Electrochemical and UV–visible spectroscopy studies of K6As2W18 − xMoxO62 (x = 0–3) Wells–Dawson heteropolyacid catalysts for oxidative dehydrogenation of benzyl alcohol

• K6As2W18 − xMoxO62 (x = 0–3) Wells–Dawson heteropolyacids were prepared.
• Reduction potentials were measured by an electrochemical method.
• Absorption edge energies were determined by UV–visible spectroscopy.
• Vapor-phase oxidative dehydrogenation of benzyl alcohol was conducted.
• Yield for benzaldehyde increased with increasing redox properties.

Redox behaviors of molybdenum-substituted Wells–Dawson tungstoarsenate heteropolyacid catalysts (α-K6As2W18 − xMoxO62 (x = 0–3)) were probed by electrochemical and UV-visible spectroscopy measurements. Reduction potential of K6As2W18 − xMoxO62 (x = 0–3) catalysts shifted to more positive potential with increasing molybdenum content. UV–visible spectroscopy analysis was conducted as a simple diagnostic method for reduction potential. Absorption edge energy determined by UV–visible spectroscopy decreased with increasing reduction potential. Gas-phase oxidative dehydrogenation of benzyl alcohol was carried out as a model reaction. Yield for benzaldehyde increased with increasing electrochemical reduction potential and with decreasing UV–visible absorption edge energy of the catalysts.

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