A preparation method of dinitrosodiammine platinum

Abstract

The present invention belongs to the technical field of precious metal compound preparation, and specifically relates to a method for preparing dinitrosodiammineplatinum, comprising the following steps: 1) dissolving platinum dichloride in dilute hydrochloric acid, reacting for a period of time, and then adjusting the concentration of platinum ions to 20 g / L to 100 g / L by adding water to obtain a chloroplatinous acid solution; 2) adding urea to the chloroplatinous acid solution, heating the reaction for a period of time, and obtaining a dichlorotetraammineplatinum solution; 3) introducing NOx gas into the dichlorotetraammineplatinum solution to react and generate a dinitrosodiammineplatinum precipitate; and 4) cooling the reaction product obtained in step 3) to room temperature, filtering, washing the filter cake with pure water, and drying to obtain the product. The present invention can produce high-purity dinitrosodiammineplatinum with low chloride and alkali metal impurity contents. The preparation method also has the advantages of simple production process operation, short production cycle, and environmentally friendly process.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of precious metal compounds, and particularly relates to a method for preparing dinitrosodiammineplatinum. Background Art

[0002] Diammine dinitrosoplatinum, commonly known as P salt, has the chemical formula Pt(NH3)2(NO2)2. Due to its moderate coordination stability, it is often used as the primary salt in alkaline platinum plating solutions in cyanide-free electroplating. The resulting coating exhibits low resistance, high hardness, and excellent stability. Diammine dinitrosoplatinum is also used in the electrochemical industry to prepare platinum electrodes, typically by electroplating onto a substrate.

[0003] There are two main traditional synthetic routes for dinitrosodiammineplatinum: (1) As disclosed in patents CN114436348A, CN114057242A, and CN117361654A, chloroplatinic acid and potassium chloride react to form a potassium chloroplatinate precipitate, which is then dissolved in water to form a paste. A saturated sodium nitrite solution is added while the mixture is heated, and concentrated ammonia is added after cooling. The resulting precipitate is filtered and recrystallized to obtain the product. (2) As disclosed in patents CN102285693A and CN113979490A, chloroplatinic acid reacts with hydrazine hydrochloride to form chloroplatinous acid, which is then reacted with concentrated ammonia under boiling conditions to form dichlorotetraammineplatinum, which is then added with sodium nitrite to form dinitrosodiammineplatinum.

[0004] Using the traditional synthesis route, a large number of impurities such as Na, K, and Cl will be introduced during the preparation process of dinitrosodiammine platinum. These impurities have a significant impact on the performance of the coating. For example, alkali metal ions (such as Na and K) will affect the stress of the coating, thereby affecting the stability of the platinum electrode; while halogens (such as Cl) have the risk of poisoning the electrode and accelerating the corrosion of the electrode and equipment. Therefore, the preparation of high-purity dinitrosodiammine platinum is the key to obtaining high-performance platinum coatings and platinum electrodes. In production, attempts to remove these impurities often require cumbersome processes such as filtering and washing, with a long production cycle and unsatisfactory removal effects. At the same time, these methods also require the use of raw materials such as aqua regia, concentrated ammonia, and hydrazine hydrochloride, and the operating environment is not friendly. Summary of the Invention

[0005] In order to overcome the defects of the prior art, the purpose of the present invention is to provide a method for preparing dinitrosodiammineplatinum, which can produce high-purity dinitrosodiammineplatinum with low chloride impurity content and low alkali metal impurity content. In addition, the preparation method has the advantages of simple production process operation, short production cycle, and environmentally friendly process.

[0006] Specifically, the present invention provides the following technical solutions:

[0007] A method for preparing dinitrosodiammine platinum comprises the following steps:

[0008] 1) Platinum dichloride is dissolved in dilute hydrochloric acid, and after a period of reaction, water is added to adjust the concentration of platinum ions to 20 g / L to 100 g / L to obtain a chloroplatinous acid solution;

[0009] 2) adding urea to the chloroplatinous acid solution under stirring, and heating the reaction for a period of time to obtain a tetraamminedichloroplatinum solution;

[0010] 3) introducing NOx gas into the tetraamminedichloroplatinum solution under stirring to react and generate a dinitrosodiammineplatinum precipitate;

[0011] 4) The reaction product obtained in step 3) is cooled to room temperature and then filtered, the filter cake is washed with pure water, and dried to obtain the product.

[0012] Preferably, in step 1), the molar concentration of HCl in the dilute hydrochloric acid is 1.5 to 4.5 mol / L.

[0013] Preferably, in step 1), the molar number of HCl in the dilute hydrochloric acid is 2.1 to 2.5 times the molar number of platinum element in platinum dichloride.

[0014] Preferably, in step 1), the reaction time is 15 to 60 minutes.

