Exhaust gas control apparatus and exhaust gas control method for internal combustion engine

摘要

An exhaust gas control apparatus for an internal combustion engine is provided with an exhaust catalyst disposed in an exhaust passage ( 4 ) of the internal combustion engine, a concentration detection unit ( 10 ) that is capable of detecting a total concentration of a sulfur oxide and a hydrogen sulfide contained in an exhaust gas that passes through the exhaust catalyst, and detecting a concentration of the sulfur oxide, and a sulfur concentration estimation unit ( 15 ) that estimates a concentration of sulfur contained in a fuel based on a detection value of the concentration detection unit ( 10 ) when it is determined that the exhaust gas is at one of a stoichiometric and rich air/fuel ratio.