A method for preparing high-purity palladium powder

Abstract

The present invention discloses a method for preparing high-purity palladium powder, which relates to the technical field of high-purity precious metals, and particularly to a method for preparing 5N high-purity palladium powder using palladium chloride as a raw material, through complex precipitation removal and secondary impurity removal by recrystallization. The preparation method of the present invention comprises: (1) dissolving palladium to prepare a solution; (2) chelating palladium precipitation: adding 1,10-phenanthroline to a palladium solution and heating it, so that a yellow precipitate gradually precipitates, and when the solution changes from reddish brown to light yellow, draining it to obtain a palladium-containing precipitate; (3) recrystallization: adding the palladium-containing precipitate to ethyl acetate for recrystallization, and filtering to obtain a palladium precipitate; (4) dissolving the palladium-containing precipitate to prepare a solution; and (5) reducing to obtain high-purity palladium powder: reducing the palladium solution with a reducing agent under slightly boiling conditions to obtain high-purity palladium powder. The preparation method of the present invention can prepare high-purity palladium powder. At the same time, since no metal element-containing reagent is added during the preparation process, no toxic or harmful gas is generated during the reaction process, and the production process is stable and high.

Description

Technical Field

[0001] The present invention relates to the technical field of high-purity precious metal catalysts, and in particular to a method for preparing high-purity palladium powder. Background Art

[0002] With the development of the electronics and information industry, metal-incorporated polymer conductive pastes have experienced rapid growth. High-purity palladium powder excels in improving the paste's resistance to erosion and preventing silver ion migration. High-purity palladium targets are irreplaceable materials in the semiconductor industry. With technological advancements, the demand for palladium purity is increasing.

[0003] Currently, the main methods for preparing high-purity palladium in China include ammonium chloropalladate precipitation, ammonia complexation, and combined methods. While ammonium chloropalladate precipitation is effective for separating base metal impurities, it is less effective for separating other platinum group metals, making it difficult to obtain high-purity palladium. The ammonia complexation method can effectively separate other precious metal impurities, but it is less effective for separating base metals such as Cu and Ni. The combined method combines ammonium chloropalladate precipitation and ammonia complexation to effectively separate precious and base metal impurities, yielding 99.99% pure palladium.

[0004] CN 110340373 B The present invention discloses a method for preparing high-purity palladium powder, which uses a process combining conventional cation exchange impurity removal, selective chemical precipitation, calcination hydrogen reduction, and washing with a dilute hydrochloric acid and hydrofluoric acid mixed solution to remove impurities. The process is complex and the hydrogen reduction step is highly dangerous.

[0005] In summary, existing palladium powder products have problems such as low product purity and complex processes. Therefore, the efficient preparation of high-purity palladium powder is of great significance. Summary of the Invention

[0006] The purpose of the present invention is to address the technical problems of low purity of the above-mentioned high-purity palladium and provide a method for preparing high-purity palladium powder without adding any metal element-containing reagents, without generating any toxic or harmful gases during the reaction, and with a stable production process.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A method for preparing high-purity palladium powder, characterized in that it comprises the following steps:

[0009] (1) Palladium dissolution and solution preparation: Add palladium chloride to deionized water, then add sodium chloride, heat to boiling point, stir and dissolve, filter and remove insoluble matter to obtain palladium solution, wherein the ratio of palladium chloride, deionized water and sodium chloride is palladium chloride: deionized water: sodium chloride is equal to 100g: 1000ml: 33g;

[0010] (2) Chelating palladium precipitation: Add 1,10-phenanthroline to the palladium solution and heat it to 70-80°C. A yellow precipitate will gradually precipitate. When the solution changes from reddish brown to light yellow, drain it to obtain a palladium-containing precipitate. The amount of 1,10-phenanthroline added is 2-3 times the molar amount of palladium chloride.

[0011] (3) Recrystallization: Add the palladium-containing precipitate into ethyl acetate for recrystallization, and filter to obtain the palladium precipitate.

[0012] (4) Dissolving the palladium-containing precipitate to prepare a solution: Add the palladium-containing precipitate to hydrochloric acid to dissolve it, obtain a palladium solution, and filter it to remove trace solid impurities, wherein the amount of hydrochloric acid used is 3.5 times the mass of the palladium-containing precipitate;

[0013] (5) Reduction to obtain high-purity palladium powder: The palladium solution is reduced with hydrazine hydrochloride under slightly boiling conditions. After the reduction is completed, the palladium powder is filtered to obtain the palladium powder. The obtained palladium powder is washed with dilute hydrochloric acid and deionized water respectively and vacuum dried to obtain high-purity palladium powder.

