Preparation of binary washcoat deposited on cordierite substrate for catalytic applications

The deposition of binary M–ZrO₂ (M = Al₂O₃, SiO₂ or TiO₂) as secondary support on cordierite substrate by dip-coating was investigated and the as-prepared M–ZrO₂/cordierite was characterized by means of XRD and SEM techniques. After two successive dip-coating processes, the highest washcoat loading of 25.1% was achieved in Al₂O₃–ZrO₂/cordierite, followed by 18.7% in TiO₂–ZrO₂/cordierite and then 17.4% in SiO₂–ZrO₂/cordierite. The optimal parameters to prepare Al₂O₃–ZrO₂ washcoat on cordierite were investigated in detail. After introduction of noble metal active components (Rh and Pd) to the secondary support, the obtained Rh/M–ZrO₂/cordierite and Pd/M–ZrO₂/cordierite were further tested as monolithic catalysts for the decomposition of nitrous oxide and the deep oxidation of benzene, respectively.