FT-IR study of the surface redox states on platinum-potassium-alumina catalysts

Pt-K/Al2O3 (Pt 1%; K 5.4% wt/wt) catalyst active for the simultaneous Diesel particulate oxidation and NOx reduction have been characterized in comparison with 1% Pt/Al2O3 catalyst. IR spectra of adsorbed CO at −140 °C and at room temperature allowed the detection of oxidized Pt centers and of their very strong oxidizing ability. TPD and IR spectra of adsorbed CO2 allowed to characterize the basicity of the samples. The data indicate that Pt centers lie in close proximity of potassium oxide species generating basicity.

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► The paper reports a detailed characterization of a catalyst constituted by platinum supported on heavily potassium doped γ-Al2O3 which is active in the so called NOx-trap technology and for the simultaneous Diesel particulate oxidation and NOx reduction.
► The characterization is made in comparison with a corresponding K-free Pt/Al2O3 catalyst.
► IR spectra of adsorbed CO at −140 °C and at room temperature allowed the detection of oxidized Pt centers and of their very strong oxidizing ability.
► TPD and IR spectra of adsorbed CO2 allowed to characterize the basicity of the samples.
► The data indicate that Pt centers lie in close proximity of potassium oxide species generating basicity.