I12-JEEP: Joint Engineering, Environmental and Processing
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Arthur
Fordham
,
Zoran
Milojevic
,
Emily
Giles
,
Wenjia
Du
,
Rhodri E.
Owen
,
Stefan
Michalik
,
Philip A.
Chater
,
Prodip K.
Das
,
Pierrot S.
Attidekou
,
Simon M.
Lambert
,
Phoebe K.
Allan
,
Peter R.
Slater
,
Paul A.
Anderson
,
Rhodri
Jervis
,
Paul R.
Shearing
,
Dan J. I.
Brett
Diamond Proposal Number(s):
[27719]
Open Access
Abstract: The growing demand for electric vehicles (EVs) continues to raise concern for the disposal of lithium-ion batteries reaching their end of life (EoL). The cells inside EVs age differently depending on multiple factors. Yet, following extraction, there are significant challenges with characterizing degradation in cells that have been aged from real-world EV usage. We employed four non-destructive techniques—infrared thermography, ultrasonic mapping, X-ray tomography, and synchrotron X-ray diffraction—to analyze the aging of Nissan Leaf large-format pouch cells that were arranged in different orientations and locations within the pack. The combination of these methods provided complementary insights into cell degradation, with rotated/vertically aligned cells exhibiting distinct aging patterns compared with flat/horizontally aligned cells. These findings offer valuable information for pack design and demonstrate how cost-effective non-destructive techniques can provide practical assessment capabilities comparable to synchrotron studies. This approach enables decision support during EoL, enhancing battery production efficiency and minimizing material waste.
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Nov 2023
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B18-Core EXAFS
I14-Hard X-ray Nanoprobe
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Diamond Proposal Number(s):
[21655, 29037]
Abstract: Air pollutant emission standards and limits were established as a measure to control pollution levels. This has led to novel solutions to meet the ever-
tightening standards, especially towards the size and quantity of particulate matter (PM), particularly ash, emissions. Recent emission standards by the European Union (EU6c), have focused on reducing the PM emissions from gasoline engines. Gasoline particulate filters (GPF) technologies which use a three-way catalyst (TWC) washcoat applied onto the particulate filter, are expected to be implemented to comply with regulatory limits.
Challenges with this system include understanding the role of the ash deposition on the catalyst washcoat and how it affects the catalytic performance. Thus, by observing how the ash interacts within particulate filters, the distribution of metal catalyst and how the regeneration of the catalyst affects performance are key towards improving aftertreatment technology. This project is focused on the analysis of GPF containing mainly PdRh/CeZrOx - La/Al2O3 (TWC) catalyst, using synchrotron-based techniques and imaging, to understand the effect of ageing (simulating use of >100 000 km) and ash deposition on the system. This project explored using
Operando XAS, which was utilised to understand the evolution of Pd during operation conditions and found that with the presence of ash the light-off temperature for CO oxidation and NO reduction increased.
On aged GPF’s, various length scale imaging techniques were performed on the same sample (to retaining spatial resolution), such as XRM, EPMA, FIB-SEM, XRF and AC-STEM and correlated. Nanoprobe XRF mapping and AC-STEM-EDS, suggest formation of large Pd species upon ageing and further co-location of Zn species (introduced by ash deposition) about engine aged ash containing samples. Further, the use of spatially resolved Zn K- edge XANES highlighted that multiple zinc compounds were present from the ash, which reacted with the catalyst upon ageing, forming a zinc spinel analogue.
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Aug 2023
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I13-2-Diamond Manchester Imaging
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Diamond Proposal Number(s):
[23490, 29116]
Abstract: A transient pore-scale model of particle deposit formation in 3D microstructure of a catalytic filter wall is introduced. It predicts location of particle deposits, dynamics of their growth, transition from deep to cake filtration regime as well as the impact on flow field, pressure drop and filtration efficiency. The model is validated against time-resolved X-ray tomography (XRT) data acquired during a filtration experiment. The validated model is then used in transient simulations of the soot filtration process in several different microstructures using cordierite filter substrate with varied Pd/-AlO catalyst distribution. The sample with the coating solely inside the wall pores provides the lowest initial pressure drop but suffers from low clean filtration efficiency and high pressure drop after the cake is formed. The sample with partial on-wall coating achieves not only a higher filtration efficiency but also a lower pressure drop in long-term operation.
