Several signs can indicate that maintenance is needed:
1. Decreased Activity: A significant drop in catalytic activity is a clear sign. 2. Increased Pressure Drop: A rising pressure drop across the catalyst bed suggests fouling or blockage. 3. Change in Selectivity: An unexpected change in the product distribution can indicate catalyst deactivation. 4. Abnormal Temperature Profiles: Deviations in the expected temperature profile can signal issues.
