Selective nox reduction catalyst

Abstract

A NOx catalyst is provided that can realize a favorable NOx reduction in a broad temperature region and that can lighten the overhead involved in production. The NOx catalyst has active components exhibiting a selective reduction activity for NOx, wherein the active components exhibiting the selective reduction activity contains a high-temperature active component having a relatively high NOx reduction activity at high temperatures and a low-temperature active component having a relatively high NOx reduction activity at low temperatures; and the high-temperature active component and the low-temperature active component are disposed in a mixed state in a primary particle of the catalyst particle, and an active component ratio on a surface side of the primary particle is larger than an active component ratio on an interior side of the primary particle, with the active component ratio being is a ratio of a concentration of the high-temperature active component to a concentration of the low-temperature active component in the primary particle.