Several factors contribute to the shortened life of a catalyst:
1. Poisoning: This occurs when foreign substances, known as poisons, bind irreversibly to the active sites of the catalyst, rendering them inactive. Common poisons include sulfur, lead, and certain organics.
2. Fouling: Fouling happens when contaminants from the reaction mixture deposit on the catalyst surface, blocking active sites and reducing accessibility. This is common in reactions involving heavy hydrocarbons or tars.
3. Sintering: Sintering is the process by which catalyst particles agglomerate or grow in size, reducing the surface area available for reactions. This typically occurs at high temperatures and can significantly reduce catalyst activity.
4. Thermal Degradation: Prolonged exposure to high temperatures can cause structural changes in the catalyst material, leading to a loss of activity. This is a common issue in high-temperature processes such as steam reforming.
5. Hydrothermal Degradation: In reactions involving steam or water, hydrothermal degradation can occur. This involves the breakdown of the catalyst material due to the presence of steam, often seen in zeolite catalysts.
