US Patent 10071368 Exhaust gas purification catalyst

An exhaust gas purification catalyst capable of stably maintaining and exhibiting excellent catalytic performance includes 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. The ratio (D2/D1) of the coating density D2 of the second catalytic layer to the coating density D1 of the first catalytic layer is 1.01 to 1.4.