Pure preparation comprising rhodium compound and a metal reduction to make two steps.
1. Preparation of pure compounds There are mainly sodium nitrite complexation, ammonia complexation, extraction and ion exchange.
(1) Sodium nitrite complex solution The chloranic acid solution containing 40-50 g/L of hydrazine is adjusted to pH ≈ 1.5 with dilute sodium hydroxide solution, and boiled with NaNO 2 to form a pale yellowish green to colorless hexanitrosoguanidine. Sodium, the reaction is:
2H 3 RhCl 6 +18NaNO 2 =====2Na 3 Rh(NO 2 ) 6 +12NaCl+3NO+3NO 2 +3H 2 O
After the reaction is completed, the pH is adjusted to 9 to 10 with an alkali solution and boiled, and the ruthenium metal and ruthenium are neutralized and hydrolyzed into a hydroxide precipitate. After filtration, the ruthenium-containing solution is added with ammonium chloride to form a white ruthenium complex precipitate, and the reaction is:
Na 3 Rh(NO 2 ) 6 +2NH 4 Cl=====(NH 4 ) 2 NaRh(NO 2 ) 6 ↓+2NaCl
Immediately after the completion of the reaction, the precipitate was filtered, and the precipitate was purified by ammonia complexation.
(2) Ammonia complex method The (NH 4 ) 2 NaRh(NO 2 ) 6 precipitate formed by sodium nitrite complexation can be dissolved in NaOH solution and re-converted into sodium hexanitroguanidine solution. The base metal and antimony remain unchanged. The hydroxide precipitation state is separated from the hydrazine, and the dissolution reaction is:
(NH 4 ) 2 NaRh(NO 2 ) 6 +2NaOH=====Na 3 Rh(NO 2 ) 6 +2NH 4 OH
The cerium-containing solution is filtered out, and after heating, ammonia water and ammonium chloride are added to precipitate a trinitrosotriazine oxime precipitate, and the reaction is:
Na 3 Rh(NO 2 ) 6 +3NH 4 OH=====Rh(NH 3 ) 3 (NO 2 ) 3 ↓+3NaNO 2 +3H 2 O
After filtration, the precipitate is washed with 5% ammonium chloride, and boiled with 4 mol/L hydrochloric acid for 4-6 hours to dissolve the ruthenium metal impurities, and at the same time, the nitroso complex of hydrazine is converted into pure yellow trichlorotriamine. The enthalpy precipitates and the reaction is:
2Rh(NH 3 ) 3 (NO 2 ) 3 +6HCl=====2Rh(NH 3 )3Cl 3 ↓+3NO 2 +3NO+3H 2 O
After filtration, it can be calcined into a metal crucible.
(3) Extraction method The chloroantimonic acid solution is neutralized with a dilute alkali solution to form a yellow precipitate of Rh(OH) 3 . After filtration, the precipitate is dissolved with hydrochloric acid and adjusted to pH ≈1 to convert Rh(III) into a hydrated cation. Is a multivalent cation equilibrium, the general formula is expressed as: [RhCl n (H 2 O) 6-n ] 3-n , (n = 0-2), with [Rh(H 2 O) 6 ] 3+ . Then extracted with an acidic agent, such as P 204, dinonyl naphthalene sulfonic acid, monoalkyl phosphorus acid cation extraction of rhodium (P 538) and the like, other noble metal complex anions remain in the aqueous phase from the organic phase back-extracted with dilute hydrochloric acid A solution of chloroantimonic acid was obtained. [next]
(4) Ion exchange method The acidic chlorinic acid solution flows through the cation exchange resin column, and the resin adsorbs the ruthenium metal cation impurities in the solution, and the effluent is a pure chlorinated acid solution.
2. Metal Preparation and Product Standards Metal ruthenium is prepared from ruthenium compounds by a calcination reduction method and a formic acid reduction method.
(1) Calcination method Pure chlorinated acid solution is added with ammonium chloride to precipitate pure ammonium chlorate, and then placed in a muffle furnace and dried at a low temperature, and then heated to 500-600 ° C to be calcined to ammonium chloride white smoke. When you get the sponge, the reaction is:
At the high temperature calcination, part of the antimony is oxidized to form cerium oxide. Therefore, after cooling, it is transferred to a hydrogen reduction furnace and reduced with hydrogen at 800 ° C, and cooled to room temperature under an inert atmosphere to obtain a metal cerium powder.
(2) Formic acid reduction method The pure chlorinated acid solution is neutralized to pH 7~8 with an alkali solution, boiled, and the formic acid is slowly added and adjusted and maintained at pH 7-8 until the reduction is complete, and the black fine powdery metal ruthenium is obtained, and the reaction is:
2H 3 RhCl 6 +3HCOOH=====2Rh↓+12HCl+3CO 2 ↑
The fine tantalum powder adsorbs a large amount of gas, and it is also necessary to reduce the metal tantalum powder by hydrogen reduction at a temperature of 800 ° C in a hydrogen reduction furnace.
The Chinese metal bismuth product standard (GB1421-78) is shown in the table.
China Metal Antimony Product Standard ( GB1421-78 ) /% | ||||||||||||||
species | Rh | Pt | Pd | Ir | Au | Ag | Cu | Fe | Ni | Sn | Pb  | Al | Si | Total impurity |
HPh-1 | 99.99 | 0.003 | 0.001 | 0.003 | 0.001 | 0.001 | 0 | 0 | 0 | 0.001 | 0.001 | 0.003 | 0.003 | 0.01 |
HPh-2 | 99.95 | 0.02 | 0.01 | 0.02 | 0.005 | 0.005 | 0.01 | 0.01 | 0 | 0.005 | 0.005 | 0.005 | 0.05 | 0.05 |
HPh-3 | 99.9 | 0.03 | 0.03 | 0.03 | 0.02 | 0.02 | 0.01 | 0.01 | 0 | 0.01 | 0.1 | 0.1 | 　 | 　 |
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