Process for production of particulate ruthenium

Abstract

Process for the production of particulate ruthenium with a purity of 99.99 wt. % and a specific surface area of 0.2-0.5 m.sup.2/g, comprising: (1) providing a hydrochloric solution prepared by dissolving RuO.sub.4 in hydrochloric acid and has a content of ruthenium in the form of dissolved ruthenium species of 15-22 wt. %; (2) providing an aqueous solution with an ammonium chloride content of 200-600 g/litre; (3) forming a reaction mixture by dosing the hydrochloric solution provided in step (1) to the aqueous solution provided in step (2) at a molar ratio of 1 mol ruthenium: 3-6 mol ammonium chloride, at a temperature of 55-90 C. over the course of 0.2-5 hours and while adjusting and maintaining a pH of 0.6 to 0; (4) separating solid material formed during step (3) from the hydrochloric reaction mixture; and (5) calcinating the solid material separated in step (4) at an object temperature of 350-1,000 C.

Claims

1. A process for the production of particulate ruthenium with a purity of 99.99 wt. % and a specific surface area of 0.2 to 0.5 m.sup.2/g, comprising the steps of: (1) providing a hydrochloric solution prepared by dissolving RuO.sub.4 in hydrochloric acid, the hydrochloric solution having a content of ruthenium in the form of dissolved ruthenium species in the range of 15 to 22 wt. %; (2) providing an aqueous solution with an ammonium chloride content in the range of 200 to 600 g/litre; (3) forming a reaction mixture by dosing the hydrochloric solution provided in step (1) to the aqueous solution provided in step (2) at a molar ratio of 1 mol ruthenium:3 to 6 mol ammonium chloride, at a temperature of 55 to 90 C. over the course of 0.2 to 5 hours and while adjusting and maintaining a pH value in the range of 0.6 to 0; (4) separating solid material formed during step (3) from the hydrochloric reaction mixture; and (5) calcinating the solid material separated in step (4) at an object temperature in the range of 350 to 1,000 C.

2. The process of claim 1, whereby the hydrochloric solution provided in step (1) has a pH value in the range of 0.9 to 0.7.

3. The process of claim 1, whereby the aqueous solution provided in step (2) consists of ammonium chloride and water.

4. The process of claim 1, whereby the temperature in step (3) is 65 to 85 C.

5. The process of claim 1, whereby the dosing duration in step (3) is 1 to 5 hours.

6. The process of claim 1, whereby the molar ratio is 1 mol ruthenium:4.5 to 6 mol ammonium chloride.

7. The process of claim 1, whereby the calcination takes place at an object temperature of 450 to 900 C.

8. The process of claim 1, whereby the duration of calcination is 1.5 to 7 hours.

9. The process of claim 1, whereby the calcination takes place on air, in an inert gas atmosphere or in a reducing atmosphere.

10. The process of claim 1, comprising a step (6), in which the particulate ruthenium thus obtained is subjected to a reducing treatment.

11. The process of claim 10, whereby the reducing treatment consists of a treatment with hydrogen at temperatures in the range of 120 to 900 C.

Description

EXAMPLES

(1) The process according to the invention comprising steps (1) to (5) has been implemented repeatedly in the laboratory while varying various parameters. Moreover, reference experiments outside the scope of the invention have been performed.

(2) Based on the material produced according to example 1 of EP 2 236 633 A1, step (1) of the process was implemented according to the example disclosed in sections [18]-[27] of EP 2 096 084 A1. The ruthenium content was varied.

(3) In step (2), aqueous ammonium chloride solutions of various concentrations were prepared.

(4) In each case, step (3) involved a molar ratio of 1:5.4 of ruthenium:ammonium chloride and a sample size of 150 to 400 mL. The pH value and the temperature of the reaction mixture as well as the dosing duration of the solution provided in step (1) were varied.

(5) In step (5), the calcination was performed for 2 hours at an object temperature of 800 C. in a nitrogen flow.

(6) In each case, particulate ruthenium with a purity of 99.99 wt. % and a mean particle diameter d50 in the range of 15 to 45 m was obtained.

(7) The following table shows the parameters used in the various examples (1-18 according to the invention, 19-21 reference) and the specific surface area as determined for the particulate ruthenium obtained using the aforementioned process.

(8) TABLE-US-00001 Ru NH.sub.4Cl Dosing content content duration BET Example (wt. %) (g/L) pH T ( C.) (h) (m.sup.2/g) 1 15 200 0.6 55 0.2 0.41 2 22 600 0 55 3 0.27 3 15 200 0.6 90 3 0.27 4 15 600 0.6 90 0.2 0.40 5 22 200 0 55 0.2 0.44 6 22 200 0.6 55 3 0.43 7 22 600 0.6 55 0.2 0.33 8 15 200 0 55 3 0.30 9 15 200 0 90 0.2 0.32 10 22 600 0 90 0.2 0.43 11 22 200 0.6 90 0.2 0.43 12 15 600 0.6 55 3 0.23 13 18.5 400 0.2 72.5 1.6 0.33 14 15 600 0 55 0.2 0.23 15 22 200 0 90 3 0.27 16 22 600 0.6 90 3 0.44 17 18.5 400 0.2 72.5 1.6 0.28 18 15 600 0 90 3 0.28 19 (ref.) 25 190 0.6 50 0.2 0.61 20 (ref.) 12 180 0 90 3 0.18 21 (ref.) 15 600 0.3 55 4 0.16