Ohmic Heating-type Exhaust Gas Purification Catalyst System and Exhaust Gas Purification Method

An ohmic heating-type exhaust gas purification catalyst system that performs purification of exhaust gas discharged from an internal combustion engine, the ohmic heating-type exhaust gas purification catalyst system comprising:

• an ohmic heating-type catalyst device
• that is arranged in an exhaust pipe of the internal combustion engine and performs purification of the exhaust gas discharged from the internal combustion engine, and includes
• an outer cylinder coupled to the exhaust pipe;
• a pair of electrodes;
• a catalyst unit including a catalyst bed that is contactable by the exhaust gas introduced into the outer cylinder and contains at least one type of catalytic metal that functions as a three-way catalyst;
• a heating element that generates heat when an electric current is caused to pass through the pair of electrodes to heat the catalyst bed;
• and
• a temperature detector that can detect temperature of the catalyst bed;
• and a control device that controls pass of the electric current to the pair of electrodes,
• wherein
• the control device is configured to perform, based on information of the temperature of the catalyst bed input from the temperature detector, electric current pass control including controls of
• (1) causing an electric current to pass through the pair of electrodes when the temperature of the catalyst bed is equal to or lower than a first threshold temperature T1 set in a range of 350±25° C.,
• (2) not causing an electric current to pass through the pair of electrodes when the temperature of the catalyst bed exceeds the first threshold temperature T1 and is equal to or lower than a second threshold temperature T2 set in a range of 450±25° C.,
• (3) causing an electric current to pass through the pair of electrodes when the temperature of the catalyst bed exceeds the second threshold temperature T2 and is equal to or lower than a third threshold temperature T3 set to be equal to or higher than 550° C., and
• (4) not causing an electric current to pass through the pair of electrodes when the temperature of the catalyst bed exceeds the third threshold temperature T3.