CN-117431408-B - Method for recycling Pt and Ir from waste electrolytic water film electrode

CN117431408BCN 117431408 BCN117431408 BCN 117431408BCN-117431408-B

Abstract

The invention provides a method for recovering Pt and Ir from a waste electrolytic water film electrode, which comprises the following steps of S1, dissolving and separating platinum and iridium, namely, adding the waste electrolytic water film electrode into an organic solvent, soaking and separating to obtain catalyst mixed slag, adding the catalyst mixed slag into a first medicament, roasting at high temperature to obtain noble metal slag, adding the noble metal slag into hydrochloric acid, dissolving and filtering to obtain mixed slag, adding the mixed slag into a dissolving agent, dissolving and filtering to obtain chloroplatinic acid and iridium slag, and then reducing and purifying the chloroplatinic acid to obtain platinum compounds or platinum black, S2, separating iridium, namely, adding the iridium slag into a second medicament, oxidizing and dissolving the iridium slag into chloroiridic acid and insoluble slag, adding ammonium chloride into the chloroiridic acid, stirring to precipitate the chloroiridic acid to obtain ammonium chloride, purifying to prepare iridium compounds or iridium black, and dissolving the insoluble slag into aqua for repeated use. According to the invention, hydroxide is added into noble gold slag for roasting, so that mechanical clamping loss is minimum, and melt splashing loss can be prevented during oxidation roasting.

Inventors

TANG TIAN
GUO FUTIAN
JIANG JIA
YUE JUN
YANG JIN
SUN XINYUE
RAO CHAO
LIU YANG
NI BEI

Assignees

无锡威孚环保催化剂有限公司

Dates

Publication Date: 20260505
Application Date: 20231025

Claims (7)

1. A method for recovering Pt and Ir from a waste electrolytic water film electrode is characterized by comprising the following steps: Step S1, dissolving and separating platinum and iridium, namely providing a waste electrolytic water film electrode, wherein the raw material of an anode catalyst layer of the waste electrolytic water film electrode is iridium catalyst, the raw material of a cathode catalyst layer is Pt/C catalyst, a proton exchange membrane is perfluorosulfonic acid proton exchange membrane, adding the waste electrolytic water film electrode into an organic solvent, soaking and separating to obtain catalyst mixed slag, adding the catalyst mixed slag into a first medicament, roasting at high temperature to obtain noble metal slag, adding the noble metal slag into hydrochloric acid, dissolving and filtering to obtain mixed slag, adding the mixed slag into a dissolving agent, dissolving and filtering to obtain chloroplatinic acid and iridium slag, and reducing and purifying chloroplatinic acid to obtain platinum compounds or platinum black; S2, separating iridium, namely slowly adding the iridium slag obtained in the step S1 into a second medicament, heating and stirring to enable the iridium slag to be oxidized and dissolved into chloroiridic acid and insoluble slag, then adding an oxidant into chloroiridic acid for oxidation, adding ammonium chloride, stirring to enable the chloroiridic acid to be precipitated to obtain ammonium chloroiridate, purifying the ammonium chloroiridate to prepare iridium compounds or iridium black, and enabling non-slag to be dissolved and reacted through aqua regia for repeated use; the second reagent in the step S2 is chloroauric acid, the concentration of gold in the chloroauric acid is 200-400 g/L, and the acidity of the chloroauric acid is 7-15 mol/L.
2. The method for recovering Pt and Ir from a waste electrolyte water membrane electrode according to claim 1, wherein the first reagent in the step S1 is selected from one of calcium hydroxide, ferric hydroxide, barium hydroxide and strontium hydroxide, the mass ratio of the first reagent to the catalyst slag is 3-7:1, the high-temperature roasting temperature is 500-800 ℃, and the roasting time is 3-7 h.
3. The method for recovering Pt and Ir from a waste electrolyte membrane electrode according to claim 1, wherein the mass of the hydrochloric acid in the step S1 is 1-4:1, the heating and dissolving time is 2-5h, and the dissolving temperature is 50-80 ℃.
4. The method for recycling Pt and Ir from the waste electrolytic water membrane electrode according to claim 1, wherein the dissolving agent in the step S1 comprises hydrochloric acid and sodium chlorate, and the mass ratio of the mixed slag to the hydrochloric acid to the sodium chlorate is 1:4-6:1-2, and the dissolving time is 2-5 h.
5. The method for recycling Pt and Ir from the waste electrolytic water membrane electrode according to claim 1, wherein the temperature of the oxidation dissolution in the step S2 is 80-130 ℃, the reaction time is 4-8 hours, and the mass ratio of chloroauric acid liquid to iridium powder is 7-13:1.
6. The method for recycling Pt and Ir from the waste electrolytic water membrane electrode according to claim 1, wherein the oxidant in the step S2 is hydrogen peroxide and 63% nitric acid, the mass ratio of the hydrogen peroxide to the 63% nitric acid to the iridium in chloroiridic acid is 2-4:2-4:1, the mass ratio of the iridium in chloroiridic acid to the ammonium chloride is 1:7-15, and the stirring time is 1-6 hours.
7. The method for recovering Pt and Ir from the waste electrolyte water membrane electrode according to claim 1, wherein in the step S2, slag is not slag, the mass ratio of hydrochloric acid to nitric acid to slag is 3-6:1-2:1, the dissolution temperature is 60-80 ℃, and the dissolution reaction time is 4-6 hours.

