三效催化剂（TWC）：同时转化CO、HC、NOx 三种有害气体
Three-way Catalyst (TWC) : Conversion of harmful gases of CO, HC and NOx
组成
Composition
载体：陶瓷蜂窝或金属蜂窝
Substrate: ceramic honeycomb or
metallic honeycomb
涂层：氧化铝、铈锆固溶体等
Coating: alumina, ceria-zirconia solid
solution
助剂：ZrO2，La2O3 等辅助材料
Additives: ZrO2, La2O3, and other
additives
活性组分：Pt、Pd、Rh 等贵金属
Active components: Pt and Pd, Rh

and other precious metals

反应原理
Reaction principle
1）氧化反应 (1) Oxidation reactions
CO + 1/2 O2 = C O2
4HC + 5O2 = 4 C O2 + 2 H2O
2）还原反应 (2) Reduction reactions
NO + CO = 1/2 N2 + C O2
NO + H2 = 1/2 N2 + H2O
3）其它反应 (3) Other reactions
2HC + 4 H2O = 2 C O2 + 5H2
CO + H2O = C O2 + H2
密偶催化剂（CCC）
Close Coupled Catalyst (CCC)
CCC 靠近发动机，主要解决发动机启动时处于富油工况，氧化过程因贫氧而燃
烧不完全，所产生的大量HC。
The CCC is close to the engine and is mainly to solve a large amount of HC produced for
incomplete combustion due to lack of oxygen in the oxidation process when the engine is
started in the oil-rich condition.
催化转化器
Catalytic Converters
催化转化器是安装在汽车排气系统中最重要的机外净化装置，它可将汽车尾气
排出的CO、HC 和NOx 等有害气体通过氧化和还原作用转变为无害的二氧化碳、
水和氮气。
The catalytic converter is the most important external cleaning device installed in the
automotive exhaust system to convert harmful gases like CO, HC and NOx in the tail gas into
harmless carbon dioxide, water and nitrogen by oxidation and reduction.