Catalyst for electrochemical reduction of oxygen

FIELD: chemistry.

SUBSTANCE: disclosed catalyst contains a single crystalline phase of a noble metal sulphide deposited on conducting carbon which essentially does not contain a phase of zerovalent metal or metal oxides, obtained via reduction of metal precursor salts and thio-precursors with boron hydride or another strong reducing agent.

EFFECT: high activity and stability of the catalyst for cathodic reduction of oxygen during electrolysis of hydrochloric acid.

13 cl, 2 dwg

 

The technical field to which the invention relates

The invention relates to a catalyst, in particular electrocatalysts for oxygen reduction, suitable for inclusion in the structure of the gas diffusion electrode, and the method of its production.

Prior art

Sulfides noble metals are widely known in the field of electrocatalysis, in particular, the electrocatalysts based on sulfide rhodium and ruthenium currently included in the structure of gas-diffusion electrodes for use as a reducing oxygen cathodes in highly aggressive environments, such as depolarized electrolysis of hydrochloric acid.

The electrocatalysts of the prior art on the basis of sulphides noble metals are, for example, barbotine the hydrogen sulfide through an aqueous solution of the corresponding predecessor of the noble metal, usually chloride, for example, as disclosed in the document US 6149782 fully entered here by reference, which relates to a catalyst based on rhodium sulfide. The synthesis of the catalysts based on noble metal sulfides with hydrogen sulfide in aqueous solutions is usually conducted in the presence of a conductive medium, in most cases consisting of carbon particles. While the noble metal sulfide villages is active is deposited on the surface of the carbon particles, and the resulting product is a catalyst on a carbon substrate, which is particularly suitable for introduction into the structure of gas-diffusion electrodes for high efficiency at low concentrations of precious metals. For these purposes, especially suitable carbon with a high surface, such as Vulcan XC-72 from Cabot Corp. USA.

Another method of producing the catalysts based on noble metal sulfides on the carbon substrate is impregnated on the capacity of the carbon carrier with a solution of salt, precursor of a noble metal such as a noble metal chloride, followed by evaporation of the solvent and the gas-phase reaction in dilute hydrogen sulfide at room temperature or above, resulting sulfide is formed in a stable phase. This is described, for example, in the document US 2004/0242412 related to the catalyst based on ruthenium sulfide.

A more advanced method of producing the catalysts based on noble metal sulfides disclosed, in addition, in the document US 6967185 fully entered here by reference, which consists in the reaction of the precursor of the noble metal with tizaidine in aqueous solution not containing sulfide ions; in this way the catalyst is essentially equivalent to the catalyst from US 6149782 obtained without ISOE is isawanya this is very dangerous and toxic reagent, as hydrogen sulphide.

Although the catalysts disclosed in the above-cited documents, proved critical to the successful commercial introduction of cells to obtain hydrochloric acid, they still have some limitations from the standpoint of activity and stability in aggressive environments, typical for such applications and consisting of hydrochloric acid, containing substantial amounts of dissolved chlorine and oxygen.

As for activity, all the sulfides of noble metals deposited by methods of the prior art obtained by separate stages of recovery, giving a mixture of different crystalline phases with different valences and stoichiometry, some of these phases have a low electrochemical activity or even have no. In addition, some of the most active compositions consist of three compounds that are not likely to get a environmentally friendly method according to document US 6967185; the only acceptable method of obtaining three-component compounds, such as RuxCozSythat is very attractive from a cost perspective, a method described in US 2004/0242412, which is still based on the hydrogen sulfide as the reagent.

As for stability, the above-mentioned system (Mus) is Anna valence, consisting of different crystalline phases, typical of the catalysts of the prior inevitably lead to some formation of the less stable phases, such as metals with zero valency, oxides of metals and non-stoichiometric perovskites. Although sulfides rhodium and ruthenium are much more stable than any other electrocatalysts prior to recovery of oxygen in the environment electrolysis of hydrochloric acid, one can still detect some loss of noble metal, especially when the electrolyzer is stopped for maintenance.

Objectives of the invention

One objective of the present invention is the provision of a new composition of sulfide catalyst for electrochemical reduction of oxygen, overcoming the limitation of the prior art; in particular, the present invention is more active and stable catalysts for the cathodic reduction of oxygen in the electrolysis of hydrochloric acid.

