FeAl nanoparticle-loaded catalytic material as well as preparation method and application thereof

Abstract

The invention discloses a FeAl nanoparticle-loaded catalytic material as well as a preparation method and application thereof, can be used as an electro-catalysis nitrogen reduction reaction catalyst, and belongs to the field of nano material synthesis and energy environment science and engineering application. Dispersed activated carbon is used as a conductive substrate and is loaded with FeAl nano active particles, and the dispersed activated carbon and the FeAl nano active particles are synergistically used for an electro-catalysis nitrogen fixation reaction. FeAl metal particles loaded in the carbon black can be clearly seen in a transmission electron microscopic image, and when an electro-catalysis nitrogen reduction reaction test is carried out, the ammonia production selectivity reaches 26.6% at most.

Description

Technical Field

[0001] The invention belongs to the field of nano material synthesis and energy environment science and engineering application, and specifically relates to a FeAl loaded nano particle catalytic material and a preparation method and application thereof. Background Art

[0002] Electrochemical nitrogen reduction is a sustainable method of nitrogen fixation that can generate ammonia from air and water when powered by a steady supply of renewable electricity. Unlike the widely used Haber-Bosch process, in which nitrogen and hydrogen are combined under extremely high temperatures (400-500°C) and ultra-high pressures (200-300 atm) to form ammonia, the electrocatalytic nitrogen reduction reaction can activate nitrogen and add hydrogen at room temperature and ambient pressure through a precisely controlled electron transfer and multi-step proton coupling process. Despite the great efforts of researchers in recent decades, the development of electrocatalysts that can selectively and efficiently reduce nitrogen to ammonia remains difficult and difficult to achieve. Most catalysts exhibit higher overpotentials in the nitrogen reduction reaction than in the hydrogen evolution reaction. Limited by the key competitive challenge of the hydrogen evolution reaction, the electrocatalytic nitrogen reduction reaction shows limited selectivity (up to about ~10%) and activity in aqueous solution.

[0003] In the Haber process, iron catalyst is the key catalyst, and its main component is Fe 3 O 4 , and often supplemented with Al 2 O 3 As an active center, Fe can effectively adsorb and activate nitrogen molecules during the catalytic process, while Al 2 O 3 As a carrier, it not only provides a larger specific surface area and more active sites, but also enhances the thermal stability and mechanical strength of the catalyst. Nitrogen adsorption is the first step in the electrocatalytic nitrogen reduction reaction and is also one of the key factors determining the reaction rate and yield. In the catalytic materials constructed with Fe and Al metals, the 3d electrons of Fe and the 2p empty orbitals of Al may interact with the antibonding orbitals and lone pair electrons of nitrogen molecules to promote nitrogen adsorption and activation. In addition, Fe and Al are both abundant elements on the earth, so the cost of the catalyst is relatively low and easy to mass produce. With the continuous exploration of catalyst design and optimization methods, FeAl-based electrocatalysts are expected to play a greater role in ammonia synthesis and other related fields. Summary of the invention

[0004] The purpose of the present invention is to construct FeAl nanoparticles loaded with conductive carbon black for electrocatalytic nitrogen reduction reaction, wherein the loaded FeAl nanoparticles are used as active species for nitrogen adsorption and activation, and the conductive carbon black is used to provide a large specific surface area and a fast electron transfer rate, and the two work together to have good electrocatalytic nitrogen reduction ammonia selectivity, which is better than most reported ammonia synthesis electrocatalysts. The catalytic material provides a reference for the research of electrocatalytic nitrogen reduction ammonia synthesis catalysts and provides a research platform for the subsequent optimization of electrocatalytic ammonia synthesis performance.

[0005] The technical solution of the present invention is as follows:

[0006] A FeAl nanoparticle-loaded catalytic material is prepared according to the following steps:

[0007] Step 1: using ethylene glycol to prepare a metal dispersion containing Al and Fe metal salts;

[0008] Step 2: Weigh the conductive carbon black, and disperse it in ethylene glycol by ultrasonication to obtain a carbon black dispersion;

[0009] Step 3: Take the metal dispersion prepared in step 1 and the carbon black dispersion prepared in step 2, mix them, stir them evenly, place them in the inner tank of a reactor to heat and react, wash and dry them to obtain a FeAl nanoparticle-loaded catalytic material.

[0010] A method for preparing a FeAl-loaded nanoparticle catalytic material comprises the following steps:

[0011] Step 1: using ethylene glycol to prepare a metal dispersion containing Al and Fe metal salts;

[0012] Step 2: Weigh the conductive carbon black, and disperse it in ethylene glycol by ultrasonication to obtain a carbon black dispersion;

[0013] Step 3: Take the metal dispersion prepared in step 1 and the carbon black dispersion prepared in step 2, mix them, stir them evenly, place them in the inner tank of a reactor to heat and react, wash and dry them to obtain a FeAl nanoparticle-loaded catalytic material.

