A Successive Phase Transition between Pt and Ti Domains Promotes Sulfur-Tolerant CO Oxidation in Sintering Flue Gas.

The carbon monoxide emitted from steel sintering flue gas seriously threatens the ecological environment and public health. Various impurities in the emission, such as sulfur dioxide and moisture, readily cause poisoning of the CO oxidation catalysts. Here, a successive phase transition between Pt and Ti domains induced by H2 reduction leads to the formation of unique Pt3Ti intermetallics with significant electron transfer. This catalyst delivers a 96% CO conversion and remains stable for 1000 h at 200 °C in a simulated sintering flue gas involving SO2, NO, 15% H2O, and 10% O2. The commendable reactivity and stability are ascribed to the sustainability of metallic Pt in Pt3Ti intermetallics under harsh oxidative circumstances. Mechanism studies reveal the well-aligned energy levels between the d-orbitals of metallic Pt with CO orbital facilitate CO oxidation, while suppress the SO2 adsorption and further increases the oxidation barrier, ultimately reduce the sulfates deposition.