A composition is provided that has heat resistance sufficient for use as a hydrocarbon adsorbent and desorbs hydrocarbons slowly with respect to an increase in temperature. The composition includes an alkali metal and a zeolite having a YFI structure. A content of the alkali metal is 1 to 40 mass % based on a total mass of the composition, and a content of the zeolite having a YFI structure is 99 to 60 mass % based on the total mass of the composition.

Disclosed herein are oxidation catalyst compositions comprising a first platinum group metal (PGM) component, a manganese (Mn) component, a first refractory metal oxide support material, and a metal component comprising yttrium, lanthanum, tin, magnesium, cerium, titanium, or a combination of any of the foregoing, wherein each of the first PGM component, the Mn component, and the metal component are supported on the first refractory metal oxide support material; catalyst articles coated with at least one such catalyst composition; and emission treatment systems including at least one such catalyst article.

An gas purification catalyst device having a catalyst coated layer formed on at least one base material, wherein: the catalyst coated layer includes a first catalyst coated layer on the upstream side of an exhaust gas flow, and a second catalyst coated layer on the downstream side of the exhaust gas flow; the first catalyst coated layer includes a hydrocarbon adsorbent and a catalytic precious metal; and the second catalyst coated layer includes a nitrogen oxide adsorbent and a catalytic precious metal.