The catalytic performance in soot oxidation of lab-scale silicon carbide (SiC) diesel particulate filters (DPFs) washcoated with metal-promoted CeO₂ has been investigated focusing on the amount and the nature of the metal (Ag or Cu), and on the preparation method for the catalytic washcoat deposition. A wide range of metal loads was explored. The metal-promoted washcoat was dispersed onto the filters according to two methods: method (A)—cycles of deposition of metal nitrate after previous deposition of nanometric CeO₂, up to the achievement of the target load; method (B)—filter dipping into a suspension containing both CeO₂ and metal nitrate in a suitable ratio. Bare Ag DPFs have also been investigated for the sake of comparison. Catalysts were characterized by SEM/EDX, Hg intrusion porosimetry and TPR and O₂-TPD techniques. All samples show a high metal dispersion and some reduction of support macro-pores. The metal addition improves the catalytic performance of bare ceria basically decreasing the temperature corresponding to the maximum soot oxidation rate. The positive effect increases with increasing metal load. As far as the method A is concerned, a better activity has been found for Cu-promoted catalysts with respect to the corresponding Ag-promoted catalysts with the same amount of metal. Ag-promoted catalysts prepared according to the method B are much more active than all other samples, showing a marked reduction of activation temperature as well. As disclosed by the analysis of redox properties and oxygen mobility, the method B significantly enhances the silver-ceria interface where highly reactive oxygen species (O_n^x−) are produced, providing the outstanding activity of these catalysts. This same effect is much less evident in the case of Cu-promoted catalysts.

研究了用金属促进的CeO ₂涂层的实验室规模的碳化硅（SiC）柴油颗粒过滤器（DPF）在烟灰氧化中的催化性能，重点研究了金属（Ag或Cu）的含量和性质，以及催化修补基面涂层沉积的制备方法。探索了广泛的金属负载。根据两种方法将金属促进的修补基面涂层分散到过滤器上：方法（A）-在先前沉积纳米CeO ₂之后直至达到目标负荷的循环金属硝酸盐的沉积；方法（B）-将过滤器浸入同时含有CeO ₂的悬浮液中和金属硝酸盐以合适的比例。为了进行比较，还对裸Ag DPF进行了研究。通过SEM / EDX，Hg侵入孔隙率法和TPR和O _2对催化剂进行了表征。-TPD技术。所有样品均显示出较高的金属分散性和支持物大孔的减少。金属的添加改善了裸露的二氧化铈的催化性能，基本上降低了与最大烟灰氧化速率相对应的温度。随着金属负载的增加，积极的影响也随之增加。就方法A而言，已发现对于Cu促进的催化剂而言，相对于具有相同金属量的相应的Ag促进的催化剂而言，具有更好的活性。根据方法B制备的Ag助催化剂比所有其他样品具有更高的活性，并且活化温度也显着降低。如通过氧化还原特性和氧迁移率的分析所揭示的，方法B显着增强了高活性氧（O _n产生了^x-），提供了这些催化剂的出色活性。在铜促进的催化剂的情况下，同样的效果要小得多。