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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 &gt, 1) as well as for their ability to reduce NOx under a slightly rich gas mixture (λ &lt, 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.

In the last decades, a worldwide investment in the recovery or substitution of platinum group metals (PGMs) has been financed. PGMs have been classified as critical raw materials (CRMs), thus a circular economy model should be implemented for their effective recovery. PGM recovery from primary ores is expensive, due to low concentrations of their ores (lower than 10 g/tn) and sophisticated processes implicated, while secondary resources have been proven technoeconomically feasible sources for PGM recycling. Secondary resources of PGMs, such as spent automotive catalytic converters, contain considerably higher PGM concentrations than their corresponding ores. It is estimated that spent automotive catalytic converters deliver more than 57% of PGMs’ European supply, being considered a crucial resource for PGM recovery. Novel recovery techniques focus not only on high recovery rates, but also on cost efficiency and environmental protection. From an industrial viewpoint, pyrometallurgy is the dominant recovery technique, hydrometallurgy is secondly chosen and biometallurgy (bioleaching, bioabsorption) is applied for lab-scale recovery -at this moment. In the present review, all major PGM recovery techniques are presented and discussed. Hydrometallurgical processes could gain a foothold in industrial scale recycling, by adopting a direct, sustainable leaching design. Milder leaching conditions, greener solvents and high solid mass leached, are the keys for the hydrometallurgical upscaling.

Background: Energy storage devices utilise platinum group metals (PGMs) for their operation and exhibit an increasing adoption rate as green energy production means. Europe consumes the largest amount of PGMs worldwide (ca. 20% of the global demand), with the EU demand reaching ~71.5 t Pd, 78.7 t Pt in 2019; ~90% and 54% respectively for the production of (electro)catalysts. PGMs prices are on the rise, while these materials exhibit a risk of supply as their production in the EU is insignificant; South Africa and Russia produce approximately 84% of the global supply. Methods: PGMs recycling and reutilisation from End-of-Life products to new ones, can drastically facilitate the reduction of the supply/demand gap. Innovation business planning is needed to commercialise the recovered PGMs, which includes marketing and financial elements utilised from an innovation perspective. Results: SWOT (Strengths-Weaknesses-Opportunities-Threats) analysis is formed alongside a Business Model Canvas to define the Business Model and commercial added value. Conclusion: The Financial Plan illustrates that a PGMs recycling facility can be profitable upon the generated market volume and assists in determining the financial sustainability by calculating the Net Present Value (NPV), Initial Rate of Return (IRR) and the break-even point for an investment made.

PROMETHEUS catalyst, a copper-based polymetallic nano-catalyst has been proven to be suitable for automotive emission control applications. This novel catalyst consists of copper, palladium and rhodium nanoparticles as active phases, impregnated on an inorganic oxide substrate, CeO2/ZrO2 (75%, 25%). The aim of PROMETHEUS catalyst’s development is the substitution of a significant amount (85%) of Platinum Group Metals (PGMs) with copper nanoparticles while, at the same time, presenting high catalytic efficiency with respect to the commercial catalysts. In this work, an extensive investigation of the catalytic activity of full scale PROMETHEUS fresh and aged catalyst deposited on ceramic cordierites is presented and discussed. The catalytic activity was tested on an Synthetic Gas Bench (SGB) towards the oxidation of CO and CH4 and the reduction of NO. The loading of the washcoat was 2 wt% (metal content) on Cu, Pd, Rh with the corresponding metal ratio at 21:7:1. The concentration of the full-scale monolithic catalysts to be 0.032% total PGM loading for meeting Euro III standard and 0.089% for meeting Euro IV to Euro VIb standards. The catalytic activity of all catalysts was tested both in rich-burn (λ = 0.99) and lean-burn conditions (λ = 1.03).