[0014] Furthermore, the palladium chloride in step (1) is a reddish-brown powder with a palladium content of 29.5%.

[0015] Furthermore, in step (2), 1,10-phenanthroline is a white powder with a purity of >99%.

[0016] Furthermore, the hydrochloric acid in step (4) is electronic grade concentrated hydrochloric acid with a concentration of 37%.

[0017] Furthermore, in step (5), hydrazine hydrochloride is a white powder with a purity of >99%, and the palladium powder is washed with dilute hydrochloric acid 3 times and deionized water 6 times, respectively.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. No metal-containing reagents are added during the preparation process, no toxic or harmful gases are generated during the reaction, and the production process is stable;

[0020] 2. It can process palladium chloride with high impurity content of iron, calcium, gold, silver, platinum, ruthenium, rhodium and iridium, and the direct recovery rate of metallic palladium reaches more than 98%. The purity of the high-purity palladium powder prepared by the present invention is greater than 99.999%. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the appearance of the high-purity palladium powder prepared by the present invention;

[0022] Figure 2 This is the SEM spectrum of the high-purity palladium powder prepared in the present invention. DETAILED DESCRIPTION

[0023] The present invention will be further described in detail below with reference to specific embodiments.

[0024] Example 1

[0025] A method for preparing high-purity palladium powder comprises the following steps:

[0026] (1) Palladium solution preparation: Add 100 g of palladium chloride to 1000 ml of deionized water, then add 33 g of sodium chloride, heat to boiling point, stir and dissolve, filter and remove insoluble matter to obtain palladium solution A;

[0027] (2) Chelating palladium precipitation: Add 201.5 g of 1,10-phenanthroline to palladium solution A and heat to 70 °C. A yellow precipitate gradually precipitates out. When the solution changes from reddish brown to light yellow, drain and obtain 356.6 g of palladium-containing precipitate B.

[0028] (3) Recrystallization: 356.6 g of palladium-containing precipitate B was added to ethyl acetate for recrystallization, and 342.3 g of palladium precipitate C was obtained by filtration;

[0029] (4) Dissolving the palladium-containing precipitate C to prepare a solution: 342.3 g of the palladium-containing precipitate C was added to 1198 g of hydrochloric acid to dissolve it to obtain a palladium solution D, which was then filtered to remove trace solid impurities;

[0030] (5) Reduction to obtain high-purity palladium powder: palladium solution D was reduced with hydrazine hydrochloride under slightly boiling conditions. After the reduction was completed, palladium powder was filtered to obtain palladium powder. The obtained palladium powder was washed with dilute hydrochloric acid and deionized water respectively and vacuum dried to obtain 57.29 g of high-purity palladium powder.

[0031] The purity of the high-purity palladium powder is greater than 99.999%, and the yield is 96.3%.

[0032] Example 2

[0033] (1) Palladium solution preparation: Add 100 g of palladium chloride to 1000 ml of deionized water, then add 33 g of sodium chloride, heat to boiling point, stir and dissolve, filter and remove insoluble matter to obtain palladium solution A;

[0034] (2) Chelating palladium precipitation: Add 232.6 g of 1,10-phenanthroline to palladium solution A and heat to 75 °C. A yellow precipitate gradually precipitates out. When the solution changes from reddish brown to light yellow, drain and obtain 356.6 g of palladium-containing precipitate B.

[0035] (3) Recrystallization: 356.6 g of palladium-containing precipitate B was added to ethyl acetate for recrystallization, and 342.2 g of palladium precipitate C was obtained by filtration;

[0036] (4) Dissolving the palladium-containing precipitate C to prepare a solution: 342.2 g of the palladium-containing precipitate C was added to 1197 g of hydrochloric acid to dissolve it to obtain a palladium solution D, which was then filtered to remove trace solid impurities;

[0037] (5) Reduction to obtain high-purity palladium powder: palladium solution D was reduced with hydrazine hydrochloride under slightly boiling conditions. After the reduction was completed, palladium powder was filtered to obtain palladium powder. The obtained palladium powder was washed with dilute hydrochloric acid and deionized water respectively and vacuum dried to obtain 57.48 g of high-purity palladium powder.

[0038] The purity of the high-purity palladium powder is greater than 99.999%, and the yield is 96.6%.