Another objective of the present invention is the provision of a gas diffusion electrode comprising the new composition of sulfide catalyst is used as the cathode in the process depolarized electrolysis of hydrochloric acid.

Another objective of the present invention is R. is this the new way of getting sulfide catalysts for electrochemical reduction of oxygen.

These and other objectives will be explained in the following description, which should not be construed as limiting the invention, the volume of which is determined solely by the applied formula.

Description of the invention

In the first aspect of the invention is the catalyst for electrochemical reduction of oxygen containing sulfide noble metal deposited as a single well-defined crystalline phase on conductive carbon; preferably the catalyst according to the invention is based on the noble metal is the only crystalline phase two - or three-component sulfide, rhodium or ruthenium.

The inventors have found that in the case of two-component rhodium sulfide, expressed the General formula RhxSythe methods of obtaining prior invariably lead to a system with a mixed valence, containing at least the components Rh2S3Rh17S15and Rh3S4with some metal rhodium (Rh0). Of all these components is the most active Rh17S15different lattice corresponding to the space group Pm-3m), followed by Rh2S3with monoclinic lattice (C2/m), and the remaining components have low activity or do not have Nike the activity, and in some cases and lower stability. Rh0unstable in the conditions of the electrolysis of hydrochloric acid and is responsible for very rapid leakage of rhodium at work. For example, in accordance with the methods in the documents US 6149782 and US 6967185 typical Rh17S15is just over 70% of all components of rhodium sulfide.

The inventors have unexpectedly discovered that the only crystalline phase (Pm-3m) Rh17S15activated carbon can be obtained by properly modifying environmentally friendly way of getting unveiled in the document US 6967185. The term "single crystal phase", as used hereinafter, means more than 90% pure crystalline phase; in the case of the catalyst according to the invention (Pm-3m) Rh17S15obtained the only crystalline phase is net of approximately 95% and no detectable amount of Rh0. The method of obtaining the only crystalline phase (Pm-3m) Rh17S15activated carbon includes the steps

interaction of salt, a predecessor of rhodium, for example, RhCl3with a source of sulfur, such as thiosulfate or tionally component, in the presence of a strong reducing agent and particles of conductive carbon, thus precipitating amorphous sulfide component in the carbon particles,

- selection of suspension, p is edocfile filtering,

- heat treatment selected suspension in an inert atmosphere at a temperature of from 500 to 1250°C to obtain single crystalline phase corresponding to (Pm-3m) Rh17S15.

In addition thiosulfate and thionatoo, you can use other sources of sulfur for the initiation phase metathesis distinguishing method according to the invention: tetrathionate, such as Na2S4O6·2H2O, and other close tionate components, such as dithionate, trithionate, pettinati and gattinara, all of them are suitable for this purpose; gaseous SO2also has regenerative ability, and the availability of sulfur to obtain an amorphous MxSycomponents on the selected substrate.

Carbon substrate particles have a surface area, comprising preferably from 200 to 300 m2/g, and preferred specific load obtained sulfide rhodium on carbon is 12 to 18%.

The sequence of addition of reagents is important to obtain the desired product: to a solution containing suspended carbon particles and Sol-precursor rhodium add selected source of sulfur (e.g., thiosulfate or tionally component), so you can begin the process of metathesis. At the same time or immediately after, depending on the particular reaction, a small aliquot add strong in stanoical, defined as a component with a reduction potential below to 0.14 In/BOO. As a preferred reducing agent sodium borohydride (NaBH4), but other suitable reagents include LiAlH4, hydrazine, formaldehyde and aluminum metal, zinc or antimony.

The reducing agent, which is defined above, has a reduction potential below the potential of the pair S0/S-2in this case, you can get instant metathesis metal ions and thiosulfate part, directly forming an amorphous sulfide of rhodium on carbon particles of the substrate and simultaneously preventing the formation of a separate state of recovery, which is the main factor controlling the output and the distribution of different phases sulfide components.

The method according to the invention can be applied to obtain the only other crystalline phases sulphides of noble metals, including not only the sulfides of one metal (two-sulfides), but also two or more metals (three or more component sulfides). This is especially useful in the case of sulphides ruthenium, as in this case, the method according to the invention gives the most active and stable only crystalline phase.

