阅读说明：本技术 一种KRu4O8纳米棒材料、其制备方法及其应用 (KRu4O8Nanorod material, preparation method and application thereof ) 是由 王银银 曹聪 鲍骏 刘彬 曾杰 于 2021-06-22 设计创作，主要内容包括：本发明提供了一种KRu-4O-8纳米棒材料,具有沿[001]方向生长的锰钡矿结构。本申请还提供了KRu-4O-8纳米棒材料的制备方法,其包括以下步骤：将氯化钌水溶液和氢氧化钾水溶液混合,反应,得到沉淀物；将所述沉淀物高温煅烧,得到KRu-4O-8纳米棒材料。本申请还提供了KRu-4O-8纳米棒材料在电化学氧化丙烯合成1,2-丙二醇反应中的应用。本申请中KRu-4O-8纳米棒材料的锰钡矿结构以及大半径钾原子的引入,提高了电化学氧化丙烯合成1,2-丙二醇的催化活性和选择性。(The invention provides KRu 4 O 8 Nanorod material with rim [001]Directionally grown barium manganese ore structure. The present application also provides KRu 4 O 8 A method for preparing a nanorod material, comprising the steps of: mixing a ruthenium chloride aqueous solution and a potassium hydroxide aqueous solution, and reacting to obtain a precipitate; calcining the precipitate at high temperature to obtain KRu 4 O 8 A nanorod material. The present application also provides KRu 4 O 8 The application of the nano-rod material in the reaction of synthesizing 1, 2-propylene glycol by electrochemical propylene oxide. KRu in the present application 4 O 8 Barium-manganese ore structure of nano rod material and introduction of large-radius potassium atomsAnd the catalytic activity and selectivity of synthesizing 1, 2-propylene glycol by electrochemically oxidizing propylene are improved.)

1. KRu₄O₈Nanorod material with rim [001]Directionally grown barium manganese ore structure.

2. KRu according to claim 1₄O₈A nanorod material, wherein KRu is defined₄O₈The length of the nano rod material is 150-300 nm, and the diameter is 30-60 nm.

3. KRu of claim 1₄O₈The preparation method of the nano rod material is characterized by comprising the following steps of:

mixing a ruthenium chloride aqueous solution and a potassium hydroxide aqueous solution, and reacting to obtain a precipitate;

calcining the precipitate at high temperature to obtain KRu₄O₈A nanorod material.

4. The method according to claim 3, wherein the concentration of the aqueous solution of ruthenium chloride is not more than 0.5mol/L and the concentration of the aqueous solution of potassium hydroxide is not less than 5 mol/L.

5. The method according to claim 3, wherein the mixing time is 20 to 60 min.

6. The preparation method according to claim 3, further comprising drying before the calcining, wherein the drying temperature is 80-120 ℃.

7. The preparation method according to claim 3, wherein the calcination is carried out at a temperature of 500 to 1000 ℃ for 2 to 8 hours.

8. The method according to claim 3, wherein the calcination is carried out in argon and oxygen at a volume ratio of 3: 1.

9. KRu according to any one of claims 1 to 2₄O₈A nanorod material or KRu prepared by the method of any one of claims 3-8₄O₈The application of the nano-rod material in synthesizing 1, 2-propylene glycol by electrochemical oxidation of propylene.

Technical Field

The invention relates to the technical field of catalysts, in particular to KRu₄O₈A nanorod material, a preparation method and application thereof.

Background

1, 2-propylene glycol is a chemical with higher added value, can be applied to the manufacture of products such as paint, liquid detergent, cosmetics, essence, food, personal care products, tobacco humectant and the like, and is mainly used as an antifreezing coolant and a deicing agent, and as a raw material for polyester resin synthesis, and is used for fiber production and medicine production.

