Method for simultaneous extraction of platinum and rhenium from spent catalysts latinoreview

 

(57) Abstract:

The invention relates to waste latinoreview catalysts on AL2ABOUT3-basis. Exhaust latinoreview the catalyst is subjected to acid leaching with application of a constant current density of 25-30 A/DM2within 7 to 8 hours in hydrochloric-sulfuric acid solution with simultaneous cathodic deposition of Pt and Re are the mass ratio T:W=1:(10-20). The process temperature of 65-70C. When the base catalyst is aluminum oxide is practically insoluble, and platinum and rhenium into solution in the form PtCL62-and ReO4-due to the resulting anode active chlorine, is then deposited on the cathode in the form of pure metals. To reduce the cost of the process can be carried out stepwise, i.e., under certain conditions, and a current density of 10 A/DM2within 6 h, and then for 2 h at a current density of 30 A/DM2. The method extracts the Pt 99%, Re - 93%. The invention allows to exclude multi-stage allocations of platinum and rhenium with exhaust catalysts and their subsequent refining, resulting in lower losses of valuable metals. 5 C.p. f-crystals, 2 tab.

The invention relates to the field of pen they use to make fresh batches of catalysts, as well as obtaining valuable metals.

There is a method of electrochemical extraction of rhenium [1] from sulfate electrolytes. Composition of bath: KReO4- 15 g/l, H2SO4- 12-15 g/L. Electrolysis is carried out at a pH of 0.9 to 1.0; a temperature of 85-90oC and a cathode current density of 10-15 A/DM2.

However, in [2] States that the maximum yield of rhenium current is observed when adding H2SO4in the amount of 25 to 100 g/L. in Addition, the relief of the electrode process is also adding (NH4)2SO4that prevents passivation of the cathode facilitates the discharge of ions of rhenium and improves the buffer properties of the electrolyte.

Precipitation of platinum can be obtained using soluble anode in electrolytes containing 10-100 g/l Na2PtCl650 - 100 g/l H2SO4. Process temperature 65 - 80oC, current density 10 A/DM2[3].

There is a method of extraction of rhenium from registergui materials [4], which is an electrochemical leaching registergui materials, including latinoreview catalyst, sodium chloride solution and then passing the solution through an anion exchange resin in chloride f is>. The Ratio Of T:W = 1 : 10. Sorption of rhenium chloride solutions carried out by anion brand EN-251, pretreated in an autoclave at 60oC 2% hydrogen peroxide solution for 6 hours and translated in the chloride form by passing a 5% solution of hydrochloric acid in dynamic conditions. Extraction of rhenium is 99.7 per cent.

The method for extracting platinum group metals from spent catalysts, sludge and concentrates [5], including leaching at elevated temperature in a solution of sodium chloride 10-25 wt.%, containing hydrochloric acid and precipitation of metals in the cell with the charging cathode, followed by separation from the cathode of the known methods. The degree of extraction of precious metals reaches 98%.

For the electrochemical extraction of platinum and rhenium from a spent catalyst is first necessary to translate them into a solution, as they are in the forms of Pt and ReO2respectively [6, 7].

But in the literature there are no data on joint electrochemical separation of platinum and rhenium, although it may be appropriate to use returnable metals in the preparation of fresh batches of catalysts.

Nai is RA, containing promoters (iron and titanium) [8]. For burning carbon deactivated catalyst is first oxidized in a stream of air or oxygen at a temperature of 300 - 500oC for 2-8 hours. The oxidized catalyst leached with 5 M hcl (nitric) acid or Aqua Regia at a temperature of 20-90oC. the resulting solution was divided in columns with ion exchangers. The noble metals and their separation is performed on a single column.

The disadvantages of this method are the energy density, multi-stage and, ultimately, separate selection of platinum and rhenium, which is accompanied with additional losses in the extraction process.

The purpose of this invention is to provide affordable and effective way to share electrochemical extraction of platinum and rhenium from a spent latinoreview catalysts that allow for the circulation of precious metals in the production and consumption of these catalysts, to exclude multi-stage operation of the extraction and refining of these metals, significantly reducing their losses.

This technical result is achieved in that in the method for simultaneous extraction of platinum and rhenium of lore ions the spent catalyst is subjected to electrochemical leaching in sulfuric acid solution containing chloride ions upon application of a constant current with simultaneous cathodic deposition in the form of pure metals platinum and rhenium. Thus the basis of the catalyst is aluminum oxide is practically insoluble, and platinum and rhenium into solution in the form tCl62-and ReO4-due to active chlorine produced at the anode, then deposited on the cathode in the form of pure metals.

Experimentally were established intervals of temperature, treatment time, concentration of the chloride ions and the current density. The sulfuric acid concentration is 50 - 100 g/l Concentration of the chloride ions is achieved by introducing into the solution of sodium chloride in the amount of 150 to 250 g/L. With further increase of the chloride ions complications during electroreduction of rhenium, which forms a number of trudnorazreshimym of oxychlorides type ReOCl52-. To improve the completeness of extraction of rhenium in the electrolyte composition is injected additive (NH4)2SO4in the amount of 0.7 - 2.2 g/l Temperature withstand 65 - 70oC, the mass ratio of T:W = 1: (10 - 20). The current density during the electrochemical extraction of platinum and R is Oh electrolytic cell with stirring. As the cathode is used graphite as the anode porous titanoecidae material. At the end of the cathode sludge, which is a metal of platinum and rhenium, dissolved in Aqua Regia and photometrically determine the content in the solution of the two metals methods [9, 10], respectively.

