RU2337062C2 - Method of obtaining carbon nanostructures fron organic compound and metal-containing substances - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: as metal-containing substance wastes of non-ferrous metallurgy production is used - metallurgical dust, obtained as result of roasting of magnetic fractions and nickel concentrate, containing oxides of cobalt, nickel, copper, sulfides of nickel and copper. In presence of water mixture of metallurgical dust and polyvinyl alcohol (PVA) is prepared in ratio 1 mole of NiO contained in metallurgical dust per 1-4 moles of PVA. 5-10% PVA solution or dry PVA, which is crushed together with metallurgical dust with addition of minimal water amount for moistening and "connecting" components, can be used. Obtained mixture is dried on glass padding at 50°C, after which thermal processing with step-by-step heating to 400°C is carried out. Tubular, fused, sphere-shaped nanostructures are obtained, which can be hollow or filled with metals and their compounds: Ni, Cu, CoO, NiO, Cu₂O are obtained.

EFFECT: reduction of energy consumption and cost of target product; use of cheap raw material and metallurgical production wastes.

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Description

The invention relates to the field of coordination chemistry, including the physiochemistry of nanostructures and colloidal systems, and consists in the fact that the preparation of metal-containing carbon nanostructures is carried out by dehydration and dehydrogenation with subsequent stages of carbonization of polyvinyl alcohol and the recovery of metals from their compounds.

Known methods for producing metal-containing carbon nanostructures, for example, by electric arc method, where to increase the efficiency of synthesis of carbon nanostructures using metals that act as catalysts [1, Y.Saito // Carbon, 1995, v 33, Is 7, p.979]. There are methods for producing carbon nanostructures containing iron by dispersion in a planetary ball mill by grinding its powders in heptane with the addition of oleic acid in a pure argon atmosphere, followed by annealing the mixture at a temperature of 800 ° C [2, A.V. Syugaev, Corrosion behavior of highly dispersed iron-based systems obtained by grinding in organic media. - Disser. Cand. Chem. Sciences, Izhevsk: FTI UB RAS, 2005]. When producing carbon nanofibers from hydrocarbon plasma (methane or a mixture of methane and hydrogen) in the presence of nickel (catalyst), it was noted [3, H.S. Kang, H.J. Yoon, C.O. Kim etal // Chem.Phys. Lett., 2001, v.349, p.196], that the metal is only at the ends of the formed cylindrical nanoproduct. The preparation of multi-walled graphitized nanotubes with inclusions of iron and its compounds is possible from polyvinyl alcohol in the presence of iron oxide and iron nanoparticles distributed in PVA at temperatures up to 800 ° C in a nitrogen atmosphere [4, А.N. Ozerin // Sat: Materials of the 17th Mendeleev Congress on General and Applied Chemistry. - Kazan: KSU, 2003, v.3, p.13]. In these methods, the preparation of metal-containing carbon nanostructures occurs at a temperature not lower than 600 ° C.

Disadvantages of analogues

When nanostructures are obtained by the electric arc method [1], the energy consumption is high and the temperature is high (more than 1000 ° C), the yield of the target nanoproduct is relatively small. In most cases, the nanoproducts obtained in this way do not contain metals. Nanostructures obtained by the mechanochemical method followed by annealing at 800 ° C [2] contain metal at the ends of tubulenes; in other words, metal nanoparticles in carbon shells are not obtained. Similar results were obtained using the method proposed in [3]. In addition, the synthesis of carbon nanofibers from carbon-containing precursors is low efficient. A method of producing nanotubes with the inclusion of iron and its compounds [4] is carried out at high temperature (800 ° C) and in a nitrogen atmosphere. The resulting nanoproducts are multi-walled carbon nanotubes.

The closest technical solution is the method of low-temperature synthesis of multilayer tubulenes from polyvinyl alcohol in the presence of copper, cobalt, nickel chlorides at a temperature of 250 ° C-400 ° C [5, V.I. Kodolov, A.A. Didik, A.Yu. Volkov , E.G. Volkova. A method of producing metal-containing carbon nanostructures from an organic compound with the addition of inorganic salts // Patent No. 2221744, 2004, СВВ 31/02].

