RU2717810C1 - Method of producing tin (iv) nitrate by oxidising tin (ii) nitrate - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention can be used in analytical control and scientific research. To obtain tin (IV) nitrate Sn(NO₃)₄, tin (II) nitrate Sn(NO₃)₂ is oxidised in the presence of nitric acid. Oxidising agent used is hydrogen peroxide with concentration in an aqueous solution of 8–15 %, which is dosed excessively with respect to a tin-containing reducing agent – tin (II) nitrate. Nitric acid is taken in form of 54 % aqueous solution in molar ratio with reducing agent (2.05–2.40):1. Process is carried out at room temperature in a bead mill with a glass bead as a grinding agent in the presence of white spirit as a basic component of the volume phase. Reagent dosage is calculated as 0.2–0.5 mol/kg of the product in the final reaction mixture and is carried out in the following sequence: glass beads, hydrogen peroxide, nitric acid. Then, white spirit and tin (II) nitrate are added and mechanical stirring is started. After practically complete consumption of tin (II) nitrate in the reaction mixture, the process is terminated and the glass beads are separated. Reaction mixture is filtered, the filter cake is washed with white spirit, removed from the filter and dried or directed for additional purification.

EFFECT: invention provides almost complete consumption of the initial tin-containing reagent with high selectivity on the end product.

1 cl, 1 dwg, 1 tbl, 9 ex

Description

The invention relates to a technology for the production of salts of tetravalent tin and can be used in various fields of chemical practice, in particular in industry, analytical control and scientific research.

A known method of producing tin (IV) nitrate by direct interaction of tin (IV) oxide with nitric acid at room temperature in a bead mill of the vertical type in the presence of glass beads as a grinding agent (RF patent No. 2655142). In accordance with it, tin (IV) oxide is taken in an amount of 0.05-0.5 mol / kg acid in the form of a solution in ethyl cellosolve in a molar ratio of acid: oxide 4.0 ÷ 12.5, the process is conducted in the absence, and preferably in the presence of a tribochemical catalyst from a number of amines.

The disadvantages of this method are:

1. It uses well-dissolving water and mineral acids ethyl cellosolve. There are a limited number of such solvents. However, there is no reason to believe that they will be suitable for the oxidation of tin (II) nitrate to tin (IV) nitrate.

2. It is noted that the filtrates can serve as the liquid phase of the downloads for subsequent processes. But as such filtrates are circulated, water introduced with acid will accumulate in them, until the limit value is reached, when hydrolysis of the obtained salt can be neglected. Next, excess water must be removed.

3. In the cited method, tribochemical catalysts are used, in particular, a number of amines. There is no reason to believe that they will be useful in the proposed method.

Closest to the claimed is the production of tin (IV) nitrate by dissolving the metal in 70% nitric acid (atomistry.com.PeriodicTableofChemicalElements. Http://tin.atomistry.com/stannic_nitrate.html).

The disadvantages of this method are:

1. The designated receipt is not framed as a method.

2. 70% nitric acid belongs to the category of special and it must be obtained as a stage of the designated method.

3. Work with 70% HNO ₃ requires special equipment and significantly complicates the hardware design of such a process.

4. Work with such an oxidizing agent requires appropriate skills of the performers and special training of the latter.

The objective of the proposed solution is to find an easier way to obtain tin (IV) nitrate by oxidizing tin-containing raw materials and to select such conditions for the oxidation of tin (II) nitrate with hydrogen peroxide in the presence of nitric acid introduced in the form of a 54% aqueous solution, as well as the hardware design of the process, which would ensure practically quantitative consumption of the initial tin-containing reagent with approaching selectivity for the target product approaching 1, as well as simple isolation of the latter from the reaction mixture by filtration, followed by washing, drying, and if necessary, additional purification.

The problem is achieved in that as an oxidizing agent of tin (II) nitrate, hydrogen peroxide is used with an initial concentration of 8-15% in an aqueous solution, dosed with a 5-15% stoichiometric excess in relation to a tin-containing reducing agent, nitrogen in the form of 54% the aqueous solution, the acid is taken in molar ratio with reducing agent (2.05-2.40): 1, the process is carried out at room temperature in the presence of white spirit as the basic component of the bulk phase in a bead mill with glass beads as a grinding agent, loading mass ratio with the rest of the load 1: 1, the dosage of the reagents is calculated on 0.2-0.5 mol / kg of product in the final reaction mixture and is carried out in the sequence: glass beads, hydrogen peroxide and nitric acid with occasional stirring to wet the beads, then white spirit and tin (II) nitrate are introduced, mechanical stirring is switched on and the process is controlled to control the consumption of tin (II) salt, occasionally acid, hydrogen peroxide and tin (IV) salt until the tin (II) salt is almost completely consumed in the reaction mixture, after which the process is stopped, glass beads are separated on a grid as a filter baffle, the reaction mixture is further filtered, the filter cake is washed with white spirit, removed from the filter and dried or sent for further purification, and the filtrate is divided into organic and aqueous phases each of which is subjected to analysis for the content of acid, hydrogen peroxide and tin (II) and (IV) compounds, while the organic phase with trace amounts of tin (II) and (IV) salts, hydrogen peroxide, acid and water and a washing solution The phone is returned without any additional operations for loading repeated processes.