When using the method according to the invention component (RuS2) and three (RuxMz y) ruthenium sulfides, where M is a transition metal, preferably selected from W, Co, Mo, Ir, Rh, Cu, Ag and Hg, are deposited as a single crystalline phase with lattice parameters corresponding to the type lattice of pyrite (space group Pa-3). It turned out that the obtained catalysts (Pa-3) RuS2or RuxMzSyare more active and more stable in the conditions of the electrolysis of hydrochloric acid than systems with mixed valence-based ruthenium sulfide, corresponding to a previous level. Preferred specific load of the catalyst and selected carbon substrate are the same as used for the rhodium sulfide; and the method of obtaining essentially the same, although suitable temperature for the heat treatment can vary from 150 to 1250°C.

Special route of the reaction in the method according to the invention has the main advantage of the effect on the recovery potential of metals and ticomponent that prevents the formation of discrete States recovery, which is a major factor regulating the output and correct the phase composition selected chalcogenide component, as mentioned above. The method according to the invention promotiom instant metathesis metal ions and tionately part. For example, the reaction of the chloride form of the transition metal, such ka is rhodium, aqueous hydrolysis of which gives a pH in the range of 1-1,5, dihydrate tetrathionate sodium (Na2S4O6·2H2O) and sodium borohydride (NaBH4in the presence of carbon can directly synthesize amorphous RhxSysupported on carbon. The reaction is carried out at room temperature and may be accompanied by measurement of pH and drip samples. At the completion of the suspension is collected and subjected to heat treatment in an inert atmosphere for a sufficient time to obtain the desired deposited catalyst with a single phase sulfide rhodium. This same method can be used for other two - and three-sulphides with a particular distribution of the crystalline phases. In some cases, the kinetics and yield of the reaction can be improved by the addition of catalytic amounts of metals such as Al, Sn, Co and others.

The described catalysts suitable for inclusion in the structure of gas-diffusion electrodes in conductive tissues, which is known in this field.

Obtaining catalysts according to the invention on the basis of sulfide, rhodium and ruthenium disclosed in the following examples, which should not be construed as limiting the invention; appropriate options and modifications obviously can be used by the specialist to get other sulfide catalysts on carbon padlock is the sole crystalline phase with the other noble and transition metals, based on the method according to the invention and without going beyond its scope.

Brief description of drawings

The drawing shows the radiograph of a catalyst based on rhodium sulfide obtained in accordance with the method according to the invention.

Example 1

Here we describe the deposition method is the only crystalline phase sulfide rhodium on carbon in accordance with the method according to the invention; precipitation reaction of other catalysts based on noble metal sulfides (such as sulfides of ruthenium, platinum, palladium or iridium) require minor adjustments that can easily be carried out by a specialist.

a 7.62 g of RhCl3·H2O was dissolved in 1 l of deionized water and the solution boiled under reflux.

7 g of carbon black Vulcan XC 72 R with high surface area from Cabot Corporation) was added into the solution and the mixture was treated with ultrasound for 1 hour at 40°C.

8,64 g (NH4)2S2O3was dissolved in 60 ml of deionized water, and then found that the pH is equal to 7.64 (sulfur source).

4,14 g NaBH4was diluted in 60 ml of deionized water (reducing agent).

A solution of rhodium/Vulcan kept at room temperature and intensively stirred, while monitoring the pH. In this case, solutions of sulfur source and a reducing agent are simultaneously added dropwise in the Rast is the PR rhodium/Vulcan. While adding monitored pH, temperature and color of solution. Continuous control of pH is important in order to avoid a complete dissociation of tizaidine at the elementary S0.

The kinetics of the reaction is very fast, so the total deposition of amorphous sulfide occurs within several minutes from the start of the reaction. If you want to slow down the kinetics can help cooling the reaction medium. The reaction of the monitor, checking the color change: initial dark pink/orange color of the solution rhodium/Vulcan abruptly changed to grey/green (repair Rh+3to Rh+2and then to colorless upon completion of the reaction, indicating, thus, the full absorption of the products of carbon. In this phase was also conducted drip samples at different points in time with a lead jet paper; was a limited number of H2's because of the minimal dissociation ticomponent. The precipitate was left to settle and then filtered; the filtrate is washed with 1000 ml of deionized water to remove any excess reagents, and then the filter cake was collected and dried in air at 110°C during the night.

Finally, the dried product was subjected to heat treatment in a stream of argon for 2 hours at 650°C, resulting in weight loss 22,15%.

