Surface Restructuring of Supported Nano-Ceria for\nImproving Sulfur Resistance

Abstract

Developing sulfur-tolerant catalysts\nis crucial, yet challenging.\nPt catalyst deposited on ceria typically shows high activity for oxidation,\nbut it suffers from sulfur poisoning, because ceria may easily convert\ninto cerium sulfates in the presence of sulfur, causing significant\ndegradation in activity. Here, a Pt catalyst deposited on CeO₂–Al₂O₃ support was synthesized\nwith the octahedral shape of nanoceria. The highly defective nanoceria\nwere immobilized on γ-Al₂O₃, which was <i>a priori</i> activated to have Al_penta³⁺ sites. Then, the CeO₂–Al₂O₃ support was hydrothermally treated at 750 °C for 25 h. The\nmorphology of supported nanoceria was stabilized into octahedra with\na minimal amount of Ce³⁺. The surface oxygen defects and\nbasicity could be controlled by varying hydrothermal treatment temperatures.\nAfter the Pt deposition on the support, the catalyst was used for\nCO oxidation in the presence of SO₂. The catalyst with\noctahedral nanoceria showed better sulfur resistance upon sulfation\nand outstanding resilience after desulfation. The formation of the\nsulfate species was hindered on the restructured nanoceria due to\nits low basicity. This work provides a useful guideline for increasing\nthe sulfur resistance in heterogeneous catalysts.