To precisely estimate CO/H2 concentration ratio in reformed gas by precisely estimating degree of deterioration of reforming catalyst, and to further improve fuel consumption and NOX purifying ability by adding the reformed gas to fuel or exhaust gas.
CO and H2O in additive gas are reformed to H2 and CO2 by watery gas shift reaction by a CO shift catalyst 4, the reformed gas is added to at least either of exhaust gas of an internal combustion engine and fuel of the internal combustion engine, and additive quantity of the reformed gas is controlled based on the CO/H2 concentration ratio in the reformed gas estimated based on oxygen storage capability (OSC) of the CO shift catalyst 4. Since an extremely high correlation exists between OSC of the CO shift catalyst 4 and watery gas shift reaction activity, the CO/H2 concentration ratio in the reformed gas can be estimated at high precision by detecting the OSC.
KIZAKI YOSHIMI
YOKOTA KOJI