Characteristics of the obtained catalyst on a carbon substrate at first is as defined in the corrosion test, in order to test its stability in the environment of the electrolysis of hydrochloric acid.

For this purpose, the portion of the sample was heated to the boil in a saturated chlorine HCl solution in the same conditions as described in example 4 of document US 6149782. The resulting solution was colorless, not even showing the characteristic traces of pink from the more stable forms of rhodium sulfide, corresponding to the level of technology.

The drawing shows a radiograph of a catalyst based on rhodium sulfide. RhxSythat is usually obtained by deposition, characterized by a balanced mixture of phases from at least three phases Rh-S: orthorhombic (Pbcn) Rh2S3, monoclinic (C2/m) Rh3S4and simple cubic (Pm-3m) Rh17S15. Phase Rh2S3is an electric insulator formed of alternating octahedra RhS6. Thus, the average bond length Rh-Rh equal 3,208 E (in comparison with 2,69 E in a face-centered metal Rh), provides no opportunity for direct binding of Rh-Rh. On the contrary, the phase Rh17S15has semiconductor properties at room temperature. In addition, Rh17S15consists of octahedra Rh8with an average distance Rh-Rh 2,59 E. Phase Rh3S4with its octahedral metal protrusions Rh6is the active site for adsorption of O(H). The left part of the drawing which has an x-ray (top) and the characteristic peaks of different Rh-S phases (bottom); the comparison clearly shows the dominance phase Rh17S15(>95%) with a characteristic set of 4 peaks at 2θ = 37,38-40,68°, presents reflexes(104), (114), (223) and (024), and high-intensity peaks at 47,64 and 52,16°, indicating reflexes (333) and (044).

This is even more clearly seen in the right part of the drawing, where the x-ray spectrum characteristic peaks superimposed phase Rh17S15.

Example 2

The catalyst based on ternary sulfide ruthenium-cobalt (3:1) was prepared similarly to the catalyst of example 1, with the difference that now tionally reagent is part of the solution of metal ions, thus, the metathesis reaction occurs in situ on centers, which metal ions.

a 7.62 g RuCl3·xH2O was dissolved in 1 l of deionized water and the solution boiled under reflux.

2,46 g CoCl2·xH2O also added in a solution containing Ru, and boiled under reflux as described above.

8 g of carbon black Vulcan XC72-R with high surface area from Cabot Corporation) was added into the solution and the mixture was treated with ultrasound for 1 hour at 40°C.

17.5 g (NH4)2S2O3was diluted with 100 ml of deionized water, after which it was found that pH = 7,72, then added to a solution of the catalyst/Vulcan (sulfur source).

6,54 g NaBH4was dissolved in 100 ml deionised the bath water (reducing agent).

The solution of the source of sulfur containing ruthenium, cobalt, and carbon black Vulcan, kept at room temperature and intensively stirred, while monitoring the pH. As soon as it was prepared solution of reducing agent, it was added dropwise into a solution of a source of sulfur. While adding reagents followed pH, temperature and color of solution. Continuous control of pH is important in order to avoid a complete dissociation of tizaidine at the elementary S0.

As in example 1, in this case, the kinetics of the reaction is also very fast, so the total deposition of amorphous sulfide occurs within several minutes from the start of the reaction. If you want to slow down the kinetics can help cooling the reaction medium. The reaction of the monitor, checking the color change: initial dark brown/orange color of the original solution is abruptly changed to colorless upon completion of the reaction, indicating, thus, the full absorption of the products of carbon. In this phase was also conducted drip samples at different points in time with a lead jet paper; was a limited number of H2's because of the minimal dissociation ticomponent. In addition, it was not observed Co0(metal); drip test for this particular metal is very simple due to the magnetic properties of Co0. The precipitate was left on stavitsa and then filtered; the filtrate is washed with 1000 ml of deionized water to remove any excess reagents, and then the filter cake was collected and dried in air at 110°C during the night.

Finally, the dried product was subjected to heat treatment in a stream of nitrogen for 2 hours at 500°C, which leads to weight loss of 32.5%.

The catalyst on a carbon substrate was subjected to the same corrosion tests and electrochemical tests, as in the previous example, and he showed identical results.

Also checked the actual behavior of the catalyst obtained in accordance with the method according to the invention and introduced into the gas diffusion structure on the conductive fabric, known in the field, in the electrolysis of hydrochloric acid.

