a rate of 5 °C / min in an air environment, and calcine it for 4 h to obtain a multi-sized Ni-based catalyst. Here, the multi-sized refers to two different sizes of Ni elements, namely Ni single atoms and Ni nanoparticles. The obtained catalyst is a catalyst Ni doped with La2O2CO3 coexisting with Ni single atoms and Ni nanoparticles. NP @Ni SA -La2O2CO3. Ni SA represents Ni single atoms, Ni NP represents Ni nanoparticles.

[0036] Perform XRD testing on the Ni NP @Ni SA -La2O2CO3 catalyst prepared in Example 1, and the obtained results are as Figure 2 shown. From Figure 2 the XRD pattern, no obvious diffraction peaks of NiO and Ni are observed, indicating that Ni is highly dispersed in La2O2CO3.

[0037] Perform scanning electron microscopy and transmission electron microscopy testing on the Ni NP @Ni SA -La2O2CO3 catalyst prepared in Example 1, and the obtained results are as Figure 3 shown. Figure 3 Among them, (a) is the scanning electron micrograph of the catalyst, and (b) is the transmission electron micrograph of the catalyst. From Figure 3 it can be seen that the catalyst Ni NP @Ni SA -La2O2CO3 is a nano-sheet structure with a thickness of 1 - 30 nm.

[0038] Perform aberration-corrected transmission electron microscopy testing on the Ni NP @Ni SA -La2O2CO3 catalyst prepared in Example 1, and the obtained results are as Figure 4 shown. Figure 4 Among them, (a) is the aberration-corrected transmission electron micrograph of NiO particles, and (b) is the aberration-corrected transmission electron micrograph of Ni single atoms. From Figure 4 it can be seen that Ni NP @NiSA -Both single-atom Ni and Ni particles (the Ni particles exist in the form of NiO) coexist in the La2O2CO3 catalyst.

[0039] Example 2

[0040] At room temperature, add about 5 mL of deionized water to a washed 50-mL measuring beaker. Weigh 2.5 g of C6H8O7·H2O, 1 g of La(NO3)3·6H2O, and 0.02 g of Ni(NO3)2·6H2O separately using a four-digit balance and add them to the beaker to form a mixed solution. The subsequent steps are the same as steps 2) to 5) in Example 1. The finally obtained catalyst is a catalyst with single-atom Ni doped in La2O2CO3, denoted as Ni SA -La2O2CO3. Since the content of Ni(NO3)2·6H2O added in this example is small, during the instantaneous expansion at 400 °C in step 4), the huge energy will make the distribution of Ni wider, forming mostly single-atom Ni morphology.

[0041] Example 3

[0042] Prepare nanosheet La2O2CO3, and its preparation method is similar to that of Ni NP @Ni SA -La2O2CO3 in Example 1. The only difference is that Ni(NO3)2·6H2O is not added.

[0043] Weigh 0.13 g of Ni(NO3)2·6H2O and 1 g of the prepared nanosheet La2O2CO3. Mix the above powders with 10 mL of deionized water in a beaker. Place the beaker in water and perform ultrasonic dispersion treatment for 30 min (ultrasonic frequency is 90 Hz). After ultrasonic dispersion, stir and add ammonia water until the pH is 10. Then perform centrifugation on the above solution. After centrifugation is completed, transfer it to a constant-temperature drying oven and dry at 100 °C for 24 hours. Then calcine it at 400 °C for 4 hours in an air atmosphere to obtain a catalyst with Ni particles loaded on La2O2CO3, denoted as Ni NP / La2O2CO3.

[0044] Perform XRD tests on the Ni SA -La2O2CO3 catalyst prepared in Example 2 and the Ni NP / La2O2CO3 catalyst prepared in Example 3. The obtained results are as Figure 5 shown. Figure 5 Among them, (a) is the Ni SA -La2O2CO3 catalyst, and (b) is the Ni NP / La2O2CO3 catalyst. From Figure 5No obvious diffraction peaks of NiO and Ni were observed, indicating that Ni was highly dispersed.

[0045] For the Ni SA -La2O2CO3 catalyst prepared in Example 2 and the Ni NP / La2O2CO3 catalyst prepared in Example 3, transmission electron microscopy tests were carried out, and the results are as Figure 6 shown. Figure 6 Among them, (a) is the Ni SA -La2O2CO3 catalyst, and (b) is the Ni NP / La2O2CO3 catalyst. From Figure 6 (a), it was observed that the Ni SA -La2O2CO3 catalyst was a nanosheet and no precipitate was observed on the surface. From Figure 6 (b), it was observed that a large amount of flocculent precipitate adhered to the surface of the Ni NP / La2O2CO3 catalyst.

