(784a) Cu/Chabazite Catalyst to Meet the Chemical and Mechanical Challenges for NOx Removal

Global attention has been drawn towards the utilization of lean burn and diesel engines as oppose to gasoline, due to the fact that they are more efficient in terms of fuel consumption and power. These more efficient engines, however, are still challenging to meet the emission regulation of harmful gas emission called nitrogen oxide (NO_x) due to excessive air-to-fuel ratio. The use of an ammonia-based selective catalytic reduction, NH₃-SCR, through the application of zeolite catalysts has been proven efficacious in terms of converting the harmful gases into nitrogen (N₂) and water (H₂O). Ultimately, we come to the task of finding catalysts that would be durable and cheap for the use of a diesel engine. Metal-exchanged molecular sieves with a Chabazite (CHA) structure has been extensively studied because of their superior NOx reduction activity, selectivity and hydrothermal stability (100 to 800^oC). Nevertheless, understanding of the structure-reactivity relationships such as the chemical nature and location of the catalytically active sites within the CHA framework, reaction intermediates, and reaction pathways of the SCR process are still not well understood.

In this study, the effect of Cu loading (0.5~6 wt%) and reaction temperatures on the catalytic activity (NH₃-SCR and NO oxidation) and productsâ?? selectivity were examined over a series of Cu exchanged CHA catalysts. A series of Cu exchanged CHA catalysts were synthesized by using the incipient wetness impregnation method and several spectroscopic techniques were applied to understand the relationship between catalysts structure and activity. In addition to the commercial zeolite catalysts, further studies of the catalyst will be done by preparation of Cu-exchanged two-dimensional zeolite model systems then examining the interaction of relevant molecule with the Cu-site. In this work, we will carry out experiments by using infrared reflection absorption spectroscopy (IRRAS) and ambient pressure XPS at the CSX-2 beamline of NSLS-II at Brookhaven National Laboratory.

ACKNOWLEDGMENT

We gratefully acknowledge the financial support for this study from SBU/BNL SEED grant and the Department of Materials Science & Engineering at Stony Brook University (SBU) through start-up research funding as well as Brookhaven National Lab and Advance Energy Centre at SBU for laboratory facilities.