Due to the fact that to achieve the full selection on the cathode Pt and Re from dilute solutions requires a higher current density than for pre-translation platinum and rhenium in the solution, in order to reduce the costs of their extraction, the authors have investigated the possibility of stepwise changes of the current density in the process of extraction of metals. The spent catalyst is treated with hydrochloric-sulfuric acid solution (see composition) at current density of 10 A/DM2the temperature of 65-70oC for 6 hours. Then the current density is increased to 30 A/DM2and continue the selection of the metal within 2 hours.

As a result of the research the authors have determined the conditions of electrochemical extraction of platinum and rhenium in hydrochloric-sulfuric acid electrolytes to obtain the impregnating solutions used in the preparation of catalysts.

2temperature - 70oC and the process time is 8 hours.

To achieve a high degree of extraction of metals may be recommended concentration of sodium chloride from 150 to 250 g/L. increasing the temperature from 65 to 70oC leads to an increase in the degree of extraction of rhenium from 92% to 93%, platinum - from 96 to 99% (experimental conditions: current density 30 A/DM2the concentration of the chloride ions 250 g/l, temperature 70oC, time - 8 hours).

It was shown that under the same conditions with increasing duration of the process from 7 to 8 hours, the degree of extraction of platinum increases from 95 to 99%, rhenium - from 89 to 93%.

When changing the current density in a hydrochloric-sulfuric acid electrolyte at a temperature of 70oC, NaCl concentration of 250 g/l, the process time - 8 hours the following results were obtained (see tab. 2).

Thus, the developed method allows to extract platinum and rhenium together for further use returnable metals in the production of latinoreview catalysts.

The essence of the method is illustrated by concrete examples.

Example 1. A portion of the crushed catalyst CU - 110 mass 10 g is placed in an electrolytic cell with a temperature-controlled l is/l, NaCl -150 g/L. the Ratio of T:W = 1:10. The current density of 25 A/DM2the extraction time is 7.5 hours. The metals deposited on the cathode, was dissolved in Aqua Regia and photometrically determined their content. The degree of extraction of platinum is 98%, rhenium - 91%.

Example 2. A portion of the crushed catalyst CU - 110 mass 10 g is placed in an electrolytic cell with a temperature-controlled to 70oC solution volume of 200 cm3containing: H2SO4- 50 g/l (NH4)2SO42 g/l, NaCl - 250 g/L. the Ratio of T:W = 1:20. The current density 30 A/DM2the extraction time is 8 hours. The amount of platinum and rhenium, released at the cathode was determined as described in example 1 by the way. The degree of extraction of platinum is 99%, rhenium - 93%.

Example 3. A portion of the crushed catalyst CU-110 mass 10 g is placed in an electrolytic cell with a temperature-controlled to 70oC solution volume of 200 cm3containing: H2SO4- 50 g/l (NH4)2SO42 g/l, NaCl - 250 g/L. the Ratio of T: W == 1:20. The current density 10 A/DM2the extraction time is 6 hours. Then the current density is increased to 30 A/DM2and continue the process within 2 hours. The amount of platinum and rhenium, released at the cathode, determined what rmacie

1. Lebedev, K. B. Rhenium. M: Metallurgizdat, 1963. S. 173.

2. Vahramyan E. Electrodeposition of metals and inhibiting adsorption. M.: Chemistry. 1969. S. 139.

3. Kadaner L. I. the Electrodeposition of noble and rare metals. M: GASINCI. 1962. C. 17.

4. USSR author's certificate N 973483, MKI C 01 G 47/00, B 01 J 41/04.

5. RF patent 2119964. IPC 6 C 22 IN 11/00.

6. Kravtsov A. C. , Ivanchina E. D. Intelligent systems in chemical technology and engineering education. Novosibirsk: Nauka. 1996. S. 18-23.

7. Johnson M. F. L. et al.The state of Rhenium in Pt-Re/Al2O3catalyst. //J. Catal. 1975. V 39. P. 487.

8. Chem. Priim. - 1986. - V. 36, N 5. - P. 243-245. //Thematic review. The extraction of valuable metals from used heterogeneous catalysts. Tsniiteneftehim. Vol. 5. Moscow. 1988. S. 22.

9. The photometric method determination of platinum. OST 3801267 1-82.

10. The technique of photometric determination of rhenium. OST 3801267 2-82.

1. Method for simultaneous extraction of platinum and rhenium from a spent latinoreview catalysts, including acid leaching in a solution containing chloride ions, characterized in that the spent catalyst is subjected to electrochemical leaching in sulfuric acid solution with the crystals of platinum and rhenium.

2. The method according to p. 1, characterized in that for electroisolative use solution composition, g/l:

H2SO4- 50 - 100

(NH4)2SO4- 0,7 - 2,2

NaCL - 150 - 250

the mass ratio T : W= 1 : (10 - 20).

3. The method according to p. 1, characterized in that the extraction of platinum and rhenium is carried out for 7.5 to 8 hours

4. The method according to p. 1, characterized in that the extraction of platinum and rhenium is performed during application of a constant current density of 25 to 30 A/DM2.

5. The method according to p. 1, characterized in that the extraction of platinum and rhenium is carried out at 65 - 70oC.

6. The method according to any of paragraphs.1, 2 and 5, characterized in that the extraction of platinum and rhenium is carried out at a current density of 10 A/DM2within 6 h, and then for 2 h at a current density of 30 A/DM2.

 

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