Method for recovering platinum from waste membrane electrode and preparing dinitroso diammineplatinum

Abstract

The invention belongs to the technical field of resource recovery and precious metal compound preparation, and relates to a method for recovering platinum from a waste membrane electrode and preparing dinitroso diammineplatinum. According to the method, a carbon material in the waste membrane electrode is decomposed through high-temperature treatment, platinum is enriched in ash, and the recovery rate of platinum is increased; then hydrogen peroxide and hydrochloric acid are used for dissolving ash, the dissolving process is mild in condition and high in safety, toxic gas containing nitric oxide is not released in the whole process, and the environmental protection property of platinum recovery is remarkably improved; subsequently, the ammonium chloroplatinate is directly subjected to deep processing to synthesize the dinitroso diammineplatinum with high added value, so that the tedious steps of roasting the ammonium chloroplatinate to recover platinum elementary substance and then processing the platinum elementary substance into a product are avoided, and the time and the cost are effectively saved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of resource recycling and noble metal compound preparation, and particularly relates to a method for recovering platinum from waste membrane electrode and preparing dinitrosoplatinum diammine. BACKGROUND

[0002] In the field of new energy, especially in the wide application of hydrogen fuel cells, membrane electrodes are used in large quantities as key components. The membrane electrode is generally composed of a proton exchange membrane, a catalyst layer and a gas diffusion layer, wherein the catalyst layer contains platinum catalyst. In view of the high cost and scarcity of platinum, it is of great economic value and strategic significance to recover platinum from waste membrane electrodes.

[0003] At present, for the recovery of noble metals, traditional methods usually adopt incineration and aqua regia leaching methods, but the recovery rate of platinum is low, about 80% to 92%, and the aqua regia leaching method has problems such as long nitration time, generation of a large amount of nitrogen oxide waste gas, etc.; after aqua regia leaching, ammonium chloroplatinate precipitation is generally used, and platinum is recovered by roasting reduction, and then processed into products, which is complicated. Dinitrosoplatinum diammine [Pt(NH3)2(NO2)2], commonly known as P salt, is the most commonly used platinizing agent in cyanide-free electroplating. The plating layer obtained by using P salt has high hardness and small resistance, and can be soldered, and is commonly used for surface plating of electronic components; the preparation method of P salt is generally as follows: metal platinum is dissolved with aqua regia to prepare chloroplatinic acid, and then reacts with potassium chloride to generate potassium chloroplatinate yellow precipitate; the potassium chloroplatinate precipitate is dissolved into paste with water and heated in oil bath; saturated sodium nitrite solution is added to the paste, and heating is continued to 105℃, and after cooling and filtering, a certain amount of ammonia water is added, and the generated precipitate is filtered and recrystallized to obtain the product.

[0004] Therefore, it is crucial to develop a method for simply, efficiently and environmentally recovering platinum from waste membrane electrodes and preparing high-purity dinitrosoplatinum diammine by linking the process chain between the recovery of noble metal waste and the synthesis of high-end compounds. SUMMARY

[0005] In view of the above technical problems, the application provides a method for recovering platinum from waste membrane electrodes and preparing dinitrosoplatinum diammine. The method does not need to obtain platinum single element, but in the recovery process, high-purity dinitrosoplatinum diammine is prepared by a new process; this process can avoid complicated steps, save energy and is simple and effective.

[0006] The above object of the application is achieved by the following technical scheme.

