Characterization of Pd-Based FCC CO/NO(X) Control Additives By in Situ FTIR And Extended X-Ray Absorption Fine Structure Spectroscopies

Journal Article · Thu May 28 04:00:00 EDT 2009 · Catal. Today 127:176,2007

OSTI ID:953534

Alexeev, O S; Krishnamoorthy, S; Ziebarth, M S; Yaluris, G; Roberie, T G; Amiridis, M D

Pd n{sup +}/Ce n{sup +}/Na{sup +}/{gamma}-Al{sub 2}O{sub 3}-type materials used as FCC additives for CO/NO{sub x} control were characterized by extended x-ray absorption fine structure (EXAFS) spectroscopy and in situ FTIR. The EXAFS data indicate that in freshly prepared samples palladium is present in the form of high dispersed PdO species. Reduction with H{sub 2} at 500{sup o}C leads to the formation of small Pd clusters incorporating on average approximately six to eight metal atoms at a Pd-Pd bond distances of 2.76 {angstrom}. All components of these materials can interact with NO and promote the formation of nitrate/nitrite species, essentially 'trapping' NO{sub x} species on the catalyst surface. However, the Na{sup +} species dominate the surface chemistry and readily form sodium nitrates with a characteristic IR band at 1370--1385 cm{sup -1}. Finally, hydroxyls from the support are also actively participating in the formation of HNO{sub x} type compounds with characteristic stretching vibrations in the 3500-3572 cm{sup -1} region.

• Research Organization: Stanford Linear Accelerator Center (SLAC)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC02-76SF00515
• OSTI ID: 953534
• Report Number(s): SLAC-REPRINT-2009-349
• Journal Information: Catal. Today 127:176,2007, Journal Name: Catal. Today 127:176,2007 Journal Issue: 1-4 Vol. 127; ISSN 0920-5861; ISSN CATTEA
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ABSORPTION
ADDITIVES
AIR POLLUTION CONTROL
ATOMS
CARBON DIOXIDE
CATALYSTS
CATALYTIC CRACKING
CHEMISTRY
CONTROL
DATA
FINE STRUCTURE
MATERIALS
METALS
NITROGEN OXIDES
Other
OTHER
PALLADIUM
REDUCTION
SODIUM NITRATES
SPECTROSCOPY
SUPPORTS
SURFACES
TRAPPING