[0039] Example 3

[0040] A method for preparing high-purity palladium powder comprises the following steps:

[0041] (1) Palladium solution preparation: Add 100 g of palladium chloride to 1000 ml of deionized water, then add 33 g of sodium chloride, heat to boiling point, stir and dissolve, filter and remove insoluble matter to obtain palladium solution A;

[0042] (2) Chelating palladium precipitation: Add 280g of 1,10-phenanthroline to palladium solution A and heat to 76°C. A yellow precipitate gradually precipitates out. When the solution changes from reddish brown to light yellow, drain and obtain 356.8g of palladium-containing precipitate B;

[0043] (3) Recrystallization: 356.8 g of palladium-containing precipitate B was added to ethyl acetate for recrystallization, and 342.6 g of palladium precipitate C was obtained by filtration;

[0044] (4) Dissolving the palladium-containing precipitate C to prepare a solution: 342.6 g of the palladium-containing precipitate C was added to 1199 g of hydrochloric acid to dissolve it to obtain a palladium solution D, which was then filtered to remove trace solid impurities;

[0045] (5) Reduction to obtain high-purity palladium powder: palladium solution D was reduced with hydrazine hydrochloride under slightly boiling conditions. After the reduction was complete, palladium powder was filtered to obtain high-purity palladium powder. The platinum powder was washed with dilute hydrochloric acid and deionized water, respectively, to obtain high-purity palladium powder. The obtained palladium powder was washed with dilute hydrochloric acid and deionized water, respectively, and vacuum-dried to obtain 57.54 g of high-purity palladium powder.

[0046] The purity of the high-purity palladium powder is greater than 99.999%, and the yield is 96.7%.

[0047] Example 4

[0048] A method for preparing high-purity palladium powder comprises the following steps:

[0049] (1) Palladium solution preparation: Add 100 g of palladium chloride to 1000 ml of deionized water, then add 33 g of sodium chloride, heat to boiling point, stir and dissolve, filter and remove insoluble matter to obtain palladium solution A;

[0050] (2) Chelating palladium precipitation: Add 300g of 1,10-phenanthroline to palladium solution A and heat to 72°C. A yellow precipitate gradually precipitates out. When the solution changes from reddish brown to light yellow, drain and obtain 356.7g of palladium-containing precipitate B.

[0051] (3) Recrystallization: 356.7 g of palladium-containing precipitate B was added to ethyl acetate for recrystallization, and 342.3 g of palladium precipitate C was obtained by filtration;

[0052] (4) Dissolving the palladium-containing precipitate C to prepare a solution: 342.3 g of the palladium-containing precipitate C was added to 1198 g of hydrochloric acid to dissolve it to obtain a palladium solution D, which was then filtered to remove trace solid impurities;

[0053] (5) Reduction to obtain high-purity palladium powder: palladium solution D was reduced with hydrazine hydrochloride under slightly boiling conditions. After the reduction was complete, palladium powder was filtered to obtain palladium powder. The platinum powder was washed with dilute hydrochloric acid and deionized water to obtain high-purity palladium powder. The obtained palladium powder was washed with dilute hydrochloric acid and deionized water, respectively, and vacuum-dried to obtain 57.59 g of high-purity palladium powder.

[0054] The purity of the high-purity palladium powder is greater than 99.999%, and the yield is 96.8%.

[0055] Example 5

[0056] A method for preparing high-purity palladium powder comprises the following steps:

[0057] (1) Palladium solution preparation: Add 100 g of palladium chloride to 1000 ml of deionized water, then add 33 g of sodium chloride, heat to boiling point, stir and dissolve, filter and remove insoluble matter to obtain palladium solution A;

[0058] (2) Chelating palladium precipitation: Add 268g of 1,10-phenanthroline to palladium solution A and heat to 80°C. A yellow precipitate gradually precipitates out. When the solution changes from reddish brown to light yellow, drain and obtain 356.5g of palladium-containing precipitate B;

[0059] (3) Recrystallization: 356.5 g of palladium-containing precipitate B was added to ethyl acetate for recrystallization, and 342.5 g of palladium precipitate C was obtained by filtration;

[0060] (4) Dissolving the palladium-containing precipitate C to prepare a solution: 342.5 g of the palladium-containing precipitate C was added to 1199 g of hydrochloric acid to dissolve it to obtain a palladium solution D, which was then filtered to remove trace solid impurities;

[0061] (5) Reduction to obtain high-purity palladium powder: palladium solution D was reduced with hydrazine hydrochloride under slightly boiling conditions. After the reduction was complete, palladium powder was filtered to obtain palladium powder. The platinum powder was washed with dilute hydrochloric acid and deionized water to obtain high-purity palladium powder. The obtained palladium powder was washed with dilute hydrochloric acid and deionized water, respectively, and vacuum-dried to obtain 57.59 g of high-purity palladium powder.

[0062] The purity of the high-purity palladium powder is greater than 99.999%, and the yield is 96.8%.

