Catalysis and corrosion studies using PGM oxides
The dissolution kinetics of metal oxide particles of homogeneous composition follow a simple inverse cubic rate law. In chapter 3 the soft-centre kinetic model is developed which describes the dissolution of a monodispersion of particles, comprising two materials A and B, the former being more corro...
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Swansea University
1994
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| Online Access: | http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636692 |
| Summary: | The dissolution kinetics of metal oxide particles of homogeneous composition follow a simple inverse cubic rate law. In chapter 3 the soft-centre kinetic model is developed which describes the dissolution of a monodispersion of particles, comprising two materials A and B, the former being more corrosion resistant than the latter. The particles are assumed to be richer in A at the surface and richer in B at the core thus leading to two phase dissolution kinetics. In chapter 4 this work is extended to analyse the dissolution kinetics of a range of samples of RuO<SUB>2</SUB>.<i>x</i>H<SUB>2</SUB>O with different water contents using bromate ions as the oxidant. The soft-centre model is used to analyse the kinetics of dissolution yielding valuable information about the nature of the particles and the process of thermal activation. In addition a study into the kinetics of oxygen catalysis that accompany the corrosion is presented. The kinetics of oxygen catalysis are found to be rapid during the initial region of slowest corrosion and <i>vice versa</i>; a modified version of the soft-centre model is used to simulate the kinetics of catalysis. In chapter 5 the effects of power ultrasound on the kinetics of RuO<SUB>2</SUB>.<i>x</i>H<SUB>2</SUB>O corrosion by bromate ions are discussed. The ultrasound permanently alters the nature of the particles, giving them increased initial corrosion resistance and a version of the soft centre model is developed to simulate the kinetics. A wide range of new catalysts suitable for mediating the oxidation of brine by Ce(IV) ions are discussed in chapter 6. The catalysts are based on ruthenium and iridium oxides; different preparation methods and the use of inert supports are explored as a route to minimize PGM use. An electrochemical model is used to interpret results of the kinetic study as a function of diffrent experimental parameters. |
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