[0007] A method for recovering platinum from waste membrane electrodes and preparing dinitrosoplatinum diammine, comprising the following steps: S1, crushing the whole waste membrane electrode; S2, the broken waste membrane electrode is placed in a tube furnace for roasting under oxygen atmosphere to obtain ash containing platinum and tail gas; S3, the ash containing platinum of S2 is put into a beaker, hydrochloric acid is added into the beaker, and after heating, hydrogen peroxide is gradually added while keeping the temperature constant, and the dissolution is continued to heat; S4, after the dissolution of S3 is completed, filtration is carried out, and the filtrate is collected; S5, the filtrate of S4 is concentrated to obtain a concentrated platinum solution; at the same time, an ammonium chloride saturated solution is prepared; S6, the concentrated platinum solution is slowly added into the above-mentioned concentrated platinum solution while stirring, and ammonium chloroplatinate yellow precipitate is generated, and the addition of the ammonium chloride solution is continued until no new precipitate is generated, and the aging is carried out for 1 hour, and the filter residue is obtained by filtration; and the filter residue is washed with a dilute ammonium chloride solution to obtain an ammonium chloroplatinate precipitate, and the ammonium chloroplatinate precipitate is vacuum dried; S7, the obtained ammonium chloroplatinate precipitate is added into water to prepare a suspension, sodium nitrite solution is added, and heating and stirring are carried out until the precipitate is dissolved to obtain a dissolved solution; S8, the above-mentioned dissolved solution is cooled, and then ammonia water is added into the solution while stirring to generate dinitrosoplatinous diammine crystal; S9, the dinitrosoplatinous diammine crystal of S8 is filtered and washed with cold water to obtain a solid product, and the solid product is recrystallized to obtain high-purity dinitrosoplatinous diammine.

[0008] Further, in S1, the membrane electrode comprises a catalyst layer, a proton membrane and a gas diffusion layer, and the catalyst layer contains one or more of platinum-cobalt, platinum-nickel, platinum-iron, platinum-copper, platinum-iridium and the like.

[0009] Further, in S2, the roasting temperature is 600-900℃, and the time is 2-6 h.

[0010] Further, in S2, the tail gas is removed by using an alkaline solution to absorb the tail gas to remove harmful substances containing fluorine and the like.

[0011] Further, in S3, the amount of hydrochloric acid added is 20-70 mL / g of platinum.

[0012] Further, in S3, the volume ratio of hydrochloric acid to hydrogen peroxide is 1-3:1.

[0013] Further, in S3, the heating temperature is 70-95℃.

[0014] Further, in S5, the concentration of the concentrated platinum solution is 200-500 g / L.

[0015] Further, in S6, the ammonium chloroplatinate precipitate is vacuum dried at 80℃, weighed, and the platinum recovery rate is calculated.

[0016] Further, in S7, the mass ratio of the ammonium chloroplatinate precipitate to water is 1:1.

[0017] Further, in S7, the mass content of sodium nitrite in the sodium nitrite solution is 30-50%; and the added mass of the sodium nitrite solution is 8-12 times the theoretical mass.

[0018] Further, in S7, the heating temperature is 90-110 DEG C.

[0019] Further, in S8, the mass concentration of the ammonia water is 25%, and the added amount is 0.1-0.4 g / g platinum.

[0020] Compared with the prior art, the method has the following beneficial effects.

[0021] The present application can improve the recovery rate of platinum by decomposing the carbon material in the waste membrane electrode through high-temperature treatment and enriching platinum in the ash; the mild and safe dissolution process of the ash by hydrogen peroxide and hydrochloric acid does not release toxic gases containing nitrogen oxides, significantly improving the environmental friendliness of platinum recovery; subsequently, the ammonium chloroplatinate is directly processed to synthesize high-value-added dinitrosoplatinum diammine, avoiding the complicated steps of roasting the ammonium chloroplatinate to recover elemental platinum and then processing it into products, effectively saving time and cost; in addition, the process can effectively remove soluble impurities through S4 filtration and S9 washing and recrystallization to prepare high-purity products. DETAILED DESCRIPTION

[0022] The present application will be further described by specific examples, but the present application is not limited to the following examples. Changes, combinations or substitutions made within the scope of the present application or without departing from the content, spirit and scope of the present application will be apparent to those skilled in the art, and are included within the scope of the present application.