Industrial processes for the production of 1, 2-propanediol, such as propylene oxide hydration and glycerol hydrogenolysis, require multiple steps and are energy intensive. The reduction of fossil fuel resources, the increase of environmental problems, and the global impact on energy, fuel, and chemical demand have greatly increased the drive for the research of electrochemical synthesis. The method for producing the high-value product 1, 2-propylene glycol by processing propylene by using an environment-friendly electrochemical method to replace the traditional propylene high-temperature high-pressure oxidation rehydration process is a very valuable research direction. Several previous reports have investigated the results of direct electrochemical oxidation of propylene, however most of the earlier studies used metallic palladium electrocatalysts which did not show high selectivity to 1, 2-propanediol, which is economically valuable. On the other hand, ruthenium-based materials have been widely used for the electro-oxidation of small organic molecules such as methanol and glycerol. According to previous literature reports, ruthenium-based materials have not been applied to the electro-oxidation of propylene.

Disclosure of Invention

The invention aims to provide KRu₄O₈The nanorod material provided by the application is applied to electrochemical propylene oxide to synthesize 1, 2-propylene glycol, and has high selectivity, activity and catalytic stability.

In view of the above, the present application provides KRu₄O₈Nanorod material with rim [001]Directionally grown barium manganese ore structure.

Preferably, said KRu₄O₈The length of the nano rod material is 150-300 nm, and the diameter is 30-60 nm.

The present application also provides said KRu₄O₈The preparation method of the nano rod material comprises the following steps:

mixing a ruthenium chloride aqueous solution and a potassium hydroxide aqueous solution, and reacting to obtain a precipitate;

calcining the precipitate at high temperature to obtain KRu₄O₈A nanorod material.

Preferably, the concentration of the ruthenium chloride aqueous solution is less than or equal to 0.5mol/L, and the concentration of the potassium hydroxide aqueous solution is more than or equal to 5 mol/L.

Preferably, the mixing time is 20-60 min.

Preferably, the calcining further comprises drying at a temperature of 80-120 ℃.

Preferably, the calcining temperature is 500-1000 ℃, and the time is 2-8 h.

Preferably, the calcination is carried out in argon and oxygen in a volume ratio of 3: 1.

The present application also provides said KRu₄O₈KRu prepared from nano rod material or said preparation method₄O₈The application of the nano-rod material in synthesizing 1, 2-propylene glycol by electrochemical oxidation of propylene.

The present application provides a KRu₄O₈A nanorod material having a rim [001]Directionally grown barium manganese ore structures; due to KRu₄O₈The MnBa ore structure of the nano-rod material forms a structural form with K atoms on the surface, and the introduction of the large-radius K atoms causes structural phase deformation, thereby regulating and controlling the adsorption strength of a propylene intermediate on the surface of the nano-rod material, improving the slow kinetics of the partial oxidation process of propylene, and improving KRu₄O₈The nano rod material has catalytic activity, selectivity and catalytic stability in the application of synthesizing 1, 2-propylene glycol by electrochemical oxidation of propylene.

Drawings

FIG. 1 shows a one-dimensional MnBazite structure KRu prepared in example 1 of the present invention₄O₈Scanning electron microscope pictures of nanorod catalysts;

FIG. 2 shows a one-dimensional MnBazite structure KRu prepared in example 1 of the present invention₄O₈Transmission electron microscope picture of nanorod catalyst;

FIG. 3 shows a one-dimensional MnBazite structure KRu prepared in example 1 of the present invention₄O₈High resolution transmission electron microscope pictures of nanorod catalysts;

FIG. 4 shows a one-dimensional MnBazite structure KRu prepared in example 1 of the present invention₄O₈X-ray diffraction pattern of nano-rod catalyst;

FIG. 5 shows a one-dimensional MnBazite structure KRu prepared in example 1 of the present invention₄O₈Nanorod catalyst and commercial RuO₂An X-ray photoelectron spectrum of the catalyst;

FIG. 6 shows a one-dimensional MnBazite structure KRu prepared in example 1 of the present invention₄O₈Nanorod catalyst and commercial RuO₂An X-ray absorption near-edge spectrum of the catalyst;

