Investigation of Zirconia Effect in Zr/CeO2- Al2O3 Catalyst for Diesel Soot Oxidation

Abstract The cost of diesel exhaust treatment is steadily rising, and soot particles in diesel engine exhaust have a negative impact on human health. The study uses efficient Zr/CeO₂-Al₂O₃ catalysts as a substitute for noble metal catalysts to lower the process cost. A part of this is because of the ever-increasing scarcity of noble metal catalysts required for diesel oxidation catalysts. The current study focuses on an alternative diesel oxidation catalyst with efficiency similar to that of a noble metal catalyst but with a much lower cost. CeO₂-Al₂O₃ catalysts are known for their oxygen storage capacity and high redox activity, making them suitable for soot oxidation. The addition of Zr to these catalysts has been shown to influence their structural and chemical properties, which significantly affect their catalytic behavior. Evaporation-induced self-assembly (EISA) was used to prepare 1, 3, and 5 wt% Zr supported mesoporous CeO₂-Al₂O₃ catalysts. Morphological, structural, and physicochemical properties of the synthesized catalysts were examined using BET, Absolute Isotherm, SEM, -XRD, FTIR, TPR, and NH3-TPD. XRD, BET, and SEM data confirmed that the catalysts were mesoporous and low-crystalline while having a high surface area. The loose contacts soot oxidation activity test using TGA suggested that 50% oxidation of soot occurred at 390oC in the absence of a catalyst. T50 of CeO₂-Al₂O₃ catalyzed soot oxidation was 296 oC. We observed a further drastic change in T50 of soot over 1, 3, and 5% Zr/CeO₂-Al₂O₃, which were 220oC, 210oC, and 193oC, respectively. According to these results, incorporating Zr into the CeO₂-Al₂O₃ catalyst greatly improved the oxidation process of soot.