PREPARATION AND CHARACTERIZATION OF MICROPOROUS CERAMIC HOLLOW-FIBER MEMBRANES

Ceramic hollow fibre membranes have been prepared out of aluminium-oxi de and silicon-nitride. The fibres have been produced in a three stage process. A polymer filled with ceramic material has been prepared in a blender, a hollow fibre precursor has been made by extrusion of the melt with a spinneret and the precursor is transformed in a ceramic fi bre by means of heat treatment at 1200-1650 degrees C. The outer diame ter of the ceramic fibres is 800-2700 mu m depending on the diameter o f the spinneret used. The hollow fibres are microporous and show gas f lues of about 4-15 X 10(-8) m(3)/m(2) s Pa. In a final step alumina fi bres have been modified by coating them with a gamma-alumina top-layer . The composite fibres have gas fluxes of about 4 X 10(-8) m(3)/m(2) s Pa and are gas selective. The selectivity is close to the value predi cted by the Knudsen diffusion theory. So it is possible to produce a d efect free ceramic composite hollow fibre membrane, This membrane can serve as a basis for a high selective membrane.