Thermochemical stress development in ceramic catalyst supports
Spherical catalyst supports of α-alumina are often used in packed-bed reactors. Exothermic reactions on the surface of the sphere can jump to the ignited state due to fluctuations in the bulk stream. The temperature field associated with the ignition creates large stresses within the support. Results are presented for a first-order reaction which ignites when the concentration in the bulk stream is suddenly increased. The thermoelastic equations are solved for constant and temperature-dependent material properties and in both cases it is shown that stresses develop which exceed the failure strength of alumina. For a material such as AlN with a smaller linear expansion coefficient and a larger thermal conductivity, the stresses in the material do not exceed the breaking strength. © 1993.