Example 3

Prepared different samples of the catalysts of examples 1 and 2 was mixed with PTFE dispersion and was inserted in the normal flow patterns of gas-diffusion electrodes on the fabric of carbon fiber. All electrodes were compared with a standard appropriate to the level of technology applied RhxSyelectrode for electrolysis of hydrochloric acid, in accordance with the ideas of the patent US 6149782 and 6967185 (sample 0). These electrodes were tested as consume oxygen cathodes in a laboratory electrolysis cell with an active area of 50 cm2with a standard anode, using by - product water is actor hydrochloric acid with isocyanate installation. Full voltage of the cell was recorded at two different current densities, namely at 3 and 6 kA/m2corresponding values are given in the table.

No. sampleVoltage at 3 kA/m2The voltage at 6 kA/m2
01,161,45
Sample 11,101,37
Sample 21,111,41

All the samples tested electrodes showed excellent catalytic activity that gives a noticeable decrease in voltage as compared with the electrodes, activated catalyst of the prior art on the basis of rhodium sulfide (sample 0).

Equivalent catalysts based on rhodium sulfide were obtained also when using as precursors trithionate, tetrathionate and gattinara sodium, previously obtained in accordance with known methods, with minor adjustments, easy produced specialist. In these cases also obtained similar results in corrosion and electrochemistry.

Held in the above description should not be construed as limiting the invention, which can be applied in practice in accordance with the variations of implementation, without going beyond its scope, its boundaries are determined solely by the applied formula.

In the description and formula of this application, the terms "include" and its variants such as "contains" and "contain", are not intended to exclude the presence of other elements or additional components.

1. The catalyst for electrochemical reduction of oxygen, containing a single crystalline phase sulfide noble metal deposited on a conductive carbon, and the specified noble metal sulfide is a sulfide of rhodium or ruthenium, and the only crystalline phase is (Pm-3m) Rh17S15having a purity of more than 90%.

2. The catalyst for electrochemical reduction of oxygen, containing a single crystalline phase sulfide noble metal deposited on a conductive carbon, and the specified noble metal sulfide is a sulfide of rhodium or ruthenium, and the specified sulfide noble metal is ruthenium sulfide and possibly additional transition metal M, and the only crystalline phase is (Pa-3) RuS2or RuxM2Sy.

3. The catalyst according to claim 2, wherein said additional p is recogni metal selected from the group consisting of W, Co, Mo, Ir, Rh, Cu, Ag, Hg.

4. Catalyst according to any one of claims 1 to 3, wherein said conductive carbon has a surface area from 200 to 300 m2/g, and unit load specified sulfide noble metal on the specified conductive carbon is equal to 12-18%.

5. Gas diffusion electrode containing a catalyst according to any one of the preceding paragraphs on the conductive fabric.

6. The method of producing catalyst according to any one of claims 1 to 4, comprising the steps
interaction of salt, precursor of the noble metal and possibly at least one additional transition metal with a source of sulfur in the presence of particles of conductive carbon in an aqueous solution,
- specified deposition of noble metal sulfide on the above conductive particles of carbon by simultaneous or successive addition specified in an aqueous solution of reducing agent having a reduction potential lower to 0.14 In/BOO,
- selection and heat treatment of the resulting suspension in an inert atmosphere to obtain a single crystalline phase.

7. The method according to claim 6, wherein said source of sulfur is thiosulfate or Tinatin component.

8. The method according to claim 6, wherein said noble metal is rhodium.

9. The method according to claim 7, wherein said noble metal is rhodium.

10. The method according to p., wherein said noble metal is ruthenium and the specified at least one additional metal selected from the group consisting of W, Co, Mo, Ir, Rh, Cu, Ag, Hg.

11. The method according to claim 7, wherein said noble metal is ruthenium and the specified at least one additional metal selected from the group consisting of W, Co, Mo, Ir, Rh, Cu, Ag, Hg.

12. The method according to any of PP-11, in which the specified suspension are filtered, and the specified heat treatment is carried out at 150-1250°C.

13. The method according to claim 6, wherein said reducing agent is NaBH4.



 

Same patents:

FIELD: chemistry.

