Iron-chromium-nickel spinel preparation method

FIELD: inorganic synthesis.

SUBSTANCE: iron-chromium-nickel spinels are prepared by homogenization of original oxides of nickel(II), iron(III), and chromium(III) in presence of 0.5-1.5% of potassium halides as mineralizing agent followed by briquetting and heat treatment of oxides at 800-1000°C.

EFFECT: enabled preparation of spinels at lowered temperatures and in shorter time.

2 tbl, 2 ex

 

The invention relates to a method of producing spinel and may find application in the chemical industry for the production of catalysts based on ferrite-chromite Nickel.

A method of obtaining iron-chromium-Nickel spinel [Technology catalysts / edited Ipomaea, L.: Chemistry, 1989. - 272 S.], by which the starting materials are applied nitrate Nickel (II), iron (III), chromium (III). Each salt take in the required amount, dissolve in a certain amount of water and gradually heated to boiling. After water evaporation, the resulting material is calcined at 935°before the termination of the flue gas (2-3 hours). The cooled mixture grind, bitteroot and calcined at a temperature of 1000-1100°C

The disadvantage of this method of obtaining iron-chromium-Nickel spinel are environmental pollution, degradation products of salts, and the high cost of energy for heating and evaporation of water.

Closest to the claimed is a method of producing spinel from a mixture of oxides [Talanova E.A., Kirsanov A.I., Ivanov V.V. study of the conditions of solid-phase synthesis of solid solutions of Cu1-xNixCr2O4"Izv. SCNC HS. Natures. Science, 1992, N 3-4, p.44-47], in which the source oxides of Nickel (II), iron (III), chromium (III) is weighed with an accuracy of 0.0005 g, homogenized for one hour soperton on the air. Then a mixture of oxides bitteroot under pressure R-15 MPa into pellets with a diameter of 20 mm and calcined at a temperature of 1200-1300°C for 90 hours.

The disadvantage of this method is the high temperature heat treatment and the duration of the synthesis, which entails large costs of electricity.

The authors faced the problem of developing a method of producing spinel-based transition elements at lower temperatures with less duration, which can significantly reduce energy consumption and thereby reduce the cost of their production.

The problem is solved by obtaining iron-chromium-Nickel spinel by homogenizing the source of the oxides of Nickel (II), iron (III), chromium (III) with the introduction of a mixture of oxides advanced mineralizer, which is a halide of an alkali metal, and heat treatment of the mixture of oxides at a temperature of 800-1000°C.

The effect of the introduction of the mineralizer is to reduce the temperature to 300°With, the duration of the synthesis of 13 times and is achieved through the education of microdisplay of halogen, transforming the structure formation process of the diffusion region into kinetic energy.

The method consists in obtaining iron-chromium-Nickel spinel by dispensing source of oxides of Nickel (II), iron (III), chromium (III) and minerals the Torah of alkali metal halide in an amount of 0.5-1.5% (wt.) by weight of oxides. Next, the original oxides and mineralizer homogenized in an agate mortar for one hour and bitteroot into tablets with a diameter of 20 mm under the pressure of R-15 MPa. The synthesis of the catalyst is carried out for 4-5 hours at a temperature of 800-1000°C. For processes in which undesirable presence of halogen ions, the obtained iron-chromium-Nickel spinel grind up grain size 315 μm and washed from the halide of the alkali metal to the negative reaction to the halogen ions.

Example 1. Was weighed with an accuracy of 0.0005 g defined by the formula number of source oxides of Nickel (II), iron (III), chromium (III), as well as the mineralizer (1 mass%), which took potassium chloride. The mixture is homogenized for one hour in an agate mortar. The resulting mixture was bitterbal into tablets with a diameter of 20 mm under a pressure of 15 MPa was placed in a muffle furnace and subjected to heat treatment at a temperature of 900°C for 4.5 hours.

The end of the process of formation of structure of iron-chromium-Nickel siinai were determined using x-ray phase analysis: synthesis of spinel was 100%.

Example 2. Prepared iron-chromium-Nickel spinel same way as described in example 1, except that as the mineralizer used the bromide of potassium in the same amount. Was weighed with an accuracy of 0.0005 g defined by the formula number of the original Nickel oxides is (II), iron (III), chromium (III), as well as the mineralizer (1 mass%). The mixture is homogenized for one hour in an agate mortar. The resulting mixture was bitterbal into tablets with a diameter of 20 mm under a pressure of 15 MPa was placed in a muffle furnace and subjected to heat treatment at a temperature of 900°C for 4.5 hours.

After the heat treatment retinopathy analysis showed that the formation of spinel structure is completed by approximately 70%.

As seen from the above examples, the method of producing spinel-based transition elements in the presence of alkali metal halides takes place more completely and in less time compared to the process without the use of a mineralizer. This can significantly reduce energy consumption and thereby reduce the cost of production of spinel-based transition elements.

Table 1.

The chemical composition of spinel NiFe2CrxO4
The mole fraction of chromium, xContent, wt.%, in the spinel NiFe2CrxO4
NiOFe2About3Cr2About3KCl
0,031,8768,13-1,00
0,231,971,52 6,511,00
0,432,0854,87of 13.051,00
0,632,1848,1719,651,00
0,832,2941,4326,281,00
1,032,4034,6432,961,00
1,232,5127,8039,791,00
1,432,6220,9246,461,00
1,632,7313,9953,281,00
1,832,847,0260,141,00
2,032,95-67,051,00
Table 2.

The chemical composition of spinel NiFe2CrxO4
The mole fraction of chromium, xContent, wt.%, in the spinel NiFe2CrxO4
NiOFe2O3Cr2About3KBr
0,031,8768,13-1,00
0,231,9761,52 6,511,00
0,432,0854,87of 13.051,00
0,632,1848,1719,651,00
0,832,2941,4326,281,00
1,032,4034,6432,961,00
1,232,5127,8039,791,00
1,432,6220,9246,461,00
1,632,7313,9953,281,00
1,832,847,0260,141,00
2,032,95-67,051,00

The method of obtaining iron-chromium-Nickel spinel by homogenizing the source of the oxides of Nickel (II), iron (III), chromium (III), briquetting and heat treatment of a mixture of oxides, wherein the homogenization is carried out in the presence of 0.5-1.5 wt.% the potassium halide as a mineralizer and a heat treatment is carried out at 800-1000°C.



 

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