CN109879327B

CN109879327B - Preparation of Fe by using metal oxide as catalyst3O4Method (2)

Info

Publication number: CN109879327B
Application number: CN201910074047.5A
Authority: CN
Inventors: 邵斌; 杨棋棋; 周兴超; 熊易; 曾文; 马毅龙; 孙建春; 陈登明; 郭东林; 李春红
Original assignee: Chongqing University of Science and Technology
Current assignee: Chongqing University of Science and Technology
Priority date: 2019-01-25
Filing date: 2019-01-25
Publication date: 2021-09-10
Anticipated expiration: 2039-01-25
Also published as: CN109879327A

Abstract

Preparation of Fe by using metal oxide catalyst₃O₄The method comprises the following steps: to Fe²⁺Adding metal M oxide powder into the solution, dispersing, adding an alkali solution to obtain a mixed solution, and carrying outHydrothermal reaction to obtain the product containing Fe₃O₄Suspension of the particles, separating the product Fe₃O₄(ii) a The metal M oxide is CuO or Cu₂O, CoO or Co₃O₄At least one of (1). Compared with the traditional preparation method, the method utilizes CuO, Cu2O, CoO and Co₃O₄Etc. as catalyst, no need of adding oxidant, and under alkaline condition making Fe be separated from Fe²⁺One-step synthesis of high-purity micron-sized single-crystal octahedron Fe by using salt solution₃O₄The preparation method has the advantages of simple process, high efficiency, rapidness and low cost.

Description

Preparation of Fe by using metal oxide as catalyst3O4Method (2)

Technical Field

The invention relates to a preparation method of an iron compound, in particular to a method for preparing Fe by using metal oxide catalysis₃O₄The method of (1).

Background

China pickling millions of tons of iron oxide every year, resulting in a large Fe content²⁺The acid pickling waste liquid of (1). The Steel industry Water pollutant discharge Standard (GB 13456.2012) U specifies that the total iron content is less than 10 mg/L. However, in general steel pickling waste liquid, Fe is present at a concentration of more than 100g/L²⁺Ions cannot be directly discharged, and need to be subjected to harmless treatment. But discharged as waste liquid, a large amount of Fe²⁺Is wastedIt not only causes huge environmental burden, but also is an economic loss. Thus, Fe in the waste liquid² ⁺Conversion to economically valuable products is an urgent need.

Preparation of Fe by using pickling waste liquor as raw material₃O₄Is a method for recovering Fe²⁺The pathway of (1). Due to the higher Fe content, Fe₃O₄Can be directly smelted to make iron, and has application in the fields of pigment, magnetic material, medical biology, catalysis and the like, and has higher value. It has been newly discovered that single crystal octahedron of Fe₃O₄Has important function in the field of fuel cells.

In a conventional hydrothermal or coprecipitation process, by Fe²⁺Direct preparation of Fe by ion starting₃O₄Usually, an oxidant is needed, or a certain proportion of Fe is added³⁺And (3) salt. To obtain pure phase Fe₃O₄Supply amount of oxidizing agent and Fe²⁺With Fe³⁺The ratio of (a) to (b) needs to be closely regulated. If Fe cannot be controlled²⁺Oxidation of ions, FeOOH, Fe in the product₂O₃And the like, the post-treatment is difficult, and the economic cost is greatly increased. Thus, the conventional method is in actual Fe²⁺The difficulty in recovery is high.

The inventors found in previous studies that Fe was transformed into²⁺Adding Cu into the solution²⁺、Ni²⁺And Co²⁺Etc. can efficiently produce high-purity Fe₃O₄This method greatly simplifies the production process as compared with the conventional method, as described in patent document CN 108751262 a. Subsequent studies have further explored Cu²⁺、Ni²⁺And Co²⁺Salts of the same in the preparation of Fe₃O₄The novel preparation method is provided on the basis of the mechanism of (1).

Disclosure of Invention

In order to solve the technical problems, the invention provides a method for preparing Fe with simple process, high yield and high product purity₃O₄The method of (1).

The technical scheme is as follows:

catalysis by metal oxideChemical preparation of Fe₃O₄The key point of the method is that the method comprises the following steps:

to Fe²⁺Adding metal M oxide powder into the solution, dispersing, adding an alkali solution to obtain a mixed solution, and carrying out hydrothermal reaction on the mixed solution to obtain the Fe-containing iron oxide₃O₄Suspension of the particles, separating the product Fe₃O₄；

The metal M oxide is CuO or Cu₂O, CoO or Co₃O₄At least one of (1).

Preferably, the atomic percentage of the M element in the metal M oxide powder to the metal element in the mixed solution is M/(M + Fe) ═ 0.1 to 50 at.%.

Preferably, the atomic percentage of the M element in the metal M oxide powder to the metal element in the mixed solution is M/(M + Fe) ═ 1 to 10 at.%.