[0015] Preferably, in step 2), the molar number of urea added is 4 to 6 times the molar number of platinum element in platinum dichloride.

[0016] Preferably, in step 2), the reaction time is 1 h to 4 h, and the reaction temperature is 80 to 100°C.

[0017] Preferably, in step 3), the NOx gas is NO, NO2, or a mixture of NO and NO2.

[0018] Preferably, in step 3), NOx gas is introduced into the tetraamminedichloroplatinum solution at a gas flow rate of 1.2 L / min to 2.0 L / min.

[0019] Preferably, in step 3), the reaction temperature is 30° C. to 80° C., and the reaction time is 4 h to 8 h.

[0020] The beneficial effects of the present invention are at least:

[0021] 1) The preparation method of dinitrosodiammineplatinum provided by the present invention uses platinum dichloride as the synthesis raw material. Although hydrochloric acid solution is also added, compared with the preparation of chloroplatinous acid by adding hydrazine hydrochloride to chloroplatinic acid, the chloride ion content is significantly reduced and controllable, which can greatly reduce the chlorine element in the product. At the same time, there is no need to add potassium chloride, thereby avoiding the introduction of potassium ions;

[0022] 2) The preparation method of dinitrosodiammineplatinum provided by the present invention uses urea as an NH3 ligand source. As heating gradually decomposes NH3 to participate in the reaction, the introduction of concentrated ammonia with a strong pungent odor is avoided, making the production environment more friendly. At the same time, excess urea can be completely converted into NH3 and CO2 by heating and escape, without introducing impurities.

[0023] 3) The preparation method of dinitrosodiammineplatinum provided by the present invention introduces nitroso groups by directly introducing NOx gas, without the need for alkali metal salts such as sodium nitrite, thus avoiding the introduction of impurities, eliminating the cumbersome washing process, simplifying the process operation, and shortening the production cycle;

[0024] 4) The preparation method of dinitrosodiammineplatinum provided by the present invention can prepare products in steps directly in the same reaction vessel, eliminating the tedious intermediate processing process. The preparation method has the advantages of high product purity, simple production process operation, short production cycle, and environmentally friendly process. It is suitable for mass production. The prepared dinitrosodiammineplatinum product can be used as the main salt for electroplating to easily obtain platinum coatings and platinum electrodes with excellent performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the infrared spectrum of the dinitrosodiammineplatinum product described in Example 1.

[0026] Figure 2 This is the infrared spectrum of dinitrosodiammineplatinum provided by Bio-Rad Laboratories. DETAILED DESCRIPTION

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described below. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention. If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the field or the product instructions shall be followed.

[0028] Example 1

[0029] (1) 1364 g of solid platinum dichloride (73.3% platinum mass fraction) was added in batches to 7700 mL of 1.5 mol / L hydrochloric acid solution and stirred (stirring speed 100 rpm, the same below) until the solid was completely dissolved. After continuing the stirring reaction for 30 min, water was added to adjust the solution volume to 25 L to obtain a chloroplatinous acid solution with a platinum content of 40 g / L.

[0030] (2) Add 1250 g of urea to the solution obtained in step (1) under stirring, raise the temperature to 90° C., and react for 2 h to obtain a tetraamminedichloroplatinum solution.

[0031] (3) The temperature of the solution obtained in step (2) was adjusted to 40° C., NO 2 gas was introduced into the solution at a rate of 1.5 L / min while stirring, and the reaction was carried out for 5 h to obtain a dinitrosodiammineplatinum precipitate.

[0032] (4) The reaction product obtained in step (3) was cooled to room temperature and then filtered. The filter cake was washed with pure water and dried to obtain 1163 g of dinitrosodiammine platinum product.

[0033] Figure 1 This is the infrared spectrum of the dinitrosodiammine platinum product obtained in Example 1. Figure 2 The infrared spectrum of Example 1 is basically consistent with the infrared spectrum of the standard spectrum, so it can be considered that the product is dinitrosodiammineplatinum.

[0034] Example 2

[0035] (1) 1364 g of platinum dichloride solid (platinum mass fraction 73.3%) was added in batches to 3900 mL of 3 mol / L hydrochloric acid solution and stirred until the solid was completely dissolved. After continuing the stirring reaction for 50 min, water was added to adjust the solution volume to 20 L to obtain a chloroplatinous acid solution with a platinum content of 50 g / L.

[0036] (2) 1540 g of urea was added to the solution obtained in step (1) under stirring, the temperature was raised to 80° C., and the reaction was carried out for 3 h to obtain a tetraamminedichloroplatinum solution.

[0037] (3) The temperature of the solution obtained in step (2) was adjusted to 50° C., and a mixed gas of NO and NO2 was introduced into the solution at a rate of 1.2 L / min under stirring, and the mixture was reacted for 7 h to obtain a dinitrosodiammineplatinum precipitate.

