Mechanistic understanding of zeolite deactivation pathways
EMSL Project ID
33216
Abstract
Three zeolite powders (Fe-MFI, Cu-MFI, and Fe-BEA) commonly used in SCR NOx reduction will be hydrothermally aged in air using a variety of temperatures, aging times and water concentrations in a Caterpillar Inc. bench oven. It is proposed that the aged powders will be characterized at PNNL-EMSL using High Resolution Transmission Electron Microscopy (HR-TEM) and solid state Nuclear Magnetic Resonance (NMR). HR-TEM will examine the physical migration of alumina and metals to aggregate species on the exterior of the zeolites. Solid-state NMR, specifically 27Al NMR, will be used to examine changes in the Al co-ordination in order to determine the relative amount of dealumination compared to a fresh analog and subsequently the degree to which the incorporated Cu or Fe is affected by the aging. Critical to the implementation of urea-SCR catalysts is a detailed understanding of the deactivation processes of these catalysts in order to develop robust and market acceptable catalytic systems. Urea-SCR catalysts are the optimal technology advocated for the control of NOx emission from heavy duty diesel engines and for Tier 2 Bin 5 emission requirements for light duty diesel engines. This fundamental research will enable NOx emissions reduction in vehicles for the future and is a topic mentioned in the current developing economic stimulus package and a means to create future green jobs.EMSL is uniquely positioned at the cutting edge in the characterization of materials/catalysts with all the necessary components: the scientific experts, the latest characterization tools and support from scientists in the Institute of Interfacial Catalysis. It was in a paper in Catalysis Today that Ja Hun Kwak and Chuck Peden (at EMSL) demonstrated for the first time an elligant means to utilize NMR to provide semi-quantitative numbers on de-alumination of Cu-zeolites. Fe zeolites have the additional challenge of the possibility to form paramagnetic species that would accelerate the relaxation of the NMR spins so much as to render NMR spectra problematic.
Project Details
Project type
Exploratory Research
Start Date
2009-03-27
End Date
2010-03-28
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Cheng Y, C Lambert, DH Kim, JH Kwak, SJ Cho, and CHF Peden. 2010. "The Different Impacts of SO2 and SO3 on Cu/Zeolite SCR Catalysts." Catalysis Today 151(3-4):266-270. doi:10.1016/j.cattod.2010.01.013
Kwak JH, RG Tonkyn, DH Kim, J Szanyi, and CHF Peden. 2010. "Excellent activity and selectivity of Cu-SSZ-13 in the selective catalytic reduction of NOx with NH3." Journal of Catalysis 275(2):187-190. doi:10.1016/j.jcat.2010.07.031
Mei D, JH Kwak, J Szanyi, Q Ge, and CHF Peden. 2010. "Catalyst Size and Morphological Effects on the Interaction of NO2 with BaO/?-Al2O3 Materials ." Catalysis Today 151(3-4):304-313. doi:10.1016/j.cattod.2010.01.005
Peden CHF, JH Kwak, SD Burton, RG Tonkyn, DH Kim, JH Lee, HW Jen, G Cavattaio, Y Cheng, and C Lambert. 2012. "Possible Origin of Improved High Temperature Performance of Hydrothermally Aged Cu/Beta Zeolite Catalysts." Catalysis Today 184(1):245-251. doi:10.1016/j.cattod.2011.11.008