[0046] The Ni NP @Ni SA -La2O2CO3 catalyst prepared in Example 1, the Ni SA -La2O2CO3 catalyst prepared in Example 2, and the Ni NP / La2O2CO3 catalyst prepared in Example 3 were applied to the catalytic steam reforming of bioethanol for hydrogen production, and the hydrogen production rate is as Figure 7 shown. Figure 7 It can be seen that the Ni NP @Ni SA -La2O2CO3 catalyst prepared in Example 1 had the highest hydrogen production rate, indicating that it had a good catalytic effect on the complex composition of bioethanol. The Ni NP / La2O2CO3 catalyst prepared in Example 3 showed a sudden drop in the hydrogen production rate after 550 °C, probably because the deposition of carbon caused the inactivation of the catalyst. The hydrogen production rate of the Ni SA -La2O2CO3 catalyst prepared in Example 2 increased relatively smoothly and did not show a sudden decrease trend, indicating that the single-atom catalyst had good anti-carbon deposition ability.

[0047] The Ni NP @Ni SA -La2O2CO3 catalyst prepared in Example 1 of the present invention can also be applied to photo-driven thermocatalytic steam reforming of bioethanol for hydrogen production. During the experiment of photo-driven thermocatalytic steam reforming of bioethanol for hydrogen production, the photo-thermal tube absorbs ultraviolet and visible light, confines the heat generated by light in the tube, reaches the activation temperature of the catalyst, and achieves the effect of photo-driven thermocatalysis. Ni NP @Ni SA- The performance of the La2O2CO3 catalyst for photocatalytic thermocatalytic steam reforming of bioethanol to hydrogen is as Figure 8 shown. From Figure 8 it can be seen that when the light intensity is 1 kW m -2 , the temperature inside the photothermal tube rises to 414 °C, reaching the activation temperature of the Ni NP @Ni SA -La2O2CO3 catalyst, and the catalytic effect can be clearly observed.

[0048] Generally speaking, the present invention discloses a preparation method for preparing multi-sized Ni-based catalysts using citric acid as a template, which is used for the photocatalytic steam reforming of bioethanol to hydrogen process, and demonstrates its pertinence and high efficiency, providing a new reference for the bioethanol steam reforming to hydrogen process.

[0049] Although the specific implementation mode of the present invention has been described in detail in combination with the embodiments, it should not be construed as a limitation of the protection scope of this application. Within the scope described in the claims, various modifications and deformations that can be made by those skilled in the art without creative work still fall within the protection scope of this patent.

Claims

1. A preparation method of a multi-size Ni-based catalyst, characterized in that It includes the following steps: a. Dissolve citric acid, nickel nitrate, and lanthanum nitrate in deionized water and stir evenly to form a mixed solution; b. Place the mixed solution in step a on a heating stirrer and stir. During the stirring process, add HNO3 and C2H8N2 dropwise. After stirring, add NH3·H2O until the pH of the solution is 6. Heat the heating stirrer to 80 °C and stir and dry for 1 h until a viscous gel is formed; c. Place the viscous gel in step b in a quartz boat and perform drying and aging in a blast dryer; d. Transfer the dried and aged sample to a quartz tube, introduce argon into the quartz tube, heat the tube furnace to 400 °C, place the quartz tube containing the sample in the tube furnace, the sample instantaneously expands in the tube furnace, and then keep the sample at 400 °C for 4 h; e. Place the sample in step d in a muffle furnace and calcine at 400 °C for 4 h to obtain a multi-sized Ni-based catalyst, which is a catalyst in which Ni nanoparticles and Ni single atoms coexist and are doped with La2O2CO3.

2. The preparation method of the multi-size Ni-based catalyst according to claim 1, characterized in that, In step d, the heating rate of the tube furnace is 5 °C / min; after heating the tube furnace to 400 °C, stabilize for 10 min, and then place the quartz tube containing the sample in the tube furnace.

3. The preparation method of the multi-sized Ni-based catalyst according to claim 1, characterized in that, In step c, perform drying and aging in a blast dryer at a temperature of 80 °C for 24 h.

Images