Description

Method for recycling Pt and Ir from waste electrolytic water film electrode Technical Field The invention relates to the technical field of noble metal catalyst recovery, in particular to a method for recovering Pt and Ir from a waste electrolytic water film electrode. Background Along with the development of new energy technology, hydrogen energy is rapidly developed in the market as a new secondary energy source, the hydrogen production links mainly comprise modes of water hydrogen production, coal hydrogen production, natural gas hydrogen production, biomass hydrogen production, photolysis hydrogen production, thermochemical hydrogen production, industrial byproduct hydrogen and the like, at present, the water splitting hydrogen production is mainly carried out through photocatalytic water splitting and electrolytic water splitting, wherein electrolytic water is superior to photochemistry, researchers reduce potential by improving aspects of electrodes, catalysts, electrolytes and the like, the most studied is to accelerate water splitting by adopting catalysts, and noble metals such as platinum, iridium and the like and compounds thereof are considered as optimal catalysts for hydrogen precipitation reactions (HERs) and OERs. The anode of the catalyst layer of the membrane electrode for producing hydrogen by electrolyzing water mainly comprises an Ir catalyst, and the cathode mainly comprises a Pt/C catalyst, but the Pt/C catalyst and the Ir catalyst gradually fail due to poisoning, caking and other reasons after working for a certain time, and the noble metal resources in China are deficient, so that the noble metal catalyst must be recycled after failure. The recovery process of the hydrogen production membrane electrode by water electrolysis mainly adopts organic solvents such as ethanol and the like to separate the catalyst from the proton exchange membrane to obtain a mixture, the mixture is calcined at high temperature to remove carbon to obtain platinum iridium slag, aqua regia is dissolved and filtered to obtain crude chloroplatinic acid and iridium slag, and finally the chloroplatinic acid and the iridium slag are refined and purified to obtain platinum and iridium final products; the method is characterized in that the method comprises the steps of directly roasting, removing carbon, enriching noble metals, generating a great amount of smoke dust and even open flame, wherein the noble metals flow away along with the smoke, so that the recovery rate of the noble metals is reduced, and the conventional process for dissolving iridium generally adopts a medium-temperature alkali dissolution method and an aqueous solution chemical dissolution method, and the medium-temperature melting method generally adopts a method for dissolving iridium in a high-temperature melting state after sodium peroxide, sodium hydroxide and iridium are mixed in proportion. The sodium peroxide has strong corrosiveness, so that an iron crucible or a nickel crucible or a corundum crucible for containing materials is easy to corrode at high temperature, thereby introducing metal impurities of iron or nickel or aluminum into iridium solution, increasing the purification difficulty of iridium, and the aqueous solution chemical dissolution method is a method for dissolving iridium by adopting hydrochloric acid and chlorine, and has high requirements on the sealing property and corrosion resistance of equipment and high safety risk because the chlorine has strong corrosiveness and extremely toxic property. Disclosure of Invention The invention aims to overcome and supplement the defects in the prior art and provide a method for recycling Pt and Ir from a waste electrolytic water film electrode, wherein the Pt and Ir are simple to purify and have small safety risk. The technical scheme adopted by the invention is as follows: A method for recovering Pt and Ir from a waste electrolytic water film electrode comprises the following steps: Step S1, dissolving and separating platinum and iridium, namely providing a waste electrolytic water film electrode, wherein the raw material of an anode catalyst layer of the waste electrolytic water film electrode is iridium catalyst, the raw material of a cathode catalyst layer is Pt/C catalyst, a proton exchange membrane is perfluorosulfonic acid proton exchange membrane, adding the waste electrolytic water film electrode into an organic solvent, soaking and separating to obtain catalyst mixed slag, adding the catalyst mixed slag into a first medicament, roasting at high temperature to obtain noble metal slag, adding the noble metal slag into hydrochloric acid, dissolving and filtering to obtain mixed slag, adding the mixed slag into a dissolving agent, dissolving and filtering to obtain chloroplatinic acid and iridium slag, and reducing and purifying chloroplatinic acid to obtain platinum compounds or platinum black; And S2, separating iridium, namely slowly adding the iridium slag obtained in