Cu-CHA zeolite-based catalysts for the selective catalytic reduction of NOx in exhaust diesel gas: addressing the issue of Sulfur Stability

We aim at building a scientific network to address the selective catalytic reduction of NOx in exhaust gas of diesel vehicles based on Cu-zeolite catalysts, which is the basis of the current technology implemented in diesel exhaust systems all over the world to meet the emission requirements imposed by law. These catalysts deactivate, i.e. the performance deteriorates with time, due to the high temperatures in the exhaust systems and the impact of the exhaust gas on the structure of the catalyst material. A notorious problem is the sensitivity of Cu-zeolites to the small amounts of SO2 that usually are present in a diesel exhaust gas, which limits their applicability an may also cause malfunction of an exhaust system. The goal of the network is to develop a fundamental molecular-level understanding of the processes that lead to the deterioration of the catalysts in general, with an enhanced focus on the impact of SO2, and to implement this knowledge in the development of improved materials for application in exhaust systems. We will address the deactivation of Cu-zeolite catalysts by combining four different approaches. First, state-of-the-art computational modeling based on density functional theory (DFT), to develop a detailed insight in the chemical processes leading to deactivation. Second, advanced spectroscopic characterization, including in-situ/operando techniques, to confirm the relevant chemical structures experimentally, and to be able to follow the processes that lead to deactivation. Third, microkinetic analysis to provide the necessary data to describe the deactivation process, and finally, the development of models that describe the deactivation processes with the aim to be implemented in the application for exhaust systems. The required competences and facilities will be made available to 4 early stage researchers (ESRs) in a network including two expert academic research groups, and two industrial units with complementary skills.