Johnson Matthey Technology Review - Volume 67, Issue 1, 2023

Measurement and control of process temperature is key to maximising product quality, optimising efficiency, reducing waste, safety and minimising carbon dioxide and other harmful emissions. Drift of temperature sensor calibration due to environmental factors such as high temperature, vibration, contamination and ionising radiation results in a progressively worsening temperature measurement error, which in turn results in suboptimal processes. Here we outline some new developments to overcome sensor calibration drift and so provide assured temperature measurement in process, including self-validating thermocouples, embedded temperature reference standards, and practical primary Johnson noise thermometry where the temperature is measured directly without the need for any calibration. These new developments will give measurement assurance by either providing measurements which are inherently stable, or by providing an in situ calibration facility to enable the detection and correction of calibration drift.

This work explores some of the key factors to consider in design and implementation of corrosion testing at a laboratory scale for the development of new chemical technologies in order that process technology scale-up risks, not least those of safety, can be minimised. This is to ensure safe and reliable introduction of new process technologies, while also pursuing the minimum capital cost of often expensive plant materials of construction (MoC). Laboratory-based corrosion testing should never be used exclusively to replace inspection and monitoring of corrosion in operating process plants, as real-world conditions are rarely possible to be wholly replicated in the laboratory. However, testing as initial screening, or to provide deeper mechanistic insights is often an essential part of the development and design of first-of-a-kind process technologies. Several methodologies to assess corrosion under highly aggressive conditions have been developed and applied in the development of new chemical processes and are demonstrated in two case studies outlined in this article. This work focuses on testing of materials in contact with corrosive fluids.

Flame is a natural phenomenon and is a basic element of any combustion process. The majority of flames consist of a gas; there is, however, a small amount of ionisation occurring in the flame. Despite the increased focus on combustion-free energy production such as wind, air and water power, and the refocus on nuclear energy now considered to be carbon-free, nonetheless combustion will remain, for the next few decades, the major energy and heat production route worldwide. Apart from carbon dioxide, which is commonly considered to be the major pollutant, there are other gases like nitric oxide and nitrogen dioxide which, although found in significantly lower amounts in the exhaust gases from combustion units, still present a large environmental impact and are a concern. There are however well-established technologies for removing combustion products from the exhaust gas, and the combustion process can in general be made CO2 and environmentally neutral. Combustion optimisation is a route for further reduction of undesirable byproducts, fuel consumption minimisation and finally an overall energy and heat production enhancement. The key parameter in any combustion process is reliable flame and (post-) combustion gas temperature measurement and control. Various combustion environments such as waste incineration, internal combustion engines or solids explosions cause the appearance of various optical emission features in different spectral ranges not accessible to the human eye. A combination of modern and newly developed fast spectral optical techniques with extensive theoretical developments in spectral and heat radiative transfer modelling allows us to obtain detailed snapshots of what is happening in the combustion process. That also gives a possibility to establish a direct link to the industrial process control and pollutant emission reduction. In this article some examples of in situ flame and gas temperature measurements in various combustion environments and advanced spectral modelling are given and perspectives for further commercial instrumentation developments are discussed.

The assessment of lithium-ion battery (LIB) safety is a multiscale challenge: from the whole-cell architecture to its composite internal three-dimensional (3D) microstructures. Substantial research is required to standardise failure assessments and optimise cell designs to reduce the risks of LIB failure. In this two-part work, the failure response of a 1 Ah layered pouch cell with a commercially available nickel manganese cobalt (NMC) cathode and graphite anode at 100% state of charge (SOC) (4.2 V) is investigated. The mechanisms of two abuse methods: mechanical (by nail penetration) and thermal (by accelerating rate calorimetry) are compared by using a suite of post-mortem analysis methods.

In Part I (1), the failure response of a 1 Ah layered pouch cell with a commercially available nickel manganese cobalt (NMC) cathode and graphite anode at 100% state of charge (SOC) (4.2 V) was investigated for two failure mechanisms: thermal and mechanical. The architectural changes to the whole-cell and deformations of the electrode layers are analysed after failure for both mechanisms. A methodology for post-mortem cell disassembly and sample preparation is proposed and demonstrated to effectively analyse the changes to the electrode surfaces, bulk microstructures and particle morphologies. Furthermore, insights into critical architectural weak points in LIB pouch cells, electrode behaviours and particle cracking are provided using invasive and non-invasive X-ray computed tomography techniques. The findings in this work demonstrate methods by which LIB failure can be investigated and assessed.