SUBSTANCE: method of producing acyl fluoride perfluorocyclohexane carboxylic acid is realised via electrochemical fluorination of acyl chloride of benzoic acid in liquid anhydrous hydrogen fluoride on nickel anodes in the presence of an electrolyte additive, where the said additive is triallyl amine and the electrolysis process is carried out with pulsed electric current, where electrolysis is carried out in an electrolysis cell with a self-contained separator of the crude material collector.

EFFECT: longer service life of the electrolyte.

2 cl, 1 tbl, 5 ex

FIELD: chemistry.

SUBSTANCE: gases formed during electrolysis enter the buckets of a turned-over vertical bucket conveyor which, under Archimedes effect, rise and pull the conveyor belt with the buckets on the opposite side of the moving conveyor. Rotation of one of the shafts of the conveyor through a drive or directly provides rotation of the shaft of the electric generator which generates electrical energy which is transmitted to a power supply unit or directly to electrodes of the electrolysis apparatus, thus reducing overall power consumption of the electrolysis apparatus.

EFFECT: low power consumption during electrolysis.

12 cl, 1 dwg

FIELD: power industry.

SUBSTANCE: as per the first version, fuel combustion device is made in the form of linear chain of convergent-divergent nozzles. At that, outlet of the previous nozzle of the chain is connected to inlet of one following nozzle of the chain, and geometrical sizes of the next nozzle of the chain exceed geometrical sizes of the previous nozzle of the chain. As per the second version, fuel combustion device is made in the form of branched chain of convergent-divergent nozzles. At that, outlet of the previous nozzle of the chain is connected to inlets of two next nozzles of the chain. In both versions, on the end of the first nozzle of the chain there is installed atomiser for supply of water or water vapour to it and electrodes for creation of electric arc meant for dissociation of this water. Each next convergent-divergent nozzle includes atomiser for supply to it of additional water or water vapour.

EFFECT: invention allows increasing efficiency of heat energy generation.

2 dwg

FIELD: electricity.

SUBSTANCE: invention refers to nonwoven fibrous materials that can be used in various electrochemical devices, hydrogen accumulators, filtration devices, catalytic substrates, etc. Nonwoven fibrous material consists of fragments of activated carbon fibre, the average characteristic ratio of which is approximately between 1 and 5.

EFFECT: increasing efficiency of electric duodielectric capacitors.

16 cl, 1 dwg

FIELD: nanotechnologies.

SUBSTANCE: invention relates to nanotechnology and may be used to produce carbon nanotubes, which are used as electrode materials in chemical sources of current, as catalysts and for production of polymer nanocomposites. Chloride electrolytes melt, containing mol % of the following components, is electrolysed: potassium chloride - 35.0-55.0, sodium chloride - 35.0-55.0 and lithium carbonate - balance. The source of carbon is carbon dioxide. The process is carried out at the temperature of 700 °C, under excessive pressure of (12-14)·105 Pa, with the current density of 3.0-7.0 A/cm2.

EFFECT: invention makes it possible to increase speed of carbon nanotubes synthesis, to reduce prime cost and to simplify process of their cleaning.

3 dwg, 3 ex

Electrolytic cell // 2427669

FIELD: electricity.

SUBSTANCE: invention refers to electrolytic cell of typical single-element design for chloralkali electrolytic plants, each of which includes anodic compartment and cathodic compartment. At that, each of two compartments includes electrode connected to rear wall of the appropriate compartment by means of parallel connection straps. Thus, electrodes are divided into several sections. According to invention, at least one of two electrodes has bent shape in each shape; at that, the above bent section protrudes in direction towards opposite electrode and presses the membrane area to opposite electrode.

EFFECT: lower voltage losses, higher efficiency of the device and higher economic factor.

15 cl, 5 dwg

Electrolytic cell // 2427669

FIELD: electricity.

SUBSTANCE: invention refers to electrolytic cell of typical single-element design for chloralkali electrolytic plants, each of which includes anodic compartment and cathodic compartment. At that, each of two compartments includes electrode connected to rear wall of the appropriate compartment by means of parallel connection straps. Thus, electrodes are divided into several sections. According to invention, at least one of two electrodes has bent shape in each shape; at that, the above bent section protrudes in direction towards opposite electrode and presses the membrane area to opposite electrode.

EFFECT: lower voltage losses, higher efficiency of the device and higher economic factor.

15 cl, 5 dwg

FIELD: machine building.

