Process for manufacturing nox traps with improved sulfur tolerance

A method for treating exhaust gases from an internal combustion engine using a nitrogen oxide absorbent, said method comprising the steps of:

• exposing a nitrogen oxide absorbent material located in the exhaust gas passage of an internal combustion engine to engine exhaust gases having a lean of stoichiometric air/fuel ratio whereby said absorbent absorbs nitrogen oxides from said exhaust gas, said absorbent made by a method which comprises the steps of:
• providing a support material of alumina/ceria including at least 0.5 wt. % ceria;
• providing the material with barium and precious metal including at least platinum so as to provide at least 1.0 wt. % barium and 0.2 wt. % platinum on the material;
• and
• overcoating the material containing barium and precious metal with a layer of 0.5-5 wt. % lithium based on the total weight of the material;
• purging said absorbed nitrogen oxides from said absorbent by subjecting said absorbent to engine exhaust gases whose air/fuel ratio is stoichiometric or rich of stoichiometry.