Effect of Metal Oxides (CeO₂, ZnO, TiO₂, and Al₂O₃) as the Support for Silver-Supported Catalysts on the Catalytic Oxidation of Diesel Particulate Matter

Abstract

This work presented the influence of metal oxides as the support for silver-supported catalysts on the catalytic oxidation of diesel particulate matter (DPM). The supports selected to be used in this work were CeO 2 (reducible), ZnO (semiconductor), TiO 2 (reducible and semiconductor), and Al 2 O 3 (acidic). The properties of the synthesized catalysts were investigated using XRD, TEM, H 2 -TPR, and XPS techniques. The DPM oxidation activity was performed using the TGA method. Different states of silver (e.g., Ag°and Ag + ) were formed with different concentrations and affected the performance of the DPM oxidation. Ag 2 O and lattice oxygen, which were mainly generated by Ag/ZnO and Ag/CeO 2 , were responsible for combusting the VOCs. The metallic silver (Ag°) formed primarily on Ag/Al 2 O 3 and Ag/TiO 2 was the main component promoting soot combustion. Contact between the catalyst and DPM had a minor effect on VOC oxidation but significantly affected the soot oxidation activity.