| 摘要 |
<P>PROBLEM TO BE SOLVED: To suppress a noble metal from growing in grains at high temperatures in a catalyst carrying the noble metal on CeO<SB>2</SB>-ZrO<SB>2</SB>double oxide powder. <P>SOLUTION: The proportion C<SB>Ce</SB>(wt.%) of CeO<SB>2</SB>and the proportion C<SB>Zr</SB>(wt.%) of ZrO<SB>2</SB>on the surface of the double oxide powder satisfy the relation of 0.5≤C<SB>Zr</SB>/C<SB>Ce</SB>≤1.5. The noble metal is deposited on the double oxide powder by using an aqueous solution of a noble metal salt showing a lower pH than the soaking pH of the double oxide powder suspended in pure water. Growth of the noble metal particles carried is suppressed under the conditions that the surface composition of the double oxide powder satisfies the relation of 0.5≤C<SB>Zr</SB>/C<SB>Ce</SB>≤1.5 and that the noble metal is deposited by using an aqueous solution of the noble metal salt showing the lower pH than the soaking pH. <P>COPYRIGHT: (C)2004,JPO&NCIPI |
