CATALYTIC CONVERTER

PROBLEM TO BE SOLVED: To provide a catalytic converter excellent in an OSC (Oxygen Storage Capacity) performance, and a NOx removal performance when an engine is heavily loaded, and also excellent in a catalyst warming performance.SOLUTION: There is provided a catalytic converter 10 comprised of a base material 1 and catalyst layers. The catalytic converter 10 has: an under catalyst layer 4 on the surface of the base material over the full length thereof; and a first upper catalyst layer 6 on the upstream side in a flow direction of an exhaust gas and a second upper catalyst layer 7 on the downstream side on the surface of the under catalyst layer 4. The under catalyst layer 4 includes palladium. The first upper catalyst layer 6 includes; a carrier composed of a zirconia-based compound oxide not containing ceria; and rhodium. The second upper catalyst layer 7 includes: a carrier composed of a zirconia-based compound oxide containing ceria; and rhodium. The first upper catalyst layer 6 is formed on the upstream side of the base material 1 in the range of X% (30-70%) of the full length of the base material. The second upper catalyst layer 7 is formed on the downstream side of the base material 1 in the range of 100-X% of the full length of the base material. The ratio of rhodium-carrying density SD1 to SD2 : SD1/SD2 in the first and second upper catalyst layers 6, 7 is 1 or more and 3 or less. 【課題】OSC 性能とエンジン高負荷時におけるNOx浄化性能に優れ、触媒暖機性能にも優れた触媒コンバーターを提供する。【解決手段】基材１と触媒層とからなる触媒コンバーター１０であって、基材１の表面においてその全長に亘って下触媒層４を有し、下触媒層４の表面において排ガスの流れ方向の上流側に第１の上触媒層６、下流側に第２の上触媒層７を有し、下触媒層４はパラジウムを有し、第１の上触媒層６はセリアを含まないジルコニア系複合酸化物からなる担体とロジウムを有し、第２の上触媒層７はセリアを含むジルコニア系複合酸化物からなる担体とロジウムを有し、第１の上触媒層６は基材１の上流側に基材の全長のX%(30〜70%)の範囲に形成され、第２の上触媒層７は基材１の下流側に基材の全長の100-X%の範囲に形成され、第１、第２の上触媒層６，７におけるロジウム担持密度SD1、SD2の比：SD1/SD2が1以上3以下である。【選択図】図２