Structural phase transitions and lean NO removal activity of copper-modified alumina

Conference · Tue Dec 31 04:00:00 EST 1996

OSTI ID:442176

Ozawa, Masakuni; Suzuki, Suguru ^[1]; Loong, C K; Richardson, Jr, J W; Thomas, R R ^[2]

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1. Nagoya Inst. of Technology, Tajimi (Japan)
2. Argonne National Lab., IL (United States)

Copper-modified alumina catalysts, designed for NO removal under lean-burn engine conditions, have been investigated from the viewpoint of the structural phase transition and thermal stability. The structural changes of crystalline components heat-treated at temperatures from 500{degrees}C to 1100{degrees}C were characterized by neutron diffraction (ND) method. In the as-prepared materials, powder-diffraction patterns revealed a mixture of crystalline {gamma}-Al{sub 2}O{sub 3} and CuO, and electron spin resonance (ESR) data showed well-dispersed Cu{sup 2+} cations coordinated by O atoms in an open-octahedron geometry. ND measurements confirmed the elimination of the CuO phase above 800{degrees}C, and suggested the stabilization of a {delta}-phase of alumina by 10 mol% CuO-doping at 900-1000{degrees}C. This Cu-alumina catalyst which was subjected to heat treatment at 900{degrees}C in air showed a 20% lean de-NOx removal efficiency in a test using a model exhaust gas mixture of space velocity =00, 000 h{sup -1}.

• Research Organization: Argonne National Lab., IL (United States)
• Sponsoring Organization: USDOE Office of Energy Research, Washington, DC (United States); Nagoya Inst. of Tech. (Japan)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 442176
• Report Number(s): ANL/IPNS/CP--90668; CONF-9611133--3; ON: DE97001997
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
66 PHYSICS
AIR POLLUTION CONTROL
ALUMINIUM OXIDES
CATALYSTS
CATALYTIC EFFECTS
COPPER
ELECTRON SPIN RESONANCE
EXHAUST GASES
HEAT TREATMENTS
NEUTRON DIFFRACTION
NITRIC OXIDE
PHASE TRANSFORMATIONS
STABILITY
SURFACE AREA