Studies on the Formation of Catalytically Active PGM Nanoparticles from Model Solutions as a Basis for the Recycling of Spent Catalysts

Abstract

The paper presents basic studies on the precipitation of platinum, palladium, rhodium, and ruthenium nanoparticles from model acidic solutions using sodium borohydride, ascorbic acid, and sodium formate as reducing agents and polyvinylpyrrolidone as a stabilizing agent. The size of the obtained PGM particles after precipitation with NaBH4 solution does not exceed 55 nm. NaBH4 is an efficient reducer; the precipitation yields for Pt, Pd, Ru, Rh are 75, 90, 65 and 85%, respectively. By precipitation with ascorbic acid, it is possible to efficiently separate Pt, Rh, and Ru from Pd from the two-component mixtures. The obtained Pt, Pd, and Rh precipitates have the catalytic ability of the catalytic reaction of p-nitrophenol to p-aminophenol. The morphological characteristic of the PGM precipitates was analyzed by AFM, SEM-EDS, and TEM.

Sustainable and Selective Modern Methods of Noble Metal Recycling

“…Sparse examples are exploring a well‐known bio‐based reductant, ascorbic acid to—even though incomplete—separation of Pt, Rh, or Ru from Pd in two‐component aqueous HCl solutions (Figure 3d ). [44] Considering environmental impact, application of UV‐ or visible‐light driven processes also presents a suitable opportunity. [45] Sequential precipitation of Pd and Ru from lanthanide (Nd) containing waste solutions that are a by‐product of spent nuclear fuel reprocessing can be, for example, realized by photoreduction using sacrificial alcohols (Figure 3e ).…”

Sustainable and Selective Modern Methods of Noble Metal Recycling

“…Sparse examples are exploring a well‐known bio‐based reductant, ascorbic acid to—even though incomplete—separation of Pt, Rh, or Ru from Pd in two‐component aqueous HCl solutions (Figure 3d). [44] Considering environmental impact, application of UV‐ or visible‐light driven processes also presents a suitable opportunity [45] . Sequential precipitation of Pd and Ru from lanthanide (Nd) containing waste solutions that are a by‐product of spent nuclear fuel reprocessing can be, for example, realized by photoreduction using sacrificial alcohols (Figure 3e).…”

Precipitation of Pt, Pd, Rh, and Ru Nanoparticles with Non-Precious Metals from Model and Real Multicomponent Solutions

“…Nanoparticles can be pure metals, metal oxides, metals, silicon compounds, ceramic compounds, organic and biological particles, semiconductors, or polymers [ 3 ]. Recently, there have also been many studies on bimetal NPs containing two different metals, e.g., Pt–Cu NPs [ 4 , 5 , 6 ], Pt–Fe NPs [ 7 , 8 ], Pd–Pt NPs [ 9 , 10 ], and Ag–Fe NPs [ 11 ], on metal NPs deposited on supports, e.g., Pt@TiO 2 , Pd@TiO 2 [ 12 ], Pt–Pd@carbon [ 13 ], and Pt–Zn@carbon [ 14 ], or on nanoliquids, e.g., nanoparticles of CuO, Al 2 O 3 , TiO 2 , or Fe 2 O 3 dispersed in water or ethylene glycol [ 3 , 15 , 16 ]. Moreover, atomically monodispersed heterogeneous Pt was proven to be an ideal heterogeneous catalytic material [ 17 ].…”

“…Pt(IV) and Pd(II) can be extracted with Cyphos IL 101 or 104 from acidic solutions obtained after PGM leaching from SAC, and then selectively stripped from the loaded organic phases with 0.1 M thiourea in 0.5 M HCl (for Pd(II)) or 3 M nitric(V) acid (for Pt(IV)). Since the solutions after subsequent steps of the process contain PGMs recovered from SAC in rather small quantities, looking for a way to manage them, we have decided to investigate the leaching and stripping solutions for the precipitation of PGM nanoparticles [ 10 , 12 ].…”

“…The aim of this research is to obtain catalytically active PGM NPs (nanocatalysts) from model and real multicomponent solutions. In our previous studies [ 10 ], catalytically active PGM NPs were precipitated from one- or two-component model solutions containing PGMs. The scientific novelty of this research is the formation of PGM NPs from real acidic solutions, obtained as a result of the hydrometallurgical processing of spent automotive catalysts, carried out by our team [ 30 ].…”