Support composition based on a cerium oxide, a zirconium oxide and a scandium or rare earth oxide and use for treating exhaust gas

摘要

A composition is disclosed for reducing nitrogen oxide emissions from gases which comprises a support based on a cerium oxide, a zirconium oxide and an oxide of scandium or a rare earth other than cerium, and a supported phase based on manganese and at least one other element which is an alkali metal, alkaline-earth metal or a rare earth.