[0014] In the above technical solution, the metal salt described in step 1 is AlCl 3 6H 2 O and FeCl 3 6H 2 O, concentration 5-50 mmol mL -1 ;

[0015] In the above technical solution, the mass concentration of ultrasonic conductive carbon black in step 2 is 1-10 mg mL -1 , ultrasonic dispersion time is greater than 1h;

[0016] In the above technical solution, the volume ratio of the metal dispersion to the carbon black dispersion in step 3 is 1:2;

[0017] In the above technical solution, the reaction temperature in step 3 is 180°C and the reaction time is greater than 15 h;

[0018] In the above technical solution, after the reaction in step 3 is completed, anhydrous ethanol is used for washing;

[0019] An application of a FeAl nanoparticle-loaded catalytic material, in an H-type reaction cell, uses a three-electrode system, wherein a carbon paper loaded with FeAl nanoparticle catalyst is a working electrode, a carbon rod is a counter electrode, an Ag / AgCl electrode filled with a saturated KCl solution is a reference electrode, and a 0.5 M Li saturated with nitrogen is used as a reference electrode. 2 SO 4 The solution is an electrolyte solution.

[0020] In the above technical scheme, the working electrode preparation method is: first, the FeAl nanoparticle catalyst loaded is dispersed in an isopropanol solution with a concentration of 5 mg mL -1 , add 50 μL of nafion solution, mix well, take 200 μL of catalyst dispersion and evenly drop it on 1 cm 2 On carbon paper, it was used as the working electrode after drying.

[0021] In the above technical solution, the maximum Faraday efficiency of the electrocatalytic nitrogen reduction reaction is 26.6%.

[0022] Beneficial effects:

[0023] 1. Improving the Faraday efficiency of synthetic ammonia means that more ammonia output can be obtained under the same electrical energy input. This not only reduces production costs but also improves production efficiency.

[0024] 2. The traditional Haber-Bosch process for synthesizing ammonia requires high temperature and high pressure, and has high energy consumption and large emissions. However, the electrocatalytic nitrogen reduction process for synthesizing ammonia can be carried out under milder conditions, with lower energy consumption and less emissions. Therefore, the application of this patent is expected to reduce environmental pollution in the process of synthesizing ammonia and promote the development of green chemistry.

[0025] 3. Conductive carbon black is used as a carrier to load FeAl nanoparticles. This composite material combines the good conductivity of conductive carbon black and the catalytic activity of FeAl nanoparticles, providing a new material option for electrocatalytic nitrogen reduction to synthesize ammonia. This composite material may have better electron transfer performance and catalytic stability, thereby improving the efficiency of the catalytic reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1: Transmission electron microscopy image of the dispersed conductive carbon black prepared in the present invention.

[0027] Figure 2 : Transmission electron microscopic image of carbon black-loaded FeAl nanoparticles prepared in the present invention.

[0028] Figure 3 : The linear voltammetric scanning image of FeAl nanoparticles loaded with dispersed conductive carbon black prepared by the present invention for electrocatalytic nitrogen reduction to synthesize ammonia.

[0029] Figure 4 : The present invention prepares dispersed conductive carbon black loaded FeAl nanoparticles for electrocatalytic nitrogen reduction to synthesize ammonia Faraday efficiency image. DETAILED DESCRIPTION

[0030] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. However, the following embodiments are limited to explaining the present invention, and the protection scope of the present invention should include the entire contents of the claims, and through the description of the following embodiments, those skilled in the art can fully implement the entire contents of the claims of the present invention.

[0031] Embodiment 1:

[0032] ① Use ethylene glycol solvent to prepare 5 mmol mL -1 FeCl 3 6H 2 O and 5 mmol mL -1 AlCl 3 6H 2 O mixed solution.

[0033] ② Weigh 10 mg of conductive carbon black and disperse it in 10 mL of ethylene glycol by ultrasonication for 2 h;

[0034] ③ Take 10 mL of metal dispersion and 20 mL of conductive carbon black dispersion, mix them, stir them evenly and place them in the inner tank of the reactor. After reacting at 180°C for 15 h, wash and dry them with anhydrous ethanol to obtain a FeAl nanoparticle-loaded catalytic material.

[0035] Embodiment 2:

[0036] ① Use ethylene glycol solvent to prepare 10 mmol mL -1 FeCl 3 6H 2 O and 10 mmol mL -1 AlCl 3 6H 2 O mixed solution.

[0037] ② Weigh 10 mg of conductive carbon black and disperse it in 10 mL of ethylene glycol by ultrasonication for 2 h;

[0038] ③ Take 10 mL of metal dispersion and 20 mL of conductive carbon black dispersion, mix them, stir them evenly and place them in the inner tank of the reactor. After reacting at 180°C for 15 h, wash and dry them with anhydrous ethanol to obtain a FeAl nanoparticle-loaded catalytic material.

[0039] Embodiment three:

[0040] ① Use ethylene glycol solvent to prepare 5 mmol mL -1 FeCl 3 6H 2 O and 5 mmol mL -1 AlCl 3 6H 2 O mixed solution.

