P-modified gamma- Al2O3/alpha-Al2O3 Foams with High Porosity as Palladium-Catalyzed Carriers

A novel method for the preparation of a-alumina foams with P-gamma-Al2O3 modified coating for the palladium catalysts was proposed. The polyurethane template method was used and the preparation parameters were optimized. The apparent porosity of the ceramic foam is 90.28%, the bulk density is 0.45 g center dot cm(-3), and the strength of ceramic foam is satisfying. The P-modified gamma-Al2O3 coating was prepared on the a-alumina foam, and then the active catalytic phase (Pd) was loaded by ultrasound-assisted impregnation. Results show that the P-containing coating increases the surface area and weakly acidic sites of the inert foam while decreasing the proportion of strongly acidic sites. Compared with the uncoated foam, the foam with modified coating can easily load the active phase. In addition, the loaded Pd metal can hardly be oxidized, and the catalytic conversion temperature (T 50, T 90) of CO reduces by about 50 degrees C. This research presents the great practical potential of low-cost modified alpha-Al2O3 ceramic foams in the palladium catalyst production.