Fast microwave leaching of platinum, rhodium and cerium from spent non-milled autocatalyst monolith

摘要: Abstract This work presents a new microwave leaching approach to solubilize platinum group metals (PGMs) and cerium from spent autocatalyst monoliths. In the proposed process, catalyst does not require be milled/pulverized prior step in 6 M HCl for 3 min absence of an oxidation agent internal mixing. Therefore, processing costs associated comminution could avoided. The highest extraction yields were achieved at 220°C liquid solid ratio 10 (Pt: 99±4%, Rh: 95±1%, Ce: 104±3%). At this temperature, composition situ generated headspace gas, including Cl2 gas that acts as oxidant, enhanced porosity cordierite, improved PGM Ce leaching. Furthermore, blocks preserved their honeycomb structure after leaching, simplifying downstream solid-liquid separation, e.g. using gravity filtration. SEM/EDX analyses residues’ cross-sections allowed identifying dissolution mechanism washcoating (150-220°C). Whereas, under same conditions ball-milled material gave significantly lower (Pt:47±4%, 48.6±0.3%) greener 1 HCl + 3.8 NaCl, higher selectivity towards PGMs, although overall decreased 68±2%, 67±5%, 39±1%). Statement Novelty Significance: novel Pt, Rh ceramic via fast process (3 min) solution 220°C, without need (i) milling pretreatment, (ii) oxidizing/reducing agent, nor (iii) energy consumption, cost chemicals complexity are reduced comparison previously described assisted routes, which might benefit its upscaling. Additionally, metal leachability was high (99±4% 95±1% Rh, 104±3% Ce), separation facilitated.