(89d) Mechanistic Differences Between Metal-Exchanged Zeolite SCR Catalysts, and Their Practical Implications

In the last decade, metal-exchanged zeolites became the technology of choice for meeting the remarkably stringent and rapidly evolving diesel emission regulations worldwide. These catalysts are used in the reaction of selective catalytic reduction of NOx with ammonia derived from urea, demonstrating outstanding efficiency across a broad range of operating conditions. Out of a large group of candidate technologies, commercial application converged to several major types of Cu- and Fe-exchanged catalysts. Due to being a part of a highly active and dynamic system, which features multiple catalysts, sensors, and actuators, and which is operated by the dedicated control and diagnostic algorithms, the successful application of these catalysts required detailed understanding of their performance and deactivation characteristics. In this presentation, we will highlight some of the significant mechanistic differences, which proved important to the performance, diagnostic characteristics, and durability of these metal-exchanged zeolites.