Investigation of the Effect of Accelerated Hydrothermal Aging on the Cu Sites in a Cu-BEA Catalyst for NH₃-SCR Applications

The influence of hydrothermal aging between 500 and 900 °C for 3 h, on the structure of a Cu-Beta catalyst was studied in this work. The XRD measurements indicated a structural breakdown of the zeolite upon 900 °C hydrothermal aging. This was confirmed from the loss of surface area as measured by BET method. The temperature for the zeolite structure break down was different between the powder bed as opposed to the sample that was washcoated on a cordierite monolith, which was most likely due to slightly different aging conditions and the presence of binders. The strong increase in the intensity of the Cu2p XPS peak indicated that the surface is enriched of copper at higher temperatures due to the zeolite structure collapse. The presence of CuO is usually accompanied by a satellite peak, which was clearly observed at higher binding energies for the catalysts aged at 800 and 900 °C. The XPS results are in good agreement with the UV–Vis experiments, which also point to the formation of copper oxide after high temperature aging.