Modifications and Improvements to the Collector Metal Method Using an mhd Pump for Recovering Platinum from Used Car Catalysts

Modelling of the Flow in the Process of Washing Out Automotive Catalyst Carriers with the PbLi Alloy

The process of platinum recovery from used car catalysts is highly desirable for both economic and environmental reasons. From the many available methods of processing used car catalysts, the article conducted both numerical and experimental studies using a device based on the collector metal method with lead as a modified medium through a magnetohydrodynamic pump for washing platinum from the channels of the ceramic catalyst carrier. It was assumed that lead alloys with the addition of lithium increase the extraction of platinum from thin catalytic layers and accelerate the platinum dissolution reaction in the Pb-Li alloy, which is the result of a greater affinity of lithium for platinum compared to lead. This assumption was verified by numerical simulations as well as laboratory tests. Tests were carried out for the secondary supply voltage range between 40 and 60 V and the catalyst flushing time between 240 and 480 s. Graphical results of the research were discussed.

Liquid- and Solid-based Separations Employing Ionic Liquids for the Recovery of Platinum Group Metals Typically Encountered in Catalytic Converters: A Review

The wide application range and ascending demand for platinum group metals combined with the progressive depletion of their natural resources renders their efficient recycling a very important and pressing matter. Primarily environmental considerations associated with state-of-the-art recovery processes have shifted the focus of the scientific community toward the investigation of alternative recycling approaches. Within this context, ionic liquids have gained considerable attention in the last two decades chiefly sparked by properties such as tunabilty, low-volatility, and relatively easy recyclability. In this review an understanding of the state-of-the-art processes, including their drawbacks and limitations, is provided. The core of the discussion is focused on platinum group metal recovery with ionic liquid-based systems. A brief insight in some environmental considerations related to ionic liquids is also provided while some discussion on research gaps, common misconceptions related to ionic liquids and outlook on unresolved issues could not be absent from this review.

First of Its Kind Automotive Catalyst Prepared by Recycled PGMs-Catalytic Performance

The production of new automotive catalytic converters requires the increase of the quantity of Platinum Group Metals in order to deal with the strict emission standards that are imposed for vehicles. The use of PGMs coming from the recycling of spent autocatalysts could greatly reduce the cost of catalyst production for the automotive industry. This paper presents the synthesis of novel automotive Three-Way Catalysts (PLTWC, Pd/Rh = 55/5, 60 gPGMs/ft3) and diesel oxidation catalysts (PLDOC, Pt/Pd = 3/1, 110 gPGMs/ft3) from recovered PGMs, without further refinement steps. The catalysts were characterized and evaluated in terms of activity in comparison with benchmark catalysts produced using commercial metal precursors. The small-scale catalytic monoliths were successfully synthesized as evidenced by the characterization of the samples with XRF analysis, optical microscopy, and N2 physisorption. Hydrothermal ageing of the catalysts was performed and led to a significant decrease of the specific surface area of all catalysts (recycled and benchmarks) due to sintering of the support material and metal particles. The TWCs were studied for their activity in CO and unburned hydrocarbon oxidation reactions under a slightly lean environment of the gas mixture (λ > 1) as well as for their ability to reduce NOx under a slightly rich gas mixture (λ < 1). Recycled TWC fresh catalyst presented the best performance amongst the catalysts studied for the abatement of all pollutant gases, and they also showed the highest Oxygen Storage Capacity value. Moreover, comparing the aged samples, the catalyst produced from recycled PGMs presented higher activity than the one synthesized with the use of commercial PGM metal precursors. The results obtained for the DOC catalysts showed that the aged PLDOC catalyst outperformed both the fresh catalyst and the aged DOC catalyst prepared with the use of commercial metal precursors for the oxidation of CO, hydrocarbons, and NO. The latter reveals the effect of the presence of several impurities in the recovered PGMs solutions.

Status of Recovery of Strategic Metals from Spent Secondary Products

The need to drive towards sustainable metal resource recovery from end-of-cycle products cannot be overstated. This review attempts to investigate progress in the development of recycling strategies for the recovery of strategic metals, such as precious metals and base metals, from catalytic converters, e-waste, and batteries. Several methods for the recovery of metal resources have been explored for these waste streams, such as pyrometallurgy, hydrometallurgy, and biohydrometallurgy. The results are discussed, and the efficiency of the processes and the chemistry involved are detailed. The conversion of metal waste to high-value nanomaterials is also presented. Process flow diagrams are also presented, where possible, to represent simplified process steps. Despite concerns about environmental effects from processing the metal waste streams, the gains for driving towards a circular economy of these waste streams are enormous. Therefore, the development of greener processes is recommended. In addition, countries need to manage their metal waste streams appropriately and ensure that this becomes part of the formal economic activity and, therefore, becomes regulated.

Performance Parameters of Inductively Coupled Plasma Optical Emission Spectrometry and Graphite Furnace Atomic Absorption Spectrometry Techniques for Pd and Pt Determination in Automotive Catalysts

Palladium (Pd) and platinum (Pt) are extensively used as catalysts in the petrochemical and automotive industries, and due to high demand for them on the market, their recycling from spent supported catalysts is clearly needed. To assess the content of Pd and Pt in catalysts in order to establish their commercial value or to evaluate the recovery efficiency of technologies used for recycling, reliable analytical methods for determination of these elements are required. Spectrometric methods, such as inductively coupled plasma optical emission spectrometry (ICP-OES) and graphite furnace atomic absorption spectrometry (GFAAS) are powerful tools that can be employed for the determination of Pd and Pt in various sample matrices. However, these methods allow only the injection of liquid samples. In this regard, the digestion of solid sample by microwave-assisted acid extraction procedures at high pressures and temperatures is often used. In this study, a microwave acid digestion method was optimized for the extraction of Pd and Pt from spent catalysts, using a four-step program, at a maximum 200 °C. The resulting solutions were analyzed using ICP-OES, at two different wavelengths for each metal (Pd at 340.458 and 363.470 nm, and Pt at 265.945 and 214.423 nm, respectively) and using GFAAS (Pd at 247.64 nm, Pt at 265.94 nm). Five types of spent catalyst were analyzed and the standard deviations of repeatability for five parallel samples were less than predicted relative standard deviations (PRSD%) calculated using Horvitz's equation for all the analyzed samples.