[0041] ② Weigh 20 mg of conductive carbon black and disperse it in 20 mL of ethylene glycol by ultrasonication for 2 h;

[0042] ③ Take 10 mL of metal dispersion and 20 mL of conductive carbon black dispersion, mix them, stir them evenly and place them in the inner tank of the reactor. After reacting at 180°C for 15 h, wash and dry them with anhydrous ethanol to obtain a FeAl nanoparticle-loaded catalytic material.

[0043] Experimental results:

[0044] In the embodiment of the present invention, a FeAl nanoparticle-loaded catalytic material is prepared. From the transmission electron microscopy image ( Figure 1 ) It can be seen that there are no metal particles in the dispersed carbon black particles without FeAl particles, while metal particles with good dispersion can be clearly seen in the conductive carbon black loaded with FeAl particles ( Figure 2 ).

[0045] The carbon black-loaded FeAl nanoparticle catalyst material prepared in Example 1 of the present invention is used for the electrocatalytic nitrogen reduction reaction to synthesize ammonia. In an H-type reaction cell, a three-electrode system is used, wherein the carbon paper loaded with FeAl nanoparticle catalyst is the working electrode, the carbon rod is the counter electrode, the Ag / AgCl electrode filled with saturated KCl solution is the reference electrode, and 0.5 mol L -1 Li 2 SO 4 The solution is an electrolyte solution. The working electrode preparation method is as follows: first, disperse the FeAl nanoparticle catalyst in an isopropanol solution at a concentration of 5 mg mL -1, add 50 μL of nafion solution, mix well, take 200 μL of catalyst dispersion and evenly drop it on 1 cm 2 On carbon paper, it was used as the working electrode after drying. Figure 3 As shown in the figure, when linear voltammetry scans were performed in different solution environments, the current density of the linear voltammetry curve under nitrogen saturation conditions was significantly lower than that under the condition without nitrogen, indicating that the adsorption of nitrogen by the catalyst inhibited the hydrogen evolution reaction. Figure 4 As shown, the maximum Faraday efficiency of the catalyst for the electrocatalytic nitrogen reduction reaction to synthesize ammonia is about 26.6%.

[0046] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A FeAl nanoparticle-loaded catalytic material, characterized in that: Prepared according to the following steps: Step 1: using ethylene glycol to prepare a metal dispersion containing Al and Fe metal salts; Step 2: Weigh the conductive carbon black, and disperse it in ethylene glycol by ultrasonication to obtain a carbon black dispersion; Step 3: Take the metal dispersion prepared in step 1 and the carbon black dispersion prepared in step 2, mix them, stir them evenly, place them in the inner tank of a reactor to heat and react, wash and dry them to obtain a FeAl nanoparticle-loaded catalytic material.

2. The method for preparing a supported FeAl nanoparticle catalytic material according to claim 1, characterized in that: Step 1: using ethylene glycol to prepare a metal dispersion containing Al and Fe metal salts; Step 2: Weigh the conductive carbon black, and disperse it in ethylene glycol by ultrasonication to obtain a carbon black dispersion; Step 3: Take the metal dispersion prepared in step 1 and the carbon black dispersion prepared in step 2, mix them, stir them evenly, place them in the inner tank of a reactor to heat and react, wash and dry them to obtain a FeAl nanoparticle-loaded catalytic material.

3. The method for preparing a FeAl nanoparticle catalyst material according to claim 2, wherein the metal salts in step 1 are AlCl3·6H2O and FeCl3·6H2O, and the concentration is 5-50 mmol mL -1 ; The mass concentration of ultrasonic conductive carbon black in step 2 is 1-10 mg mL -1 , the ultrasonic dispersion time is greater than 1h; in step 3, the volume ratio of the metal dispersion and the carbon black dispersion is 1:2, the reaction temperature is 180°C, and the reaction time is greater than 15h.

4. The use of a FeAl nanoparticle catalytic material as claimed in claim 1, characterized in that: In the H-type reaction cell, a three-electrode system was used, in which the carbon paper loaded with FeAl nanoparticle catalyst was the working electrode, the carbon rod was the counter electrode, the Ag / AgCl electrode filled with saturated KCl solution was the reference electrode, and the lithium sulfate solution was the electrolyte solution.

5. The use of a FeAl nanoparticle catalytic material as claimed in claim 4, characterized in that: The working electrode preparation method is as follows: first, the FeAl nanoparticle catalyst is dispersed in an isopropanol solution at a concentration of 5 mg mL -1 , add 50 μL of nafion solution, mix well, take 200 μL of catalyst dispersion and evenly drop it on 1 cm 2 On carbon paper, it was used as the working electrode after drying.

6. The use of a FeAl nanoparticle catalytic material as claimed in claim 4, characterized in that: The maximum Faradaic efficiency of the electrocatalytic nitrogen reduction reaction is 26.6%.

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