Influence of Al sub(2)O sub(3)/CeZrAl composition on the catalytic behavior of Pd/Rh catalyst

Al sub(2)O sub(3) and Ce-Zr mixed oxides are important components of the automobile three-way catalyst. Various contents modifying A1 sub(2)O sub(3)(GAL) was physically introduced into Ce-Zr-Al mixed oxides (CZA) to form series of GAL/CZA composition. The Pd/Rh catalyst samples were prepared by different GAL/CZA support loading Pd/Rh, then aged at 950 degree C for 6 h. The catalytic behavior of different Pd/Rh catalyst samples was studied. Surface area, oxygen storage capacity (OSC) and H sub(2) adsorption capacity (TPR) of fresh and aged samples were examined by means of BET and H sub(2)-TPR. The analysis results of surface area and chemical absorption reduction showed that GAL content in GAL/CZA composition was the main effect on surface area stability of Pd/Rh catalyst. Compared with pure CZA, CZA by mixing physically with GAL could promote the surface area and stability of Pd/Rh catalyst. On the other hand, higher OSC and OSC stability should depend on CZA content in GAL/CZA composition. Compared with pure GAL, higher CZA content in GAL/CZA can promote the OSC and OSC stability of Pd/Rh catalyst. TPR showed that the optimal range of composition (CZA>60%) could obtain high reduction activity. GAL and CZA had a synergistic effect on the surface area and OSC of catalyst. The suitable mixing ratio of GAL and CZA in GAL/CZA could simultaneously get more surface area and OSC to make better catalytic activity of Pd/Rh catalyst.