Characterization of Pd-based FCC CO/NOx Control Additives by in situ FTIR and Extended X-ray Absorption Fine Structure Spectrscopies

Journal Article · Mon Jan 01 04:00:00 EST 2007 · Catalysis Today

DOI:https://doi.org/10.1016/j.cattod.2007.05.016· OSTI ID:930011

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

Pd{sup n+}/Ce{sup n+}/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 highly dispersed PdO species. Reduction with H{sub 2} at 500 C leads to the formation of small Pd clusters incorporating on average approximately six to eight metal atoms at a Pd-Pd bond distance 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: Brookhaven National Laboratory (BNL) National Synchrotron Light Source
• Sponsoring Organization: Doe - Office Of Science
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 930011
• Report Number(s): BNL--80625-2008-JA
• Journal Information: Catalysis Today, Journal Name: Catalysis Today Journal Issue: 39451 Vol. 127; ISSN CATTEA; ISSN 0920-5861
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
54 ENVIRONMENTAL SCIENCES
ADDITIVES
AIR POLLUTION CONTROL
ALUMINIUM OXIDES
CARBON MONOXIDE
CATALYSIS
CATALYTIC EFFECTS
CERIUM
NITROGEN OXIDES
PALLADIUM
SODIUM
national synchrotron light source