US Patent 10076725 Exhaust gas purification catalyst

A wall-flow-type exhaust gas purification catalyst with an oxygen storage material that has an increased OSC and exhibits its OSC without a compromise provides an exhaust gas purification catalyst having a wall-flow-type substrate, a first catalytic layer and a second catalytic layer. The first catalytic layer is provided to an internal portion of a partition wall in contact with an entrance cell. The second catalytic layer is provided to an internal portion of a partition wall in contact with an exit cell. Each of the first and second catalytic layers has an oxygen storage material. The ratio (D1/D2) of the coating density D1 of the first catalytic layer to the coating density D2 of the second catalytic layer is 1.1 to 1.8.