Surface Restructuring of Supported Nano-Ceria for Improving Sulfur Resistance

Abstract

Developing sulfur-tolerant catalysts is crucial, yet challenging. Pt catalyst deposited on ceria typically shows high activity for oxidation, but it suffers from sulfur poisoning, because ceria may easily convert into cerium sulfates in the presence of sulfur, causing significant degradation in activity. Here, a Pt catalyst deposited on CeO2-Al2O3 support was synthesized with the octahedral shape of nanoceria. The highly defective nanoceria were immobilized on gamma-Al2O3, which was a priori activated to have Al-penta(3+) sites. Then, the CeO2-Al2O3 support was hydrothermally treated at 750 degrees C for 25 h. The morphology of supported nanoceria was stabilized into octahedra with a minimal amount of Ce3+. The surface oxygen defects and basicity could be controlled by varying hydrothermal treatment temperatures. After the Pt deposition on the support, the catalyst was used for CO oxidation in the presence of SO2. The catalyst with octahedral nanoceria showed better sulfur resistance upon sulfation and outstanding resilience after desulfation. The formation of the sulfate species was hindered on the restructured nanoceria due to its low basicity. This work provides a useful guideline for increasing the sulfur resistance in heterogeneous catalysts.