SUBSTANCE: installation consists of reservoir divided inside into three departments with two partitions directing flow. Also, three departments are communicated and form a crooked path of caustic soda flow facilitating sedimentation of micro-drops of mercury owing to effect of centrifuging. Mercury is extracted in an installation for decomposition of amalgam positioned upstream. In the disclosed device for separation of mercury the first and second departments are connected with a zone of mercury separation having a pass with converged cross section which facilitates increased rate of flow of caustic product.

EFFECT: raised electric efficiency of process of electrolysis of alkali metals chloride solutions, also reduced corrosion effect to finished product by reduced contents of mercury in it.

19 cl, 2 dwg

FIELD: electricity.

SUBSTANCE: method to produce an electrode for electrolysis of a halogen-containing solution with reduced working potential of electrolysis includes production of the electrode base from a valve metal, application of an intermediate electrolytic coating layer on it. Then the upper coating layer is applied onto the specified base made of the valve metal by means of a solution comprising at least one oxide of a transition metal selected from the group, which includes palladium oxide, rhodium oxide and cobalt oxide, in the amount of approximately 0.01 mole % to approximately 10 mole % per total content of transition metal oxides in the coating.

EFFECT: electrolytic coating may be used as an anode component in an electrolytic cell for electrolysis of halogen-containing solutions, the specified components reduce the working potential of the anode and eliminate the necessity in the interruption period for reduction of the anode potential.

40 cl, 2 tbl, 2 ex

FIELD: electricity.

SUBSTANCE: method to produce an electrode for electrolysis of a halogen-containing solution with reduced working potential of electrolysis includes production of the electrode base from a valve metal, application of an intermediate electrolytic coating layer on it. Then the upper coating layer is applied onto the specified base made of the valve metal by means of a solution comprising at least one oxide of a transition metal selected from the group, which includes palladium oxide, rhodium oxide and cobalt oxide, in the amount of approximately 0.01 mole % to approximately 10 mole % per total content of transition metal oxides in the coating.

EFFECT: electrolytic coating may be used as an anode component in an electrolytic cell for electrolysis of halogen-containing solutions, the specified components reduce the working potential of the anode and eliminate the necessity in the interruption period for reduction of the anode potential.

40 cl, 2 tbl, 2 ex

FIELD: chemistry.

SUBSTANCE: particles of a noble metal sulphide are mono-dispersed on activated carbon particles whose surface area is between 200 and 300 m2/g. The ratio of the surface area of the particles of noble metal sulphide to the surface area of particles of activated carbon is less than 0.20.

EFFECT: high catalyst activity during electrochemical reduction of oxygen, high stability thereof in chemically aggressive media.

11 cl, 5 dwg

FIELD: chemistry.

SUBSTANCE: invention claims the method of the electrocatalyst synthesis on the base of the precious metals sulphide including the following stages: 1) reaction of the precursor solution (at least one noble metal) with water solution containing thionic compound in the media not containing the substantial amounts of sulphide ions whereby the said precursor solution contains the carbon particles; 2) separation of the formed catalyst and its thermic treatment.

EFFECT: elaboration of the catalyst synthesis method on the base of the noble metals sulphides in water media without using of highly inflammable and highly toxic compounds.

12 cl, 4 ex

FIELD: chemistry.

SUBSTANCE: oxygen recovering catalyst ruthenium sulphide chemically stable in hydrochloric medium with dissolved chlorine and, optionally dissolved oxygen added. Aforesaid catalyst is prepared from impregnated carrier or from conducting carrier impregnated in initial humidifying with solution containing, at least, one ruthenium precursor salt, or from ruthenium oxide precipitated on conducting carrier dispersed in aqueous solution. Impregnated carrier is dried. Derived product is processed in medium of hydrogen sulphide optionally diluted with inert gas-carrier.

EFFECT: high corrosion stability and availability for electrolysis of oxydepolarised aqueous hydrochloric acid.

47 cl, 1 tbl, 5 ex

FIELD: chemistry.

SUBSTANCE: oxygen recovering catalyst ruthenium sulphide chemically stable in hydrochloric medium with dissolved chlorine and, optionally dissolved oxygen added. Aforesaid catalyst is prepared from impregnated carrier or from conducting carrier impregnated in initial humidifying with solution containing, at least, one ruthenium precursor salt, or from ruthenium oxide precipitated on conducting carrier dispersed in aqueous solution. Impregnated carrier is dried. Derived product is processed in medium of hydrogen sulphide optionally diluted with inert gas-carrier.