According to the strict European exhaust emissions standards that have been imposed by European legislation there is an elevated need for the decrease of the toxic gas emissions from vehicles. Therefore, car manufacturers have implemented a series of catalytic devices in the aftertreatment of the engine to comply with the standards. All catalytic devices (such as three-way catalysts, diesel particulate filters and diesel oxidation catalysts) accumulate concentrated loading of platinum group metals (PGMs, platinum, palladium, rhodium) as the active catalytic phase. Thus, the demand for PGMs is constantly increasing with a subsequent increase in their market prices. As a result, the research on catalytic converters of high activity and reduced cost/PGM loading is of great interest. In the present work, the Prometheus catalyst, a polymetallic nanosized copper-based catalyst for automotive emission control applications, is presented in two different metal loadings (2 wt% and 5 wt%) and metal ratios (Cu/Pd/Rh = 21/7/1 and Cu/Pd/Rh = 21/7/3). For the first time, a three-metal (copper, palladium, rhodium) nano-catalyst has been synthesized and characterized on a large scale. By using copper as an active catalytic phase, a reduction of PGMs loading is achieved (up to 85%) resulting in a novel catalytic device with similar or improved catalytic performance compared to commercial ones. The Prometheus catalyst is prepared by a wet impregnation method, using as a carrier an inorganic mixed oxide (CeZrO4) exhibiting elevated oxygen storage capacity (OSC). The heterogeneous catalytic powders produced were characterized by both spectroscopic and analytical methods. The metal content and ratio were determined by inductively coupled plasma mass spectrometry (ICP-MS), X-ray fluorescence (XRF) and energy-dispersive X-ray spectroscopy (EDS). The morphology and the catalyst particle size were determined with scanning electron microscopy (SEM) and X-ray diffraction (XRD). The investigation revealed homogeneous particle formation and dispersion. The deposition of the metal nanoparticles on the porous inorganic carrier was verified with N2 sorption. Catalytic performance and reactivity of a catalyst (pure wash coat) with molar ratio 21/7/1 and a full-scale Prometheus catalyst with the desired loading of 15 g/ft3 were tested on an in-house synthetic gas bench (SGB) for the abatement of CO, CH4 and NO, both presenting high catalytic activity.

PLATInum group metals Recovery Using Secondary raw materials (PLATIRUS), a European Union (EU) Horizon 2020 project, aims to address the platinum group metal (pgm) supply security within Europe by developing novel and greener pgm recycling processes for autocatalysts, mining and electronic wastes. The initial focus was on laboratory-scale research into ionometallurgical leaching, microwave assisted leaching, solvometallurgical leaching, liquid separation, solid phase separation, electrodeposition, electrochemical process: gas-diffusion electrocrystallisation and selective chlorination. These technologies were evaluated against key performance indicators (KPIs) including recovery, environmental impact and process compatibility; with the highest scoring technologies combining to give the selected PLATIRUS flowsheet comprising microwave assisted leaching, non-conventional liquid-liquid extraction and gas-diffusion electrocrystallisation. Operating in cascade, the PLATIRUS flowsheet processed ~1.3 kg of spent milled autocatalyst and produced 1.2 g palladium, 0.8 g platinum and 0.1 g rhodium in nitrate form with a 92‐99% purity. The overall recoveries from feedstock to product were calculated as 46 ± 10%, 32 ± 8% and 27 ± 3% for palladium, platinum and rhodium respectively. The recycled pgm has been manufactured into autocatalysts for validation by end users. This paper aims to be a project overview, an in‐depth technical analysis into each technology is not included. It summarises the most promising technologies explored, the technology evaluation, operation of the selected technologies in cascade, the planned recycled pgm end user validation and the next steps required to ready the technologies for implementation and to further validate their potential. PLATIRUS project has received funding from the European Union’s Horizon 2020 Research and Innovation programme under Grant Agreement n° 730224.

In this work, tubular γ-alumina ultrafiltration membranes have been modified with a sodium alginate/α-alumina suspension based on a modified polyol process in order to be used as forced flow membrane reactors. A C/Cu nanocomposite layer containing Cu nanoparticles of small and uniform size (ca. 14 nm) was deposited and stabilized on the external and internal surface of the membrane. The structural, morphological and gas permeance properties of the obtained catalytic membranes have been studied and their DeNO x performance has been evaluated in flow through mode of operation. NO catalytic abatement evaluation in flow through dead-end mode with 1% NO in N 2 fed from shell to lumen showed high efficiency even at low temperatures and reached 75% at 400 °C. Steady state NO conversion efficiency reached about 30% at 400 °C and heat treatment in He atmosphere at 440 °C revealed the role of NO sorption onto the carbon dressing.

