RU2530188C1 - Method of producing osmium tetraoxide - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method of producing osmium tetraoxide includes loading a container with powdered osmium metal into a quartz tube which is placed in an electric furnace. Osmium is then oxidised while heating in a current of a dry oxygen-containing gas and the formed osmium tetraoxide is trapped in a cooled receiving flask. The oxygen-containing gas used for oxidising osmium is dry air which contains nitrogen oxides. After the oxidation process, nitrogen oxides are removed from the receiving flask by passing dry air.

EFFECT: obtaining solid osmium tetraoxide with high extraction of metal into the end product and which does not contain impurities of insoluble substances.

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Description

The method of producing osmium tetrooxide (OsO ₄ ) relates to the chemical and metallurgical production of platinum group metals (PGM) and their compounds.

Pure osmium tetroxide, as a rule, is obtained from the refined powder of osmium by its oxidation by oxygen when heated.

A known method of producing osmium tetroxide, including loading a powder of metallic osmium into a quartz tube placed in an electric furnace, oxidizing osmium when heated in a stream of dry oxygen-containing gas and trapping osmium tetrooxide in a cooled receiver flask [1]. This method is the closest in technical essence to the claimed method and adopted as a prototype.

The main disadvantage of this method is that it does not guarantee the receipt of the target product without impurities of insoluble osmium oxide (OsO ₂ ). The envisaged control purification of the product from insoluble impurities by washing with nitric acid and then with ice water leads to large losses of osmium.

The technical result, the achievement of which the invention is directed, is the elimination of these disadvantages.

The desired technical result is achieved by the fact that in the known method for producing osmium tetroxide, which includes loading a container with metallic osmium powder into a quartz tube placed in an electric furnace, oxidizing osmium when heated in a stream of dry oxygen-containing gas, trapping the resulting osmium tetroxide in a cooled receiver flask - dry oxygen containing nitrogen oxides is used as an oxygen-containing gas for the oxidation of osmium, and after completion of the oxidation process, hydroxy is removed from the receiver flask nitrogen by passing dry air.

, который в небольших количествах отгоняется из раствора и вместе с сухим воздухом направляется в кварцевую трубу, в которую помещен порошок металлического осмия, а затем вместе с образующимся газообразным тетраоксидом осмия поступает в охлаждаемую колбу-приемник. Таким образом, в процессе синтеза соединения осмия в системе создаются условия, практически исключающие попадания влаги и восстановителей в реакционную зону и колбу-приемник.The essence of the method is as follows. The main stage of the production of osmium tetroxide consists in calcining the metal osmium powder in a medium containing oxygen and not containing water as an oxidizing agent. The resulting gaseous osmium tetroxide is captured in a cooled receiver flask. During the entire process, a sufficient amount of oxidizing agent is required to oxidize the osmium powder to OsO ₄ . In the proposed method, the oxidation of osmium powder is carried out with air, which is bubbled through a mixture of concentrated sulfuric and nitric acids, poured into Drexel. The purpose of sulfuric acid is the absorption of moisture from air. In addition, gaseous impurities (organic solvents, hydrogen chloride, sulfur oxides, carbon monoxide and others) that exhibit reducing properties with respect to OsO ₄ and reduce it to OsO ₂ may be present in the air of the working zone in small amounts. To oxidize these impurities, nitric acid is added to Drexel with sulfuric acid. A strong oxidizing agent is formed in a mixture of these acids, nitronium - a cation $$(N{O}_2^{+})$$

which, in small quantities, is distilled off from the solution and, together with dry air, is sent to a quartz tube into which osmium metal powder is placed, and then, together with the resulting gaseous osmium tetroxide, it enters a cooled receiver flask. Thus, in the process of synthesis of the osmium compound in the system, conditions are created that practically exclude moisture and reducing agents from entering the reaction zone and the receiver flask.

After the stage of oxidation of the osmium powder is completed, the heating of the electric furnace is turned off, Drexel with a mixture of acids is replaced by Drexel with sulfuric acid, and dry air is bubbled through the unit to remove nitrogen oxides. The process is completed after the disappearance of brown gases in the flask-absorber.

EXAMPLE

50 g of metal osmium powder was loaded into a quartz boat and placed in a quartz tube located in an electric furnace. At the entrance, the quartz tube was tightly closed with a fluoroplastic stopper with an inserted glass tube, which was connected to Drexel containing 50 ml of concentrated sulfuric acid and 10 ml of concentrated nitric acid. At the outlet of the electric furnace, the pipe is sealed and has in the center an outlet in the form of a small-diameter tube, which is connected to a receiver flask placed in a cell cooled by a cryothermostat. Next, the receiver flask was sequentially connected with two drexels with a solution of sodium hydroxide. Last Drexel connected to the vacuum line. To connect all the parts of the installation used fluoroplastic tubes.

Turned on the cooling cell with the receiver flask. They opened the valve on the vacuum line and turned on the heating of the furnace. The temperature in the furnace was increased stepwise from 400 ° C to 800 ° C with an interval of 200 ° C. At each temperature, exposure was carried out for 1 hour. During the heat treatment, all the metal osmium was oxidized to OsO ₄ and in the form of a gas mixture with air entered the cooled receiver flask. The main part of osmium tetroxide, when cooled, turned into powder and remained in the receiver flask. Residues of the osmium compound were captured in Drexel with sodium hydroxide solution. After the metal oxidation process was completed, the furnace heating was turned off, the valve on the vacuum line was closed, Drexel with a mixture of sulfuric and nitric acids was replaced with Drexel with sulfuric acid, the valve was opened on the vacuum line and the residual nitrogen oxides were removed from the reaction system. Control was carried out by the disappearance of brown gases in the receiver flask. Then, the receiver flask was disconnected from the quartz tube and absorbers, while cooling, a product sample was quickly taken and submitted for analysis. According to spectrophotometric analysis, the mass fraction of osmium in the resulting product was 74.78%. Impurities of insoluble substances in osmium tetroxide were not found. The extraction of osmium in the target product was 93%.

Literature

1. G. Brower, F. Weigel and others. Guide to inorganic synthesis. T.5. Per. from German / ed. G. Brauer. - M.: Mir, 1985.S. 1846-1847.

Claims (1)

A method of producing osmium tetroxide, comprising loading a container with metallic osmium powder into a quartz tube placed in an electric furnace, oxidizing osmium by heating in a stream of dry oxygen-containing gas, trapping the resulting osmium tetroxide in a cooled receiver flask, characterized in that as an oxygen-containing gas for Osmium oxidation uses dry air containing nitrogen oxides, which are removed after completion of the oxidation process from the receiver flask by passing dry air.