How to Control Vehicle Exhaust Emissions?
1 Answers
Methods to control vehicle exhaust emissions are as follows: 1. The most fundamental and ultimate approach is to change the vehicle's power source, such as developing electric vehicles and alternative fuel vehicles. This approach ensures that vehicles either produce no or minimal pollutant gases. 2. Improve the vehicle's power system and fuel quality. Using well-designed engines, optimizing combustion chamber structures, adopting new materials, and enhancing fuel quality can all reduce vehicle exhaust emissions, though achieving 'zero emissions' remains unattainable. 3. Employ purification technologies. Advanced exhaust after-treatment technologies can purify the gases emitted by vehicles to minimize pollution. Vehicle exhaust purification catalysts are the most effective means to control emissions and reduce pollution. These primarily use precious metals or rare earth elements as catalysts. Precious metal catalysts, typically made from platinum and palladium, offer high activity, long lifespan, and excellent purification efficiency, making them highly practical but difficult to widely adopt. Rare earth vehicle exhaust purification catalysts are prepared using rare earth elements, alkaline earth metals, and some alkali metals, sometimes with small amounts of precious metals. The rare earth elements used in these catalysts mainly consist of a mixture of cerium oxide, praseodymium oxide, and lanthanum oxide, with cerium oxide being the key component. Due to cerium oxide's redox properties, it effectively controls the composition of exhaust emissions by supplying oxygen in reducing atmospheres or consuming oxygen in oxidizing atmospheres. Cerium dioxide also stabilizes the precious metal atmosphere, maintaining the catalyst's high catalytic activity.
