ALKALI RESISTANCE OF TAPE-CAST SIC POROUS CERAMIC MEMBRANES

The possibility to limit the alkali poisoning of the internal reformin g catalyst in a direct internal reforming-molten carbonate fuel cell ( DIR-MCFC) has been investigated by testing porous ceramic membranes in a reactor which simulated DIR-MCFC operative conditions. Silicon carb ide (SiC) has been chosen as starting material for the membranes; they have been prepared by adopting the tape-casting procedure, and the re producibility of this preparative has been verified through several mo rphological characterizations. Some tests at different lifetimes (150, 700 and 1500 h) have been carried out and it has been found that the membranes are able to retain 50-65% of the potassium after 150 h and t his capability decreases at 32% after 1500 h. Because of no variations on the porous ceramic membranes characteristics, before and after the tests, have been evidenced from porosimetric and SEM analyses, we hav e supposed that the adsorbed K gradually covers the SiC grains surface by forming a thin film without modification of the structure of the s amples. (C) 1998 Elsevier Science B.V.