Influence of Doping of Niobium Oxide on the Catalytic Activity of Pt/Al2O3 for CO Oxidation

Pt-based alumina catalysts doped with varying niobium contents (i.e., 0, 1.20, 2.84, and 4.73 wt%, denoted as Pt/Nb–Al₂O₃) were synthesized via stepwise impregnation for catalytic CO oxidation. The effective incorporation of Nb species without altering the fundamental properties of the Al₂O₃ support was confirmed by the characterization using XRD, Raman, and TEM. Pt metallic particles were uniformly deposited on the niobium-doped alumina (Nb–Al₂O₃) support. H₂-TPR and CO–TPD analyses were performed to reveal the influence of niobium doping on catalyst reduction and CO adsorption properties. The results consistently demonstrate that the doping of niobium affects reducibility and alleviates the competitive adsorption between CO and O₂ during the CO reaction. Particularly, when compared to both undoped and excessively doped Pt/Al₂O₃ catalysts, the catalyst featuring a 2.84 wt% Nb content on Pt_1.4/Nb_2.8–Al₂O₃ displayed the most promising catalytic performance, with a turnover frequency of 3.12 s⁻¹ at 180 °C. This superior performance can be attributed to electron transfer at the Pt/NbOx interface.