RU2541065C2 - Method of obtaining titanium sulphides - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention can be applied in inorganic chemistry. Method of obtaining titanium sulphide includes interaction of titanium with sulphur. Synthesis of sulphides in carried out in mode of self-propagating high-temperature synthesis (SHS) in vacuum 10^-3 atm. As initial substances, applied are powder-like mixture of titanium and crystalline sulphur, taken in accordance with stoichiometrical ratio with 5% sulphur excess.

EFFECT: invention makes it possible to simplify obtaining titanium sulphides, increase speed and ecological purity of the process, reduce energy consumption.

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Description

The invention relates to the field of inorganic chemistry, namely to the technology of self-propagating high-temperature synthesis, and can be used to produce titanium sulfides.

A known method of producing titanium disulfide, including heating sulfur to a vapor state and a powder of titanium metal and their interaction in a closed volume. Sulfur is heated to 450-470 ° C and the interaction is carried out by passing sulfur vapor through a layer of titanium powder in two stages, with 50-60% of the calculated amount of sulfur being used in the first stage, after which the resulting product is ground and treated with the remaining sulfur [patent SU 1079610 , C01G 23/00, Method for the production of titanium disulfide / G. M. Zagorovsky, A. N. Belous, A. A. Velikanov, A. P. Grinyuk].

There is also a method for producing titanium disulfide by heating titanium metal with sulfur at 400-1000 ° C for 7 days in an evacuated vessel, followed by annealing for 7 days of the resulting non-stoichiometric titanium disulfide at 400-600 ° C in the atmosphere, the partial vapor pressure of which corresponds to equilibrium sulfur pressure over stoichiometric titanium disulfide [patent US 3980761, C01G 23/00, Production of finely divided, low defect, stoichiometric titanium disulfide / Arthur H., Fred R. C. 423-565, 1976].

There is also known a method for producing titanium disulfide by the interaction of titanium and sulfur, taken in a stoichiometric ratio. The titanium sponge and elemental sulfur are loaded at different ends of the quartz tube, which, after evacuation, is hermetically sealed and placed in a horizontal electric furnace with two heating zones. Titanium is heated from 475 to 600 ° C, and sulfur from 200 to 360 ° C. The partial pressure of sulfur vapor during the reaction varies from 0.05 to 0.75 atm. After holding the tube for 41 hours, the latter is broken and stoichiometric titanium disulfide is removed [patent GB 1556503A, C01G 23/00, Preparation of stoichiometric titanium disulfide. / M.S. Whittigham. 1976].

Titanium sulfides with a lower sulfur content are obtained either by synthesis from simple substances, or by reacting titanium metal with TiS ₂ , or by reducing TiS _{2 with} hydrogen at high temperatures to almost monosulfide [Inorganic Synthesis Guide / Ed. G. Brauer, T. 4, M .: Mir, 1985, p. 1467].

The disadvantage of the considered methods is the multi-stage process and the duration, as well as significant energy costs.

The closest technical solution, the prototype is a method for the synthesis of titanium sulfides of any composition by the interaction of titanium with sulfur. To do this, use either crushed pieces of titanium sheet or powdered titanium. First, four grams of titanium with 4 grams of sulfur are heated to 650 ° C for four days in thick-walled ampoules made of Supremax glass, before being carefully sealed in a high vacuum from the presence of gases. The metal grains remaining in the preparation are crushed separately and, together with the obtained sulfide (~ 3 g in total), are again heated for 2 days in an ampoule to 600 ° C, adding 1.7 g of sulfur. In conclusion, pump out the volatile components in a vacuum. The product obtained in this way is a mixture of graphite titanium trisulfide and unreacted sulfur. By heating in vacuo to 400 ° C, free sulfur can be distilled off. Above 500 ° C, thermal decomposition of TiS ₃ occurs and TiS _{2 is formed} [Inorganic Synthesis Guide / Ed. G. Brauer, T. 4, M .: Mir, 1985, p. 1467].

The disadvantages of this method are the complexity, multi-stage synthesis, significant energy costs for heating mixtures to 600-1200 ° C and homogenization of the product for a long time.

In the inventive method, these disadvantages are eliminated by the fact that the synthesis of titanium sulfides is carried out by the method of self-propagating high-temperature synthesis (SHS), which allows you to drastically reduce the cost of obtaining refractory materials. Such a process, based on the use of the internal chemical energy of the system, allows synthesis at high temperatures, short synthesis times, and low energy costs. The simplicity of equipment, high technological productivity, high speed and environmental friendliness of the process also indicate the appropriateness of using this method.

