ABSTRACT
Permanent magnets are fundamental constituents in key sectors such as energy and transport, but also robotics, automatization, medicine, etc. High-performance magnets are based on rare earth elements (RE), included in the European list of critical raw materials list. The volatility of their market increased the research over the past decade to develop RE-free magnets to fill the large performance/cost gap existing between ferrites and RE-based magnets. The improvement of hard ferrites and Mn-Al-C permanent magnets plays into this important technological role in the near future. The possible substitution advantage was widely discussed in the literature considering both magnetic properties and economic aspects. To evaluate further sustainability aspects, the present paper gives a life cycle assessment quantifying the environmental gain resulting from the production of RE-free magnets based on traditional hexaferrite and Mn-Al-C. The analysis quantified an advantage of both magnets that overcomes the 95% in all the considered impact categories (such as climate change, ozone depletion, human toxicity) compared to RE-based technologies. The benefit also includes the health and safety of working time aspects, proving possible reduction of worker risks by 3-12 times. The results represent the fundamentals for the development of green magnets that are able to significantly contribute to an effective sustainable transition.
ABSTRACT
The global trend in restrictions on pollutant emissions requires the use of catalytic converters in the automotive industry. Noble metals belonging to the platinum group metals (PGMs, platinum, palladium, and rhodium) are currently used for autocatalysts. However, recent efforts focus on the development of new catalytic converters that combine high activity and reduced cost, attracting the interest of the automotive industry. Among them, the partial substitution of PGMs by abundant non-PGMs (transition metals such as copper) seems to be a promising alternative. The PROMETHEUS catalyst (PROM100) is a polymetallic nanosized copper-based catalyst for automotives prepared by a wet impregnation method, using as a carrier an inorganic mixed oxide (CeO2-ZrO2) exhibiting elevated oxygen storage capacity. On the other hand, catalyst deactivation or ageing is defined as the process in which the structure and state of the catalyst change, leading to the loss of the catalyst's active sites with a subsequent decrease in the catalyst's performance, significantly affecting the emissions of the catalyst. The main scope of this research is to investigate in detail the effect of ageing on this low-cost, effective catalyst. To that end, a detailed characterization has been performed with a train of methods, such as SEM, Raman, XRD, XRF, BET and XPS, to both ceria-zirconia mixed inorganic oxide support (CZ-fresh and -aged) and to the copper-based catalyst (PROM100-fresh and -aged), revealing the impact of ageing on catalytic efficiency. It was found that ageing affects the Ce-Zr mixed oxide structure by initiating the formation of distinct ZrO2 and CeO2 structures monitored by Raman and XRD. In addition, it crucially affects the morphology of the sample by reducing the surface area by a factor of nearly two orders of magnitude and increasing particle size as indicated by BET and SEM due to sintering. Finally, the Pd concentration was found to be considerably reduced from the material's surface as suggested by XPS data. The above-mentioned alterations observed after ageing increased the light-off temperatures by more than 175 °C, compared to the fresh sample, without affecting the overall efficiency of the catalyst for CO and CH4 oxidation reactions. Metal particle and CeZr carrier sintering, washcoat loss as well as partial metal encapsulation by Cu and/or CeZrO4 are identified as the main causes for the deactivation after hydrothermal ageing.
ABSTRACT
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.
ABSTRACT
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).
ABSTRACT
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.
ABSTRACT
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.
