Cu–Mn bimetal ion-exchanged SAPO-34 as an active SCR catalyst for removal of NOx from diesel engine exhausts

• The co-doping of Cu and Mn can maintain the crystal and physical structure of SAPO-34.
• The co-doping of Cu and Mn can increase the exchange amount of Cu and active centers.
• The co-doping of Cu and Mn can enhance the acidic strength.
• Cu-Mn/SAPO-34 catalyst shows high low-temperature deNOx activity.
• Cu-Mn/SAPO-34 shows high hydrothermal stability and resistance to HC.

Mn/SAPO-34, Cu/SAPO-34, and Cu-Mn/SAPO-34 were prepared through ion-exchanged method and used to remove NOx from diesel engine exhausts. The original crystal and physical structure of SAPO-34 is maintained in the catalysts. The ion-exchanged amount of Cu in Cu–Mn/SAPO-34 is higher than that in Cu/SAPO-34, and more Cu+ is formed as active center for low-temperature selective catalytic reduction (SCR). After co-doping of Cu and Mn, the acidic strength of the catalyst increases and formation of NH3NOx surface intermediate species is promoted. Cu–Mn/SAPO-34 exhibits high deNOx activity, hydrothermal stability, and resistance to hydrocarbon (HC).

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