Fibrous ceramics filters for gases at high temperature

Abstract

Fibrous structures are specially indicated for high temperature gas filtration, due to their high permeability and high retention capacity. Fibrous filters were produced using fibrous silico-aluminous refractory mantels, using 10% polyvinyl acetate (PVA) as binder. After cold pressing the samples were submitted to a thermal treatment at 750°C for 1 hour for degradation of the polymer into carbon with simultaneous oxidation in CO/CO2. Subsequently, the filters were sintered at temperatures between 900 and 1000°C, for 1 hour, finally resulting in an interconnected fibrous network with relative densities varying from 0.28 to 0.43 g/cm3, which correspond to porosities in the range from 72% to 57%. The microstructure and morphology of the fibrous filters was evaluated by scanning electron microscopy. Permeability of the fibrous filters was determined in function of temperature. The Darcyan permeability, k1, was in the order of magnitude expected for hot gas filters and, therefore, suitable for several industrial applications.