CATALYST DETERIORATION DETERMINATION METHOD AND EXHAUST GAS PURIFICATION SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a catalyst deterioration determination method and an exhaust gas purification system capable of: estimating a particle diameter of a catalyst from a difference between a temperature of exhaust gas before passing a wall surface of a carrier carrying the catalyst and the temperature of the exhaust gas after passing the wall surface; and determining a degree of deterioration in the catalyst corresponding to a growth of the particle diameter.SOLUTION: The catalyst deterioration determination method: measures a temperature differenceΔtx between a pre-passing temperature t1 of exhaust gas before the same passes through a wall surface 6a of a porous cell 6, which is installed in a DPF (diesel particulate filter) 3 to collect PMs (particulate matters) in exhaust gas and allows the same to pass therethrough, and a post-passing temperature t2 of the exhaust gas after the same passes through the wall surface 6a; estimates a particle diameterΦx of precious metal Pt in the catalyst 7 using the temperature differenceΔtx; and determines a degree of deterioration in the catalyst corresponding to the particle diameterΦx.