[0023] A method for recovering platinum from waste membrane electrodes to prepare dinitrosoplatinum diammine, comprising the following steps: S1, breaking the whole waste membrane electrode to destroy the structure of the carbon carrier for subsequent processing; S2, placing the broken waste membrane electrode in a tube furnace and roasting it in an oxygen atmosphere, the roasting temperature is 600-900 DEG C, and the time is 2-6 h, so that the carbon material is decomposed to obtain ash containing platinum and tail gas; S3, placing the platinum-containing ash of S2 in a beaker and adding hydrochloric acid to the beaker, the added amount of hydrochloric acid is 20-70 mL / g platinum; after heating, gradually add hydrogen peroxide, the volume ratio of hydrochloric acid to hydrogen peroxide is 1-3:1, keep the temperature constant, continue to heat and dissolve; the heating temperature is 70-95 DEG C; S4, after the completion of dissolving S3 and S2, filter to remove insoluble residues and collect the filtrate; S5, concentrate the filtrate of S4 to obtain a concentrated platinum solution, the concentration of the concentrated platinum solution is 200-500 g / L; at the same time, prepare a saturated ammonium chloride solution; S6, slowly add the saturated ammonium chloride solution to the above-mentioned concentrated platinum solution while stirring, produce an ammonium chloroplatinate yellow precipitate, continue to add the ammonium chloride solution until no new precipitate is generated, age for 1 hour, filter to obtain a filter residue; wash the filter residue with a dilute ammonium chloride solution to remove soluble impurities, obtain an ammonium chloroplatinate precipitate, and vacuum dry the ammonium chloroplatinate precipitate at 80°C, weigh, and calculate the platinum recovery rate; S7, add the above-mentioned ammonium chloroplatinate precipitate to water to prepare a suspension, the mass ratio of the ammonium chloroplatinate precipitate to water is 1:1; add a sodium nitrite solution, heat to 90-110°C and stir to react until the precipitate dissolves, obtain a dissolved solution; the mass content of sodium nitrite in the sodium nitrite solution is 30-50%; the added mass of the sodium nitrite solution is 8-12 times the theoretical mass; S8, cool the above-mentioned dissolved solution, then add ammonia water to the solution while stirring, the mass concentration of the ammonia water is 25%, the added amount is 0.1-0.4 g / g platinum, generate a dinitrosyl diaminoplatinum crystal; S9, filter the dinitrosyl diaminoplatinum crystal of S8, wash with cold water to obtain a solid product, then recrystallize the solid product to obtain high-purity dinitrosyl diaminoplatinum.

[0024] Further, in S1, the membrane electrode comprises a catalyst layer, a proton membrane, and a gas diffusion layer, the catalyst layer contains one or more of platinum-cobalt, platinum-nickel, platinum-iron, platinum-copper, platinum-iridium, and the like.

[0025] Further, in S2, the tail gas is absorbed by an alkaline solution to remove harmful substances such as fluorine.

[0026] Example 1.

[0027] Take 10 pieces of waste membrane electrodes with an active area of 50 cm 2 , the theoretical total platinum amount of which is 3g.