[0038] (4) The reaction product obtained in step (3) was cooled to room temperature and then filtered. The filter cake was washed with pure water and dried to obtain 1174 g of dinitrosodiammine platinum product.

[0039] Example 3

[0040] (1) 1364 g of platinum dichloride solid (73.3% platinum mass fraction) was added in batches to 2600 mL of 4.5 mol / L hydrochloric acid solution and stirred until the solid was completely dissolved. After continuing the stirring reaction for 60 min, water was added to adjust the solution volume to 10 L to obtain a chloroplatinous acid solution with a platinum content of 100 g / L.

[0041] (2) 1840 g of urea was added to the solution obtained in step (1) under stirring, the temperature was raised to 100° C., and the mixture was reacted for 2 h to obtain a tetraamminedichloroplatinum solution.

[0042] (3) The temperature of the solution obtained in step (2) was adjusted to 70° C., and a mixed gas of NO and NO2 was introduced into the solution at a rate of 2.0 L / min under stirring, and the mixture was reacted for 4 h to obtain a dinitrosodiammineplatinum precipitate.

[0043] (4) The reaction product obtained in step (3) was cooled to room temperature and then filtered, the filter cake was washed with pure water, and dried to obtain 1170 g of dinitrosodiammine platinum product.

[0044] Comparative Example 1

[0045] The difference between the comparative example and Example 1 is that step (1) in Example 1 is changed to: 527 g of hydrazine hydrochloride is prepared into a 35% mass fraction solution for standby use, 2100 g of commercially available chloroplatinic acid is added to 10 L of water to prepare a solution, the oil bath is heated to 50° C., the pre-prepared hydrazine hydrochloride solution is slowly added, and after the addition is complete, stirring is continued until a scarlet chloroplatinous acid solution is generated, and the volume of the solution is adjusted to 25 L.

[0046] Comparative Example 2

[0047] The only difference between the comparative example and Example 1 is that step (3) in Example 1 is changed to: adjusting the temperature of the solution obtained in step (2) to 85° C., slowly adding a 20% by mass sodium nitrite aqueous solution (containing 1061 g of sodium nitrite), and reacting for 2 h to obtain a dinitrosodiammineplatinum precipitate.

[0048] Performance Tests of Examples and Comparative Examples

[0049] The samples obtained in the Examples and Comparative Examples were measured for chlorine content using an ion chromatograph (Thermo Fisher Scientific, Model ICS-5000+). The alkali metal (K, Na) impurity content was measured using an inductively coupled plasma spectrometer (ICP, Agilent 5110).

[0050] The results are shown in Table 1 below:

[0051] Table 1

[0052]

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing dinitrosodiammine platinum, characterized in that: The following steps are involved: 1) Platinum dichloride is dissolved in dilute hydrochloric acid, and after a period of reaction, water is added to adjust the concentration of platinum ions to 20 g / L to 100 g / L to obtain a chloroplatinous acid solution; 2) adding urea to the chloroplatinous acid solution under stirring, and heating the reaction for a period of time to obtain a tetraamminedichloroplatinum solution; 3) introducing NOx gas into the tetraamminedichloroplatinum solution under stirring to react and generate a dinitrosodiammineplatinum precipitate; 4) The reaction product obtained in step 3) is cooled to room temperature and then filtered, the filter cake is washed with pure water, and dried to obtain the product.

2. The method for preparing dinitrosodiammine platinum according to claim 1, wherein In step 1), the molar concentration of HCl in the dilute hydrochloric acid is 1.5 to 4.5 mol / L; And / or, in step 1), the molar number of HCl in the dilute hydrochloric acid is 2.1 to 2.5 times the molar number of platinum element in platinum dichloride.

3. The method for preparing dinitrosodiammine platinum according to claim 1 or 2, wherein: In step 1), the reaction time is 15 to 60 minutes.

4. The method for preparing dinitrosodiammine platinum according to claim 1 or 2, wherein: In step 2), the molar number of urea added is 4 to 6 times the molar number of platinum element in platinum dichloride.

5. The method for preparing dinitrosodiammine platinum according to claim 1 or 2, wherein: In step 2), the reaction time is 1 h to 4 h, and the reaction temperature is 80 to 100°C.

6. The method for preparing dinitrosodiammine platinum according to claim 1 or 2, wherein: In step 3), the NOx gas is NO, NO2 or a mixture of NO and NO2.

7. The method for preparing dinitrosodiammine platinum according to claim 1 or 2, wherein: In step 3), NOx gas is introduced into the tetraamminedichloroplatinum solution at a gas flow rate of 1.2 L / min to 2.0 L / min.

8. The method for preparing dinitrosodiammine platinum according to claim 1 or 2, wherein: In step 3), the reaction temperature is 30° C. to 80° C., and the reaction time is 4 h to 8 h.

Images