SUMMARY OF THE INVENTION

In the inventive method for producing titanium sulfides, including grinding, pressing of the starting materials, ignition, burning and synthesis of sulfides in the SHS mode in vacuum, a powdered mixture of titanium and crystalline sulfur, taken in accordance with a stoichiometric ratio with a 5% mass excess sulfur due to its sublimation at high temperatures.

The claimed technical solution has the following set of essential distinguishing features in relation to the selected prototype:

- the synthesis of titanium sulfides is carried out by the method of self-propagating high temperature synthesis (SHS);

- as the reagents use a powdery mixture of titanium and crystalline sulfur, taken in stoichiometric ratio with a 5% mass excess of sulfur, due to its sublimation at high temperatures, to prevent the formation of metal phases;

- synthesis of sulfides in the combustion mode is carried out in vacuum with a vacuum of 10 ^-3 atm, until the synthesis products are completely cooled.

The implementation of the invention is achieved by performing technological operations in the following sequence.

In accordance with the stoichiometry of the reaction, the required amount of powdered titanium and elemental sulfur with a 5% mass excess is taken, due to its sublimation at high temperatures.

Weighed portions of the reagents are ground in an agate mortar, then the powders are thoroughly mixed in a mechanical ball mill for 6 hours. The resulting mixture was tabletted. The tablets are burned in SHS mode in a vacuum unit. The setup scheme for synthesis in SHS mode is shown in the drawing.

Brief description of the drawing.

The installation platform (1) is equipped with a gas outlet channel (2) and electrical terminals (3). Tablets (4) are placed on a refractory substrate (5) under a nichrome spiral (6), to which a voltage is applied to initiate a reaction. Between the bell (7) and the platform is a rubber gasket (8). Using a vacuum pump connected to the gas outlet channel, a vacuum of 10 ^-3 atm is created in the bell of the vacuum system.

As a result of initiation in a heated surface layer of the sample, a chemical reaction is excited and a synthesis wave is formed, which propagates along the axis of the sample at a certain speed. The propagation of the synthesis wave is accompanied by a bright glow. The tablet burns out in a few seconds. After the reaction, the system remained under vacuum until the synthesis products cooled completely.

The proposed method is implemented in laboratory conditions, illustrated by the following examples.

Example 1

The amount of starting materials for the synthesis of titanium sulfide is determined by the reaction equation: 2Ti + S = Ti ₂ S.

For this, 1.31 g of crystalline sulfur of the qualification of “special hours” is added to 3.75 g of powdered titanium of TPM grade taking into account a 5% mass excess. Weighed portions of the reagents are ground in an agate mortar, then the powders are thoroughly mixed in a ball mill for 6 hours until a homogeneous mixture. The resulting mixture was tabletted in the form of a cylinder with a diameter of 10 mm.

The tablet is placed on a refractory substrate under a nichrome spiral, which is energized to initiate the reaction. Using a vacuum pump in the system creates a vacuum of 10 ^-3 atm.

By briefly applying an electrical impulse to a nichrome spiral, combustion and synthesis of titanium sulfide are initiated. In this case, a chemical reaction is excited in the heated surface layer of the sample and a synthesis wave is generated, which propagates along the axis of the sample at a certain speed. The propagation of the synthesis wave is accompanied by a bright glow. The tablet burns out in a few seconds. After the reaction, the system remains under vacuum until the synthesis products are completely cooled.

According to x-ray phase analysis, combustion results in the formation of a phase of titanium sulfide Ti ₂ S having an orthorhombic cell with lattice parameters: a = 11.35 Å, b = 14.06 Å and c = 3.32 Å.

Example 2

The amount of starting materials for the synthesis of titanium sulfide was determined by the reaction equation: Ti + S = TiS.

A mixture of 2.1 g of crystalline sulfur (taking into account a 5% mass excess) and 3 g of powdered titanium is prepared and pressed in the same way as in example 1. The tablets are burned in SHS mode. As a result of combustion, a phase of titanium (II) sulfide TiS is formed, having a hexagonal cell with lattice parameters: а = 3.416 Å, c = 26.4 Å, NiAs structural type with the densest hexagonal packing of sulfur atoms, in which the octohedral voids are filled with titanium atoms.

The problem solved by the claimed technical solution is to simplify the method and the possibility of obtaining a wide range of titanium sulfides with minimal energy costs.

Titanium sulfide powders obtained by burning mixtures were studied by X-ray diffraction (a D8-GADDS diffractometer from Bruker, powder method, CoKα radiation).

Claims (1)

A method of producing titanium sulfides, including the synthesis of titanium sulfides by the interaction of titanium with sulfur, characterized in that the synthesis of sulfides is carried out in the SHS mode in a vacuum of 10 ^-3 atm, and a powder mixture of titanium and crystalline sulfur, taken in accordance with stoichiometric, is used as starting materials ratio with 5% excess sulfur, due to its sublimation at high temperatures.

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