April 2005
http://www.dieselnet.com/
SAE 2005 World Congress
The SAE 2005 World Congress was held this year on April 11-14 in
Detroit. Papers on diesel emission control, grouped into several
topical sessions, covered the newest developments in such
technologies as diesel oxidation catalysts (DOC), diesel particulate
filters (DPF), NOx adsorbers and lean NOx catalysts, urea-SCR, as
well as in emission control modeling.
Several papers on DOC technology discussed the new platinum-
palladium diesel oxidation catalyst formulations. The use of
palladium in diesel oxidation catalysts has been made possible with
the introduction of ultra low sulfur fuels, as palladium is much more
sensitive to sulfur poisoning than platinum. The new catalysts can be
formulated as a mixture of Pd on Zr-Ce material with Pt/Al2O3 (paper
number 2005-01-0476 by S. Verdier). It was shown that while the
addition of Pd to the Pt-based diesel catalyst can lower the activity
of the fresh catalyst, it results in improved thermal durability and
improved performance in aged catalysts (2005-01-1759, T. Nakane).
Another DOC durability aspect--phosphorus poisoning--was subject of
an interesting study by researchers from the Oak Ridge laboratory
(2005-01-1758, B. Bunting).
New and improved DPF materials have been reported by filter
manufacturers. Corning presented its new aluminum titanate-based
wall-flow filter substrate (2005-01-0583, C. Warren). The filter is
designed for light-duty applications in Europe. Ibiden talked about
its new alumina-doped SiC formulation, still under development, of
improved oxidation resistance (2005-01-0579). The material may allow
for soot mass loads as high as 14 g/l. A number of papers discussed
catalyzed particulate filters--a common component in OEM filter
systems for both light-and heavy-duty applications. It was confirmed
that decreased NOx levels, such as those occurring in newer engines,
make it more challenging to oxidize the collected soot (2005-01-0663,
N. Soeger). Improved DPF catalyst coating techniques for EU cars were
reported, which may allow to integrate the functions of a separate
DOC and DPF into the particulate filter catalyst, thus resulting in a
simpler, one component filter system (2005-01-1756, M. Pfeifer).
Component manufacturers presented their work on systems for exhaust
injection of diesel fuel to assist in DPF regeneration
(2005-01-0671). New developments in retrofit DPF systems included an
active filter for TRU engines (2005-01-0662, A. Mayer) and a fuel
additive dosing system for additive-regenerated filters for
heavy-duty engines (2005-01-0669, P. Richards).
There is ongoing development in lean NOx catalysts, with focus on the
Ag/Al2O3 formulation (2005-01-1082, J. Thomas). High NOx reduction
rates are possible, but specialized reductants, such as alcohols, are
needed. The lean NOx catalyst performance is also improved by the
presence of hydrogen.
Studies on NOx adsorber catalysts (NAC) ranged from basic work on Pt-
Ba interactions (2005-01-1085) through NAC control strategies (2005-
01-1090, D. Sunohara) to engine bench evaluations (2005-01-1084, P.
Blakeman). The latter study, as well as a number of other papers,
emphasized the need for improvement in NAC desulfation strategies. An
update was presented on the US DOE sponsored development of a Tier 2
Bin 5 compliant diesel car, with the development work conducted by
the FEV (2005-01-1755, M. Tatur). The vehicle--a EU 3 car with a 1.9
l prototype diesel engine fitted with an NAC/DPF system--is perhaps
the most advanced prototype targeting the US EPA Tier 2 standards.
After aging equivalent to 50,000 miles, the vehicle could meet the
Tier 2 Bin 5 NOx, PM, and CO limits, but failed NMHC emissions.
Another concept to meet the Tier 2 standards in light-duty vehicles
was presented by the SwRI, which involved advanced combustion
strategies including low temperature combustion (LTC) and premixed
controlled compression ignition (PCCI) (2005-01- 1091, G. Neely).
In the urea-SCR session, a report was presented on the commercial SCR
system for heavy-duty trucks launched last year in Japan by Nissan
Diesel (2005-01-1860, K. Hirata). The system utilized a zeolite SCR
catalyst (health concerns exist in Japan against vanadium catalysts)
with an upstream NO2 generating catalyst and a downstream NH3
oxidation catalyst. The engine was also equipped with EGR to control
NOx at low temperatures. Fuel economy advantage of 4% was measured
relative to an equivalent truck fitted with an EGR/DPF system. The
paper describes the SCR system and its components, emission
performance, as well as the OBD strategy. Other SCR papers included a
summary of the SCR demonstration program carried by Mack in the USA
(2005-01-1861, M. Block); development of a new, promising
titania/precious metal-based SCR catalyst formulation by Japan's
Babcock Hitachi (2005-01-1859); and a description of the ammonium
formate reductant developed as a replacement of urea for cold climate
applications (2005-01-1856).
Technical sessions:
http://www.sae.org/congress/techbiz/
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