Methods for exhaust gas purification

A method for exhaust gas purification, comprising the steps of:

• attaching an exhaust gas purification catalyst to an exhaust system of an internal combustion engine, and
• supplying an exhaust gas to the exhaust gas purification catalyst, wherein
• the exhaust gas purification catalyst comprises
• an upper layer containing first carrier particles which are particles of an inorganic oxide and rhodium, and
• a lower layer containing second carrier particles which are particles of an inorganic oxide,
• the upper layer includes a rhodium-rich portion near the surface of the upper layer on the upstream side of the exhaust gas flow,
• the existence range of the rhodium-rich portion is in a range of greater than 50% to 80% of the length of the upper layer from a downstream side end of an exhaust gas flow and of less than 20 μm in the depth direction from an outermost surface of the upper layer, and
• the rhodium-rich portion contains rhodium in an amount of 55% to less than 100% of the total rhodium included in the upper layer, and
• the exhaust gas purification catalyst is attached to the exhaust system so that the rhodium-rich portion thereof faces the downstream side of the exhaust gas flow.