Zirconia-based compositions for use in passive NOx adsorber devices

Abstract

A passive NOX adsorbent includes: palladium, platinum or a mixture thereof and a mixed or composite oxide including the following elements in percentage by weight, expressed in terms of oxide: 10-90% by weight zirconium and 0.1-50% by weight of least one of the following: a transition metal or a lanthanide series element other than Ce. Although the passive NOX adsorbent can include Ce in an amount ranging from 0.1 to 20% by weight expressed in terms of oxide, advantages are obtained particularly in the case of low-Ce or a substantially Ce-free passive NOx adsorbent.

Dependencies are inferred from the claim text.