[0028] First, the waste membrane electrode is crushed using a crusher and then placed in a tube furnace and calcined at 600°C for 5 hours in an oxygen atmosphere to oxidize and remove the carbon carrier, obtaining a platinum-containing ash and tail gas; at the same time, the tail gas generated by calcination is passed into a calcium hydroxide solution to convert the fluorine-containing component into a solid precipitate for environmental protection. Subsequently, the obtained platinum-containing ash is moved into a beaker, 100 mL of 12 mol / L hydrochloric acid is added and heated to 80°C, and then 60 mL of 30% hydrogen peroxide is slowly added, and the solution is kept at this condition for 2 hours. After dissolution, the insoluble material is removed by filtration to obtain a platinum filtrate, and the filtrate is concentrated to about 10 mL. Next, saturated ammonium chloride solution is added to the concentrated solution under stirring until a large amount of yellow ammonium chloroplatinate precipitate is precipitated and no new precipitate is generated, then aged for 1 hour, the precipitate is collected by filtration, and washed with dilute ammonium chloride solution several times to remove soluble impurities, and finally the ammonium chloroplatinate precipitate is dried at 80°C under vacuum. The dried ammonium chloroplatinate is prepared into a suspension, 25 g of 40% sodium nitrite solution is added, and the reaction is stirred in an oil bath at 110°C for 2 hours until the precipitate is completely dissolved. After the reaction solution is cooled to room temperature, 1 mL of ammonia is added dropwise while stirring, and the dinitrosoplatinous diammine crystal is precipitated, and the reaction is fully stirred for 1 hour. The obtained solid is filtered and washed with cold water, and then purified by recrystallization to obtain high-purity dinitrosoplatinous diammine product.

[0029] The final analysis shows that the recovery rate of platinum is 93.5%; the platinum content in dinitrosoplatinous diammine is 59.8%, and the purity is 99.5%.

[0030] Example 2.

[0031] Take 10 pieces of waste membrane electrode with an active area of 50 cm² (the platinum load of anode and cathode is 6 mg / cm²), and the theoretical total platinum amount is 3 g.

[0032] First, the waste membrane electrode is crushed using a crusher and then placed in a tube furnace and calcined at 700°C for 5 hours in an oxygen atmosphere to completely oxidize and remove the carbon carrier to obtain a platinum-containing ash and tail gas; at the same time, the tail gas generated by calcination is passed into a calcium hydroxide solution to convert the fluorine-containing component into a solid precipitate for environmental protection. Subsequently, the obtained platinum-containing ash is moved into a beaker, 100 mL of 12 mol / L hydrochloric acid is added and heated to 80°C, and then 60 mL of 30% hydrogen peroxide is slowly added, and the condition is maintained for 2 hours. After dissolution, the insoluble material is removed by filtration to obtain a platinum filtrate, and the filtrate is concentrated to about 10 mL. Next, under stirring, saturated ammonium chloride solution is added to the concentrated solution until a large amount of yellow ammonium chloroplatinate precipitate is precipitated and no new precipitate is generated, and then aged for 1 hour. The precipitate is collected by filtration and washed with dilute ammonium chloride solution several times to remove soluble impurities, and finally the ammonium chloroplatinate precipitate is dried at 80°C under vacuum. The dried ammonium chloroplatinate is prepared into a suspension, 25 g of 40% sodium nitrite solution is added, and the reaction is stirred in an oil bath at 110°C for 2 hours until the precipitate is completely dissolved. After the reaction solution is cooled to room temperature, 1 mL of ammonia is added dropwise while stirring, and di-nitroso-diammine platinum crystals are precipitated, and the reaction is fully stirred for 1 hour. The obtained solid is filtered and washed with cold water, and then purified by recrystallization to finally obtain high-purity di-nitroso-diammine platinum product.

[0033] The final analysis shows that the recovery rate of platinum is 94.1%; the platinum content in di-nitroso-diammine platinum is 60.01%, and the purity is 99.6%.

[0034] Example 3.

[0035] Take 10 pieces of waste membrane electrode with an active area of 50 cm² (the platinum load of anode and cathode is 6 mg / cm²), and the theoretical total platinum amount is 3 g.