This prototype has the following disadvantages:

- the use of metal chlorides as a raw material, first of all, is the consumption of material, which is not a cheap raw material for synthesis, and also in the process of synthesis the main by-product is hydrogen chloride - a toxic gas.

- for the synthesis, chlorides of copper, cobalt, nickel are used separately, and not their combinations. When using combinations, we can talk about the complex effect of the catalyst.

Objectives of the invention:

1) obtaining metal-containing nanostructures using waste metallurgical production;

2) reduction in the release of toxic by-products;

3) obtaining a relatively inexpensive nanoproduct that can be used as an active modifying additive in various materials.

These tasks are solved, first of all, by the correct selection of metallurgical production waste. As an inorganic component of the synthesis, metallurgical dust obtained by burning the magnetic fraction and nickel concentrate was selected.

The rationale for the choice: 1) the dust contains metal compounds that are widely used in various methods for producing nanostructures, including metal-containing carbon nanoparticles; 2) the dust consists of 90% of metal oxides, which will help reduce the yield of toxic by-products; 3) the dust is finely dispersed, which will reduce the time and energy for preparing the material for synthesis.

The reaction mixture is prepared by mechanical grinding of the solid components with the addition of a small amount of water to “bind” the components or by mixing an aqueous solution of polyvinyl alcohol with finely divided powder of metallurgical dust, then the mixtures are dried to obtain a gel film or, in the case of mixing the solid components, the mixture is solid.

Effect: the use of metallurgical waste for the synthesis of nanostructures at relatively low temperatures. The formation of both single nanotubes (hollow or filled with a metal-containing phase) and their clusters was noted, spherical nanostructures with metal (or its compounds) inside are also formed. The emission of toxic gases as a result of synthesis is reduced due to the use of dust, which contains 90% oxides, as an inorganic phase.

In a reaction mixture consisting of PVA and metallurgical dust with a composition of 81.2% NiO, 8.1% NiS, 6% CuO, 2.5% CuS, 2% CoO, during mechanical grinding or when a mixture of an aqueous solution and finely divided metallurgical dust occurs initially the formation of a monomolecular polymer layer on the surface of the inorganic phase. Further, due to the active interaction of metal ions of these compounds with the hydroxyl groups of polyvinyl alcohol, the inorganic phase is coordinated with respect to polyvinyl alcohol molecules. When heated, the processes of dehydration and dehydrogenation of polyvinyl alcohol chains occur under the influence of metal compounds, followed by carbonization of PVA and the reduction of metals from their compounds. Thus, spherical and cylindrical nanostructures are formed, filled with a metal-containing phase. The main by-products of the synthesis are water vapor and in minimal quantities hydrogen sulfide or sulfur dioxide. The concentration of toxic gas compared to the prototype is very low due to the presence of metal oxides in the dust. The inorganic phase is both a structuring and oxidizing component that promotes the carbonation of PVA.

When mixing solid components with a total mass of 3 g, approximately 2 g of nanoproduct is formed. Accordingly, the yield is about 90% in terms of carbon and nickel. After a temperature treatment of 250 ° C to study the structure, the resulting sample is washed with hot distilled water to remove the remaining polyvinyl alcohol and dried. After heat treatment up to 400 ° C, the obtained nanoproduct, unlike the prototype, was not washed.

The structure and composition of the obtained carbonization products are studied by transmission electron microscopy, electron diffraction, and X-ray photoelectron spectroscopy (XPS).

A JEM-200CX transmission electron microscope with an accelerating voltage of 160 kV and an electron diffraction prefix is used; XPS studies are carried out on an electronic magnetic spectrometer with Al _Kα line excitation. The vacuum in the chamber of the spectrometer is 10 ^-3 Pa. The resolution of the device is 1.2 eV, the accuracy of the position of the peaks is 0.1 eV.

