Precursor Engineering of SO42⁻-Rich CeO2-Pt-TiO2-Fe2O3 Catalyst with Oxygen Vacancy-Mediated Ternary Synergy for Ultralow-Temperature Methane Combustion

Current Pt-based methane combustion catalysts require high noble metal loadings (≥1 wt%) and exhibit insufficient low-temperature activity. To address this, we developed a 0.5 wt% Pt catalyst supported by sulfate-modified Fe-Ce-TiO2 (denoted 0.5Pt/CFT-TS) via sol–gel synthesis using titanium oxysulfate (TiOSO4) precursor. Control catalysts prepared with TiCl4, titanium butoxide, or commercial TiO2 showed inferior performance. Structural characterization revealed that the TiOSO4 derived carrier possesses a mesoporous framework (156.2 m2/g surface area, 8.1 nm pore size) with residual SO42⁻ inducing strong Brønsted acidity (1.23 mmol/g NH3 adsorption) and elevated Ce3⁺ concentration (49.45%). These properties synergistically enhanced oxygen vacancy density (51.16% Oα fraction) and stabilized sub-nm Pt nanoparticles. The resulting Pt0-Fe3⁺/Ce4⁺-Oᵥ interface facilitated dynamic redox cycling (Fe3+ + Ce4+ + 0.5O2⁻ ⇌ Fe2+ + Ce3+ + 0.5Oᵥ + 0.25O2), lowering oxygen vacancy regeneration barriers (H2-TPR peak reduced by 45 °C) and decreasing methane activation energy to 46.77 kJ/mol. This catalyst achieved T90 = 163 °C and complete conversion at 450 °C under industrial conditions (1% CH4/4% O2, GHSV = 30,000 h−1), establishing a novel design strategy for low-Pt combustion catalysts.