[0036] First, the waste membrane electrode is crushed using a crusher and then placed in a tube furnace and calcined at 700°C for 5 hours in an oxygen atmosphere to completely oxidize and remove the carbon carrier to obtain a platinum-containing ash and tail gas; at the same time, the tail gas generated by calcination is passed into a calcium hydroxide solution to convert the fluorine-containing component into a solid precipitate for environmental protection. Subsequently, the obtained platinum-containing ash is moved into a beaker, 200 mL of 12 mol / L hydrochloric acid is added and heated to 80°C, and then 120 mL of 30% hydrogen peroxide is slowly added, and the condition is maintained for 2 hours. After dissolution, the insoluble material is removed by filtration to obtain a platinum filtrate, and the filtrate is concentrated to about 10 mL. Next, under stirring, saturated ammonium chloride solution is added to the concentrated solution until a large amount of yellow ammonium chloroplatinate precipitate is precipitated and no new precipitate is generated, and then aged for 1 hour. The precipitate is collected by filtration and washed with dilute ammonium chloride solution several times to remove soluble impurities, and finally the ammonium chloroplatinate precipitate is dried at 80°C under vacuum. The dried ammonium chloroplatinate is prepared into a suspension, 25 g of 40% sodium nitrite solution is added, and the reaction is stirred in an oil bath at 110°C for 2 hours until the precipitate is completely dissolved. After the reaction solution is cooled to room temperature, 1 mL of ammonia is added dropwise while stirring, and di-nitroso-diammine platinum crystals are precipitated, and the reaction is fully stirred for 1 hour. The obtained solid is filtered and washed with cold water, and then purified by recrystallization to finally obtain high-purity di-nitroso-diammine platinum product.

[0037] The final analysis shows that the recovery rate of platinum is 94.7%; the platinum content in di-nitroso-diammine platinum is 60.08%, and the purity is 99.8%.

[0038] Example 4.

[0039] Take 10 pieces of waste membrane electrode with an active area of 50 cm² (the platinum load of anode and cathode is 6 mg / cm²), and the theoretical total platinum amount is 3 g.

[0040] First, the waste membrane electrode is crushed using a crusher and then placed in a tube furnace and calcined at 800°C for 3 hours in an oxygen atmosphere to completely oxidize and remove the carbon carrier to obtain a platinum-containing ash and tail gas; at the same time, the tail gas generated by calcination is passed into a calcium hydroxide solution to convert the fluorine-containing component into a solid precipitate for environmental protection. Subsequently, the obtained platinum-containing ash is moved into a beaker, 200 mL of 12 mol / L hydrochloric acid is added and heated to 90°C constant temperature, and then 120 mL of 30% mass fraction hydrogen peroxide is slowly added and dissolved for 2 hours under this condition. After dissolution is completed, the insoluble matter is removed by filtration to obtain a platinum filtrate, and the filtrate is concentrated to about 10 mL. Next, under stirring, saturated ammonium chloride solution is added to the concentrated solution until a large amount of yellow ammonium chloroplatinate precipitate is precipitated and no new precipitate is generated, and then aged for 1 hour. The precipitate is collected by filtration and washed with dilute ammonium chloride solution several times to remove soluble impurities, and finally the ammonium chloroplatinate precipitate is vacuum dried at 80°C. The dried ammonium chloroplatinate is prepared into a suspension, 25 g of 40% sodium nitrite solution is added, and the reaction is stirred in an oil bath at 110°C for 2 hours until the precipitate is completely dissolved. After the reaction solution is cooled to room temperature, 1 mL of ammonia water is added dropwise while stirring, and dinitrosoplatinous diammine crystals are precipitated, and the reaction is fully stirred for 2 hours. The obtained solid is filtered and washed with cold water, and then purified by recrystallization to finally obtain high-purity dinitrosoplatinous diammine product.

[0041] The final analysis shows that the recovery rate of platinum is 95.1%; the platinum content in dinitrosoplatinous diammine is 60.5%, and the purity is 99.9%.

[0042] Example 5.

[0043] Take 20 pieces of waste membrane electrode (anode and cathode platinum loadings are both 6 mg / cm²) with an active area of 50 cm², and the theoretical total platinum amount is calculated to be 6 g.

