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

Results in brief

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

Emission of nitrogen oxides (NOx) is an important contributor to air pollution world-wide. The main sources of NOx emissions are power plants and combustion engines. To reduce NOx emissions from vehicles, catalytic exhaust systems are used. The focus of CHASS is on freight transport, an important driving force of EU economy but also a contributor to emissions, with consequences on citizen’s health and social costs. NH3-SCR (Ammonia Selective Catalytic Reduction) is an important technology to mitigate unwanted NOx emissions from diesel engines, using Cu-zeolites as catalysts. Cu-CHA shows an excellent performance in the low temperature range (150-300 °C)., which is important in view of the development of engines with improved fuel efficiency. Despite the superior stability of Cu-CHA, repeated exposures to high temperature and the harsh environment in exhaust systems still cause deactivation, i.e. the performance deteriorates with time. Small amounts of sulphur dioxide, a common component in diesel exhaust gas, can result in deactivationat low temperature. As deactivation may cause malfunction, the applicability of Cu-CHA requires ultra-low Sulphur diesel. Even then, exhaust systems must be designed to handle possible deactivation. The CHASS project has generated knowledge to enhance the performance of Cu-zeolite for the abatement of NOx by NH3-SCR, with the following specific objectives: - Understanding the interaction of sulphur oxides with Cu-CHA at different operating conditions at the atomic level. - Determine the influence of sulphur oxides on the reaction. - Understanding the processes leading to hydrothermal aging of Cu-zeolites at the atomic level. - Characterization and identification of the critical atomic structures responsible for hydrothermal aging. - Determine the influence of hydrothermal aging on the deactivation by sulphur oxides. - Development of kinetic model(s) for activity, deactivation, and performance of Cu-zeolites for NH3-SCR, including the effects of sulphur oxides and hydrothermal aging, based on atomistic first principles data, applicable for commercial exhaust systems.

Data: CORDIS, © European Union

Project objective

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.

Original text from CORDIS.

Participants

UNIVERSITA DEGLI STUDI DI TORINO · TorinoCoordinatorItaly
CHALMERS TEKNISKA HOGSKOLA AB · GoteborgSweden
UMICORE AG & CO KG · Hanau WolfgangGermany
UMICORE DENMARK APS · HORSHOLMDenmark

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

Results in brief

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

Project objective

Participants

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