Since the 1990s, platinum, palladium, and rhodium three-way automobile exhaust purification catalysts (Three Way Catalysts, TWCs) have been widely used in the automotive industry. The three-way catalyst is the most important external purification device installed in the automobile exhaust system. It can convert harmful gases such as CO, HC, and NOx emitted from automobile exhaust into harmless carbon dioxide, water, and nitrogen through oxidation and reduction reactions. Purify car exhaust gas.
Currently, there are two methods for recovering valuable elements from waste automobile exhaust catalysts: fire method and wet method. Pyrotechnic technology has the advantages of large processing capacity, strong adaptability, and high recovery rate of valuable metals, while wet technology has the advantages of small investment and quick results, high process flexibility, strong adaptability, low energy consumption, and low pollution. In terms of environmental protection, fire treatment technology is prone to produce air pollutants, while wet treatment produces more wastewater pollutants. In comparison, hydrometallurgical technology plays an important role in precious metal extraction and is more in line with the new environmental management requirements of environmental protection, energy saving, green efficiency, and collaborative recovery of valuable elements in the new era.
Solvent extraction and separation technology mainly uses the difference between the valence state of the central ion of metal complexes and the structural state of the complex to achieve the purpose of extraction and separation. Solvent extraction, as an advanced hydrometallurgical technology, is widely used in the field of platinum group metal scrap recycling. It is mainly divided into extraction agents containing oxygen, sulfur, phosphorus, nitrogen, etc. The difference between the hydration energy and solvation energy of substances is the main factor affecting the extraction effect. With the development of technology, some additives (such as SnCl2, SnBr2, SCN-, I-, Br-, etc.) are generally added to the oxygen-containing extraction agent. Pyridine, etc.) to form compounds with low hydration energy and high solvation energy, thereby improving extraction performance. The study pointed out that the tributyl phosphate (TBP) extractant and 2,4,4-trimethylpentyl-thiophosphate (Cy⁃anex302) additives can increase the recovery rate of platinum (IV) from 10% to 10% in 1 hour through synergistic reaction. Increase to 80%.