Johnson Matthey Technology Review - Volume 67, Issue 2, 2023

The Euro 7 exhaust emissions regulation will be important both from the perspective of how it further improves air quality, but also of certain greenhouse gas emissions and the economics of the internal combustion engine. This paper sets out the ongoing importance of ozone to urban air quality, and how tailpipe volatile organic compound (VOC) emissions contribute to that as well as having direct human health effects through inhalation. The paper then sets out a novel method for the measurement of speciated VOCs and nitrous oxide (N2O) at the tailpipe in real-world conditions, and presents initial results across a range of modern light-duty vehicles. Based on the results, it may be the case that VOCs should be a higher priority for future regulation than N2O, although more research is required to achieve a consensus on typical real-world N2O emissions.

The native platinum group elements (PGE), namely, the light PGE (ruthenium, rhodium and palladium) and the heavy PGE (osmium, iridium and platinum), are important historically, scientifically and industrially. Some of the scientists who discovered and refined these metals in the 18th and early 19th centuries, besides being chemists, were also physicians, but all were also knowledgeable of mineralogy. We cannot but be impressed by their achievements because of the complexity of the minerals they studied. The PGE alloys occurred as a fraction of the heavy minerals concentrated from alluvial deposits. Today we can understand why some details of their discovery and mineralogy have not been well understood because of a lack of modern mineralogical studies and misunderstandings of some of the early literature, especially for native palladium and platinum. Though reported widely, highlights of the historical discoveries are here assembled in a single paper and discussed with respect to the mineralogy of the samples studied.

Fabrics with water-repellent properties are widely valued in the textile industry. It is known that fluorocarbon compounds, which are widely used for this purpose, are harmful to the environment. Therefore, within the scope of this study, a water-repellent chemical that does not contain fluorocarbon compounds was used to treat 100% cotton fabrics and compared with fluorocarbon compounds. The results show that the environmentally friendly chemical is at least as effective as the fluorocarbon compounds. According to the spray test, water repellency at ISO 5 level was obtained. In addition, the fabrics’ usage properties were assessed and high water vapour permeability, air permeability and low bending stiffness (280 mg cm) were obtained. This has yielded important results in terms of sustainability and the potential for eliminating the use of fluorocarbons for this application.

The need to avoid health issues and pollution of the environment from the use of chemicals and synthetic materials inspires scientists to search for new biological compounds beneficial to human beings. Caves, being extreme environments, might be potential sources of these compounds. Actinobacteria, one of the main groups that colonise these environments, are known to generate natural bioactive compounds. To investigate the potential uses of Parsık Cave Actinobacteria, identification of this group of isolates and the investigation of their secreted biological compounds constituted the principal aim of the present study. The identification was achieved by sequencing 16S rRNA genes of 41 selected bacteria of which 28 species were identified as Actinobacteria. Microbacterium (21%) and Pseudarthrobacter (14%) were the most identified Actinobacteria genera. Antimicrobial effects of the isolates P1 and P16 were observed against standard microorganisms like Candida albicans. The gas chromatography-mass spectrometry (GC-MS) analysis of their broth showed compounds with known antimicrobial, antioxidant or anticancer properties as well as unknown compounds. Polyketide synthase (PKS) and non-ribosomal peptide synthases (NRPS) respectively were amplified in 32.1% and 53.5% of the identified Actinobacteria while 25% were found to have both NRPS and PKS amplified. Amylase, gelatinase, cellulase, deoxyribonuclease (DNase), urease and casein hydrolysing activities were observed in the identified Actinobacteria. These results show that Actinobacteria from Parsık Cave might be good sources of industrial and biotechnological compounds. Furthermore, discovery of new bioactive compounds from these bacteria is promising due to the many unknown compounds observed in the GC-MS analysis and the high percentage of NRPS and PKS gene amplification.

