FAILURE MECHANISMS OF CERAMIC MEMBRANE REACTORS IN PARTIAL OXIDATION OF METHANE TO SYNTHESIS GAS

In the course of generating synthesis gas (H-2, CO) from methane, we h ave observed two types of fractures occurring an the Sr(Co, Fe)O-x-typ e oxygen membrane reactors. The first type occurred shortly after the reaction started and the second type often occurred days after the rea ction. To determine the causes of these fractures, we have examined th e starting material and fractured membranes using a combination of X-r ay diffraction and thermogravimetric analyses. We found that the first type of fracture was the consequence of an oxygen gradient in the mem brane, pointing from the reaction side to the air side. This causes a lattice mismatch inside the membrane, leading to fracture. The second type of fracture, however, was the result of a chemical decomposition. We found that the Sr(Co, Fe)O-x-type membrane had been reduced to SrC O3, and elemental Co and Fe by the synthesis gas generated in the reac tion. The decomposition causes enormous expansion leading to a large c rack along the axis of tube.