EFFECT: high corrosion stability and availability for electrolysis of oxydepolarised aqueous hydrochloric acid.

47 cl, 1 tbl, 5 ex

FIELD: chemistry.

SUBSTANCE: invention claims the method of the electrocatalyst synthesis on the base of the precious metals sulphide including the following stages: 1) reaction of the precursor solution (at least one noble metal) with water solution containing thionic compound in the media not containing the substantial amounts of sulphide ions whereby the said precursor solution contains the carbon particles; 2) separation of the formed catalyst and its thermic treatment.

EFFECT: elaboration of the catalyst synthesis method on the base of the noble metals sulphides in water media without using of highly inflammable and highly toxic compounds.

12 cl, 4 ex

FIELD: chemistry.

SUBSTANCE: particles of a noble metal sulphide are mono-dispersed on activated carbon particles whose surface area is between 200 and 300 m2/g. The ratio of the surface area of the particles of noble metal sulphide to the surface area of particles of activated carbon is less than 0.20.

EFFECT: high catalyst activity during electrochemical reduction of oxygen, high stability thereof in chemically aggressive media.

11 cl, 5 dwg

FIELD: chemistry.

SUBSTANCE: disclosed catalyst contains a single crystalline phase of a noble metal sulphide deposited on conducting carbon which essentially does not contain a phase of zerovalent metal or metal oxides, obtained via reduction of metal precursor salts and thio-precursors with boron hydride or another strong reducing agent.

EFFECT: high activity and stability of the catalyst for cathodic reduction of oxygen during electrolysis of hydrochloric acid.

13 cl, 2 dwg

FIELD: chemistry.

SUBSTANCE: photocatalyst for obtaining hydrogen from a water solution of glycerol under impact of visible radiation with a composition: Pt/Cd1-xZnxS/ZnO/Zn(OH)2, where: x=0.5-0.9, a weight part of platinum constitutes 0.1-1%, is prepared from a mixture of solutions of cadmium and zinc salts, hydroxides of which are precipitated by addition of sodium hydroxide. After that, sulphidation of hydroxides with sodium sulphide is performed. The obtained sediment is dried at a temperature of 60-150°C, impregnated with a solution of H2PtCl6 in hydrochloric acid and reduced with NaBH4 solution.

EFFECT: invention makes it possible to increase the photocatalytic activity of the catalyst.

3 cl, 1 dwg, 5 ex, 1 tbl

FIELD: chemistry.

SUBSTANCE: invention relates to reforming catalyst, which contains platinum, at least one metal-promoter selected from group consisting of rhenium and iridium, and at least one halogen selected from group consisting of fluorine, chlorine, bromine and iodine. Content of platinum in said catalyst is from 0.02 to 2 wt% of total weight of catalyst, content of each metal promoter ranges from 0.02 to 10 wt% of total weight of catalyst and halogen content ranges from 0.1 to 15 wt% of total weight of catalyst. At that, said catalyst is produced on base of substrate from aluminium oxide, in which sulphur content ranges from 500 to 1,200 in weight parts per million of total weight of substrate, and content of phosphorus ranges from 0.04 to 1 wt% of total weight of substrate. Invention also relates to a method of catalytic reforming using said catalyst and use of substrate from aluminium oxide with low content of sulphur and phosphorus for producing a catalyst.

EFFECT: disclosed catalyst has high activity and selectivity in process of reforming, as well as improved ability to retain chlorine.

12 cl, 2 tbl, 3 ex

FIELD: processes and equipment for treatment of water with oxygen-containing gas, water bottling and treatment of bottles for adequate storage of water, may be used in industrial enterprises.

SUBSTANCE: method involves producing oxygen-saturated water by ejection-floatation mixing of water with oxygen-containing gas; bottling oxygen-saturated water and capping, with gas-and-vapor H2O2+O2 mixture synthesized by plasma chemotronical method being used in all above operations. Complex of equipment comprises ejection-floatation unit for oxygen saturation of water and installation for supplying and bottling of oxygen-saturated water.

EFFECT: improved quality of bottled oxygen-saturated potable water, increased storage time and reduced consumption of power and materials.

4 cl, 1 dwg, 4 tbl

Up!