Plasma-assisted catalytic storage reduction system

Patent · Tue Jan 01 00:00:00 EST 2002

OSTI ID:874355

Penetrante, Bernardino M ^[1]; Vogtlin, George E ^[2]; Merritt, Bernard T ^[3]; Brusasco, Raymond M ^[3]

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1. San Ramon, CA
2. Fremont, CA
3. Livermore, CA

A two-stage method for NO.sub.x reduction in an oxygen-rich engine exhaust comprises a plasma oxidative stage and a storage reduction stage. The first stage employs a non-thermal plasma treatment of NO.sub.x gases in an oxygen-rich exhaust and is intended to convert NO to NO.sub.2 in the presence of O.sub.2 and hydrocarbons. The second stage employs a lean NO.sub.x trap to convert such NO.sub.2 to environmentally benign gases that include N.sub.2, CO.sub.2, and H.sub.2 O. By preconverting NO to NO.sub.2 in the first stage with a plasma, the efficiency of the second stage for NO.sub.x reduction is enhanced. For example, an internal combustion engine exhaust is connected by a pipe to a first chamber in which a non-thermal plasma converts NO to NO.sub.2 in the presence of O.sub.2 and hydrocarbons, such as propene. A flow of such hydrocarbons (C.sub.x H.sub.y) is input from usually a second pipe into at least a portion of the first chamber. The NO.sub.2 from the plasma treatment proceeds to a storage reduction catalyst (lean NO.sub.x trap) that converts NO.sub.2 to N.sub.2, CO.sub.2, and H.sub.2 O, and includes a nitrate-forming catalytic site. The hydrocarbons and NO.sub.x are simultaneously reduced while passing through the lean-NO.sub.x trap catalyst. The method allows for enhanced NO.sub.x reduction in vehicular engine exhausts, particularly those having relatively high sulfur contents.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• DOE Contract Number: W-7405-ENG-48
• Assignee: The Regents of the University of California (Oakland, CA)
• Patent Number(s): US 6374595
• OSTI ID: 874355
• Country of Publication: United States
• Language: English

Related Subjects

plasma-assisted
catalytic
storage
reduction
two-stage
method
nosubx
oxygen-rich
engine
exhaust
plasma
oxidative
stage
employs
non-thermal
treatment
gases
intended
convert
nosub2
presence
osub2
hydrocarbons
lean
trap
environmentally
benign
nsub2
cosub2
hsub2
preconverting
efficiency
enhanced
example
internal
combustion
connected
pipe
chamber
converts
propene
flow
csubx
hsuby
input
portion
proceeds
catalyst
nitrate-forming
site
simultaneously
reduced
passing
lean-nosubx
allows
vehicular
exhausts
sulfur
contents
internal combustion
combustion engine
engine exhaust
non-thermal plasma
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