Johnson Matthey Technology Review - Volume 63, Issue 3, 2019

Size dependent characterisation is important for applications in nanoelectromechanical systems (NEMS), nanogenerators, biosensors and other related areas at higher temperature regimes. In this paper we have computed elastic, mechanical, thermal and ultrasonic properties of zinc oxide nanowires (ZnO-NWs) of different diameters at high temperatures. The higher order elastic constants of ZnO-NWs were computed using a simple interaction potential model. The mechanical properties such as bulk modulus, Young’s modulus, shear modulus and Poisson’s ratio were determined based on the formulated elastic constants. Various ultrasonic parameters such as ultrasonic wave velocities, ultrasonic Grüneisen parameter and ultrasonic attenuation were obtained with the help of elastic constants and density. The temperature dependent ultrasonic wave velocities propagating along the length of the nanowire at different orientations were calculated using elastic constants to determine anisotropic behaviour. The diameter dependent ultrasonic losses and thermal characteristics of ZnO-NWs were also determined. The ultrasonic attenuation due to the phonon-viscosity mechanism is predominant for the total ultrasonic attenuation for ZnO-NWs. The correlation among the ultrasonic parameters, thermal conductivity and size of ZnO-NWs is established leading to potential industrial applications.

A catalyst support is often used to disperse a catalyst material to enhance the contact area for reaction. In catalytic converters, a coating called the catalyst layer contains both the catalyst support and catalytically active material. Given the role of the catalyst layer in catalytic converters, its mechanical strength is of great importance as it determines the service life of catalytic converters. This review paper therefore summarises a number of methods which are currently used in the literature to measure the strength of a catalyst layer. It was identified that the methods applied at present could be divided into two groups. All methods regardless of the group have been successfully used to investigate the effect of a range of formulation and process parameters on the strength of a catalyst layer. In terms of measurement principles, Group 1 methods measure the strength based on mass loss after the layer sample is subjected to a destructive environment of choice. Group 2 methods tend to give more direct measurements on the strength of bonding between particles in a catalyst layer. Therefore, strength data generated by Group 2 methods are more reproducible between different researchers as the results are less dependent on the testing environment. However, methods in both groups still suffer from the fact that they are not designed to separately measure the cohesive and the adhesive strength of a catalyst layer. Two new methods have been recently proposed to solve this problem; with these methods, the cohesive and adhesive strength of a catalyst layer can be measured separately.

Squalene (SQE) was fully converted into squalane (SQA) in a continuous reactor. The design of a three-dimensional (3D) printed support allowed selectivity to be tuned towards squalane. The advantages of being able to design the geometry of the catalytic support using 3D printing technology are presented in this paper.

The formulation and delivery of the biologically active ingredients (AIs) (for example, agrochemicals and active pharmaceutical ingredients (APIs)) is an inherently interdisciplinary area of research and development. In this short review we discuss the evolution of AI and API delivery systems towards smart stimuli-responsive formulations with precisely controlled delivery for specific applications. We also highlight a few examples of such systems using AIs from Johnson Matthey’s controlled substance and API portfolio.

The recent upsurge of interest in manufacturing techniques using metal powders, including additive manufacturing (AM), metal injection moulding (MIM) and hot isostatic pressing (HIP), has made methods for manufacturing alloyed metal powders especially iron-, nickel- and cobalt-based alloys, a topic of much increased importance. Drawing on 45 years of experience in the field, the author reviews the range of methods available for this purpose, their advantages and limitations and likely fields of application.