[0044] First, the waste membrane electrode is crushed using a crusher and then placed in a tube furnace and calcined at 800°C for 3 hours in an oxygen atmosphere to completely oxidize and remove the carbon carrier to obtain a platinum-containing ash and tail gas; at the same time, the tail gas generated by calcination is passed into a calcium hydroxide solution to convert the fluorine-containing component into a solid precipitate for environmental protection treatment. Subsequently, the obtained platinum-containing ash is moved into a beaker, 400 mL of 12 mol / L hydrochloric acid is added and heated to 90°C, and then 240 mL of 30% hydrogen peroxide is slowly added, and the solution is kept for 2 hours. After dissolution, the insoluble material is removed by filtration to obtain a platinum filtrate, and the filtrate is concentrated to about 20 mL. Next, saturated ammonium chloride solution is added to the concentrated solution under stirring until a large amount of yellow ammonium chloroplatinate precipitate is precipitated and no new precipitate is generated, and then aged for 1 hour. The precipitate is collected by filtration and washed with dilute ammonium chloride solution several times to remove soluble impurities, and finally the ammonium chloroplatinate precipitate is dried at 80°C under vacuum. The dried ammonium chloroplatinate is prepared into a suspension, 50 g of 40% sodium nitrite solution is added, and the reaction is stirred in an oil bath at 110°C for 2 hours until the precipitate is completely dissolved. After the reaction solution is cooled to room temperature, 2 mL of ammonia is added dropwise while stirring, and the dinitrosoplatinous diammine crystals are precipitated, and the reaction is fully stirred for 2 hours. The obtained solid is filtered and washed with cold water, and then purified by recrystallization to finally obtain high-purity dinitrosoplatinous diammine product.

[0045] The final analysis shows that the recovery rate of platinum is 95.2%; the platinum content in dinitrosoplatinous diammine is 60.4%, and the purity is 99.9%.

[0046] Example 6.

[0047] Take 20 pieces of waste membrane electrode with an active area of 50 cm² (the platinum load of anode and cathode is 6 mg / cm²), and the theoretical total platinum amount is calculated to be 6 g.

[0048] First, the waste membrane electrode was crushed using a crusher and then placed in a tube furnace and calcined at 800°C for 3 hours in an oxygen atmosphere to completely oxidize and remove the carbon carrier to obtain a platinum-containing ash and tail gas; at the same time, the tail gas produced by calcination was passed into a calcium hydroxide solution to convert the fluorine-containing components into solid precipitates for environmental protection. Subsequently, the obtained platinum-containing ash was moved into a beaker, 400 mL of 12 mol / L hydrochloric acid was added and heated to 90°C constant temperature, and then 240 mL of 30% mass fraction hydrogen peroxide was slowly added and kept for 2 hours. After dissolution, the insoluble material was removed by filtration to obtain a platinum filtrate, and the filtrate was concentrated to about 20 mL. Next, saturated ammonium chloride solution was added to the concentrated solution under stirring until a large amount of yellow ammonium chloroplatinate precipitate was precipitated and no new precipitate was generated, and then aged for 1 hour. The precipitate was collected by filtration and washed with dilute ammonium chloride solution several times to remove soluble impurities, and finally the ammonium chloroplatinate precipitate was vacuum dried at 80°C. The ammonium chloroplatinate was prepared into a suspension, 60 g of 40% sodium nitrite solution was added, and the reaction was stirred in an oil bath at 110°C for 2 hours until the precipitate was completely dissolved. After the reaction solution was cooled to room temperature, 2.5 mL of ammonia was added dropwise while stirring to precipitate dinitrosoplatinous diammine crystals, and the reaction was fully stirred for 2 hours. The obtained solid was filtered and washed with cold water, and then purified by recrystallization to finally obtain high-purity dinitrosoplatinous diammine product.

[0049] The final analysis showed that the recovery rate of platinum was 94.9%, the platinum content in dinitrosoplatinous diammine was 60.8%, and the purity was 99.9%.