Quantitative thermal imaging, the measurement of temperature by use of thermal imaging devices, is reviewed here from a metrological perspective with a focus on measurement confidence and system application to fields such as condition monitoring and healthcare diagnostics. Thermal imaging has seen greatly increased application for the measurement of temperature following dramatic improvements in practicality and price. Selected thermal imaging systems are reviewed here by providing some example measurements outputs from devices, highlighting their outcomes on measurement confidence and impact on practical use, such as in condition monitoring and healthcare diagnostics.

Temperature is the most frequently measured process variable in almost all industrial sectors from the chemical industry to glass and ceramics, refrigeration and power generation. During many manufacturing processes, continuous temperature control is an important part of product quality assurance and a matter of avoiding malfunctions or detecting them at an early stage. Measuring points can be located at different places such as in containers, pipe systems, machines, ovens or reactors, whereby different gaseous, liquid or solid media, for instance, steam, water, oil or special chemical substances may be involved. In view of these extremely complex tasks, flexibility is one of the most important requirements for measurement technology and signal processing. And this is where thermocouples, which can be adapted to almost all measuring tasks due to their simple design, become relevant. The basic design and operating principle of thermocouples are described in this paper; issues relating to calibration, traceability and measurement uncertainty are addressed. Recent developments to improve temperature measurement with thermocouples are presented. New, drift-optimised thermocouples, novel designs and alternative calibration methods are described, and their advantages over conventional thermocouples or calibration methods are specified.

In May 2019 four of the seven base units of the International System of Units (the SI) were redefined and are now founded on defined values of fundamental physical constants. One of these was the kelvin which is no longer defined by the triple point of water but instead through a fixed value of the Boltzmann constant. In this paper the kelvin redefinition is introduced and the implications for temperature traceability and practical temperature sensing discussed. This will include outlining new approaches for temperature traceability, as well as discussing the rise of in-process calibration through practical primary temperature sensing approaches (where, in principle, no sensor calibration is required). These forthcoming changes are likely to have significant impact on everyone in the temperature calibration chain, whilst the advent of in-process temperature calibration should lead to step change improvements in process control, energy efficiency and product quality consistency and will help facilitate autonomous production.

The leather sector has global economic importance. Overcoming microbiological problems, especially arising from halophilic bacteria, will greatly reduce product losses. In this study, lichen species including Usnea sp., Platismatia glauca, Ramalina farinacea, Evernia divaricata, Bryoria capillaris, Hypogymnia tubulosa, Pseudevernia furfuracea and Lobaria pulmonaria were examined for their antibacterial efficacies against Staphylococcus saprophyticus subsp. saprophyticus (TR5) and Salinicoccus roseus (KV3) which are proteolytic and lipolytic Gram-positive moderately halophilic bacteria. The extracts of P. glauca, B. capillaris, P. furfuracea and L. pulmonaria had no antibacterial efficacy against the test bacteria. On the other hand, the extracts of H. tubulosa, R. farinacea, Usnea sp. and E. divaricata had considerable antibacterial effect with varying percentages of inhibition. The maximum inhibition ratios at the tested concentrations of 15–240 μg ml^–1 for lichen samples of H. tubulosa, R. farinacea, Usnea sp. and E. divaricata were detected as 94.72 ± 0.75%, 76.10 ± 1.85%, 99.36 ± 0.04%, 89.49 ± 2.26% for TR5 and 97.44 ± 0.14%, 95.92 ± 0.29%, 97.97 ± 0.39%, 97.58 ± 0.53% for KV3, respectively. The most remarkable suppression was obtained with Usnea sp. extracts against KV3. These results indicate the need for further studies investigating the applicability of these natural resources to control moderately halophilic bacteria in the preservation of raw hides and skins.

This is a focused review of recent highlights in the literature in cathode development for low temperature electrochemical carbon dioxide and carbon monoxide reduction to multi-carbon (C2+) products. The major goals for the field are to increase Faradaic efficiency (FE) for specific C2+ products, lower cell voltage for industrially relevant current densities and increase cell lifetime. A key to achieving these goals is the rational design of cathodes through increased understanding of structure-selectivity and structure-activity relationships for catalysts and the influence of catalyst binders and gas diffusion layers (GDLs) on the catalyst microenvironment and subsequent performance.

This is Part II of a focused review of recent highlights in the literature in cathode development for low temperature electrochemical carbon dioxide and carbon monoxide reduction to multi-carbon (C2+) products. Part I (1) introduced the role of CO2 reduction in decarbonising the chemical industry and described the catalysts and modelling approaches. Part II describes in situ characterisation to improve the understanding and development of catalysts, the catalyst layer and the gas diffusion layer.