Pd/Rh 基三效催化器分区涂覆的优化设计研究

为研究分区涂覆工艺对Pd/Rh基三效催化器(three-way catalytic converter, TWC)起燃性能的影响机制,文章建立基于分区涂覆的催化器和反应机理模型,结合台架起燃数据标定并验证模型的准确性,探究贵金属配比、前后分区长度、贵金属负载量3个关键因素对TWC起燃性能的作用规律,并运用正交试验法开展Pd/Rh基TWC分区涂覆优化设计。研究结果表明:当负载量一定时, $ m(\mathrm{Pd}):m(\mathrm{Rh})=10:1 $工况下催化器催化性能优于 $ m(\mathrm{Pd}):m(\mathrm{Rh})=5:1 $和 $ m(\mathrm{Pd}):m(\mathrm{Rh})=20:1 $;分区长度和前后区负载量比值均会显著影响催化器起燃性能,当前区长度为45 mm、后区长度为73 mm且前后区负载量比值为10:1时,催化器的综合催化性能最佳。正交试验结果表明,影响TWC整体催化转化效率最关键的因素是前后区的负载量比值。

In order to investigate the effect of zonal coating on the ignition performance of Pd/Rh-based three-way catalytic converter (TWC), a zonal coating-based catalytic converter and reaction mechanism model was developed, and the model was calibrated and validated based on the bench-scale ignition data, so as to investigate the influence of three key factors, namely the ratio of noble metal, the length of the front and rear zones, and the amount of noble metal loading, on the ignition performance of the TWC. The orthogonal test method was used to optimize the design of Pd/Rh-based TWC zonal coating. The results showed that under the condition that the $ m(\mathrm{Pd}):m(\mathrm{Rh}) $ was 10:1, the catalytic performance of the TWC was better than that under the ratios of 5:1 and 20:1 at a certain loading level. The length and load ratio of the front and rear zones significantly affected the ignition performance of the TWC, and the overall catalytic performance of the TWC was best when the length of the front zone was 45 mm, the length of the rear zone was 73 mm, and the load ratio of the front and rear zones was 10:1. The results of the orthogonal test showed that the most critical factor affecting the overall catalytic efficiency of the TWC was the load ratio of the front and rear zones.