As a result of a study using transmission electron microscopy and X-ray photoelectron spectroscopy, carbon nanostructures, carbon metal-containing nanostructures, and metal nanoparticles were found in samples subjected to heat treatment at 400 ° C.

The invention is illustrated in graphic materials.

Figure 1 shows a fragment of a carbon nanotube partially filled with a metal-containing phase.

Figure 2 presents spherical carbon nanostructures filled with a metal-containing phase.

Figure 3 presents a fragment of a cluster of carbon nanostructures partially filled with a metal-containing phase.

Figure 4 presents a metal-containing nanoparticle.

Figure 5 presents carbon-containing films with incorporated metal nanoparticles and their compounds.

6 shows elongated film nanostructures like nanotubes filled with a metal and metal oxide phase.

Figure 7 presents the X-ray electron spectra of C1s of samples 1, 2 (sample 1 is metallurgical dust, sample 2 is the resulting product in the interaction of PVA and metallurgical dust).

On Fig presents x-ray spectra of Ni3p samples 1, 2 (sample 1 - metallurgical dust, sample 2 - PVA + metallurgical dust).

Example 1. The proposed method for producing metal-containing carbon nanostructures is implemented as follows.

A mixture of polyvinyl alcohol and metallurgical dust with the composition NiS - 8.1%, CuO - 6%, CuS - 2.5%, NiO - 81.2%, CoO - 2% in a molar ratio of 1: 4 (4 moles of PVA elementary units correspond to 1 mol of nickel oxide, since this compound is the predominant mass in metallurgical dust) is obtained by grinding in a porcelain mortar with the addition of a small amount of water to "bind" the components. Then it is placed on a glass substrate and maintained at a temperature of 50 ° C in an oven until solidified. The resulting solid mixture is placed in crucibles and subjected to stepwise heat treatment to a temperature of 400 ° C. Figures 1 and 2 show the nanostructures obtained by this synthesis method. The diameter of the nanotube in figure 1 is 120 nm, the nanostructure in figure 2 is from 30 to 240 nm. Figure 1 shows the electron diffraction pattern, which indicates the presence of nickel in the nanotube, the existing "strands" give reason to talk about the formation of a carbon nanotube. The obtained nanostructures also contain metal particles of Cu and Ni and the oxides CoO, NiO, Cu ₂ O are present. In Fig. 8, when comparing the spectra of the samples with the reference, one can see a difference in peaks, a decrease in the amount of metal in the second sample compared to the first. This is another confirmation that there are metal reduction processes during the interaction of polyvinyl alcohol with metallurgical dust and the presence of metal in the carbon layers, i.e. the formation of carbon metal-containing nanostructures. Figure 4 presents a nickel nanoparticle located on the surface of a carbon film. 7, in the sample 2 is present in significant quantities component C-Csp ² is another confirmation of the nanotubes in the sample.

Example 2. The method for producing metal-containing carbon nanostructures according to example 1, in which the initial mixture is prepared by mixing a 10% aqueous solution of PVA with fine metallurgical dust, followed by drying in an oven at a temperature of 50 ° C to obtain a gel film. The dried films are crushed in a porcelain mortar and then subjected to processing similar to that described in example 1. Figure 3 shows the nanostructures obtained by this method. The diameter is from 10 to 50 nm. In nanotubes are metals - nickel and copper, and also there are oxides of copper (I), cobalt, nickel. Metals and their compounds are unevenly distributed in nanostructures. X-ray electron spectra are similar to those obtained in example 1.

Example 3. A method of obtaining a metal-containing carbon nanostructures according to example 2, where the synthesis temperature is adjusted to 250 ° C. Figure 5 b and 6 shows the intermediate stages of the formation of nanostructures. These are carbon-containing films with metal nanoparticles and their compounds included in them and elongated film nanostructures like nanotubes filled with a metal and metal oxide phase: Ni, Cu, Cu ₂ O, NiO, CoO.

