MATERIALS SELECTION AND DESIGN OF HIGH-TEMPERATURE CATALYTIC COMBUSTION UNITS

The range of operating conditions of catalytic combustors focuses atte ntion on low temperature reactivity and high temperature stability of materials. Under lean fuel:air mixtures, catalysts operate at low temp eratures and improved reactivity is required. Metal-support interactio ns improve reactivity as demonstrated with precious metal-ceria system s. However the reasons for enhanced reactivity and the means of optimi sing the catalysts are still not clear. The need for high temperature stability has led to detailed studies of washcoats, with the mechanism of sintering and the means of prevention now being understood. The de mands of still higher temperature operation re-opens the question of m aterials selection and of combustor design, with two bed systems appea ring to offer several advantages. Reassessment of materials in the lig ht of revised design parameters is required.