FIG. 7 shows a one-dimensional MnBazite structure KRu prepared in example 3 of the present invention₄O₈Nanorod catalyst and commercial RuO₂The effective current density of the catalyst under different overpotentials is shown;

FIG. 8 shows a one-dimensional MnBazite structure KRu prepared in example 3 of the present invention₄O₈The faradaic efficiency of the nanorod catalyst for producing 1, 2-propylene glycol under different overpotentials;

FIG. 9 shows a one-dimensional MnBazite structure KRu prepared in example 4 of the present invention₄O₈The faradaic efficiency of the nanorod catalyst for producing 1, 2-propylene glycol under the condition that the overpotential of the nanorod catalyst relative to a standard hydrogen electrode is 1.5V is shown as a time-dependent change graph.

Detailed Description

For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.

In view of the current situation of propylene electro-oxidation, the application provides a one-dimensional brahmite structure KRu₄O₈The nano rod material has high selectivity and activity and good catalytic stability in the reaction of synthesizing 1, 2-propylene glycol by electrochemical oxidation of propylene. Specifically, the embodiment of the invention discloses KRu₄O₈Nanorod material with rim [001]Directionally grown barium manganese ore structure.

In the present application, said KRu₄O₈The length of the nano rod material is 150-300 nm, and the diameter is 30-60 nm.

The present application also provides said KRu₄O₈The preparation method of the nano rod material comprises the following steps:

mixing a ruthenium chloride aqueous solution and a potassium hydroxide aqueous solution, and reacting to obtain a precipitate;

calcining the precipitate at high temperature to obtain KRu₄O₈A nanorod material.

In preparation KRu₄O₈In the process of preparing the nano rod material, firstly, mixing a ruthenium chloride aqueous solution and a potassium hydroxide aqueous solution, and reacting to obtain a precipitate; in this process, potassium hydroxide reacts with ruthenium chloride to give a ruthenium hydroxide precipitate, which adsorbs a portion of the KOH in solution to form a precipitate. In the process, the concentration of the ruthenium chloride aqueous solution is less than or equal to 0.5mol/L, and the concentration of the potassium hydroxide aqueous solution is more than or equal to 5 mol/L; in a specific embodiment, the concentration of the ruthenium chloride aqueous solution is 0.5mol/L, and the concentration of the potassium hydroxide aqueous solution is 5 mol/L. The concentrations of the potassium hydroxide aqueous solution and the ruthenium chloride aqueous solution can affect the purity, length and thickness of the nanorod phase; the aqueous potassium hydroxide solution is in excess and has a concentration of 5mol/L or more, otherwise RuO will occur₂A heterogeneous phase; likewise, the concentration of the aqueous ruthenium chloride solution is less than or equal to 0.5mol/L, otherwise RuO will occur₂Miscellaneous phase, reduction of RuCl₃The rod-shaped material is shortened by the feeding amount. The mixing needs to be continuously stirred for 20-60 min so as to fully carry out the reaction. The application then dries the precipitate at 80-120 ℃.

The precipitate is finally calcined at high temperature to give KRu₄O₈A nanorod material. During the calcination, ruthenium hydroxide and potassium hydroxide react with oxygen to obtain KRu₄O₈(ii) a The concentration of the above raw materials and the reaction conditions were controlled to obtain KRu₄O₈A nanorod material. During the calcination processThe calcination is carried out in a mixed gas of argon and oxygen in a volume ratio of 3:1, the calcination temperature is 500-1000 ℃, the calcination time is 2-8 hours, more specifically, the calcination temperature is 750 ℃, and the calcination time is 4 hours.

The present application also provides the KRu described above₄O₈The application of the nano-rod material in synthesizing 1, 2-propylene glycol by electrochemical oxidation of propylene.

