Deactivation mechanisms of iron-exchanged zeolites for NH3-SCR applications

• Deactivation mechanisms of Fe-BEA as NH3-SCR catalyst.
• Regeneration using high temperature hydrogen treatment.
• Hydrothermal deactivation.
• Chemical deactivation due to phosphorous and potassium exposure.
• Kinetic deactivation model.

Emissions of nitrogen oxides (NOX) from internal combustion engines are a major contributor to global air pollution, and with more stringent environmental legislations, the need for more efficient and durable NOX emission control systems increases. In the present paper, experimental results of hydrothermal deactivation and regeneration using hydrogen, and chemical deactivation due to phosphorous and potassium exposure of Fe-BEA as NH3-SCR catalyst are summarized. Based on the experimental results, a multi-site kinetic model is developed to predict deactivation of Fe-BEA. The kinetic model predicts deactivation well by decreasing the number of active sites in the model representing loss of active iron sites due to migration or chemical blockage of the sites. It is discussed that by performing a systematic study of different deactivation mechanisms, a deactivation expression for the active sites could be formulated.

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