Understanding the features of PGMs in spent ternary automobile catalysts for development of cleaner recovery technology

• Published in: Journal of cleaner production Vol. 239; p. 118031
• Main Authors: Wei, Xuan, Liu, Chunwei, Cao, Hongbin, Ning, Pengge, Jin, Wei, Yang, Zhanbing, Wang, Haijuan, Sun, Zhi
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-12-2019
• Subjects: Characterization; Metal recovery; Platinum group metals; Spent ternary automobile catalysts; Characterization; Spent ternary automobile catalysts; Metal recovery; Platinum group metals
• ISSN: 0959-6526; 1879-1786
• DOI: 10.1016/j.jclepro.2019.118031

With the penetration of automobiles, the number of spent automobile catalysts keeps increasing. The spent catalysts contain a significant amount of platinum group metals (PGMs) as active components. Recycling of precious metals from complex mixtures of auto-catalysts, however, is of great difficulty owing to their heterogeneity and complexity. More importantly, the lack of comprehensive characterization of spent catalysts results in an incomplete understanding of their physicochemical properties. This article analyzed the failure mechanisms and the particular structure between precious metals and aluminosilicate carriers in the spent automotive catalysts. The particle size distribution, compositional distribution, morphology, phase and thermal behavior properties of the spent auto-catalysts were investigated with various techniques, including X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS), laser particle size analyzer, and thermogravimetric differential scanning calorimeter analysis (TG-DSC). With a detailed understanding of the characterization results and thermodynamic analyses, the importance and potential obstacles to enable effective PGMs recovery of corresponding physiochemical features can be identified. On this basis, the pretreatment method of mechanochemical activation associated with the hydrochloric acid leaching system were preliminarily explored. The total leaching rate of PGMs reached 93.42%. The leaching rates of Pt, Rh and Pd were 77.2%, 62.1% and 97.4%, respectively.
•The natures of spent catalysts have been obtained by comprehensive characterization.•The distributions of PGMs and carrier phase are crucial to PGMs recycling.•93.42% of PGMs is leached using HCl and H2O2 system.•Some treatment strategies for spent ternary catalysts are discussed and compared.