Tuning Ce‐Zr‐Al Mixed Oxide Supports to Enhance Pt‐Pd Catalyst Performance for Low‐Temperature CO and C ₃ H ₆ Oxidation in Diesel Emissions

Diesel oxidation catalysts (DOCs) with low‐temperature activity are required for low‐temperature combustion diesel (LTC‐D) engine technologies to meet emission regulations. To probe the impact of oxygen availability on activity, bimetallic Pt‐Pd catalysts supported on Ce‐Zr‐Al mixed oxides with varying Ce/Zr/Al contents were systematically investigated for CO and C 3 H 6 oxidation and co‐oxidation. Various characterization techniques, including X‐ray Photoelectron Spectroscopy (XPS) and in‐situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS), were used to gain insight into the oxidation performance. Catalysts with optimized supports, particularly Pt‐Pd/C(0.1)Z‐50A and Pt‐Pd/C(0.78)Z‐71A, exhibited superior low‐temperature activity, achieving light‐off as low as 109°C for CO and 198°C for C 3 H 6 . XPS indicated that high surface concentrations of Pt 0 and Pd 2+ species, with elevated O ads /O latt ratios and Ce 3+ fractions, promoted redox activity. Under co‐oxidation, competitive adsorption reduced activity, particularly for CO, yet catalysts with higher oxygen mobility such as Pt‐Pd/C(0.1)Z‐50A, maintained stronger performance. DRIFTS revealed early CO 2 formation during CO oxidation and the presence of oxygenated intermediates (acetates, carbonates, aldehydes) during C 3 H 6 oxidation. Under co‐oxidation, both CO and C 3 H 6 ‐derived species formed concurrently. These findings demonstrate that optimizing Ce‐Zr‐Al composition enhances metal‐support interactions and oxygen dynamics, offering a pathway toward high‐performance DOCs for future emission control.