Exhaust gas purification catalyst

A wall-flow-type exhaust gas purification catalyst to be placed in an exhaust pipe of an internal combustion system to purify exhaust gas emitted from the internal combustion system, the exhaust gas purification catalyst comprising:

• a substrate having a wall-flow structure with an exhaust inlet-side end and an exhaust outlet-side end, the substrate having an entrance cell that is open on the exhaust inlet-side end and an exit cell that is open on the exhaust outlet-side end, separated with a porous partition wall,
• a first catalytic layer provided to an internal portion of the partition wall in contact with the entrance cell, having a length L1 from the exhaust inlet-side end in the running direction of the partition wall with L1 being less than the total length Lw of the partition wall in the running direction,
• a second catalytic layer provided to an internal portion of the partition wall in contact with the exit cell, having a length L2 from the exhaust outlet-side end in the running direction of the partition wall with L2 being less than the total length Lw of the partition wall in the running direction;
• wherein
• in the internal portion of the partition wall in contact with the entrance cell, near the exhaust outlet-side end, the exhaust gas purification catalyst has a substrate-exposing segment free of the first and second catalytic layers,
• each of the first and second catalytic layers comprises an oxygen storage material, and
• the first catalytic layer has a coating density D1 and the second catalytic layer has a coating density D2 with a D1/D2 ratio value of 1.1 or higher, but 1.8 or lower.