摘要
三效催化剂是机外治理机动车尾气污染最常采用的有效方法,车用三效催化剂已发展到第4代。目前车用三效催化剂的研究主要集中在:开发稀燃型三效催化剂和紧耦合三效催化剂及发展三效催化剂低温冷起燃技术等。国内应以稀土添加少量贵金属的三效催化剂为主要研究方向,开发适合我国现状的车用净化催化剂技术。
The present paper aims to introduce three way catalysts and its application in China. As is known, air pollution in China has mainly resulted from the exhausted emissions of transportation vehicles and industrial production. To solve this problem the government has established rigorous standards and laws. So far as we know, three way catalysts has already been developed into its fourth generation and proved to be one of the right solutions to purify tail exhaustions. So far, the researchers of the above said catalysts have now focused on the following three areas: 1) To improve on the so-called lean-burn three way catalysts. The re searchers attach great attention to the use of lean burn technology in the areas of automotive emission control in recent years, as one of the key measures to reduce the exhausted carbon dioxides by elevating the combustion efficiency. However, since oxygen is excessive under the lean conditions, it seems rather difficult to reduce nitro oxides, one of the three major pollutants in the tail ex haustion. Thus, it has become an urgent need to develop new kinds of three way catalysts able to reduce nitro oxides in such a con dition. 2) To develop close coupled catalysts. As we know, about 80% percent of pollutants at present results at the cold-start stage, when the surface temperature of the main body of the three way catalysts remains too low to initiate the catalytic reaction. It is just for this reason that the catalysts are installed close to the draining tap of the engine so that the closed coupled catalysts can be heated at the cold-start stage as quickly as possible by the hot exhausted gas to speed up the catalytic reaction. In so doing, it is necessary for closed coupled three way catalysts to keep high thermal stability at normal running situation as the engine is being speeded up. That is, the surface temperature of the closed coupled catalysts could reach 1 373 K or above. 3) To further reduce the light-off temperature of the three way catalysts. In this case another way can be suggested to reduce the exhausted emission at cold-start stage, that is, to decrease the light-off temperature of the under-body catalysts below 423 K. 4) To develop palladium only three way catalysts and/or non precious metal catalysts. In order to reduce the cost of automotive catalysts, a lot of researchers are trying to develop such catalysts with some advances already gained.
出处
《安全与环境学报》
CAS
CSCD
2003年第5期21-26,共6页
Journal of Safety and Environment
关键词
催化剂工程
机动车尾气
净化
三效催化剂
进展
catalyst engineering
exhausted emission
air pollution and treatment
three way catalysts
research progress
