三元催化，是指將汽車尾氣排出的CO、HC和NOx等有害氣體通過氧化和還原作用轉變為無害的二氧化碳、水和氮氣的催化。主要是用三元催化器，
三元催化器的載體部件是一塊多孔陶瓷材料，安裝在特製的排氣管當中。稱它是載體，是因為它本身並不參加催化反應，而是在上面覆蓋著一層鉑、銠、鈀等貴重金屬。是安裝在汽車排氣系統中最重要的機外淨化裝置。
工作原理
三元催化器的工作原理是：當高溫的汽車尾氣通過淨化裝置時，三元催化器中的淨化劑將增強CO、HC和NOx三種氣體的活性，促使其進行一定的氧化-還原化學反應，其中CO在高溫下氧化成為無色、無毒的二氧化碳氣體；HC化合物在高溫下氧化成水(H20)和二氧化碳；NOx還原成氮氣和氧氣。三種有害氣體變成無害氣體，使汽車尾氣得以淨化。
三元催化反應器類似消聲器。它的外面用雙層不鏽薄鋼板製成筒形。在雙層薄板夾層中裝有絕熱材料----石棉纖維氈。內部在網狀隔板中間裝有淨化劑。
淨化劑由載體和催化劑組成。載體一般由三氧化二鋁製成，其形狀有球形、多棱體形和網狀隔板等。淨化劑實際上是起催化作用的，也稱為催化劑。催化劑用的是金屬鉑、銠、鈀。將其中一種噴塗在載體上，就構成了淨化劑。
三元催化一般不用清洗，如果三元催化氧化厲害了就直接更換。因為，三元催化的工作溫度在350度左右，所以最好沒有液態水殘留，所以清洗並不好。
——————————————————————————————————————
Tricatalysis is the catalytic conversion of harmful gases such as CO, HC and NOx from vehicle exhausts into harmless carbon dioxide, water and nitrogen by oxidation and reduction. It is mainly used in three-way catalytic converters, the carrier component of which is a porous ceramic material installed in a specially designed exhaust pipe. It is called a carrier because it does not take part in the catalytic reaction itself, but is covered with a layer of precious metals such as platinum, rhodium and palladium. It is the most important external purification device installed in the exhaust system of a vehicle.
Principle of operation
The working principle of the three-way catalytic converter is that when high temperature vehicle exhaust gases pass through the purification device, the purifying agent in the three-way catalytic converter will enhance the activity of the three gases CO, HC and NOx, prompting them to carry out a certain oxidation-reduction chemical reaction, in which CO is oxidised at high temperature to become colourless, non-toxic carbon dioxide gas; HC compounds are oxidised at high temperature to water (H20) and carbon dioxide; NOx is reduced to nitrogen and oxygen. is reduced to nitrogen and oxygen. The three harmful gases are transformed into harmless gases, making the vehicle exhaust clean.
The three-dimensional catalytic reactor is similar to a silencer. The outside of the reactor is made of a double layer of stainless steel sheeting in the form of a cylinder. The double-layered sheet is laminated with an insulating material ---- asbestos fibre felt. Internally, a purifying agent is installed between the mesh partitions. The purifying agent consists of a carrier and a catalyst. The carriers are generally made of aluminium trioxide and are available in the form of spherical, multi-prismatic and reticulated partitions. The purifying agent actually acts as a catalyst and is also known as a catalyst. The catalysts are platinum, rhodium and palladium. When one of these is sprayed onto the carrier, it constitutes a purifying agent.
If the catalyst oxidises badly, it is replaced. As the temperature of the catalyst is around 350°C, it is best to have no liquid water residue, so cleaning is not a good idea.
0 Comments