| 摘要 |
PROBLEM TO BE SOLVED: To ensure a method for obtaining a packing density and a quality of a catalyst storing a gas, by obtaining a physical characteristic of a catalyst coat changing in according with a storage process, and confirming a complex impedance Z including a d.c. resistance. SOLUTION: A coat 12 (storage medium) which determines a function of a catalyst 10 is applied to an inner wall 16 of a carrier structure body having a path 14. In the case of an NOx storage medium, the coat 12 is formed of a noble metal having a catalytic activity and BaCO3 . A nitrogen oxide generated at an engine is oxidized to NO2 because the noble metal having the catalytic activity absorbs oxygen. The NO2 and BaCO3 react with each other to be BaNO3 and CO2 . The storage continues at most until the whole BaCO3 is transformed to BaNO3 . Thereafter, electrodes 22 and 24 having power feed conductors 26 and 28 are inserted to the catalyst 10, thereby forming a capacitive device for measuring an impedance. A size of the electrodes 22, 24 also determines an impedance Z. An exhaust gas can reach well to the coat material 12 between the electrodes 22 and 24 in this apparatus. |