In a specific embodiment of the present application, the process of electrochemical oxidation is:

KRu mg of one-dimensional MnBaite structure₄O₈Dispersing the nanorod catalyst, 5 mg of activated carbon and 25 microliters of 5% mass fraction Nafion solution in 475 milliliters of ethanol, and performing ultrasonic mixing for at least 45 minutes to obtain a uniform catalyst ink; then spraying catalyst ink on the carbon-based fiber gas diffusion layer, wherein the loading amount of the catalyst is kept to be 1 mg/square centimeter; the gas diffusion layer is used as a working electrode, the calomel electrode is used as a reference electrode, and the platinum wire is used as a counter electrode. The reaction for synthesizing 1, 2-propylene glycol by electrochemical propylene oxide is carried out in a three-channel flow cell, the electrolyte is sulfuric acid electrolyte containing 0.5mol/L, and overpotential and current density detection are applied through an electrochemical workstation.

Commercial RuO₂Preparation of electrodes and KRu₄O₈The electrode preparation remains the same.

With commercial RuO₂Comparing the nano-catalyst, in the reaction of synthesizing 1, 2-propylene glycol by electrochemical oxidation of propylene, under the overpotential of 1.5V relative to the standard hydrogen electrode, the one-dimensional manganese barium ore structure KRu₄O₈The nanorod catalyst has a current density of about 18.3 mA/cm, faradaic efficiency of 1, 2-propanediol production up to 62%, an effective current density of 11.3 mA/cm, as compared to commercial RuO₂The nano-catalyst does not show the activity of synthesizing 1, 2-propylene glycol by the electro-oxidation of propylene. One-dimensional brahmite structure KRu for use in the present invention₄O₈Compared with other catalytic materials, the nanorod catalyst is easy to synthesize in a large scale and low in cost. In the catalytic reaction, the catalyst used in the invention has high selectivity and good stability.

For a further understanding of the present invention, KRu is provided below in connection with the examples₄O₈The nanorod materials, the preparation method thereof and the application thereof are explained in detail, and the scope of the present invention is not limited by the following examples.

Example 1

The invention provides a one-dimensional manganite structure KRu₄O₈The nano-rod catalyst has a length of 150-300 nm, a diameter of about 50 nm, and a length of [001 ]]Directional growth; the synthesis method comprises the following steps:

0.5 ml of an aqueous ruthenium chloride solution (0.5 mol/l) was added to 50 ml of an aqueous potassium hydroxide solution (5 mol/l) and stirring was continued for 30 minutes, the precipitate becoming thicker with increasing time; then, the precipitate was filtered and kept in an oven at 100 ℃ overnight; after grinding, the precipitated powder was calcined at 750 ℃ for 4 hours in a mixed gas of argon and oxygen (3:1) while maintaining the gas pressure at 8 torr; the final product was centrifuged 5 times with deionized water to remove excess ions to give KRu₄O₈A nanorod material.

One-dimensional MnBaite structure KRu₄O₈The scanning electron microscope picture of the nanorod catalyst is shown in figure 1, the transmission electron microscope picture is shown in figure 2, the high-resolution transmission electron microscope picture is shown in figure 3, the X-ray diffraction spectrum is shown in figure 4, the X-ray photoelectron energy spectrum is shown in figure 5, and the X-ray absorption near-edge spectrum is shown in figure 6.

Example 2

One-dimensional MnBaite structure KRu₄O₈The nano-rod catalyst is used as an electro-catalyst of an active ingredient and the electrochemical propylene oxide test condition.