Preferably, the hydrothermal reaction is carried out at a temperature of 100 to 200 ℃.

Preferably, the hydrothermal reaction is carried out at a temperature of 120 to 150 ℃.

Preferably, the hydrothermal reaction time is 0.5-48 h.

According to a preferable technical scheme, the hydrothermal reaction time is 4-6 h.

Preferably, Fe is used as the main component²⁺Fe in solution²⁺The concentration of (b) is 0.01-5 mol/L.

Preferably, OH in the alkali solution is^-The concentration of (b) is 0.2-8 mol/L.

Drawings

FIG. 1 is an X-ray diffraction (XRD) pattern of a sample prepared in a comparative example;

FIG. 2 is a sample XRD pattern prepared according to some of the examples, wherein: (a) example 8; (b) example 9 (top) and example 5 (bottom); (c) example 10; (d) example 11;

FIG. 3 is a typical Scanning Electron Microscope (SEM) picture and Energy Dispersive Spectroscopy (EDS) scan of a sample prepared with copper oxide as a catalyst.

Detailed Description

The invention is further illustrated by the following examples and figures.

(I) Fe₃O₄Preparation of

Preparation of Fe by using metal oxide catalyst₃O₄The method comprises the following steps:

to Fe²⁺Adding oxide powder of metal M into the solution and dispersing, wherein the addition amount is that M/(M + Fe) is 0.1-50 at%, calculated by the atomic percentage of M element in the metal M oxide powder and the total metal elements in the mixed suspension;

then stirring and adding an alkali solution to obtain a mixed solution, and carrying out hydrothermal reaction on the mixed solution to obtain the Fe-containing iron₃O₄Suspension of the particles, separating the product Fe₃O₄。

The oxide of the metal M is CuO or Cu₂O, CoO or Co₃O₄One or a combination of several of them. The product can be separated by centrifugation, filter membrane filtration, magnetic filtration and other modes, and when CuO or CuO is used as a catalyst, the CuO or CuO can be conveniently removed by magnetic filtration due to the non-magnetism.

The amounts of reactants, concentrations and reaction conditions of examples 1 to 20 and comparative examples are shown in Table 1, wherein the powder of the oxide of the metal M was added as a catalyst in each example, while the oxide of the metal M was not added in the comparative example, and the remaining steps were not changed. Wherein the hydrothermal reaction is carried out in a reaction kettle at the temperature of 100-200 ℃ for 0.5-48 h. It was found that the reaction time can be suitably shortened as the reaction temperature is higher, and the amount of the oxide powder of the metal M to be added can be suitably reduced. Therefore, the amount of the oxide powder catalyst to which the metal M is added can be adjusted according to the predetermined reaction temperature and time.

Said Fe²⁺The solution may be inorganic salt such as ferrous chloride and ferrous sulfate, or mixed salt thereof, or organic salt such as citrate and acetate, or mixed salt thereof. Fe²⁺Fe in solution²⁺The concentration of (b) is 0.01-5 mol/L.

The alkaline solution can be common inorganic alkali such as NaOH, KOH, LiOH and the like, and can also be organic alkali such as ammonia water, Polyethyleneimine (PEI) and the like; in addition, an inorganic base may be used in combination with an organic base, and when PEI is used, it may serve as both a dispersant to help disperse the metal oxide in the reaction system and itself as an alkaline agent. OH in alkaline solution^-The concentration of (A) or the theoretical concentration of complete ionization is 0.2-8 mol/L. All reagents were purchased from Shanghai Aladdin Biotechnology Ltd.

Specifically, taking example 5 as an example, Fe was prepared₃O₄The process comprises the following steps:

preparing a reaction reagent: 0.02mol of FeSO is taken₄Dissolving in 100ml water, preparing 0.2M ferrous sulfate solution for standby; dissolving 0.1mol of NaOH in 100ml of water, and preparing 1M NaOH solution for later use; taking CuO powder for later use.

Preparation of Fe₃O₄The process is as follows: 20ml of FeSO is taken₄Adding the solution into a hydrothermal reaction kettle, then adding 0.03mmol of CuO powder, stirring and dispersing, and then dropwise adding 10ml of NaOH solution while stirring. And (3) sealing the hydrothermal reaction kettle, putting the hydrothermal reaction kettle into a constant-temperature oven, reacting for 1h at 120 ℃, and cooling to room temperature to obtain black suspension.

After the reaction is finished, filtering and separating solid particles from the black suspension by using a magnetic filter, washing and drying to obtain a product Fe₃O₄。

The experimental process of the comparative example is similar, but the CuO powder is not added in the ferrous sulfate solution, the reaction is carried out for 4 hours at 150 ℃ after the NaOH solution is added, the product after the reaction is green, and the product is quickly oxidized to orange in the collecting process.

TABLE 1 reactants and reaction conditions for the different examples and comparative examples

Note: OH^-The concentration is the OH present in the alkaline solution^-And potentially theoretically ionizable OH^-Concentration of (e.g. NH in aqueous ammonia solution)₃·H₂The concentration of O.