Example 4. A method of obtaining a metal-containing carbon nanostructures according to example 1, in which the synthesis temperature is adjusted to 300 ° C. The microstructure and quality composition are similar to those described in example 3.

Example 5. A method for producing metal-containing carbon nanostructures according to example 1, where the synthesis temperature is increased to 250 ° C. The microstructure and quality composition are similar to those described in example 3.

Example 6. A method for producing metal-containing carbon nanostructures according to example 2, in which the synthesis temperature is increased to 300 ° C. The microstructure and quality composition are similar to those described in example 3.

Example 7. A method for producing metal-containing carbon nanostructures according to example 1, where the molar ratio of PVA to metallurgical dust (nickel oxide) is 1: 1. The microstructure and qualitative composition are similar to those described in examples 1 and 2, the only difference is the increased content compared to examples 1 and 2 on the surface of metal-containing nanoparticles.

Example 8. The method of producing metal-containing carbon nanostructures according to example 2, in which the molar ratio of PVA and metallurgical dust (nickel oxide) corresponds to 1: 1. The microstructure and quality composition are similar to those described in example 7.

Example 9. A method for producing metal-containing carbon nanostructures according to example 7, where the synthesis temperature is increased to 250 ° C. Figure 5a shows a fragment of a carbon-containing film with nanoparticles of metals and their compounds included: Ni, Cu, Cu ₂ O, NiO, CoO.

Example 10. A method of obtaining a metal-containing carbon nanostructures according to example 8, in which the synthesis temperature is increased to 250 ° C. The microstructure and quality composition are similar to those described in example 9.

Example 11. A method for producing metal-containing carbon nanostructures according to example 2, where a 5% solution of polyvinyl alcohol is used to prepare the mixture. The microstructure and quality composition are similar to those described in example 2.

Example 12. A method for producing metal-containing carbon nanostructures according to example 11, in which the synthesis temperature is increased to 250 ° C. The microstructure and quality composition are similar to those described in example 3.

Using the proposed method for producing metal-containing carbon nanostructures provides the following advantages compared to existing methods.

1. The use of metallurgical waste as a reagent for the synthesis of nanostructures — metallurgical dust obtained by burning the magnetic fraction and nickel concentrate in the production of nickel, allows us to attribute this method to resource-saving methods for producing nanostructures.

2. Reduction as a result of synthesis using metallurgical dust containing metal oxides, emissions of toxic products.

3. The ability to obtain carbon nanostructures with a combination of metals inside, the ability to recover metal from their compounds.

4. The technological simplicity of this method, the method does not require expensive equipment and can be used in the production of cheap nanoproduct in a significant amount.

5. A set of nanoproducts that can be divided and used for various purposes.

Claims (5)

1. A method of producing carbon metal-containing nanostructures, including preparing a mixture of polyvinyl alcohol (PVA) with a metal-containing substance and heat treatment of the resulting mixture, characterized in that the non-ferrous metallurgy waste is used as the metal-containing substance — metallurgical dust obtained by burning magnetic fractions and nickel concentrate containing oxides of cobalt, nickel, copper, sulfides of Nickel and copper, and the ratio of metallurgical dust and PVA is chosen at the rate of 1 mo l NiO, contained in the metallurgical dust, 1-4 mol PVA mixture is prepared in the presence of water, followed by drying ^at 50 ° C, and heat treating the obtained mixture is carried out at stepwise heating to a temperature not exceeding 400 ° C. 2. The method according to claim 1, characterized in that they use a 5-10% solution of PVA. 3. The method according to claim 1, characterized in that they use dry PVA, which is co-milled with metallurgical dust by adding a minimum amount of water to wet and “bind” the components. 4. The method according to any one of claims 1 to 3, characterized in that the stepwise heating is carried out to 300 ° C. 5. The method according to claim 3, characterized in that the step heating is carried out up to 250 ° C.

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