(122e) Understanding Catalyst Failure Mechanisms in Plant Operation

Unexpected catalyst failures have strong economic consequences on plant operation. The catalyst life time is determined by various factors, such as loss of catalytic activity and/or selectivity or reaching unsafe operational limits. Solid catalyst deactivation can be grouped into six intrinsic mechanisms: (1) poisoning, (2) fouling, (3) thermal degradation, (4) vapor compound formation and/or leaching accompanied by transport from the catalyst surface or particle, (5) vapor–solid and/or solid–solid reactions, and (6) attrition/crushing. Catalyst degradation under industrial conditions is often due to a combination of mechanical and chemical sources as well as process operation parameters. Thus proper root cause analysis is very complex and often multidimensional fundamental scientific approaches are needed.

This study will show application of microscopy, spectroscopy and development of accelerating aging methodologies on different length scales to understand catalyst failure modes. Herein, challenges of plant catalyst examination will be discussed using as an example CuZnO catalyst. The spent catalyst may not be directly compared with the fresh catalyst because of structure modifications due to reduction and oxidation, thermal stress and mechanical unloading. However, careful interpretation of the results from microscopy analysis enables identification characteristic fingerprints of the failure mechanisms. Origins of different degradation modes for two CuZnO catalysts with very similar composition will be explained (Figure). This work will demonstrate the great potential of post-mortem catalyst structure analysis in understanding the root cause of failure.