In figure 1. presents the initial conditions and results of the method, characterized by the value of the initial charge of tin nitrate, the content of hydrogen peroxide in the dosed solution and the excess oxidizer and acid in the initial charge (according to example 1).

Characteristics of the raw materials used:

Tin (II) nitrate was obtained by the oxidation of tin with tin (IV) nitrate in white spirit in the presence of a stimulating iodine additive at room temperature in a vertical type bead mill [Pozhidaeva SD, Ageeva LS, Ivanov AM Some features of the oxidation of tin by tin (IV) compounds in the presence of molecular iodine // Metal Technology. 2018.- No. 8. - S.3-12].

The indicated salt was accumulated in the solid phase, separated by filtration, washed with a solvent, dried in air and dried in a drying oven to constant weight. Equivalent to 243 ± 1, which corresponds to the formula Sn (NO ₃ ) ₂ .

Hydrogen peroxide - substandard (according to TU 2123-533-05763441-2011)

GOST 4461-77 nitric acid

White Spirit GOST 3134-78

The process of the claimed method is as follows. Glass beads are introduced into a vertical-type bead mill with a glass case with a flat bottom, a high-speed mechanical mixer of a blade type with a textolite blade, and glass beads as a grinding agent, which are wetted with occasional mixing with an aqueous solution of hydrogen peroxide and nitric acid and then dosed with white Spirit and tin (II) oxide, include mixing in a bead mill, and this moment is taken as the beginning of the process. The process is carried out with stable mechanical stirring with the current control over the consumption of tin (II) salt and occasional control over the consumption of hydrogen peroxide, acid and the accumulation of tin (IV) salt. When the tin (II) nitrate content approaches zero, stirring is stopped, the reactor vessel is disconnected from the lid with the stuffing box and the mixer and lowered so that the mixer blade is higher than the level of the reaction mixture in the case. They wait for some time, allowing the remaining reaction mixture to drain from the blade and shaft of the mechanical stirrer. Then, the case with the reaction mixture is removed from the frame frame nest, moved to the glass bead separation unit from the rest of the reaction mixture, and this operation is performed on a mesh with mesh sizes of 0.3 × 0.3 mm as a filter partition. The grinding agent remaining on the grid is returned to the bead mill body, the latter is collected in working condition, a certain amount of white spirit is introduced and the walls of the reactor and its internal elements, as well as the grinding agent, are washed from the residues of the reaction mixture. Then the grinding agent is re-separated, which is weighed, dried and sent to the loading of the repeated process. The washing solvent is collected and subsequently used in operations to separate the reaction mixture.

The reaction mixture separated from the grinding agent is filtered, the filter cake washed several times with the filtrate, then with a washing solvent, squeezed, transferred from the filter to a drying tank and left in air until a constant mass is obtained, crushing it periodically until it turns into a powder state. A sample is taken from the dried product and the equivalent is determined, on the basis of which a conclusion is drawn on the advisability of additional purification of the obtained product.

The obtained filtrate is divided into organic and aqueous phases, which are weighed and analyzed for the content of soluble components in them. The organic phase, as well as the washing solvent, containing traces of hydrogen peroxide, acid and tin salts (II) and (IV) without any additional operations is returned to the loading of repeated processes. The aqueous phase containing excess and unreacted acid, hydrogen peroxide, as well as traces of tin (II) and (IV) salts are accumulated and used for various purposes.

Example No. 1

In a bead mill of the vertical type with a glass case in the form of a thick-walled cup with an internal diameter of 52.1 mm and a height of 130 mm with a flat bottom and a high-speed (1560 rpm) paddle mixer with a 51 × 39 × 2.5 mm pad of PCB, pockets for 100 g of glass beads, 10.71 g of 11% aqueous hydrogen peroxide and 7.97 g of 54% nitric acid are loaded into the sampler and temperature sensor so that the grinding agent is well wetted with the indicated aqueous solutions, for which occasional mixing is used the contents orpusa reactor. After that, 73.24 g of white spirit and 8.02 g of tin (II) nitrate are charged. The reactor vessel is placed in the corresponding socket of the frame frame, connected to the lid, in which the paddle mixer is mounted with the corresponding stuffing box, the shaft rotation is checked, mechanical stirring is turned on and this moment is taken as the beginning of the process. During the process, without stopping mixing, samples of the reaction mixture are taken, which are analyzed for the content of tin (II) salt, or tin (IV) salt and acid, or tin (II) salt and hydrogen peroxide, and in the final all three reagents and tin salt ( Iv). Based on these data, the dependence of the product yield on the process time is built. This dependence is presented in table 1.

