Boosted low-temperature C₃H₈ oxidation and sulfur resistance of Pt/CeO₂ via post Co₃(PO₄)₂ modification: Synergy of interfacial electronic modulation and phosphate-derived acidity

The widely presented industrial light alkanes (LAs) have posed significant hazards to the environment and human health; however, the efficacious catalytic purification of LAs is still greatly suffered from their strong chemical stability and catalyst deactivation due to the presence of sulfur-containing impurity in practical exhausts. Herein, cobalt phosphate (Co₃(PO₄)₂)-modified Pt/CeO₂ catalysts (Pt/CeO₂-xCP) with boosted activity and sulfur resistance were rationally engineered. Results revealed that Pt/CeO₂-0.2CP shows the highest C₃H₈ oxidation activity with 90 % of which oxidized at 260 °C and apparent activation energy (E_a) of 84.39 kJ∙mol⁻¹, obviously lower than that of Pt/CeO₂. Remarkably, the activity of Pt/CeO₂-0.2CP is well-maintained in 24 h of successive operation with the co-existence of 250 H₂S, while over 20 % of C₃H₈ conversion reduction can be found over Pt/CeO₂ due to the deactivation of Pt⁴⁺ active sites by surface sulfation. The Co₃(PO₄)₂-Pt interface promotes the electron transfer from Pt^δ+ to phosphorus component and weakens the Pt-O-Ce bond, thereby generating more highly active Pt⁴⁺ sites and oxygen vacancy, polarizing the electron cloud around the C-H bond and oxygen molecules and promoting C₃H₈ oxidation. Meanwhile, the Co₃(PO₄)₂ modification optimizes the surface acidity of Pt/CeO₂-CP, effectively weakens the adsorption and oxidation of H₂S, and maintains the formation and consumption of high active oxygen species, resulting in strong sulfur resistance. This work provides important insights for the rational design of efficient sulfur-tolerant catalysts towards LAs purification under harsh conditions.