The [(NH 3 ) 4 Cu 2 O 2 ] 2+ -Peroxo Complex as the Key Intermediate for NH 3 -SCR Activity and Deactivation of Cu-CHA Catalysts.

• In NH3-SCR over Cu-CHA catalysts in the low-temperature range 150–300 °C, the activation of oxygen occurs via oxidation of a pair of mobile (NH3)2CuI-complexes located in the cages of the zeolite. In this step, a reactive [(NH3)4Cu2O2]2+-peroxo complex (μ-η2,η2-peroxo diamino dicopper(II)-complex) is formed. The chemistry of this complex determines several catalytic properties of the Cu-CHA catalyst. The reaction of NO with the [(NH3)4Cu2O2]2+-peroxo complex governs the NH3-SCR activity. A reaction of the [(NH3)4Cu2O2]2+-peroxo complex with ammonia hinders the reaction of NO with the complex, thus leading to an inhibition of the NH3-SCR reaction. Finally, the deactivation in presence of SO2 is due to a reaction of SO2 with the [(NH3)4Cu2O2]2+-peroxo complex, leading to the formation of Cu−S compounds in the catalyst. In this review, the characterization and the reactions of the [(NH3)4Cu2O2]2+-peroxo complex with NO, NH3, and SO2, and mean-field kinetic models based on first principles calculations for NH3-SCR activity and SO2 poisoning are discussed.

Subject headings

NATURVETENSKAP  -- Kemi -- Oorganisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Inorganic Chemistry (hsv//eng)

NATURVETENSKAP  -- Kemi -- Fysikalisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Physical Chemistry (hsv//eng)

NATURVETENSKAP  -- Kemi -- Organisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Organic Chemistry (hsv//eng)

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