NO
x
adsorber catalysts are leading candidates for improving NO
x
aftertreatment in diesel exhaust. The major challenge in the use of adsorbers that capture NO
x
in the form of nitrates is their susceptibility to sulfur poisoning. Sulfur, which is present in diesel fuel, adsorbs and accumulates as sulfate (SO
4-2
) at the same adsorption sites as NO
x
, and, since it is more stable than nitrates, inhibits the ability of the catalyst to adsorb NO
x
. It is found that high temperature (> about 650 °C) in the presence of a reducing gas is required to release sulfur rapidly from the catalyst. Since the peak temperatures of diesel engine exhaust are below 400 °C, additional heat is required to remove the sulfur. This work describes a reformate-assisted “sulfur purge” method, which employs heat generated inside the NO
x
trap catalyst by exothermic chemical reactions between the oxygen in diesel exhaust and injected reformate (H
2
+ CO). Our results with a laboratory gas bench system show that catalyst desulfation is successful following a desulfation schedule with an inlet gas temperature of about 300 °C. In addition, we have examined impact of temperature, duration of exposure, and reformate-based gas compositions employed for rich-gas desulfation on NO
x
adsorber efficiency.
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