Several signs can indicate that under washing is occurring:
Decreased catalytic activity: A noticeable drop in the rate of reaction can be a clear sign that active sites are being blocked. Change in selectivity: An increase in unwanted side products can indicate that impurities are affecting the catalytic process. Increased pressure drop: In fixed-bed reactors, an increase in pressure drop across the catalyst bed can suggest that pores are being blocked by contaminants.
