>> i was referring to the possibility of PGM substitution with something entirely different. that's what is not in the cards imo. their efficiency as catalysts can't be reproduced with other materials as of yet. <<
WaRD’S ENGINE
AND VEHICLE TECHNOLOGY UPDATE
Powertrain/Chassis/Electronic
Design/Material/Manufacturing
VOLUME 25, NUMBER 22 / NOVEMBER 15, 1999
With platinum group metals (PGM) platinum and palladium now in excess of $400 an ounce and headed soon to $500, according to some commodities analysts, the automotive industry and its suppliers are scrambling fast to come up with substi-tutes, as well as practical answers for lean/diesel engine emissions control. During the recent Society of Automotive Engineers (SAE) Truck and Bus meeting in Detroit, Johnson Matthey’s Barry Cooper is asked what level of short-age of PGMs is ahead. He says that Russia controls the palladium supply situation and
that there is a 100-year supply of platinum in Africa, but with increased demand for diesel, fuel cell and expanded world gaso-line engine use, the platinum producers are “happily looking forward to sinking new
mine shafts.” Considering that the “happily” factor translates into higher prices and profits, and that the trend will be accelerated by regulator focus on new applications and tighter new-vehicle emissions standards (rather than the more important problem of older-vehicle repair), interest in options is intense.
Among the possibilities in various stages of development are the corona dis-charge
system by Litex (see WEVTU — Oct. 1, ‘99, p.3 and graphic at right) and Delphi Automotive Systems’ non-thermal plasma—as well as non-PGM catalysts.
WEVTU has learned from one industry source that the Corona discharge system
with only 25 Watts of input current—in con-junction with a conventional 3-way catalyst
applied to a gasoline engine—has shown that half the normal precious-metal loading
delivers equal performance versus normal loading, that the system is sulfur tolerant and it may extend the life of oxygen sensors (costly to replace in older vehicles).
An automaker specialist in corona/plasma technology comments to WEVTU that the Litex system, “sounds too good to be true.” The total system is said to have an
OE cost of $70. Litex says its corona discharge unit (about the size of a spark plug), positioned
in the engine-out exhaust stream, increases the reactivity of the gases in the catalyst
unit. Perhaps of even greater importance for those seeking relief from fast-increasing
PGM prices is a catalyst system being devel-oped by Delphi, which contains no PGMs.
Delphi engineer Joachim Kupe tells WEVTU that 77% reduction in diesel NOx
has been demonstrated with the proprietary non-PGM catalyst in conjunction with a
non-thermal plasma reactor (NTP) which increases the reactivity of exhaust gases
ahead of the new catalyst. An 80% NOxreduction is the development target.
Nitrogen dioxide (NO 2 ) produced by the reactor also can reduce particulates by
90% when combined with a separate filter, which is continuously regenerated by the reactive gases.
The current developmental NTP reac-tor has an active internal volume of 1.26L, with total outside dimensions about twice this, but is expected to be reduced in time. Mr. Kupe says the NTP reactor system power input requirement at the present stage of development is 400 Watts for a 2Ldiesel operating at idle. He declined to give
power data for road load or other condi-tions. Asked how a vehicle maker might best configure a total system for diesel NOx and PM control, i.e. whether the NOx catalyst unit would preceed or follow the PM filter,
Mr. Kupe says that fit would be up to Delphi’s customer. Asked about the outlook for use of
Delphi’s NTP reactor and non-PGM catalyst technology applied to conventional 3-way
catalyst gasoline engines, Mr. Kupe says information on this will be presented in
June, 2000 at engineering meetings in the U.S. and France. In this connection, it must be consid-ered whether it may be possible to employ the low-power advantages of the Litex sys-tem with Delphi’s non-PGM catalyst as a
way out of the PGM cost problem. Mr. Kupe adds another dimension to
the overall issue by saying Delphi’s NTP reactor is sulfur tolerant and that indica-tions
from development work to date indi-cate the non-PGM catalyst has the same
advantage. Also in the running with sulfur toler-ance is an “Electrocat (self-cleaning) diesel particulate filter” developed by AEA in the United Kingdom, which employs an internal non-thermal reactor for which the company
has developed a claimed 90% efficient 42-volt alternator. Also up for grabs may be the age-old question of retrofit systems for older vehi-cles that have good residual transportation value. q
— Bob Brooks
Reprinted with permission of Ward’s
Engine And Vehicle Technology Update.
Escalating PGM costs puts focus on alternatives
FUELS/EMISSIONS |
