Johnson Matthey Technology Review - Volume 62, Issue 1, 2018

It is over 100 years since the Haber-Bosch process began in 1913 with the world’s first ammonia synthesis plant. It led to the first synthetic fixed nitrogen, of which today over 85% is used to make fertiliser responsible for feeding around 50% of the world’s human population. With a growing population and rising living standards worldwide, the need to obtain reliable, economic supplies of this vital plant nutrient for crop growth is as important as ever. This article details the historic background to the discovery and development of a process “of greater fundamental importance to the modern world than the airplane, nuclear energy, spaceflight or television” (1, 2). It covers the role of the Billingham, UK, site in developing the process up to the present day. The technology was pioneered in Germany and developed commercially by BASF. In 1998 ICI’s catalyst business, now Johnson Matthey, acquired BASF’s catalytic expertise in this application and now Johnson Matthey is a world-leading supplier of catalyst and technology for ammonia production globally.

The thermodynamic properties were reviewed by the author in 1995. A new assessment of the enthalpy of fusion has led to a revision of the thermodynamic properties of the liquid phase and although the enthalpy of sublimation at 298.15 K is retained as 377 ± 4 kJ mol^–1 the normal boiling point is revised to 3272 K at one atmosphere pressure.

Palladium impregnated activated carbon (Pd/C) filters play a major role in air quality management by the removal of toxic carbon monoxide from confined environments. However, Pd is an expensive metal and therefore, recovery and reuse of Pd from spent filter cartridges is highly desirable. The objective of the present study was to biosynthesise Pd nanoparticles (NPs) using green tea as a reducing agent. The source of Pd for the NP synthesis was spent Pd/C. Three different acid based Pd extraction protocols constituting of hydrochloric acid-hydrogen peroxide (HCl-H2O2), 2 M HCl and aqua regia were systematically explored. The Pd impregnated carbon was characterised using scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), ultraviolet-visible (UV-vis) spectroscopy, X-ray powder diffraction (XRD) and atomic absorption spectrometry (AAS) before and after Pd extraction. It was found that the aqua regia based extraction protocol was the most efficient among the three chosen acid or acid mixtures with an average absolute yield of 96%. Finally, an attempt was made towards one pot biosynthesis of Pd NPs from the recovered extract by using green tea as a reducing agent. The synthesised NPs were characterised using UV-vis spectroscopy, SEM and XRD.

Hexamethylenetetramine (hmta) was chosen as a model ligand. Each of the four nitrogen atoms has a pair of unshared electrons and behaves like an amine base, undergoing protonation and N-alkylation and being able to form coordination compounds with many inorganic elements. The ligand can be used as an outer coordination sphere modulator of the inner coordination sphere and as a crosslinking agent in dinuclear and multinuclear coordination compounds. It can also be used as a model for bioactive molecules to form a great number of complexes with different inorganic salts containing other molecules. Studies of hmta coordination compounds with different metal salts have therefore attracted much attention. The present review summarises the synthesis, preparation, structure analysis and applications of coordination compounds of hmta with different metal salts.

World trade has transformed food retailing and driven the development of technology for the transportation and storage of horticultural products, providing year-round supply of fruit and vegetables. Horticultural produce is highly perishable, as fruit and vegetables continue their metabolic processes that lead to ripening and senescence after harvest, making them ultimately unmarketable. Advanced postharvest technologies are essential for reducing food waste while maintaining high standards of safety and quality. Together with cold storage, controlled atmosphere (CA) and modified atmosphere packaging (MAP) have been applied to alter the produce’s internal and external environment, decreasing its metabolic activity and extending shelf-life. Both CA and MAP have benefitted from technological innovation. Respiratory quotient control has improved the management of conventional and recently developed CA systems; gas scavengers have made MAP more efficient; and the inclusion of natural additives has enhanced food safety across the supply chain. This paper critically reviews the application of new postharvest techniques to manipulate gaseous environments and highlights areas that require further study.

Fast pyrolysis for liquids has been developed in recent decades as a fast and flexible method to provide high yields of liquid products. An overview of this promising field is given, with a comprehensive introduction as well as a practical guide to those thinking of applying fast pyrolysis liquids (bio-oil) in various applications. It updates the literature with recent developments that have occurred since the reviews cited herein. Part I contains an introduction to the background, science, feedstocks, technology and products available for fast pyrolysis. Part II will detail some of the promising applications as well as pre-treatment and bio-oil upgrading options. The applications include use of bio-oil as an energy carrier, precursor to second generation biofuels, as part of a biorefinery concept and upgrading to fuels and chemicals.