Palladium Encapsulated by an Oxygen-Saturated TiO Overlayer for Low-Temperature SO -Tolerant Catalysis during CO Oxidation.

The development of oxidation catalysts that are resistant to sulfur poisoning is crucial for extending the lifespan of catalysts in real-working conditions. Herein, we describe the design and synthesis of oxide-metal interaction (OMI) catalyst under oxidative atmospheres. By using organic coated TiO , an oxide/metal inverse catalyst with non-classical oxygen-saturated TiO overlayers were obtained at relatively low temperature. These catalysts were found to incorporate ultra-small Pd metal and support particles with exceptional reactivity and stability for CO oxidation (under 21 vol % O and 10 vol % H O). In particular, the core (Pd)-shell (TiO ) structured OMI catalyst exhibited excellent resistance to SO poisoning, yielding robust CO oxidation performance at 120 °C for 240 h (at 100 ppm SO and 10 vol % H O). The stability of this new OMI catalyst was explained through density functional theory (DFT) calculations that interfacial oxygen atoms at Pd-O-Ti sites (of oxygen-saturated overlayers) serve as non-metal active sites for low-temperature CO oxidation, and change the SO adsorption from metal(d)-to-SO (π*) back-bonding to much weaker σ(Ti-S) bonding.