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Accession Number DE2012-1043312
Title Nano Catalysts for Diesel Engine Emission Remediation.
Publication Date Jun 2012
Media Count 43p
Personal Author C. K. Narula D. Mullins M. M. Debusk S. M. Mahurin Z. Wu
Abstract The objective of this project was to develop durable zeolite nanocatalysts with broader operating temperature windows to treat diesel engine emissions to enable diesel engine based equipment and vehicles to meet future regulatory requirements. A second objective was to improve hydrothermal durability of zeolite catalysts to at least 675 C. The results presented in this report show that we have successfully achieved both objectives. Since it is accepted that the first step in NO(sub x) conversion under SCR (selective catalytic reduction) conditions involves NO oxidation to NO(sub 2), we reasoned that catalyst modification that can enhance NO oxidation at low-temperatures should facilitate NO(sub x) reduction at low temperatures. Considering that Cu-ZSM-5 is a more efficient catalyst than Fe-ZSM-5 at low-temperature, we chose to modify Cu-ZSM-5. It is important to point out that the poor low-temperature efficiency of Fe-ZSM-5 has been shown to be due to selective absorption of NH(sub 3) at low-temperatures rather than poor NO oxidation activity. In view of this, we also reasoned that an increased electron density on copper in Cu-ZSM-5 would inhibit any bonding with NH(sub 3) at low-temperatures. In addition to modified Cu-ZSM-5, we synthesized a series of new heterobimetallic zeolites, by incorporating a secondary metal cation M (Sc(sup 3+), Fe(sup 3+), In(sup 3+), and La(sup 3+)) in Cu exchanged ZSM-5, zeolite-beta, and SSZ-13 zeolites under carefully controlled experimental conditions. Characterization by diffuse-reflectance ultra-violet-visible spectroscopy (UV-Vis), X-ray powder diffraction (XRD), extended X-ray absorption fine structure spectroscopy (EXAFS) and electron paramagnetic resonance spectroscopy (EPR) does not permit conclusive structural determination but supports the proposal that M(sup 3+) has been incorporated in the vicinity of Cu(II).
Keywords Absorption
Aging
Bonding
Catalysts
Cations
Copper
Diesel engines
Diffraction
Electron density
Electron spin resonance
Emission
Fine structure
Modification
Oxidation
Spectroscopy
Synthesis
X-ray diffraction
Zeolites

 
Source Agency Technical Information Center Oak Ridge Tennessee
NTIS Subject Category 81J - Reciprocation & Rotating Combustion Engines
68 - Environmental Pollution & Control
Corporate Author Oak Ridge National Lab., TN.
Document Type Technical report
Title Note N/A
NTIS Issue Number 1226
Contract Number DE-AC05-00OR22725

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