The invention provides low temperature NO2 trap compositions useful
for adsorbing NO2 from a gas stream at lower temperatures, and releasing
the NO2 at higher temperatures. The low temperature trap compositions
are useful for incorporation into a diesel exhaust system equipped with a soot
filter. The NO2 from the diesel exhaust can be stored when the exhaust
temperature is cool, e.g., during startup and at times of low load, and released
when the exhaust is at higher temperatures. The released NO2 serves
as an effective oxidant for the combustion of soot deposited on the soot filter.
These temperatures are significantly lower than those required for the combustion
of soot using O2 as an oxidant. The methods of the invention thereby
provide a method for regenerating the soot filter within operating temperature
ranges typical of diesel engine exhaust systems.
