1. Catalyst Efficiency: Impurities can block active sites on the catalyst, reducing its effectiveness. 2. Selectivity: Contaminants can lead to unwanted side reactions, producing undesired byproducts. 3. Longevity: Impurities can cause deactivation of the catalyst over time, necessitating frequent replacements. 4. Product Quality: High purity ensures that the final product is free from contaminants, which is particularly important in pharmaceuticals and fine chemicals.