The main challenges of compressed natural gas (CNG) engine fuelling in terms of methane abatement in the aftertreatment system are addressed in this study using differently loaded platinum group metal (pgm) catalysts. A dual-fuel injection strategy of methane-gasoline was implemented where methane gas was port-injected into the intake in stoichiometric conditions at levels corresponding to 20% and 40% energy density replacement of gasoline fuel. High, medium and low loaded palladium-rhodium catalysts were used and compared to study the effect of pgm loading on the catalyst light-off activity for methane. Results indicate that increasing the palladium loading led to significantly earlier light-off temperatures achieved at relatively lower temperatures of 340°C, 350°C and 395°C respectively. However, the benefit diminishes above palladium loading >142.5 g ft^–3. The study has also demonstrated that ammonia is formed over the CNG catalyst due to steam-reforming reactions from the increased levels of methane in the exhaust with dual-fuelling. Hence aftertreatment technologies such as selective catalytic reduction (SCR) should be adopted to remove them. This further highlights the need to regulate the harmful ammonia emissions from future passenger cars fuelled with CNG. In addition, the benefits of the dual-fuel system in terms of lower engine output carbon dioxide, non-methane hydrocarbon (NMHC) and particulate matter (PM) emissions compared to the gasoline direct injection (GDI) mode alone are presented.

Lozenge-patterned surfaces obtained with laser texturing can reduce the risk of infection by preventing or delaying biofilm formation of Escherichia coli. To investigate this aspect, the biofilm formation ability of E. coli on both lozenge-patterned and untreated surfaces of 630 stainless steel coupons was examined over 48 h. Biofilm on the coupons was analysed for bacterial enumeration and total carbohydrates concentration and was observed using scanning electron microscopy (SEM). The surface modification by texturing caused a 6 h delay in the attachment of E. coli and an approximately 99% decrease in the number of adhered bacteria. However, it was determined that E. coli produced more extracellular polymeric substances (EPS) (p<0.01) to attach to the lozenge-patterned surface and formed a multi-layered biofilm. In conclusion, lozenge-patterned surfaces can be applied to reduce bacterial count and induce a delay in attachment, but the increased amount of EPS limits its use.

Many additive manufacturing (AM) processes have been developed to fabricate lightweight metal matrix composites (LMMCs) from constituent materials. However, the improvement in mechanical properties is significantly affected by the added reinforcing materials in the LMMC compared to metallic materials and their alloys. Recent advances in understanding the selecting criteria and effect of the reinforcement, preparation methods and AM process on the properties of LMMCs are summarised in this review. The preparation methods of particle-reinforced LMMCs include ex situ and in situ synthesis. The effect of various reinforcement and AM processes such as powder bed fusion (PBF) processes and direct energy deposition (DED) processes on the mechanical properties of LMMC parts are discussed.

Membranes and Catalysts Beyond Economical and Technological Hurdles (MACBETH) is a European funded project that aims to implement a catalytic membrane reactor (CMR) technology at Technology Readiness Level 7 (TRL7) in four industrially relevant use cases. This paper gives the background, status quo and future perspective of that innovative technology that could transform current chemical processes into more sustainable ones.

Gasoline vehicles have generally relied upon a combination of palladium and rhodium for more than 25 years to facilitate the required oxidative and reductive reactions of carbon monoxide (CO), hydrocarbons (HCs), and nitrogen oxides (NOx). Recently, steady increases in the price of palladium relative to platinum have fuelled demand to reincorporate platinum into three-way catalysts (TWCs). However, the fundamental properties of platinum, including susceptibility toward sintering and inhibition under typical gasoline operating conditions, present significant challenges. This article presents an overview of the origins for these challenges, as well as select strategies for maximising platinum’s contribution to modern-day TWCs. Optimisation of ceria-zirconia supports is one route by which platinum’s performance can be significantly improved through tuning of the ceria-to-zirconia ratio. Additionally, alloying platinum with a secondary platinum group metal (pgm), such as rhodium, leverages complimentary properties of both metals, imparting stability and overall activity enhancements. Such routes not only enable pgm flexibility, but also provide opportunities to further improve TWC performance.

New dilatometric measurements allow the evaluated thermal expansion of osmium to be increased from the previous limit of 1300 K to the melting point at 3400 K. The new data is reported in the form of Equations and Tables. The revision confirms that osmium is the densest solid at all temperatures above room temperature. A new equation is given for the density of liquid osmium.