The behavior of platinum group metals (PGMs) during their recovery with smelting of spent automotive ceramic catalysts powder in the presence of metallic copper at elevated temperatures is studied in this paper. Two different metal recovery mechanisms proved to be active in this process: 1) Wetting of micro-dispersed particulates of PGMs in the slag by molten copper, formation of copper droplets with attracted microparticles of PGMs and settling of the molten droplets of Cu-PGMs alloy through the slag at the bottom of the crucible (“wetting”); 2) Settling of solid PGMs microparticles through the molten slag and formation of a solid solution with the molten copper at the bottom of the crucible (“settling”). The PGMs are divided in two separate groups. Platinum has under the same experimental conditions substantially higher recovery in comparison with the palladium and rhodium that behave as a group having almost identical recoveries. The heavier Pt is recovered primarily in big extent (almost 88%) through the “settling” mechanism while Pd and Rh are recovered following a more balanced mixture of both mechanisms with the “settling” one to be again more important (66% for Pd and 57% for Rh). Slag viscosity is the most important physical property and the design of an appropriate slag system is the most important issue in developing an efficient process for the recovery of PGMs.

The real life experimental protocol for the preparation of spent automobile catalyst samples for elemental analysis is thoroughly described in the following study. Collection, sorting and dismantling, homogenization and sample preparation for X-Ray fluorescence spectroscopy and Atomic Adsorption Spectroscopy combined with Inductive coupled plasma mass spectrometry are discussed in detail for both ceramic and metallic spent catalysts. The concentrations of Platinum Group Metals (PGMs) in spent catalytic converters are presented based on typical consignments of recycled converters (more than 45,000 pieces) from the Greek Market. The conclusions clearly denoted commercial metallic catalytic foil contains higher PGMs loading than ceramic honeycombs. On the other hand, the total PGMs loading in spent ceramic catalytic converters has been found higher than the corresponding value for the metallic ones.

Prediction of phase equilibrium for multicomponent systems containing associating compounds (e.g., water and alcohols) is essential in a number of engineering applications (e.g., environmental technology, gas hydrate inhibition) and at the same time represents one of the most stringent tests for a thermodynamic model. Conventional models (e.g., cubic equations of state and excess Gibbs free energy models) provide rapid and often reliable estimates of phase equilibrium in many cases but extension to multicomponent systems, especially those containing water is often troublesome. On the other hand, novel association equations of state perform considerably better but are slower compared to conventional models. Furthermore, the extension of several of them to cross-associating systems (e.g., water–alcohols) exhibits problems. In this work, the performance of two well-known conventional models (SRK and NRTL) is compared for multicomponent systems to a recently proposed association equation of state both in terms of accuracy of predictions and timing. The proposed model incorporates the Wertheim chemical association theory (employed previously in models such as SAFT) and the SRK equation. The model is applied in this work to multicomponent systems in such a way that the inclusion of the Wertheim theory does not give execution times much higher than conventional models. The model yields very satisfactory predictions of multicomponent equilibria for aqueous (both vapor–liquid and liquid–liquid equilibria) systems containing methanol, gases and hydrocarbons, which are moreover, as will be demonstrated in this work, considerably better compared to SRK and NRTL.

The Cubic Plus Association Equation of State (CPA EoS) is applied to the prediction of Vapor–Liquid Equilibrium (VLE) and Liquid–Liquid Equilibrium (LLE) in ternary associating mixtures containing water, alcohols and alkanes. The appropriate set of combining rules for the cross-association energy and volume parameters of the EoS is identified by evaluating the performance of four such sets in the correlation of VLE and LLE for water/alcohol mixtures. Using only one interaction parameter per binary mixture, in the physical part of the EoS, CPA gives very satisfactory predictions of ternary VLE and LLE.

