New Method Unveiled for Assessing Platinum Valence State in Catalysts

A recent study published in Spectrochimica Acta Part B: Atomic Spectroscopy details a novel method for determining the platinum valence state in alumina-based catalysts (1). The study, led by Victor M. Chubarov of the Vinogradov Institute of Geochemistry, helps advance and improve catalyst performance, which is an essential process in modern oil refining.

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The research team, comprised of scientists from the Vinogradov Institute of Geochemistry, Irkutsk State University, and Irkutsk National Research Technical University, unveiled a novel approach that involved X-ray fluorescence (XRF) spectrum analysis. In their study, the team used XRF analysis to estimate the platinum valence state, which required leveraging the intensities of specific L- and M-series lines (1).

The research involved measurements of metallic platinum (Pt⁰) and potassium tetrachloroplatinate K₂[PtCl₄] (PtII) using a wavelength-dispersive spectrometer (1). By focusing on the ratios of closely spaced platinum XRF spectrum L-series lines (Lα₂/Lα₁, Lβ₂/Lβ₁, Lβ_4,6/Lβ₁), as well as examining the broadening of PtMα_1,2 line as influential parameters, the team made significant strides (1).

Once the data was collected, the team used a pseudo-Voight function to analyze the Lα₁ to Lα₂ peak amplitudes (1). The findings revealed that the Lα₁ to Lα₂ peak amplitudes for K₂[PtCl₄] stood at 0.118, while for Pt⁰, it measured 0.162 (1). The team also observed variations in the ratio of peak amplitudes in the Lβ lines. Notably, the broadening of the Mα_1,2 line showcased a substantial intensity difference (25 rel.%) between Pt⁰ and K₂[PtCl₄] at 2.044 keV (1).

The research team found out that the analytical parameters studied for the alumina-based catalysts closely mirrored values for Pt⁰ rather than those of K₂[PtCl₄] (1). This alignment strongly suggests that platinum within the examined catalysts exists in a state akin to metallic, potentially with a nuanced inclination towards the ionic state (1).

The study of the L- and M-series X-ray fluorescence spectrum of metallic platinum (Pt⁰) and potassium tetrachloroplatinate (Pt^II) demonstrated the sensitivity of Pt Lα₂ and Pt Lα₁ lines intensities ratio, as well as the broadening of the Pt Mα_1,2 line, in determining the platinum chemical state.

The methodology used in this study advances catalyst analysis. As a result, it could be used to enhancing the understanding and optimization of catalyst performance in various industrial applications.

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Reference

(1) Chubarov, V. M.; Finkelshtein, A. L.; Skornikova, S. A. Determination of Platinum Valence State in Alumina-based Catalysts by X-Ray Fluorescence Spectrometry. Spectrochimica Acta Part B. At. Spectrosc. 2023, 209, 106803. DOI: 10.1016/j.sab.2023.106803