RU2057706C1 - Method for producing oxygen - Google Patents

Abstract

FIELD: autonomous sources of oxygen. SUBSTANCE: into H₂O₂ solution having concentration not more 5 mass % Na₂CO₃ is added, molar ratio of H₂O₂: Na₂CO₃, being not more 1.5 and catalyst. Said catalyst contains MnO₂ and KCIO₄.. Nonproductive losses of oxygen is 6-14 %. EFFECT: improves efficiency of method. 1 dwg, 3 tbl

Description

 The invention relates to methods for generating gases, in particular to the chemical generation of oxygen in systems requiring a compact autonomous oxygen source, for example, in medicine, in the fishing industry for enriching water with oxygen when transporting fish, in agriculture for germination in seed tanks, etc. .

 Known methods for producing oxygen by decomposing solutions containing hydrogen peroxide under the action of manganese dioxide molded into a single block [1] The evolution of oxygen begins immediately when the catalyst is immersed in the solution.

 The method allows you to adjust the gas flow, when removing the catalyst from the solution, gas generation stops. The main disadvantage of this method is that due to the blocking of the catalyst surface by gas bubbles, the intensity of the gas stream decreases rapidly. The restoration of active centers on the surface of the catalytic unit is provided by special devices (vibrator, brush or heater). The actuation of devices activating the catalyst requires a supply of energy, which narrows the scope of the method.

 The closest in technical essence to the invention is a method for producing oxygen by decomposing aqueous solutions of hydrogen peroxide in the presence of manganese dioxide, molded into a single unit, with sparingly added potassium perchlorate [2] Stability of the gas flow is ensured by updating the surface of the catalyst and gradually adding dioxide to the solution manganese with a slow dissolution of the additive, the addition of additional energy to activate the catalyst is not required. Oxygen begins to be released when the catalytic unit is immersed in a solution of hydrogen peroxide. The method allows the regulation of the gas stream. The main disadvantage of this method is the unproductive loss of oxygen due to the relatively slow exit of generation to the regime and the significant time of its deceleration.

 The invention solves the problem of reducing unproductive oxygen losses by reducing the time the process takes to the mode and the time of slowing down the process.

This is achieved by the fact that the decomposition of a hydrogen peroxide solution under the action of a catalytic unit consisting of manganese dioxide and a sparingly soluble substance is carried out in the presence of sodium carbonate. The invention allows several times to reduce the time the process goes into mode and the time to slow down the generation, thereby reducing unproductive oxygen losses. The maximum reduction in oxygen overhead, in comparison with the prototype, is achieved by using oxygen-evolving solutions with a molar ratio of sodium carbonate to hydrogen peroxide, close to the molar ratio of components in a solution of sodium carbonate peroxolate Na ₂ CO ₃ x х1,5H ₂ O ₂ with a content of H ₂ O ₂ no more than 5%
Example 1. The drawing shows a compact generator comprising a reaction vessel 1 with a capacity of 300 cm ³ , a catalytic unit 2, a gas outlet 3 and a feed opening with a cover 4 and a holder for the catalytic unit 5. The catalytic unit 2 is fixed in the holder 5, arranged so that the working surface is only the end part of the catalytic unit 2 (the surface is 1.81 cm ² ).

The volume of oxygen released through hole 3 is measured with a gas burette. The reference time is the time of immersion of the catalytic unit 2 in the solution. The decomposition of the oxygen carrier solution is carried out at 20 ^about C.

The time for the generation process to enter the regime was determined by the time it took for the oxygen generation rate to reach at least 70% of the average; generation slowdown time oxygen generation time (at the end of the process) with a gas flow rate of less than 70% of the average. Unproductive oxygen losses were determined by the volume of oxygen (in relative total volume) released at a gas flow intensity of less than 70% of the average. The average intensity (speed) of the gas flow was determined by the formula V _total / t, where V _total total volume of oxygen released, cm ³ , t the time of complete decomposition of the oxygen carrier in solution, min

 In experiments 1-5 (table. 1) in a reaction vessel 2, aqueous solutions of sodium carbonate and hydrogen peroxide are mixed, the catalytic unit is immersed. The total weight of the solution is 132 g. The content of hydrogen peroxide in the solution is 3%. The catalytic unit contained 2.5% manganese peroxide.