Table 1

Product yield.% Of theoretical 25 50 75 98 and more Time to reach, min 6 13 32 140

Upon reaching the product yield 98 or more according to the results of the analysis, the process is stopped, the mechanical stirring of the bead mill is stopped, the reactor vessel is disconnected from the cover and lowered into the frame frame socket so that the lower edge of the mixer is higher than the content level in the housing. They stand in this position for 5 minutes, allowing the reaction mixture to drain from the shaft and agitator blades. After that, the housing with the contents is removed from the nest of the frame frame, its contents are transferred to a funnel to separate glass beads from the reaction mixture on a grid with dimensions of 0.3 × 0.3 mm. The beads are carefully removed from the net and returned to the reactor vessel. The plant is reassembled, 30 g of white spirit are introduced, mechanical stirring is switched on, and glass beads, as well as the surfaces of the casing, mixer and its shaft, are removed from the residual reaction mixture for 12 minutes. After the specified time, the stirring is stopped and the beads are again separated from the washing solvent, which is collected in a container designed for this purpose.

The reaction mixture separated from the grinding agent is left for 2 hours and then filtered. The precipitate is squeezed on the filter, washed with a washing solvent, removed from the filter, weighed and sent to air drying with periodic stirring, grinding to a powder state and weighing. The latter is repeated until a constant mass of 11.2 g is reached, which is 92.6% of the theoretical value. The equivalent product 366 ± 1, which corresponds to the formula Sn (NO ₃ ) ₄ .

The bulk phase (filtrate) is divided into organic and aqueous components, each is analyzed for their soluble components, the organic phase, as well as the washing solvent, are returned to any additional operations to load the repeated processes, and the aqueous phase is sent to a container for accumulation and use in other directions.

Examples 2-9

Reactor, starting reagents, volumetric phase solvent, sequence of operations when loading the reaction mixture, conducting the process, controlling the progress, completion of the reaction, separating the reaction mixture from beads, washing the beads and internal elements of the reactor from the residual reaction mixture, and returning the organic phase of the filtrate and washing solvent for loading the repeated process are similar to those described in example 1. They differ in the initial loading of tin nitrate, the content of hydrogen peroxide in the dosed solution and the excess oxidizing agent and acid in the initial load. These differences and other characteristics are summarized in table 2 of Figure 1 (RS - reaction mixture).

The positive effect of the proposed solution is that:

1. In the proposed solution, the bulk of the product accumulates in the form of a suspended solid phase and is separated by simple filtration.

2. The process is carried out at room temperature and does not require boiler supervision equipment

3. In the proposed process, hydrogen peroxide is consumed almost completely on the main process with the formation of water as a product of its conversion, which is present in the reaction mixture and is not considered to be a concomitant product requiring utilization or environmental pollution. In the worst case scenario, the aqueous phase will turn into wastewater. But the volume of the latter is very small.

4. The proposed process is characterized by high selectivity for the target product and the practically quantitative conversion of the tin-containing reagent into the product. The difference between the theoretical yield and the selected product with the increase in load will decrease and when loading 1 kg or more will decrease to values in the limit of 1%.

5. The process is not complicated by the strict necessity of processing the organic and aqueous phases of the final reaction mixture and the washing solvent.

6. Finding the product mainly in the organic phase suspended in a water-insoluble and water-insoluble, small volumes of the aqueous phase, which also contains residual acid, almost completely eliminates the hydrolysis of the product and its clogging with basic salts.

Claims (2)

1. The method of producing tin (IV) nitrate by oxidation of tin (II) nitrate in the presence of nitric acid, characterized in that hydrogen peroxide is used as an oxidizing agent with an initial concentration of 8-15% in an aqueous solution, dosed with 5-15% with a stoichiometric excess with respect to the tin-containing reducing agent, nitric acid in the form of a 54% aqueous solution is taken in a molar ratio with the reducing agent (2.05-2.40): 1, the process is carried out at room temperature in the presence of white spirit as the basic component of the bulk phase in bead mills with glass beads as a grinding agent, loaded in a mass ratio with the rest of the load 1: 1, the dosage of the reagents is calculated on 0.2-0.5 mol / kg of product in the final reaction mixture and are in the sequence: glass beads, hydrogen peroxide and nitrogen acid with occasional stirring to wet the beads, after which white spirit and tin (II) nitrate are introduced, they include mechanical stirring and the process is controlled by controlling the consumption of tin (II) salt, occasionally acid, hydrogen peroxide and tin (IV) salt about the almost complete consumption of tin (II) salt in the reaction mixture, after which the process is stopped, glass beads are separated on the grid as a filter screen, the reaction mixture is further filtered, the filter cake is washed with white spirit, removed from the filter and dried or sent to an additional purification, and the filtrate is divided into organic and aqueous phases, each of which is subjected to analysis for the content of acid, hydrogen peroxide and tin compounds (II) and (IV). 2. The method according to claim 1, characterized in that the organic phase with traces of salts of tin (II) and (IV), hydrogen peroxide, acid and water and a washing solvent is returned without any additional operations to download the repeated processes.

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