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Title: Formation of NO+ and its possible roles during the selective catalytic reduction of NOx with NH3 on Cu-CHA catalysts

Journal Article · · Catalysis Today
 [1];  [2];  [3];  [2];  [2];  [2];  [2]
  1. Johnson Matthey Inc., Wayne, PA (United States)
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Inst. for Integrated Catalysis
  3. Johnson Matthey Inc., Wayne, PA (United States); Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Inst. for Integrated Catalysis
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The catalytic activities of small-pore Cu-CHA and large-pore Cu-BEA catalysts for the selective catalytic reduction of NO with NH3 were measured at a very high flow rate. Cu-CHA clearly exhibited much higher intrinsic SCR activity and lower N2O selectivity. In situ DRIFT spectra were recorded during the adsorption and desorption following NO and (NO+O2) exposure to fully oxidized samples in a flow cell. The results are in agreement with what we have reported previously based on in situ transmission IR studies of partially reduced samples. Both suggest that different SCR reaction pathways might exist on these two catalysts and that NO+ could be an important reaction intermediate for Cu-CHA. Detailed IR studies with various isotopically labeled gas mixtures of (NO+O2), (15NO+O2), (NO+18O2) and (15N18O+O2) were conducted to understand the origin of the surface adsorption complexes on Cu-CHA. Formation of NO+ was not the consequence of a simple charge transfer reaction, NO+Cu2+=NO+ + Cu+. Instead, O2 was found to be essential in changing the oxidation state of N from +2 to +3 although it did not participate in new N$$-$$O bond formation. In conclusion, the majority of the adsorbed NO+ maintained its isotopic origin of the feed gas.

Research Organization:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Biological and Environmental Research (BER); USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V)
Grant/Contract Number:
AC05-76RL01830
OSTI ID:
1415772
Alternate ID(s):
OSTI ID: 1702798
Report Number(s):
PNNL-SA-129558; PII: S0920586117308441; TRN: US1800847
Journal Information:
Catalysis Today, Vol. 320; ISSN 0920-5861
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 27 works
Citation information provided by
Web of Science

Figures / Tables (11)

Table 1(p. 3)table Table 1
Fig 1.(p. 4)figure Fig 1.
Fig. 2(p. 4)figure Fig. 2
Fig. 3(p. 5)figure Fig. 3
Fig. 4(p. 5)figure Fig. 4
Fig. 5(p. 6)figure Fig. 5
Fig. 6(p. 7)figure Fig. 6
Table 2(p. 7)table Table 2
Fig. 7(p. 8)figure Fig. 7
Fig. 8(p. 9)figure Fig. 8
Fig. 9(p. 9)figure Fig. 9

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Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Zeolite supported Cu catalysts
Cu-CHA catalysts
Selective catalytic reduction of NOx
NO+ formation
Surface NO adsorption complexes