Experiment 6 (Table. 1) differs from the experiments 1-5 that, in the reaction vessel 2 was placed peroksosolvata sodium carbonate solution, prepared by dissolving (t20 ^{° C)} under vigorous stirring for 15 min peroksolvata granular sodium carbonate (trade name "Purcell" ) In the process of preparing the solution, oxygen loss is about 5%
In experiment 7 (Table 1), the technical grade peroxosolvate of sodium carbonate was used as an oxygen carrier. To reduce oxygen losses during the slow dissolution of peroxosolvate granules, the solution was not previously prepared. Granules were placed in reaction vessel 2, water was added, and the catalytic block was immersed. The total weight of the solution was 132 g. The catalytic block contained 2.5% manganese peroxide.

As follows from the table. 1, the introduction of sodium carbonate in solutions of hydrogen peroxide can significantly reduce the time the output of the generation process to the mode and time of slowing down the reaction. The maximum reduction (by half) of oxygen overhead is achieved with a molar ratio of sodium carbonate to hydrogen peroxide in a solution corresponding to the ratio of these components in a solution of sodium carbonate peroxosolvate Na ₂ CO ₃ · 1.5H ₂ O ₂ and is 1: 1.5. An increase in the sodium carbonate content in the solution of more than 6.2% does not lead to an improvement in the process characteristics; moreover, when the content of sodium carbonate in the initial solution is more than 9%, unproductive oxygen losses increase (Table 1, experiment 5).

 As can be seen from experiments 6 and 7, when using sodium carbonate peroxosolvate solutions as oxygen carriers, unproductive oxygen losses are several times higher than when using hydrogen peroxide solutions with sodium carbonate additives (op. 1-5, table 1).

PRI me R 2. The conditions of the experiments do not differ from the conditions of experiments 1-5 described in example 1. We studied solutions with a concentration of hydrogen peroxide of 3.5 and 10% and the ratio of the components Na ₂ CO ₃ : H ₂ O ₂ 1: 1.5. The catalytic block contained 2.5% manganese peroxide.

 For comparison, in all cases under identical conditions, experiments were carried out on the decomposition of hydrogen peroxide solutions not containing sodium carbonate.

 The results are shown in table. 2.

As follows from the table. 2, when creating an optimal molar ratio between sodium carbonate and hydrogen peroxide in the solution of 1: 1.5, in the case of 3 and 5% solutions, unproductive oxygen losses are halved. The introduction of sodium carbonate into more concentrated hydrogen peroxide solutions, for example, 10% (Table 2), is ineffective: the time of generation slowdown increases, and unproductive oxygen losses increase. This is apparently due to the blocking of catalytic sites by the poorly soluble sodium carbonate peroxosolvate, which precipitates in significant quantities in solutions with a concentration of hydrogen peroxide above 5%
PRI me R 3. The conditions of the experiments do not differ from the conditions described in example 1 (op. 1-5). The decomposition of solutions was carried out in the presence of catalytic blocks of different composition.

 In the table. Figure 3 shows the characteristics of the oxygen generation process using different catalyst compositions.

For comparison, the results of experiments on the decomposition of solutions of H ₂ O ₂ not containing Na ₂ CO ₃ carried out under identical conditions are given.

 As follows from the table. 3, the introduction of sodium carbonate in oxygen-evolving solutions effectively reduces the unproductive loss of oxygen when using catalytic blocks of different compositions. The composition of the catalytic unit can change the characteristics of the gas stream.

Claims (1)

METHOD FOR PRODUCING OXYGEN, including the decomposition of a hydrogen peroxide solution by introducing into it a molded catalyst block containing manganese dioxide and potassium perchlorate, characterized in that they take a hydrogen peroxide solution with a concentration of not more than 5 wt. and additionally, sodium carbonate is introduced into it in a molar ratio of H ₂ O ₂ Na ₂ CO ₃ not exceeding 1.5.

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