Using an extensive database of experimental critical properties for heavy compounds, which have been compiled mostly from recent literature sources, it is shown that the ratio Tc: Pc (critical temperature over critical pressure) can be expressed in terms of the van der Waals surface area (Qw), which is readily available for any compound from the group contributions of Bondi (given also in UNIFAC tables). The proposed correlation is based on the hole theory of Kurata and Isida for n-paraffin liquids, which is mathematically equivalent to Flory's theory of polymer solutions. The method is suitable for medium to high molecular weight compounds with unknown critical constants. For example, if only one of the two critical constants is available, then the proposed generalized equation offers a useful rapid procedure for the estimation of the other critical property for use in corresponding states, and other relevant applications where knowledge of the critical properties is required. Furthermore, the Tc: Pc method can be used in many cases for identifying the most suitable among the existing group contribution methods for estimating the critical properties of heavy and complex compounds for which experimental values are, very often, not available.

A recently developed equation of state, which combines the physical term of the classical SRK EoS with the association term based on the perturbation theory of Wertheim, called the Cubic Plus Association Equation of State (CPA EoS) (Kontogeorgis et al. [1]), is applied to liquid-liquid equilibrium (LLE) calculations in alcohol hydrocarbon mixtures. The CPA EoS performs very well in all cases using the conventional van der Waals one-fluid mixing rules in the parameters of the physical term and a temperature-independent interaction parameter. The performance of the CPA EoS is compared to that of the conventional SRK EoS and UNIFAC models, and with another association model, the ESD EoS of Suresh and Elliott [2]. The CPA EoS gives much better results than the two conventional models and results comparable to those obtained with the ESD model.

The recently developed Cubic-Plus-Association Equation of State (CPA EoS) is extended in this study to binary systems containing one associating compound (alcohol) and an inert one (hydrocarbon). CPA combines the Soave-Redlich-Kwong (SRK) equation of state for the physical part with an association term based on perturbation theory. The classical van der Waals one-fluid mixing rules are used for the attractive and co-volume parameters, α and b, while the extension of the association term to mixtures is rigorous and does not require any mixing rules. Excellent correlation of Vapor-Liquid Equilibria (VLE) is obtained using a small value for the interaction parameter (kij) in the attractive term of the physical part of the equation of state even when it is temperature-independent. CPA yileds much better results than SRK and its performance is similar to that of other association models, like the Anderko EoS, and the more complex SAFT and Simplified SAFT EoS.

The properties of single-walled carbon nanotubes and carbon fullerenes in molten alkali carbonates (MACs) were studied as a function of the considered nanomaterial and the ions into the molten salt using classical molecular dynamics simulations. The adsorption and confinement in carbon nanotubes is developed by efficient interaction of carbonate ions in the inner and outer walls of the nanotubes whereas alkali cations do not show a remarkable interaction with the nanomaterial. Analogous solvation mechanisms are inferred for carbon fullerenes with large disruption of the liquid structuring of MAC at high fullerene concentrations. The solvation ability of the studied lithium–sodium–potassium carbonate eutectic mixture for both types of nanomaterials is essential for considering this fluid in the development of composite materials for advanced technological applications., European Union H2020- MSCA-RISE-2016-CO2MPRISE-734873

The properties and structure of relevant interfaces involving molten alkali carbonates are studied using molecular dynamics simulation. Lithium carbonate and the Li/Na/K carbonate eutectic mixture are considered. Gas phases composed of pure CO2 or a model flue gas mixture are analyzed. Similarly, the adsorption of these gas phases on graphene are studied, showing competitive CO2 and N2 adsorption that develops liquid-like layers and damped oscillation behavior for density. The interaction of the studied carbonates with graphene is also characterized by development of adsorption layers through strong graphene–carbonate interactions and the development of hexagonal lattice arrangements, especially for lithium carbonate. The development of molten salts–vacuum interfaces is also considered, analyzing the ionic rearrangement in the interfacial region. The behavior of the selected gas phases on top of molten alkyl carbonate is also studied, showing the preferential adsorption of CO2 molecules when flue gases are considered., European Union’s H2020- MSCA-RISE-2016-CO2MPRISE-734873