Effect of UiO-66 Precursors with Different Ce/Zr Ratios on the Performance of Pt-Based Catalysts in Dry Methane Reforming Reactions
Dry reforming of methane (DRM) converts CH4 and CO2 into syngas with a unity H2/CO ratio, but suffers from catalyst deactivation via sintering and carbon deposition at high temperatures. This study addresses these challenges by employing UiO-66 as a precursor to modify Pt-based catalysts. A series of Pt/CeO2-ZrO2 catalysts were synthesized via incipient wetness impregnation using supports with varying Ce/Zr ratios prepared hydrothermally. Comprehensive characterization—including CO2-TPD, CH4-TPD, XPS, XAFS, in situ DRIFTS, TG, and Raman spectroscopy—revealed a volcano-type correlation between DRM performance and Ce/Zr ratio. Optimal activity and stability were achieved with Pt/3CeO2-ZrO2 (Ce/Zr = 3:1). This catalyst features highly dispersed platinum, primarily as single atoms and thermally stable PtOx clusters. It exhibits the highest concentration of Ce3+ and Zr3+ species, abundant oxygen vacancies, and high defect density, indicating strong metal-support interaction. Mechanistically, stable DRM is facilitated by oxygen-assisted CH4 dissociation and hydrogen-assisted CO2 dissociation. At 800 °C, CH4 and CO2 conversions reached 86% and 93%, respectively, with H2/CO ratio near unity. A 10 h stability test showed no detectable carbon deposition. These results confirm that the catalyst enhances reaction kinetics while demonstrating superior activity, stability, and resistance to coking and sintering.