Claims

1. A process for the recovery of platinum from spent membrane electrodes for the preparation of platinum dinitrosodiiminate, characterized in that, The method comprises the following steps: S1, crushing the whole piece of waste film electrode; S2, placing the crushed waste film electrode in a tube furnace and roasting it in an oxygen atmosphere to obtain a platinum-containing ash and tail gas; S3, placing the platinum-containing ash of S2 into a beaker, adding hydrochloric acid into the beaker, heating it, gradually adding hydrogen peroxide, keeping the temperature constant, and continuing to heat and dissolve; S4, after the dissolution of S3 is completed, filtering and collecting the filtrate; S5, concentrating the filtrate of S4 to obtain a concentrated platinum solution; at the same time, preparing a saturated ammonium chloride solution; S6, slowly adding the saturated ammonium chloride solution into the above concentrated platinum solution while stirring, generating an ammonium chloroplatinate yellow precipitate, continuing to add the ammonium chloride solution until no new precipitate is generated, aging for 1 hour, filtering to obtain a filter residue; and washing the filter residue with a dilute ammonium chloride solution to obtain an ammonium chloroplatinate precipitate, which is vacuum dried; S7, adding the obtained ammonium chloroplatinate precipitate into water to prepare a suspension, adding a sodium nitrite solution, heating and stirring to react until the precipitate is dissolved, to obtain a dissolved solution; S8, cooling the above dissolved solution, then adding ammonia water into the solution while stirring to generate a dinitrosoplatinum diamin complex crystal; S9, filtering the dinitrosoplatinum diamin complex crystal of S8 and washing it with cold water to obtain a solid product, and then recrystallizing the solid product to obtain high-purity dinitrosoplatinum diamin complex.

2. The process of claim 1, wherein the platinum is recovered from the scrap membrane electrode to produce platinum bis-nitrosodiaminoplatinum. In S2, the roasting temperature is 600-900℃, and the time is 2-6 h.

3. The process of claim 1, wherein the platinum is recovered from the scrap membrane electrode to produce platinum bis-nitrosodiaminoplatinum. In S2, the tail gas is removed by using an alkaline solution to absorb the tail gas to remove harmful substances such as fluorine.

4. The process of claim 1, wherein the platinum is recovered from the scrap membrane electrode to produce platinum bis-nitrosodiaminoplatinum. In S3, the amount of hydrochloric acid added is 20-70 mL / g of platinum; the volume ratio of hydrochloric acid to hydrogen peroxide is 1-3:1; and the heating temperature is 70-95℃.

5. The process as claimed in claim 1, wherein the process for recovery of platinum from scrap membrane electrode for the preparation of platinum dinitrosopentammine. In S5, the concentration of the concentrated platinum solution is 200-500 g / L.

6. The process as claimed in claim 1, wherein the process for recovery of platinum from scrap membrane electrode for the preparation of platinum dinitrosopentammine. In S6, the ammonium chloroplatinate precipitate is vacuum dried at 80℃, weighed, and the platinum recovery rate is calculated.

7. The process as claimed in claim 1, wherein the process for recovery of platinum from scrap membrane electrode for the preparation of platinum dinitrosopentammine. In S7, the mass ratio of the ammonium chloroplatinate precipitate to water is 1:

1.

8. The process as claimed in claim 1, wherein the process for recovery of platinum from scrap membrane electrode for the preparation of platinum dinitrosopentammine chloride is characterized by, In S7, the mass content of sodium nitrite in the sodium nitrite solution is 30-50%; and the added mass of the sodium nitrite solution is 8-12 times the theoretical mass.

9. The process of claim 1, wherein the platinum is recovered from the scrap membrane electrode to produce platinum bis-nitrosodiaminoplatinum. In S7, the heating temperature is 90-110℃.

10. The process of claim 1, wherein the platinum is recovered from the scrap membrane electrode to produce platinum bis-nitrosodiaminoplatinum. In S8, the mass concentration of ammonia water is 25%, and the added amount is 0.1-0.4 g / g of platinum.