Platinum and palladium are platinum group metals (PGMs) used in automotive catalysts. Recycling PGMs is necessary because of their low production volumes. Recycling of Pt and Pd, there is a need to develop effective methods for recovering Pt and Pd from metal based automotive catalysts and methods for acid dissolution of Pt and Pd that do not require strong oxidant. Recently, it has been shown that PGMs can be made into complex oxides, which can be dissolved in HCl without oxidant. In this study, we investigated the formation conditions of complex oxides of Pt, Pd and PbO, and their solubility in HCl. As a result, PbPt2O4 was prepared at 873–973 K, Pb2PtO4 at 873–973 K, and PbPdO2 at 773–1073 K. These complex oxides exhibited high solubility in HCl without oxidant. There were differences in solubility in Pt and Pd complex oxides.
BettaharN, ConflantP, AbrahamF, ThomasD.1987. Pb2PtO4, a new platinum–lead oxide with edge-shared PtO6 octahedral chains. J Solid State Chem. 67:85–90. doi:10.1016/0022-4596(87)90342-2.
2.
EzawaN, InoueH, TakadaS, MasudaH.2001. Japan Patent, P3222894.
3.
JacobKT, RajithaG, KaleGM.2009. Thermodynamic properties of Pb2PtO4 and PbPt2O4 and phase equilibria in the system Pb–Pt–O. J Alloys Compd. 481:228–232. doi:10.1016/j.jallcom.2009.03.051.
4.
Johnson Matthey. 2022. PGM market report May 2022. Johnson Matthey, Inc.
5.
KasuyaR, MikiT, MorikawaH, TaiY.2013b. Synthesis of alkali metal platinates and their dissolution behavior in hydrochloric acid. J Ceram Soc Jpn. 121:884–890. doi:10.2109/jcersj2.121.884.
6.
KasuyaR, MikiT, MorikawaH, TaiY.2014a. Synthesis of sodium platinates and their dissolution behaviors in hydrochloric acid: effects of lithium carbonate addition on platinate formation. Int J Miner Process. 128:33–39. doi:10.1016/J.MINPRO.2014.02.005.
7.
KasuyaR, MikiT, MorikawaH, TaiY.2014b. Development of new dissolution process of platinum via double oxides. J Jpn Inst Metals Mater. 78:242–249. doi:10.2320/jinstmet.JA201403.
8.
KasuyaR, MikiT, MorikawaH, TaiY.2015a. Enhanced dissolution of alkali metal platinates in dilute hydrochloric acid by addition of calcium chloride. Miner Eng. 76:135–140. doi:10.1016/j.mineng.2014.10.011.
9.
KasuyaR, MikiT, MorikawaH, TaiY.2015b. Dissolution process of palladium in hydrochloric acid: a route via alkali metal palladates. Metall Mater Trans B. 46:2476–2483. doi:10.1007/s11663-015-0431-x.
10.
KasuyaR, MikiT, TaiY.2013a. Preparation of Li2PtO3 and its dissolution properties in hydrochloric acid. J Ceram Soc Jpn. 121:261–264. doi:10.2109/jcersj2.121.261.
11.
KasuyaR, NomuraK, NaritaH.2020. Solubilization of rhodium in hydrochloric acid using an alkali metal salt method. Metall Mater Trans B. 51:377–385. doi:10.1007/s11663-019-01740-8.
12.
KobayashiY, YamadaS, NagaiT.2019. New dissolution process of iridium to hydrochloric acid. In: AzimiG, KimH, AlamS, OuchiT, NeelamegghamNR, BabaAA, editors. Rare metal technology 2019. The Minerals, Metals & Materials Series. Cham: Springer; p. 197–200. https://doi.org/10.1007/978-3-030-05740-4_19.
13.
LazarevVB, ShaplyginIS.1979. Properties and structure of PbPdO2. Russ J Inorg Chem. 24:493–495.
14.
MommaK, IzumiF.2011. VESTA 3 for three-dimensional visualization of crystal, volumetric and morphology data. J Appl Crystallogr. 44:1272–1276. doi:10.1107/S0021889811038970.
15.
MullerO, RoyR.1971. Synthesis and crystal chemistry of some new complex palladium oxides. In: RaoU, editor. Platinum group metals and compounds. Washington DC: American Chemical Society; p. 28–38. doi:10.1021/ba-1971-0098.ch003.
16.
Nippon PGM Co. Ltd. 1997. Recycling. Recovery of platinum group metals from waste catalysts. Shigen-to-Sozai. 113:1146–1147. doi:10.2473/shigentosozai.113.1146.
17.
ObbadeS, TancretN, AbrahamF, SuardE.2002. Synthesis, electrical properties, and powder neutron crystal structure refinement of Pb1–xBixPt2O4 compounds (0 ≤ x ≤ 0.3). J Solid State Chem. 166:58–66. doi:10.1006/jssc.2002.9559.
18.
OkabeTH.2019. Smelting, refining, and recycling of precious metals. Mater Jpn. 58:557–562. doi:10.2320/materia.58.557.
19.
OtaH, ShimizuH, KohnoM, FukudaK, IshiiH.2013. Development of stainless steel foil with excellent heat resistance used for catalytic system for diesel engines ‘JFE-18-3USR’. Mater Jpn. 52:29–31. doi:10.2320/materia.52.29.
20.
SanekataR, KobayashiY, NagaiT.2023. Synthesis of Ir–CaO complex oxides and their solubilities in hydrochloric acid. J Sustain Metall. 9:240–248. doi:10.1007/s40831-022-00643-4.
21.
SanekataR, TakahashiK, NagaiT.2022. Recycling of platinum group metals by volatile separation. Resour Process. 69:18–20.
22.
ShibataJ, OkudaA.2002. Recycling technology of precious metals. Shigen-to-Sozai. 118:1–8. doi:10.2473/shigentosozai.118.1.
23.
SuzukiT, KasuyaR, NaritaH.2021. Review of recent progress on dissolution of precious metals and speciation of their complexes in aqueous solutions. J Jpn Inst Metals Mater. 85:305–315. doi:10.2320/jinstmet.JA202104.
24.
Yamabe-MitaraiY, ZebinB, MurakamiH, AbeH, MatsumotoT.2011. Effective use of platinum group metals. J Jpn Inst Met. 75:10–20. doi:10.2320/jinstmet.75.10.