(II) product characterization

X-ray diffraction (XRD) analysis, Scanning Electron Microscope (SEM) analysis and energy spectrum analyzer (EDS) elemental analysis are common crystal characterization methods, wherein an XRD spectrum can reflect the crystal structure of a test sample, the appearance of the sample can be visually observed by means of the SEM, and the content of the elemental composition of the sample can be detected by the aid of the EDS.

Typical XRD patterns of the samples prepared by the above method are shown in fig. 1 and 2. FIG. 1 shows a sample prepared in a comparative example, from which it can be seen that the product is substantially FeOOH. Fe (OH) which is presumed to be green after the reaction is completed based on the color change of the product during the reaction₂It rapidly oxidizes to orange-colored FeOOH during collection.

In fig. 2, XRD patterns of samples prepared by the following preparation methods are shown, respectively: (a) example 8; (b) example 9 (top) and example 5 (bottom); (c) example 10; (d) example 11. Known by a map, Fe can be prepared under various process conditions₃O₄And (4) crystals. With CuO, Cu₂O is catalyst, and the product is Fe₃O₄The purity is high. With CoO and Co₃O₄The product obtained by separation contains trace impurities as a catalyst.

Comparison of the samples obtained in the comparative example and the examples shows that small amounts of CuO and Cu are added₂O, CoO or Co₃O₄The powder enters a reaction system, namely the Fe under the alkaline condition can be changed²⁺In the direction of reaction of (2) to produce Fe₃O₄The orientation of the crystals proceeds, indicating the catalytic action of these several oxide powders. Compared with the traditional preparation method, the method has the advantages of simple preparation process, no need of strictly controlling the reaction system to be an oxidizing or reducing atmosphere, and strong adaptability to reaction conditions.

A typical SEM photograph of the sample was taken (a)And EDS spectra (b, c, d, e) are shown in FIG. 3, which sample was prepared by the method of example 5. In FIG. 3, (b), (c), and (d) are the area views of the elements O, Fe, and Cu, respectively, and the bright portions in the views represent the distribution regions of the respective elements. As can be seen, Fe was produced₃O₄The particles are octahedral single crystals, and the size of the particles is in the range of hundreds of nanometers to microns. The elemental analysis results showed that the product had a very low Cu content, with Cu/(Cu + Fe) ═ 0.63 at.%.

Has the advantages that: compared with the traditional preparation method, the method utilizes CuO and Cu₂O、CoO、Co₃O₄Etc. as catalyst, no need of adding oxidant, and under alkaline condition making Fe be separated from Fe²⁺One-step synthesis of high-purity micron-sized single-crystal octahedron Fe by using salt solution₃O₄The preparation method has the advantages of simple process, high efficiency, rapidness and low cost. In addition, CuO and Cu₂O, etc. are not magnetic, but Fe₃O₄Is a paramagnetic material, and can obtain Fe through magnetic recovery and separation in large-scale application₃O₄Therefore, the method has good industrial application prospect and is a harmless and recycling treatment method for the industrial steel pickling waste liquid.

Finally, it should be noted that the above-mentioned description is only a preferred embodiment of the present invention, and those skilled in the art can make various similar representations without departing from the spirit and scope of the present invention.

Claims

1. Preparation of Fe by using metal oxide as catalyst₃O₄The method is characterized by comprising the following steps:

The metal M oxide is CuO or Cu₂O, CoO or Co₃O₄At least one of;

the atomic percentage of the M element in the metal M oxide powder to the metal element in the mixed solution is M/(M + Fe) = 0.1-50 at.%;

the temperature of the hydrothermal reaction is 80-300 ℃;

the hydrothermal reaction time is 0.5-48 h;

the alkali solution is an inorganic alkali solution or an organic alkali solution or a mixed solution of the inorganic alkali solution and the organic alkali solution, wherein the inorganic alkali solution is one of a NaOH solution, a KOH solution, a LiOH solution or ammonia water, and the organic alkali solution is a Polyethyleneimine (PEI) solution;

said Fe²⁺Fe in solution²⁺The concentration of (A) is 0.01-5 mol/L;

OH in the alkali solution^-The concentration of (b) is 0.2-8 mol/L.

2. The method for preparing Fe by using metal oxide catalysis as claimed in claim 1₃O₄The method of (2), characterized by: the atomic percentage of the M element in the metal M oxide powder to the metal element in the mixed solution is M/(M + Fe) = 1-10 at.%.

3. The method for preparing Fe by using metal oxide catalysis as claimed in claim 1₃O₄The method of (2), characterized by: the temperature of the hydrothermal reaction is 120-150 ℃.

4. The method for preparing Fe by using metal oxide catalysis as claimed in claim 1₃O₄The method of (2), characterized by: the hydrothermal reaction time is 4-6 h.