KRu mg of one-dimensional MnBaite structure₄O₈A nano rod material, 5 mg of activated carbon, 500. mu.l of ethanol, 475. mu.l of water and 25. mu.l of Nafion solution (mass fraction: 5%) were ultrasonically mixed for at least 45 minutes to prepare a catalyst ink; then spraying catalyst ink on the carbon-based fiber gas diffusion layer, wherein the loading amount of the catalyst is kept to be 1 mg/square centimeter; the gas diffusion layer is used as a working electrode, the calomel electrode is used as a reference electrode, and the platinum net is usedAs a counter electrode; the electrochemical propylene oxide reaction electrolyte is 0.5mol/L sulfuric acid solution, the catalytic reaction is carried out in a three-channel flow cell with the channel size of 2 cm multiplied by 0.5 cm multiplied by 0.15 cm, and the gas flow flowing into the flow cell is controlled at 10 standard milliliters/minute through a Brooks GF40 mass flow controller. The flow rates of the catholyte and anolyte are controlled by peristaltic pumps, with the flow rate of the catholyte ranging from 0.1 to 1 ml/min, depending on the current density (low flow rates are used at low current densities to allow sufficient accumulation of liquid product); the anode liquid flow rate was fixed at 5 ml/min. The cathode and anode were separated by a hydroxide exchange membrane (FAA-3; Fumatech). The back pressure of the gas in the flow cell was controlled to atmospheric pressure using a back pressure controller (Cole-Parmer).

Example 3

One-dimensional MnBaite structure KRu₄O₈And (3) testing the current density and the product selectivity of the nanorod catalyst in a test for synthesizing 1, 2-propylene glycol by electrochemical oxidation of propylene.

Under the reaction conditions of example 2, a potentiostatic test was employed. Setting the overpotential of a relative standard hydrogen electrode to be 1.4V, and carrying out constant potential test for 10 minutes; and the concentration of the 1, 2-propylene glycol generated after the reaction is finished is detected and calculated by a nuclear magnetic resonance hydrogen spectrum. After the test is finished, the overpotential is changed to 1.45V, 1.5V, 1.55V, 1.6V, 1.65V and 1.7V, and the test is respectively carried out by using the same process. One-dimensional MnBaite structure KRu₄O₈The current density of the nanorod catalyst under the overpotentials is shown in figure 7, and the faradaic efficiency of 1, 2-propanediol production under different potentials is shown in figure 8; FIG. 7 shows that the pressure at 0.5M H₂SO₄(ii) a propylene electro-oxidation polarization curve recorded in the electrolyte; the current density increased with increasing applied voltage, indicating that the mass transport limit of propylene is not significant; using commercial RuO₂And KRu₄O₈Nanorod contrast, commercial RuO₂Shows much lower current density at the same applied potential under a propylene atmosphere. As can be seen from fig. 8, as the potential increases, the faradaic efficiency of 1, 2-propanediol first increases and then decreases, reaching a peak of 62% at 1.5V over the standard hydrogen electrode; electrooxidation of propyleneThe total Faraday efficiency reaches the maximum value of 71 percent when the overpotential of the relative standard hydrogen electrode is 1.5V; further increasing the applied potential to greater than 1.5V over the standard hydrogen electrode significantly reduced the selectivity to 1, 2-propanediol while increasing the selectivity to formic and acetic acids due to excessive oxidation of propylene.

Example 4

Under the condition that the overpotential relative to a standard hydrogen electrode is 1.5V, the one-dimensional manganite structure KRu₄O₈And (3) testing the stability of the nanorod catalyst in the synthesis of 1, 2-propylene glycol by electrochemical oxidation of propylene.

Under the reaction conditions of example 2, a potentiostatic test was employed. Setting the overpotential of the standard hydrogen electrode to be 1.5V, and carrying out constant potential test for 8 hours. During the reaction, the liquid product is taken every 1 hour, and the concentration of the 1, 2-propylene glycol is calculated by testing the hydrogen nuclear magnetic resonance spectrum. One-dimensional MnBaite structure KRu₄O₈The current density of the nanorod catalyst at the potential and the faradaic efficiency of 1, 2-propanediol production are plotted with time in FIG. 9; as can be seen from FIG. 9, KRu occurred during 8 hours of the stability test₄O₈The current density of the nano-rod and the faradaic efficiency of producing 1, 2-propylene glycol are kept stable.

The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.