The Effect of ZrO₂ on the Rh/γ-Al₂ O₃ Catalyst for NO Catalytic Reduction

The effect of ZrO₂ additives on Rh/γ-Al₂ O₃ was studied. The TPR, XRD, BET surface area and the catalytic activity of NO+C₂ H₄ and NO+C₂ H₄ +O₂ reactions were measured for the catalysts with variety of crystal phases and doping manners of ZrO₂ .It is found that the ZrO₂ possesses the ability of depressing the interaction between Rh³⁺ and γ-Al₂ O₃ and retarding the phase transition of γ-Al₂ O₃ to some extent. The reaction activity of NO+C₂ H₄ is pronounced enhanced during ZrO₂ doped onto the Rh/γ-Al₂ O₃ after aging at 850 ℃ in atmosphere for 2h than that of the Rh/γ-Al₂ O₃ , while the activity of SCR for the samples is low and the sample containing ZrO₂ is lower than that of the Rh/γ-Al₂ O₃ . It implicates that the re action mechanism is quite different between NO+C₂ H₄ and NO+C₂ H₄ +O₂ . The competitive full oxidation of C24promoting by ZrO₂ is suggested.