[0063] Example 6

[0064] A method for preparing high-purity palladium powder comprises the following steps:

[0065] (1) Palladium solution preparation: Add 100 g of palladium chloride to 1000 ml of deionized water, then add 33 g of sodium chloride, heat to boiling point, stir and dissolve, filter and remove insoluble matter to obtain palladium solution A;

[0066] (2) Chelating palladium precipitation: Add 302.2 g of 1,10-phenanthroline to palladium solution A and heat to 80 °C. A yellow precipitate gradually precipitates out. When the solution changes from reddish brown to light yellow, drain and obtain 356.9 g of palladium-containing precipitate B.

[0067] (3) Recrystallization: 356.9 g of palladium-containing precipitate B was added to ethyl acetate for recrystallization, and 342.8 g of palladium precipitate C was obtained by filtration;

[0068] (4) Dissolving the palladium-containing precipitate C to prepare a solution: 342.8 g of the palladium-containing precipitate C was added to 1200 g of hydrochloric acid to dissolve it to obtain a palladium solution D, which was then filtered to remove trace solid impurities;

[0069] (5) Reduction to obtain high-purity palladium powder: palladium solution D was reduced with hydrazine hydrochloride under slightly boiling conditions. After the reduction was complete, palladium powder was filtered to obtain palladium powder. The platinum powder was washed with dilute hydrochloric acid and deionized water to obtain high-purity palladium powder. The obtained palladium powder was washed with dilute hydrochloric acid and deionized water, respectively, and vacuum-dried to obtain 57.65 g of high-purity palladium powder.

[0070] The purity of the high-purity palladium powder is greater than 99.999%, and the yield is 96.9%.

[0071] The purity analysis of the high-purity palladium powder prepared in Example 6 is shown in Table 1.

[0072]

[0073] As can be seen from Table 1, the high-purity palladium powder prepared by the present invention has very low contents of non-metallic elemental impurities such as B and S, and also extremely low contents of alkali metals such as Li and Cs, indicating that the method disclosed in the present invention is very effective in removing non-metallic impurities and some alkali metals from palladium chloride. Since other platinum group metals such as Pt have very similar chemical properties to Pd and are extremely difficult to separate, they are definitely the focus of attention and research.

[0074] The above descriptions are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing high-purity palladium powder, characterized in that: The following steps are involved: (1) Palladium dissolution and solution preparation: Add palladium chloride to deionized water, then add sodium chloride, heat to boiling point, stir and dissolve, filter and remove insoluble matter to obtain palladium solution; (2) Chelating palladium precipitation: Add 1,10-phenanthroline to the palladium solution and heat it to 70-80°C. A yellow precipitate will gradually precipitate. When the solution changes from reddish brown to light yellow, it is drained to obtain a palladium-containing precipitate. The amount of 1,10-phenanthroline added is 2-3 times the molar amount of palladium chloride. (3) Recrystallization: Add the palladium-containing precipitate into ethyl acetate for recrystallization, and filter to obtain the palladium precipitate; (4) Dissolving the palladium-containing precipitate to prepare a solution: adding the palladium-containing precipitate to hydrochloric acid to dissolve it, obtaining a palladium solution and filtering it to remove trace solid impurities; (5) Reduction to obtain high-purity palladium powder: The palladium solution is reduced with hydrazine hydrochloride under slightly boiling conditions. After the reduction is completed, the palladium powder is filtered to obtain the palladium powder. The obtained palladium powder is washed with dilute hydrochloric acid and deionized water respectively, and vacuum dried to obtain high-purity palladium powder.

2. The preparation method of high-purity palladium powder according to claim 1, wherein: In step (1), the ratio of palladium chloride, deionized water and sodium chloride is palladium chloride: deionized water: sodium chloride equal to 100g:1000ml:33g.

3. The preparation method of high-purity palladium powder according to claim 1, wherein: In step (4), the amount of hydrochloric acid used is 3.5 times the mass of the palladium-containing precipitate.

4. The preparation method of high-purity palladium powder according to claim 1, wherein: In step (1), palladium chloride is a reddish-brown powder with a palladium content of 29.5%.

5. The preparation method of high-purity palladium powder according to claim 1, wherein: In step (2), 1,10-phenanthroline is a white powder with a purity of >99%.

6. The preparation method of high-purity palladium powder according to claim 1, wherein: In step (4), the hydrochloric acid is electronic grade concentrated hydrochloric acid with a concentration of 37%.

7. The method for preparing high-purity palladium powder according to claim 1, wherein: In step (5), hydrazine hydrochloride is a white powder with a purity of >99%. The palladium powder is washed with dilute hydrochloric acid 3 times and deionized water 6 times, respectively.

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