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Aug 2023
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I22-Small angle scattering & Diffraction
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Diamond Proposal Number(s):
[27903]
Open Access
Abstract: High strength AA7xxx are attractive for use in the automotive industry, offering significant strength/weight benefits. These alloys are often used in tempers that require long ageing times of several hours. Pre-ageing has been proposed to be effective in suppressing natural ageing, and reducing the total ageing time by integrating the final ageing step into the paint bake cycle. However, the precipitate evolution during the pre-ageing and subsequent paint bake processes remains to be fully understood. In the present work, the pre-ageing process was studied for AA7075 over a wide range of temperatures and times. Small angle X-ray scattering (SAXS) was used as the main technique to investigate the precipitate evolution during the pre-ageing, natural ageing and paint bake, with the support from transmission electron microscopy (TEM) and isothermal calorimetry. For the first time, the results show that 8 h pre-ageing at 80 °C can produce a microstructure consisting of GP zones with an average radius of approximately
0.9 nm, which remains stable up to at least 7 months. After a short paint bake process, 94% of the T6 hardness can be obtained by uniformly distributed precipitates with an average radius of approximately
2.6 nm. The final size and strengthening effect of the precipitates after 20 min baking is found to be insensitive to the heating rate, which has not been reported previously. The present results further suggest this process is robust for industrial application.
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Apr 2023
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I22-Small angle scattering & Diffraction
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Abstract: Thermoplastic fibre reinforced composites have the potential to reduce the CO
2
emissions of automotive vehicles through processes such as vehicle lightweighting. In comparison to the current structural metallic components, composites offer considerable improvements in the strength-to- weight ratio of automotive parts, ultimately enhancing the fuel efficiency of the vehicle. Polyamide 66 (PA66) is an affordable, tough and durable engineering thermoplastic with intrinsically good tribological and chemical resistance properties. Further, the mechanical properties and dimensional stability of polyamides can be improved by the addition of continuous glass fibre reinforcement. This work aims to characterise through-thickness crystallinity and microstructural morphology in stamp formed glass fibre reinforced polyamide 66 (PA66/GF).
As determined by calorimetry, the through-thickness degree of crystallinity of an 11-ply PA66/GF composite was shown to be inversely proportional to the rate of heat loss throughout the stamp forming process. Within the surface layers of the composite, where cooling rates were observed to reach 1400 °C/min, crystallinity was found to be 3.0% lower than that of the central layers which, by comparison, crystallised under quasi-isothermal conditions. The variation in crystallinity owing to the disparity in cooling rates was further confirmed by x-ray diffraction (XRD). Analysis of one- dimensional (1D) wide angle x-ray scattering (WAXS) patterns demonstrated that despite the distinctly non-isothermal crystallisation conditions of the stamp forming process, the matrix polyamide rapidly crystallises into a triclinic unit cell characteristic of the \alpha-phase of PA66. However, despite this, the intensities of the
α
1
and
α
2
peaks representative of the (100) and (010)/(110) crystallographic planes, respectively, were found to differ through the thickness of the laminate, indicative of a change in crystal structure.
Isothermal crystallisation kinetics of PA66/GF were analysed over a crystallisation temperature (T
c
) range of 245 to 249 °C where, owing to both models accounting for the contribution of secondary crystallisation, the parallel Velisaris-Seferis and Hay equations were shown to provide the best fit to the experimental data (R
2
> 0.995). Hay’s assumption that both primary and secondary crystallisation occur simultaneously and that total crystallinity at time t, is the sum of the two contributions, was confirmed. Further, having not previously been applied to polyamides or thermoplastic reinforced composites, the findings of this study support the use of the Hay model in determining the isothermal crystallisation kinetics of polymeric materials.
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Apr 2022
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B18-Core EXAFS
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Diamond Proposal Number(s):
[22225]
Open Access
Abstract: Aiming at knowledge-driven design of novel metal-ceria catalysts for automotive exhaust abatement, current efforts mostly pertain to the synthesis and understanding of well-defined systems. In contrast, technical catalysts are often heterogenous in their metal speciation. Here, we unveiled rich structural dynamics of a conventional impregnated Pd/CeO2 catalyst during CO oxidation. In situ X-ray photoelectron spectroscopy and operando X-ray absorption spectroscopy revealed presence of metallic and oxidic Pd states during the reaction. Using transient operando infrared spectroscopy, we probed the nature and reactivity of the surface intermediates involved in CO oxidation. We found that while low-temperature activity is associated with sub-oxidized and interfacial Pd sites, the reaction at elevated temperatures involves metallic Pd. These results highlight the utility of the multi-technique operando approach for establishing structure-activity relationships of technical catalysts.
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Mar 2022
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B18-Core EXAFS
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Abstract: Ceria (cerium oxide) based materials have been widely used for catalytic applications including; fluid catalytic cracking, water gas shift reactions, solid oxide fuel cells and automotive catalytic after-treatment. It has often been the material of choice for supporting precious metals in many of the applications previously mentioned, as it can provide a high surface area and has excellent redox properties. This enables ceria to absorb oxygen into its structure and release it again, to facilitate oxidation reactions. Cerium is also one of the most abundant rare earth metals, making it a relatively cost effective material to use in industrial applications. For these reasons, cerium oxide remains to be a material of high interest for the development of cost-effective industrial catalysts and is, therefore, the focal material for this work.
