Palladium Encapsulated by an Oxygen‐Saturated TiO₂ Overlayer for Low‐Temperature SO₂‐Tolerant Catalysis during CO Oxidation

Abstract

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 TiO2, an oxide/metal inverse catalyst with non‐classical oxygen‐saturated TiO2 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% O2 and 10 vol% H2O). In particular, the core (Pd)–shell (TiO2) structured OMI catalyst exhibited excellent resistance to SO2 poisoning, yielding robust CO oxidation performance at 120 °C for 240 h (at 100 ppm SO2 and 10 vol% H2O). 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 SO2 adsorption from metal(d)‐to‐SO2(π*) back‐bonding to much weaker σ(Ti–S) bonding.

Sulfur Migration Enhanced Proton-Coupled Electron Transfer for Efficient CO2 Desorption with Core-Shelled C@Mn3O4

“…By-reaction in heterogeneous catalysis was unavoidable in practice application and presented longer-term challenges for functional materials design in the field of green production . Current efforts mainly focused on avoiding adverse effects of impurity or intermediate components on catalysts, by weakening undesirable species absorption, engineering protective or sacrificial layers, promoting catalytic reaction selectivity, etc. − However, these strategies of passivity defense were still insufficient to deal with complicated reactions in industrial production. From the opposite perspective, it could be treated as positive strategy by converting some unexpected species into active sites through in situ surface reconstruction, participated and accelerated original catalytic reaction. , Chemical carbon dioxide (CO 2 ) capture technologies, which demonstrate encouraging progress and feasibility in mitigating human-induced CO 2 emissions, rely on the rapid reversible zwitterion-mediated reaction combined with amine solvent and CO 2 . , Unfortunately, the intricate hydrogen-bonding network in alkaline amine solvents severely hampers the CO 2 desorption kinetics. , Additionally, sulfur dioxide (SO 2 ), a strong acid coexists with CO 2 , tends to preferentially bind with amines to form S–N bonds, inevitably resulting in SO 2 poisoning of amine solvent in practice .…”