Full Text for Volume 49 Number 2 (April 2005)

 

This issue contains the following:

‘Diffusion Choke’ – A New Effective Stirrer Design in Glass Making
The extreme conditions needed to manufacture high quality glass require the services of large quantities of platinum. The stirring devices that are needed to achieve homogeneous glass account for a large part of that platinum. To help to reduce costs (in some cases by over 90 per cent) without compromising effective stirring or stirrer lifetimes, a new stirrer design has been developed. The design incorporates a gauze of finely knitted 10%Rh-Pt alloy, the ‘diffusion choke’, between the stirrer shaft of, for instance, PM 2000 superalloy, and the outer metal cladding, typically 20%Rh-Pt. Duncan R. Coupland and Paul Williams (Johnson Matthey Noble Metals, Royston, U.K.) describe how an in-service ‘diffusion choke’ provided 20 months’ service with integrity projected to last from 5 to 10 years. The ‘choke’ acts as a barrier to prevent stirrer degradation.

 

Iridium/Carbon Films Prepared by MOCVD
The composition, structure and electrochemical properties of some Ir/C films prepared by MOCVD, using iridium acetylacetonate as the precursor, are described by Changyi Hu and Jigao Wan (Kunming Institute of Precious Metals, China) and Jiaoyan Dai (Institute of Materials and Engineering, Central South University, China). Small additions of oxygen to the source gas greatly decrease the carbon content of the films. Ir grains (£ 3 nm in diameter) are formed in the amorphous carbon. Ir/C films with higher carbon content have better catalytic performance than Ir/C film of lower carbon content. The electrochemical properties of an oxygen concentration cell using Ir/C films as the electrodes proved to be almost identical to those for a commercial sensor, but the response time was faster.

 

Palladium Reagents and Catalysts
The book, "Palladium Reagents and Catalysts: New Perspectives for the 21st Century" by J. Tsuji, is reviewed by Mark Hooper (Johnson Matthey Catalysts, Royston, U.K.). This book is an update to the original title by the same author published in 1995. The book gives a detailed overview of the main recent advances in organopalladium chemistry from a synthetic organic chemist’s viewpoint. It is to be used in conjuction with the original book to cover the whole of organopalladium chemisty.

 

Potential Applications of Fission Platinoids in Industry
Fission-generated platinoids recovered from high-level liquid radioactive wastes could supplement metals from natural sources. Fission palladium and rhodium are of particular interest as they can be decontaminated from other fission products to a non-hazardous level, when only their intrinsic radioactivity remains. In fission palladium intrinsic radioactivity is weak, while in fission rhodium the intrinsic radioactivity decays to an acceptable level after 30 years. Some potential applications of non-nuclear applications of fission platinoids are described by Zdenek Kolarik (formerly of Forschungszentrum Karlsruhe, Germany), and Edouard V. Renard (All-Russian Institute of Inorganic Materials, Russia). The intrinsic radioactivity should not play a negative role when fission platinoids are used in nuclear technology applications.

 

Treatment of Organic Wastewater Using Ruthenium Catalysts
YuanJin Lei, ShuDong Zhang, JingChuan He, JiangChun Wu and Yun Yang (Kunming Institute of Precious Metals, China), describe a treatment for highly concentrated organic wastewater that is difficult to degrade biochemically. The treatment involves a catalytic wet oxidation process using a liquid phase oxidation with a solid catalyst at elevated temperature and pressure. The most effective catalyst tested contained Ru-Group IIIB elements supported on TiO₂. This reduced the severity of the reaction, improved the chemical oxygen demand conversion and the total nitrogen conversion of organic wastewater.

 

Advice to Scientists on Patenting Their Inventions
Ian Wishart (Corporate Patents & Licensing Director of Johnson Matthey PLC) provides advice on intellectual property – covering both patents and copyright. Some of the key defining platinum group metals patents in various technologies from the early 19th century to the 20th century are highlighted.

 

PGM Literature and Patent Selection
The issue also contains a selection of abstracts based on recently published patent and scientific literature.

 

Final Analysis: Thermocouples – Compensating Circuits
Roger Wilkinson (Johnson Matthey Noble Metals, U.K.) discusses how compensating circuits reduce the cost of thermocouples while still generating the same voltage as the thermocouple wires they replace. This is the fourth and final part in a series describing how to look after platinum/rhodium thermocouples to extend their service life.

Susan V. Ashton
Editor

Contact
The Editor, Platinum Metals Review, Johnson Matthey PLC, Orchard Road, Royston, Hertfordshire SG8 5HE, United Kingdom; Fax +44 (0) 1763 256359; Email jmpmr@matthey.com

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