Modern internal combustion engine technology is being directed towards lean burn operation, involving higher air-fuel ratios in order to improve thermal efficiency. In turn, the operating temperature of modern engines is being reduced, providing less of the heat energy required to activate the catalysts in the after-treatment system. Therefore, in order to mitigate the emission from efficient lean burn engines and comply with emission regulations, the requirement for low temperature automotive catalysts is apparent. The objective of this work is to develop effective ceria based materials for the application of modern automotive after-treatment catalysis.
The first approach is the use of a novel method for the preparation of a mixed oxide catalysts, which show high activity for CO and HC oxidation at low temperature. The preparation of ceria/manganese mixed oxide catalysts using a novel synthesis method has been studied and the materials were characterised to gain insights of their structure and morphology. Temperature programmed reactions using a complex mixture of reactants, before and after hydrothermal aging, were carried out to investigate their application for automotive emission control. The results from these studies were compared with more conventional ceria based materials that are often used for automotive after-treatment.
A second approach used in this work is a post synthesis technique for the surface modification of ceria catalysts using ion bombardment. This technique was carried out on a commercially sourced, model catalyst. A Pt-CeO2/ZrO2 was treated with nitrogen ion irradiation and the effects of the adjustable parameters of the ion beam were investigated by carrying out temperature programmed reactions. The samples were also extensively characterised using XAFS and XPS techniques to understand the effects of the ion beam treatment on the structure, morphology and Pt dispersion of the materials.
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Dec 2021
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I14-Hard X-ray Nanoprobe
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Diamond Proposal Number(s):
[20841, 23858]
Abstract: Battery electrodes are composed of many millions of particles. Lithium-ions entering and leaving these particles charge and discharge the battery. Defects in the particles reduce the battery’s capacity. This would impact electric vehicle range in automotive applications, for example, requiring drivers to stop more frequently to recharge. Therefore, it is crucial to investigate which particles
contain defects, whether different types of defects exist, and how we might prevent them forming.
Electrode particles are spheres with diameters on the order of tens of microns (smaller than a human hair). Due to their small size, investigating their properties requires high-resolution specialist facilities, such as those at the Hard X-Ray Nanoprobe beamline (I14) at Diamond Light Source. The defects have complex origins, requiring the use of multiple investigation techniques at once, for which I14 was specifically designed.
Batteries that are nickel-based (around 80%), with manganese and cobalt making up the other 20%, are of particular interest to the automotive industry. By analysing various particles at I14 and comparing the results with data collected in the labs at University College London (UCL), researchers found a correlation between the manganese content and the ordering of the particle’s crystals. However, they attributed the amount of cracking within the particle to the crystal orientations. Preventing the manganese from leaving the particles may maintain the crystal ordering. Aligning the crystals, or making larger single crystals, may avoid - or at least delay - particle cracking. Overcoming these issues would allow electric vehicles to travel for longer before needing to recharge.
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Jul 2021
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B18-Core EXAFS
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Diamond Proposal Number(s):
[22225]
Abstract: In recent years, noble metals atomically dispersed on solid oxide supports have become a frontier of heterogeneous catalysis. In pursuit of an ultimate atom efficiency, the stability of single-atom catalysts is pivotal. Here we compare two Pd/CeO2 single-atom catalysts that are active in low-temperature CO oxidation and display drastically different structural dynamics under the reaction conditions. These catalysts were obtained by conventional impregnation on hydrothermally synthesized CeO2 and one-step flame spray pyrolysis. The oxidized Pd atoms in the impregnated catalyst were prone to reduction and sintering during CO oxidation, whereas they remained intact on the surface of the Pd-doped CeO2 derived by flame spray pyrolysis. A detailed in situ characterization linked the stability of the Pd single atoms to the reducibility of the Pd–CeO2 interface and the extent of reverse oxygen spillover. To understand the chemical phenomena that underlie the metal–support interactions is crucial to the rational design of stable single-atom catalysts.
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Jun 2021
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B18-Core EXAFS
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Diamond Proposal Number(s):
[14239]
Abstract: Platinum functions exceptionally well as a nanoparticulate catalyst in many important fields, such as in the removal of atmospheric pollutants, but it is scarce, expensive and not always sufficiently durable. Here, we report a perovskite system in which 0.5 wt% Pt is integrated into the support and its subsequent conversion through exsolution to achieve a resilient catalyst. Owing to the instability of most Pt oxides at high temperatures, a thermally stable platinum oxide precursor, barium platinate, was used to preserve the platinum as an oxide during the solid-state synthesis in an approach akin to the Trojan horse legend. By tailoring the procedure, it is possible to produce a uniform equilibrated structure with active emergent Pt nanoparticles strongly embedded in the perovskite surface that display better CO oxidation activity and stability than those of conventionally prepared Pt catalysts. This catalyst was further evaluated for a variety of reactions under realistic test environments—CO and NO oxidation, diesel oxidation catalysis and ammonia slip reactions were investigated.
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May 2021
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